{
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      "slug": "cats-and-feline-care",
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      "slug": "natural-remedies-and-herbs",
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      "slug": "lucid-dreaming-and-sleep",
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      "slug": "culinary-and-food-science",
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      "slug": "interactive-art-and-living-worlds",
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      "iconId": "icon-mind-blowing-demos"
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      "slug": "algorithms-and-computer-science",
      "name": "Algorithms & Computer Science",
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      "icon": "🖥️",
      "iconId": "icon-algorithms-and-computer-science"
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      "slug": "saas-and-business-killers",
      "name": "SaaS & Business Killers",
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      "icon": "💼",
      "iconId": "icon-saas-and-business-killers"
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      "slug": "survival-and-emergency-readiness",
      "name": "Survival & Emergency Readiness",
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      "icon": "🆘",
      "iconId": "icon-survival-and-emergency-readiness"
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      "slug": "aquatics-and-fishkeeping",
      "name": "Aquatics & Fishkeeping",
      "count": 10,
      "icon": "🌊",
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      "slug": "anime-and-otaku-culture",
      "name": "Anime & Otaku Culture",
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      "icon": "🔬",
      "iconId": "icon-science-and-engineering"
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      "slug": "writing-and-language",
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      "icon": "✍️",
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      "slug": "productivity-and-lifestyle",
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      "slug": "virtual-worlds-and-gaming",
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      "slug": "horror-and-paranormal",
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      "slug": "halloween",
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      "iconId": "icon-halloween"
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      "slug": "field-investigation-and-evidence",
      "name": "Field Investigation & Evidence",
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      "icon": "🗂️",
      "iconId": "icon-field-investigation-and-evidence"
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      "slug": "museum-and-collection",
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      "slug": "trucking-and-freight",
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      "slug": "fire-and-rescue-service",
      "name": "Fire & Rescue Service",
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      "iconId": "icon-fire-and-rescue-service"
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      "slug": "3d-spirograph-nebula",
      "title": "🌀 3D Spirograph Nebula",
      "description": "A true 3D spirograph: torus knots, quantum roses and harmonograph spiros woven into space with perspective, additive glow, phosphor trails, echo interference, an orbiting starfield, gesture orbit and.",
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          "unit": "",
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          "name": "sg3-sl-p",
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          "name": "sg3-sl-e",
          "type": "range",
          "label": "sl e",
          "unit": "",
          "min": 0,
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          "step": 1,
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      ],
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      },
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      "sources": [],
      "tags": [
        "spirograph",
        "nebula",
        "interactive",
        "art",
        "living",
        "worlds",
        "true",
        "torus",
        "knots",
        "quantum"
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      "featured": false,
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    },
    {
      "slug": "808-sub-bass-tuner-calculator",
      "title": "🔊 808 Sub-Bass Note Tuner & Harmonics Designer",
      "description": "An untuned 808 sub-bass creates mud, phase cancellation, and clashes with your melodic sample. Select your song's root key to find the exact fundamental frequency (Hz), room wavelength standing nod...",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/808-sub-bass-tuner-calculator.html",
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      "standaloneUrl": null,
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            "D",
            "D#",
            "E",
            "F",
            "F#",
            "G",
            "G#",
            "A",
            "A#",
            "B"
          ],
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        },
        {
          "name": "sbt-octave",
          "type": "select-one",
          "label": "Octave Register",
          "unit": "",
          "options": [
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            "2"
          ],
          "default": "1"
        },
        {
          "name": "sbt-drive",
          "type": "select-one",
          "label": "Saturation Drive",
          "unit": "",
          "options": [
            "clean",
            "warm",
            "tape",
            "drill"
          ],
          "default": "warm"
        }
      ],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "808",
        "sub",
        "bass",
        "tuner",
        "sub-bass",
        "note",
        "harmonics",
        "designer",
        "music",
        "audio"
      ],
      "popularity": 4695,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "a1c-average-glucose-converter",
      "title": "🩸 HbA1c ⇄ Average Glucose",
      "description": "Convert HbA1c (%) to estimated average glucose with the NGSP/DCCT formula (eAG mg/dL = 28.7 × A1c − 46.7). Educational only — lab methods differ (IFCC mmol/mol vs NGSP %), and this is not a diagnosis.",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/a1c-average-glucose-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=a1c-average-glucose-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "a1cg-pct",
          "type": "number",
          "label": "HbA1c %",
          "unit": "",
          "min": 4,
          "max": 15,
          "step": 0.1,
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        },
        {
          "name": "a1cg-ifcc",
          "type": "number",
          "label": "IFCC mmol/mol",
          "unit": "",
          "min": 20,
          "max": 140,
          "default": "39"
        }
      ],
      "outputs": [
        {
          "name": "a1cg-out",
          "type": "output"
        }
      ],
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        "runs": false,
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      },
      "formula": "eAG(mg/dL) = 28.7 × HbA1c(%) − 46.7 — NGSP/DCCT; eAG(mmol/L) = 1.59 × A1c − 2.59.",
      "sources": [],
      "tags": [
        "a1c",
        "average",
        "glucose",
        "converter",
        "hba1c",
        "health",
        "fitness",
        "convert",
        "estimated",
        "ngsp"
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "ab-test-significance-calculator",
      "title": "🧪 Split Test Lab",
      "description": "The two numbers every experiment platform charges you to see: is this difference real, and how long must the test run? Frequentist z-test with confidence intervals, a proper sample-size and duratio...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/ab-test-significance-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=ab-test-significance-calculator&embed=1",
      "standaloneUrl": null,
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        {
          "name": "abl-c-n",
          "type": "number",
          "label": "Control visitors",
          "unit": "",
          "min": 1,
          "default": "4200"
        },
        {
          "name": "abl-c-x",
          "type": "number",
          "label": "Control conversions",
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          "min": 0,
          "default": "126"
        },
        {
          "name": "abl-v-n",
          "type": "number",
          "label": "Variant visitors",
          "unit": "",
          "min": 1,
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        },
        {
          "name": "abl-v-x",
          "type": "number",
          "label": "Variant conversions",
          "unit": "",
          "min": 0,
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        },
        {
          "name": "abl-base",
          "type": "number",
          "label": "Baseline conversion rate",
          "unit": "%",
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          "step": 0.01,
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        },
        {
          "name": "abl-mde",
          "type": "number",
          "label": "Minimum lift to detect",
          "unit": "% relative",
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          "step": 0.5,
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        {
          "name": "abl-traffic",
          "type": "number",
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          "unit": "both arms",
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        },
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          "name": "abl-power",
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          "label": "Statistical power",
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            "0.9",
            "0.95"
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          "name": "abl-alpha",
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          "label": "Significance level",
          "unit": "α",
          "options": [
            "0.05",
            "0.01",
            "0.1"
          ],
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        }
      ],
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        {
          "name": "abl-verdict",
          "type": "live"
        },
        {
          "name": "abl-size-out",
          "type": "live"
        },
        {
          "name": "abl-bayes-out",
          "type": "live"
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        {
          "name": "abl-panel-results",
          "type": "output"
        }
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      },
      "formula": "Sample size uses the standard two-sided formula n = (z 1−α/2 √(2p̄(1−p̄)) + z power √(p₁(1−p₁)+p₂(1−p₂)))² ÷",
      "sources": [],
      "tags": [
        "test",
        "significance",
        "split",
        "lab",
        "saas",
        "business",
        "killers",
        "two",
        "numbers",
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      ],
      "popularity": 6235,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "abg-blood-gas-interpreter",
      "title": "🫁 Arterial Blood Gas Interpreter",
      "description": "pH, PaCO₂ and bicarbonate classified into the primary disorder with the expected compensation checked against Winter's formula, plus A-a gradient, P/F ratio and respiratory failure typing. kPa or m...",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/abg-blood-gas-interpreter.html",
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      "standaloneUrl": null,
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          "type": "number",
          "label": "pH",
          "unit": "",
          "min": 6.5,
          "max": 7.9,
          "default": "7.25"
        },
        {
          "name": "abgx-co2",
          "type": "number",
          "label": "PaCO₂",
          "unit": "",
          "min": 0,
          "default": "3.2"
        },
        {
          "name": "abgx-hco3",
          "type": "number",
          "label": "HCO₃⁻",
          "unit": "mmol/L",
          "min": 0,
          "default": "12"
        },
        {
          "name": "abgx-po2",
          "type": "number",
          "label": "PaO₂",
          "unit": "",
          "min": 0,
          "default": "12"
        },
        {
          "name": "abgx-fio2",
          "type": "number",
          "label": "FiO₂",
          "unit": "%",
          "min": 21,
          "max": 100,
          "default": "21"
        },
        {
          "name": "abgx-age",
          "type": "number",
          "label": "Age",
          "unit": "years",
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          "max": 120,
          "step": 1,
          "default": "40"
        },
        {
          "name": "abgx-unit",
          "type": "select-one",
          "label": "Gas unit",
          "unit": "",
          "options": [
            "kpa",
            "mmhg"
          ],
          "default": "kpa"
        },
        {
          "name": "abgx-chronic",
          "type": "select-one",
          "label": "If respiratory, is it…",
          "unit": "",
          "options": [
            "acute",
            "chronic"
          ],
          "default": "acute"
        }
      ],
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        {
          "name": "abgx-out",
          "type": "live"
        }
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      },
      "formula": "Metabolic acidosis: Winter's formula, expected PaCO₂ = 1.5 × HCO₃⁻ +",
      "sources": [],
      "tags": [
        "abg",
        "blood",
        "gas",
        "interpreter",
        "arterial",
        "health",
        "fitness",
        "paco",
        "bicarbonate",
        "classified"
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "abv-proof-dilution-calculator",
      "title": "🥃 ABV, Proof & Dilution",
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        {
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        {
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        {
          "name": "abvd-target",
          "type": "number",
          "label": "Target ABV %",
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      "sources": [],
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        "abv",
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        "culinary",
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      "slug": "accessible-text-prep",
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            "dyslexia",
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      "sources": [],
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        "accessible",
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    {
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      "standaloneUrl": null,
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      ],
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        {
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      "sources": [],
      "tags": [
        "account",
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        "productivity",
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        "get",
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      "popularity": 6418,
      "featured": false,
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      "sources": [],
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        "acoustic",
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      "featured": false,
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    },
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      "slug": "acres-hectares-sqm-converter",
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      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/acres-hectares-sqm-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=acres-hectares-sqm-converter&embed=1",
      "standaloneUrl": null,
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        {
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        {
          "name": "acre-m",
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        },
        {
          "name": "acre-ft",
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      ],
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        {
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        "hectares",
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      "featured": false,
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=acupressure-somatic-point-map&embed=1",
      "standaloneUrl": null,
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        {
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            "li4",
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      "tags": [
        "acupressure",
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      "featured": false,
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      "slug": "adaptogen-matcher-matrix",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=adaptogen-matcher-matrix&embed=1",
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            "tired_wired",
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            "immune_depleted",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=adaptogen-matcher-matrix&<id>=<value>",
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      "tags": [
        "adaptogen",
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      "featured": false,
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      "category": "wellbeing-and-community",
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        {
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        {
          "name": "atla-stuck",
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          "unit": ""
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        {
          "name": "atla-beep",
          "type": "checkbox",
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        },
        {
          "name": "atla-cat",
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            "Household",
            "Admin",
            "Work",
            "Errand",
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            "Getting ready"
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          "default": "Household"
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      ],
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        {
          "name": "atla-clock",
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      ],
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      "slug": "adhesive-selector",
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      "category": "home-and-diy",
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          "name": "adh-load",
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          "options": [
            "light",
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            "structural"
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      ],
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        {
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        "adhesive",
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      "featured": false,
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    {
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      },
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        "adulting",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "age-calculator",
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        },
        {
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      ],
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      "featured": true,
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      "slug": "ai-advanced-rag-playground",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "ai-agent-orchestrator",
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      "category": "ai-and-autonomous-agents",
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        "agents",
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          "name": "at-bmr-weight",
          "type": "number",
          "label": "Weight",
          "unit": "kg"
        },
        {
          "name": "at-bmr-height",
          "type": "number",
          "label": "Height",
          "unit": "cm"
        },
        {
          "name": "at-bmr-age",
          "type": "number",
          "label": "Age",
          "unit": "years"
        },
        {
          "name": "at-blood-weight",
          "type": "number",
          "label": "Weight",
          "unit": "kg"
        },
        {
          "name": "at-facts-toggle",
          "type": "checkbox",
          "label": "Show Amazing Body Facts",
          "unit": "",
          "default": "1"
        },
        {
          "name": "at-bmr-sex",
          "type": "select-one",
          "label": "Sex",
          "unit": "",
          "options": [
            "male",
            "female"
          ],
          "default": "male"
        }
      ],
      "outputs": [
        {
          "name": "at-results",
          "type": "output"
        },
        {
          "name": "at-result-display",
          "type": "output"
        },
        {
          "name": "at-single-fact-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=anatomy&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=anatomy&at-facts-toggle=1&at-bmr-sex=male&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "anatomy",
        "tools",
        "facts",
        "science",
        "engineering",
        "body",
        "mass",
        "index"
      ],
      "popularity": 4085,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "ancient-egypt-quiz",
      "title": "🐫 Ancient Egypt Quiz",
      "description": "Test your knowledge of ancient Egypt — pharaohs, pyramids, gods and everyday life — in ten-question rounds with streaks.",
      "category": "museum-and-collection",
      "categoryName": "Museum & Collection",
      "url": "https://www.themostusefulsiteintheworld.com/tool/ancient-egypt-quiz.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=ancient-egypt-quiz&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [
        {
          "name": "aeq-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=ancient-egypt-quiz&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "ancient",
        "egypt",
        "quiz",
        "museum",
        "collection",
        "test",
        "knowledge",
        "pharaohs",
        "pyramids",
        "gods"
      ],
      "popularity": 6812,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "anime-binge-watch-calculator",
      "title": "⏱️ Anime Binge Calculator",
      "description": "Calculate the exact time required to binge any anime series. Account for OP/ED skipping, filler elimination, playback speeds ($1.0\\times - 2.0\\times$), and view your estimated completion date.",
      "category": "anime-and-otaku-culture",
      "categoryName": "Anime & Otaku Culture",
      "url": "https://www.themostusefulsiteintheworld.com/tool/anime-binge-watch-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-binge-watch-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ab-total-eps",
          "type": "number",
          "label": "Total Episodes",
          "unit": "",
          "min": 1,
          "max": 5000,
          "step": 1,
          "default": "1110"
        },
        {
          "name": "ab-current-ep",
          "type": "number",
          "label": "Current Episode",
          "unit": "",
          "min": 0,
          "max": 5000,
          "step": 1,
          "default": "1"
        },
        {
          "name": "ab-skip-fillers",
          "type": "checkbox",
          "label": "Skip All Filler Episodes ( 122 filler eps )",
          "unit": "",
          "default": "1"
        },
        {
          "name": "ab-preset-select",
          "type": "select-one",
          "label": "Popular Series Preset",
          "unit": "",
          "options": [
            "custom",
            "one_piece",
            "naruto_shippuden",
            "naruto_original",
            "bleach",
            "hxh",
            "aot",
            "fmab",
            "jojo",
            "jujutsu",
            "demon_slayer",
            "death_note"
          ],
          "default": "one_piece"
        },
        {
          "name": "ab-skip-mode",
          "type": "select-one",
          "label": "Watch Style",
          "unit": "",
          "options": [
            "23.5",
            "19.5",
            "18.0"
          ],
          "default": "19.5"
        },
        {
          "name": "ab-speed",
          "type": "select-one",
          "label": "Playback Speed",
          "unit": "",
          "options": [
            "1.0",
            "1.1",
            "1.25",
            "1.5"
          ],
          "default": "1.0"
        },
        {
          "name": "ab-pace",
          "type": "select-one",
          "label": "Daily Viewing Pace",
          "unit": "",
          "options": [
            "1",
            "3",
            "5",
            "10",
            "20"
          ],
          "default": "3"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-binge-watch-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-binge-watch-calculator&ab-total-eps=1110&ab-current-ep=1&ab-skip-fillers=1&ab-preset-select=one_piece&ab-skip-mode=19.5&ab-speed=1.0"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "anime",
        "binge",
        "watch",
        "otaku",
        "culture",
        "calculate",
        "exact",
        "time",
        "required",
        "any"
      ],
      "popularity": 6735,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "anime-character-archetype-matrix",
      "title": "👑 Anime Character Archetypes",
      "description": "Explore the psychological Dere spectrum of anime character archetypes. Inspect behavioral triggers, iconic representatives, and take the 4-question archetype diagnostic quiz.",
      "category": "anime-and-otaku-culture",
      "categoryName": "Anime & Otaku Culture",
      "url": "https://www.themostusefulsiteintheworld.com/tool/anime-character-archetype-matrix.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-character-archetype-matrix&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [
        {
          "name": "dm-quiz-result",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-character-archetype-matrix&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "anime",
        "character",
        "archetype",
        "matrix",
        "archetypes",
        "otaku",
        "culture",
        "explore",
        "psychological",
        "dere"
      ],
      "popularity": 4846,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "anime-convention-budget-planner",
      "title": "🎪 Anime Con Budget Planner",
      "description": "Plan your anime convention expedition (Anime Expo, Otakon, Anime NYC, MCM). Split hotel costs across roommates, budget Artist Alley prints and scale figures, and enforce the golden 5-2-1 survival r...",
      "category": "anime-and-otaku-culture",
      "categoryName": "Anime & Otaku Culture",
      "url": "https://www.themostusefulsiteintheworld.com/tool/anime-convention-budget-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-convention-budget-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cp-badge-cost",
          "type": "number",
          "label": "Convention Badge",
          "unit": "",
          "min": 0,
          "max": 2000,
          "step": 5,
          "default": "145"
        },
        {
          "name": "cp-hotel-night",
          "type": "number",
          "label": "Hotel / Night",
          "unit": "",
          "min": 0,
          "max": 2000,
          "step": 10,
          "default": "260"
        },
        {
          "name": "cp-nights",
          "type": "number",
          "label": "Nights Stayed",
          "unit": "",
          "min": 1,
          "max": 10,
          "step": 1,
          "default": "3"
        },
        {
          "name": "cp-roommates",
          "type": "number",
          "label": "Roommate Count",
          "unit": "",
          "min": 1,
          "max": 12,
          "step": 1,
          "default": "4"
        },
        {
          "name": "cp-artist-alley",
          "type": "number",
          "label": "Artist Alley & Figures",
          "unit": "",
          "min": 0,
          "max": 5000,
          "step": 10,
          "default": "180"
        },
        {
          "name": "cp-food-daily",
          "type": "number",
          "label": "Food & Drinks / Day",
          "unit": "",
          "min": 10,
          "max": 200,
          "step": 5,
          "default": "35"
        },
        {
          "name": "cp-travel",
          "type": "number",
          "label": "Travel & Transit",
          "unit": "",
          "min": 0,
          "max": 2000,
          "step": 10,
          "default": "80"
        },
        {
          "name": "cp-cosplay-repair",
          "type": "number",
          "label": "Emergency Cosplay Kit",
          "unit": "",
          "min": 0,
          "max": 200,
          "step": 5,
          "default": "25"
        }
      ],
      "outputs": [
        {
          "name": "cp-res-hotel-total",
          "type": "output"
        },
        {
          "name": "cp-res-food-total",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-convention-budget-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-convention-budget-planner&cp-badge-cost=145&cp-hotel-night=260&cp-nights=3&cp-roommates=4&cp-artist-alley=180&cp-food-daily=35"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "anime",
        "convention",
        "budget",
        "planner",
        "con",
        "otaku",
        "culture",
        "plan",
        "expedition",
        "expo"
      ],
      "popularity": 5829,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "anime-cosplay-prop-scaler",
      "title": "🗡️ Cosplay Prop Scaler",
      "description": "Scale anime weapons and props proportionally to your exact real-world body height. Calculate blade length, hilt dimensions, EVA foam sheet requirements, and convention-legal weight estimates.",
      "category": "anime-and-otaku-culture",
      "categoryName": "Anime & Otaku Culture",
      "url": "https://www.themostusefulsiteintheworld.com/tool/anime-cosplay-prop-scaler.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-cosplay-prop-scaler&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cc-user-height",
          "type": "number",
          "label": "Your Real Height",
          "unit": "",
          "min": 120,
          "max": 230,
          "step": 1,
          "default": "175"
        },
        {
          "name": "cc-canon-height",
          "type": "number",
          "label": "Character Canon Height",
          "unit": "",
          "min": 100,
          "max": 250,
          "step": 1,
          "default": "173"
        },
        {
          "name": "cc-canon-prop-len",
          "type": "number",
          "label": "Canon Prop Length",
          "unit": "",
          "min": 20,
          "max": 350,
          "step": 1,
          "default": "185"
        },
        {
          "name": "cc-weapon-preset",
          "type": "select-one",
          "label": "Iconic Anime Weapon Preset",
          "unit": "",
          "options": [
            "buster_sword",
            "dragonslayer",
            "nichirin",
            "scissor_blade",
            "elucidator",
            "moon_stick",
            "custom"
          ],
          "default": "buster_sword"
        },
        {
          "name": "cc-foam-density",
          "type": "select-one",
          "label": "Core Material",
          "unit": "",
          "options": [
            "45",
            "75",
            "15",
            "600"
          ],
          "default": "45"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-cosplay-prop-scaler&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-cosplay-prop-scaler&cc-user-height=175&cc-canon-height=173&cc-canon-prop-len=185&cc-weapon-preset=buster_sword&cc-foam-density=45"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "anime",
        "cosplay",
        "prop",
        "scaler",
        "otaku",
        "culture",
        "scale",
        "weapons",
        "props",
        "proportionally"
      ],
      "popularity": 5097,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "anime-filler-canon-guide",
      "title": "📜 Anime Filler Guide",
      "description": "Distinguish manga canon, anime canon, and skippable studio filler arcs across major long-running anime. Search any episode number or generate a streamlined, filler-free binge list.",
      "category": "anime-and-otaku-culture",
      "categoryName": "Anime & Otaku Culture",
      "url": "https://www.themostusefulsiteintheworld.com/tool/anime-filler-canon-guide.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-filler-canon-guide&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "af-search-ep",
          "type": "number",
          "label": "Check Episode #",
          "unit": "",
          "min": 1,
          "max": 2000
        },
        {
          "name": "af-series-select",
          "type": "select-one",
          "label": "Select Anime Series",
          "unit": "",
          "options": [
            "naruto_shippuden",
            "naruto",
            "bleach",
            "one_piece",
            "dbz",
            "hxh",
            "fairy_tail",
            "boruto"
          ],
          "default": "naruto_shippuden"
        }
      ],
      "outputs": [
        {
          "name": "af-check-result",
          "type": "output"
        },
        {
          "name": "af-res-total",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-filler-canon-guide&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-filler-canon-guide&af-series-select=naruto_shippuden"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "anime",
        "filler",
        "canon",
        "guide",
        "otaku",
        "culture",
        "distinguish",
        "manga",
        "skippable",
        "studio"
      ],
      "popularity": 4422,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "anime-japanese-phrases-tropes",
      "title": "🎌 Anime Phrases & Tropes",
      "description": "Decode iconic anime verbal tics (*dattebayo*, *de gozaru*, *nya*), battle cries (*omae wa mou shindeiru*), and dialogue tropes with native Japanese audio pronunciation.",
      "category": "anime-and-otaku-culture",
      "categoryName": "Anime & Otaku Culture",
      "url": "https://www.themostusefulsiteintheworld.com/tool/anime-japanese-phrases-tropes.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-japanese-phrases-tropes&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "aj-search-input",
          "type": "text",
          "label": "Search phrase or meaning (e.g. yare yare, baka, nani)...",
          "unit": ""
        },
        {
          "name": "aj-category-filter",
          "type": "select-one",
          "label": "category filter",
          "unit": "",
          "options": [
            "all",
            "catchphrase",
            "verbal_tic",
            "battle",
            "archetype"
          ],
          "default": "all"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-japanese-phrases-tropes&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-japanese-phrases-tropes&aj-category-filter=all"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "anime",
        "japanese",
        "phrases",
        "tropes",
        "otaku",
        "culture",
        "decode",
        "iconic",
        "verbal",
        "tics"
      ],
      "popularity": 4163,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "anime-oped-music-analyzer",
      "title": "🎵 Anime Music BPM Analyzer",
      "description": "Analyze the rhythmic energy of iconic Anime Openings and Endings. Explore the legendary Japanese TV 89-second broadcast rule, tap along with the real-time BPM tapper, and audition metronome tempos.",
      "category": "anime-and-otaku-culture",
      "categoryName": "Anime & Otaku Culture",
      "url": "https://www.themostusefulsiteintheworld.com/tool/anime-oped-music-analyzer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-oped-music-analyzer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "abm-song-select",
          "type": "select-one",
          "label": "Iconic Anisong Preset",
          "unit": "",
          "options": [
            "idol",
            "gurenge",
            "kickback",
            "blingbang",
            "silhouette",
            "unravel",
            "cruel_angel",
            "rumbling",
            "blue_bird",
            "haruka_kanata"
          ],
          "default": "idol"
        }
      ],
      "outputs": [
        {
          "name": "abm-bpm-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-oped-music-analyzer&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-oped-music-analyzer&abm-song-select=idol"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "anime",
        "oped",
        "music",
        "analyzer",
        "bpm",
        "otaku",
        "culture",
        "analyze",
        "rhythmic",
        "energy"
      ],
      "popularity": 6902,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "anime-recommendation-mood-engine",
      "title": "🔮 Anime Mood Matcher",
      "description": "Find the perfect anime tailored to your exact emotional state and available time. Filter by desired mood (cathartic tears, adrenaline hype, psychological mind-games, or cozy healing), episode lengt...",
      "category": "anime-and-otaku-culture",
      "categoryName": "Anime & Otaku Culture",
      "url": "https://www.themostusefulsiteintheworld.com/tool/anime-recommendation-mood-engine.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-recommendation-mood-engine&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "am-mood-select",
          "type": "select-one",
          "label": "Desired Vibe / Mood",
          "unit": "",
          "options": [
            "cry",
            "hype",
            "psychological",
            "cozy",
            "worldbuilding",
            "comedy",
            "romance"
          ],
          "default": "cry"
        },
        {
          "name": "am-length-filter",
          "type": "select-one",
          "label": "Episode Commitment",
          "unit": "",
          "options": [
            "all",
            "short",
            "medium",
            "long"
          ],
          "default": "all"
        },
        {
          "name": "am-era-filter",
          "type": "select-one",
          "label": "Anime Era",
          "unit": "",
          "options": [
            "all",
            "retro",
            "modern"
          ],
          "default": "all"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-recommendation-mood-engine&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-recommendation-mood-engine&am-mood-select=cry&am-length-filter=all&am-era-filter=all"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "anime",
        "recommendation",
        "mood",
        "engine",
        "matcher",
        "otaku",
        "culture",
        "find",
        "perfect",
        "tailored"
      ],
      "popularity": 5931,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "anime-release-schedule-converter",
      "title": "🕒 Anime Schedule Converter",
      "description": "Convert Tokyo Japan Standard Time (JST / UTC+9) anime broadcasts to your local timezone. Decodes Japanese TV late-night 30-hour clock conventions (e.g. 25:30 JST = 1:30 AM next day) and calculates ...",
      "category": "anime-and-otaku-culture",
      "categoryName": "Anime & Otaku Culture",
      "url": "https://www.themostusefulsiteintheworld.com/tool/anime-release-schedule-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-release-schedule-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "as-broadcast-hour",
          "type": "number",
          "label": "JST Broadcast Hour",
          "unit": "0 - 29",
          "min": 0,
          "max": 29,
          "step": 1,
          "default": "24"
        },
        {
          "name": "as-broadcast-min",
          "type": "number",
          "label": "Minute",
          "unit": "0 - 59",
          "min": 0,
          "max": 59,
          "step": 5,
          "default": "30"
        },
        {
          "name": "as-broadcast-day",
          "type": "select-one",
          "label": "Japanese Broadcast Day",
          "unit": "",
          "options": [
            "0",
            "1",
            "2",
            "3",
            "4",
            "5",
            "6"
          ],
          "default": "5"
        },
        {
          "name": "as-simulcast-delay",
          "type": "select-one",
          "label": "Streaming Sub Delay",
          "unit": "",
          "options": [
            "0",
            "60",
            "90",
            "120"
          ],
          "default": "60"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-release-schedule-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=anime-release-schedule-converter&as-broadcast-hour=24&as-broadcast-min=30&as-broadcast-day=5&as-simulcast-delay=60"
      },
      "formula": "JST Broadcast Hour (0 - 29) 24:00 = 00:00, 25:30 = 01:30 AM Minute (0 -",
      "sources": [],
      "tags": [
        "anime",
        "release",
        "schedule",
        "converter",
        "otaku",
        "culture",
        "convert",
        "tokyo",
        "japan",
        "standard"
      ],
      "popularity": 4575,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "anion-gap-electrolyte-corrector",
      "title": "🧂 Anion Gap & Corrected Electrolytes",
      "description": "Anion gap with albumin correction and delta ratio, corrected sodium for hyperglycaemia, corrected calcium for albumin, calculated osmolality with the osmolar gap, and the urine anion gap. SI or US ...",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/anion-gap-electrolyte-corrector.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=anion-gap-electrolyte-corrector&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "agap-na",
          "type": "number",
          "label": "Sodium",
          "unit": "",
          "default": "130"
        },
        {
          "name": "agap-k",
          "type": "number",
          "label": "Potassium",
          "unit": "",
          "default": "4.0"
        },
        {
          "name": "agap-cl",
          "type": "number",
          "label": "Chloride",
          "unit": "",
          "default": "100"
        },
        {
          "name": "agap-hco3",
          "type": "number",
          "label": "Bicarbonate",
          "unit": "",
          "default": "12"
        },
        {
          "name": "agap-alb",
          "type": "number",
          "label": "Albumin",
          "unit": "",
          "default": "25"
        },
        {
          "name": "agap-glu",
          "type": "number",
          "label": "Glucose",
          "unit": "",
          "default": "28"
        },
        {
          "name": "agap-urea",
          "type": "number",
          "label": "Urea",
          "unit": "",
          "default": "8"
        },
        {
          "name": "agap-ca",
          "type": "number",
          "label": "Calcium",
          "unit": "",
          "default": "2.10"
        },
        {
          "name": "agap-osm",
          "type": "number",
          "label": "Measured osmolality",
          "unit": ""
        },
        {
          "name": "agap-una",
          "type": "number",
          "label": "Urine Na",
          "unit": ""
        },
        {
          "name": "agap-unk",
          "type": "number",
          "label": "Urine K",
          "unit": ""
        },
        {
          "name": "agap-uncl",
          "type": "number",
          "label": "Urine Cl",
          "unit": ""
        },
        {
          "name": "agap-refag",
          "type": "number",
          "label": "Lab midpoint anion gap",
          "unit": "",
          "default": "12"
        },
        {
          "name": "agap-units",
          "type": "select-one",
          "label": "Units",
          "unit": "",
          "options": [
            "si",
            "us"
          ],
          "default": "si"
        }
      ],
      "outputs": [
        {
          "name": "agap-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=anion-gap-electrolyte-corrector&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=anion-gap-electrolyte-corrector&agap-na=130&agap-k=4.0&agap-cl=100&agap-hco3=12&agap-alb=25&agap-glu=28"
      },
      "formula": "Anion gap. AG = Na⁺ − (Cl⁻ + HCO₃⁻). Including potassium, (Na⁺ + K⁺) − (Cl⁻ +",
      "sources": [],
      "tags": [
        "anion",
        "gap",
        "electrolyte",
        "corrector",
        "corrected",
        "electrolytes",
        "health",
        "fitness",
        "albumin",
        "correction"
      ],
      "popularity": 4961,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "antipode-gravity-tunnel-explorer",
      "title": "🕳️ Antipode & Gravity Tunnel Explorer",
      "description": "Find the exact point on the far side of the planet from anywhere, then drill a straight frictionless tunnel to any second place and drop a capsule down it. The fall time is integrated through the r...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/antipode-gravity-tunnel-explorer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=antipode-gravity-tunnel-explorer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "agte-lat1",
          "type": "number",
          "label": "From latitude",
          "unit": "",
          "min": -90,
          "max": 90,
          "step": 0.0001,
          "default": "51.8787"
        },
        {
          "name": "agte-lon1",
          "type": "number",
          "label": "From longitude",
          "unit": "",
          "min": -180,
          "max": 180,
          "step": 0.0001,
          "default": "-0.4200"
        },
        {
          "name": "agte-lat2",
          "type": "number",
          "label": "To latitude",
          "unit": "",
          "min": -90,
          "max": 90,
          "step": 0.0001,
          "default": "-33.8688"
        },
        {
          "name": "agte-lon2",
          "type": "number",
          "label": "To longitude",
          "unit": "",
          "min": -180,
          "max": 180,
          "step": 0.0001,
          "default": "151.2093"
        },
        {
          "name": "agte-from",
          "type": "select-one",
          "label": "From",
          "unit": ""
        },
        {
          "name": "agte-to",
          "type": "select-one",
          "label": "To",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "agte-stats",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=antipode-gravity-tunnel-explorer&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=antipode-gravity-tunnel-explorer&agte-lat1=51.8787&agte-lon1=-0.4200&agte-lat2=-33.8688&agte-lon2=151.2093"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "antipode",
        "gravity",
        "tunnel",
        "explorer",
        "science",
        "engineering",
        "find",
        "exact",
        "point",
        "far"
      ],
      "popularity": 6942,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "apgar-score-calculator",
      "title": "👶 APGAR Score Calculator",
      "description": "The five components at 1, 5 and 10 minutes with the trend across all three, the resuscitation bands, and the caveats about prematurity. Held in memory only — nothing is written to this browser.",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/apgar-score-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=apgar-score-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [
        {
          "name": "apgar-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=apgar-score-calculator&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "apgar",
        "score",
        "health",
        "fitness",
        "five",
        "components",
        "minutes",
        "trend",
        "across",
        "all"
      ],
      "popularity": 4185,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "apology-builder",
      "title": "🤝 Sincere Apology Builder",
      "description": "Most apologies fail for one of four reasons: they contain “but”, they apologise for the other person’s feelings instead of your behaviour, they explain rather than own it, or they promise nothing. ...",
      "category": "wellbeing-and-community",
      "categoryName": "Wellbeing & Community",
      "url": "https://www.themostusefulsiteintheworld.com/tool/apology-builder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=apology-builder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sab-what",
          "type": "textarea",
          "label": "1. What you actually did",
          "unit": ""
        },
        {
          "name": "sab-impact",
          "type": "textarea",
          "label": "2. What it did to them",
          "unit": ""
        },
        {
          "name": "sab-change",
          "type": "textarea",
          "label": "3. What you will do differently",
          "unit": ""
        },
        {
          "name": "sab-amends",
          "type": "textarea",
          "label": "4. What would make it right",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "sab-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=apology-builder&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "apology",
        "builder",
        "sincere",
        "wellbeing",
        "community",
        "most",
        "apologies",
        "fail",
        "one",
        "four"
      ],
      "popularity": 4965,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "appliance-running-cost-calculator",
      "title": "🔌 Appliance Running Cost Calculator",
      "description": "The kettle costs pennies and the tumble dryer costs a fortune — build your house as a list, see what each appliance really costs per day, month and year, and find the ones worth changing first.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/appliance-running-cost-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=appliance-running-cost-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "aprc-rate",
          "type": "number",
          "label": "Your unit rate",
          "unit": "p/kWh",
          "min": 0,
          "step": 0.1,
          "default": "25"
        },
        {
          "name": "aprc-watts",
          "type": "number",
          "label": "Watts",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "1500"
        },
        {
          "name": "aprc-mins",
          "type": "number",
          "label": "Minutes used per day",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "20"
        },
        {
          "name": "aprc-preset",
          "type": "select-one",
          "label": "Appliance",
          "unit": "",
          "options": [
            "custom",
            "kettle",
            "shower",
            "oven",
            "airfryer",
            "microwave",
            "hob",
            "wash",
            "dish",
            "dryer",
            "heater",
            "ev",
            "tv",
            "console",
            "pc",
            "laptop",
            "fridge",
            "router",
            "dry",
            "blanket"
          ],
          "default": "custom"
        }
      ],
      "outputs": [
        {
          "name": "aprc-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=appliance-running-cost-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=appliance-running-cost-calculator&aprc-rate=25&aprc-watts=1500&aprc-mins=20&aprc-preset=custom"
      },
      "formula": "Method. Cost = watts ÷ 1000 × hours used ×",
      "sources": [],
      "tags": [
        "appliance",
        "running",
        "cost",
        "finance",
        "money",
        "kettle",
        "costs",
        "pennies",
        "tumble",
        "dryer"
      ],
      "popularity": 5556,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "apr-apy-converter",
      "title": "🏦 APR ⇄ APY Converter",
      "description": "APY = (1 + APR/n)n − 1, where n is compounds per year. APR is the quoted nominal rate; APY (EAR in the UK) is what you actually earn or pay after compounding. Savings ads in Britain must show AER.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/apr-apy-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=apr-apy-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "apyx-apr",
          "type": "number",
          "label": "APR / nominal %",
          "unit": "",
          "default": "5"
        },
        {
          "name": "apyx-apy",
          "type": "number",
          "label": "APY / AER %",
          "unit": "",
          "default": "5.12"
        },
        {
          "name": "apyx-n",
          "type": "select-one",
          "label": "Compounds / year",
          "unit": "",
          "options": [
            "1",
            "2",
            "4",
            "12",
            "365"
          ],
          "default": "12"
        }
      ],
      "outputs": [
        {
          "name": "apyx-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=apr-apy-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=apr-apy-converter&apyx-apr=5&apyx-apy=5.12&apyx-n=12"
      },
      "formula": "APR ⇄ APY Converter APY = (1 + APR/",
      "sources": [],
      "tags": [
        "apr",
        "apy",
        "converter",
        "finance",
        "money",
        "where",
        "compounds",
        "per",
        "year",
        "quoted"
      ],
      "popularity": 4645,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "aquarium-co2-drop-checker-calculator",
      "title": "🫧 Aquarium CO₂ Calculator",
      "description": "Dial in high-tech planted tank CO₂ injection. Calculate dissolved CO₂ concentration (ppm) from pH/KH equilibrium, simulate 4 dKH drop checker reagent colors, and estimate cylinder gas lifespan.",
      "category": "aquatics-and-fishkeeping",
      "categoryName": "Aquatics & Fishkeeping",
      "url": "https://www.themostusefulsiteintheworld.com/tool/aquarium-co2-drop-checker-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=aquarium-co2-drop-checker-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ac2-kh",
          "type": "number",
          "label": "Carbonate Hardness",
          "unit": "dKH",
          "min": 0.5,
          "max": 25,
          "step": 0.5,
          "default": "4.0"
        },
        {
          "name": "ac2-ph-on",
          "type": "number",
          "label": "CO₂ Injected Peak pH",
          "unit": "",
          "min": 5,
          "max": 8.5,
          "step": 0.05,
          "default": "6.6"
        },
        {
          "name": "ac2-ph-off",
          "type": "number",
          "label": "Degassed Base pH",
          "unit": "CO₂ Off",
          "min": 5,
          "max": 9,
          "step": 0.05,
          "default": "7.6"
        },
        {
          "name": "ac2-bps",
          "type": "number",
          "label": "Bubble Rate",
          "unit": "BPS",
          "min": 0.5,
          "max": 15,
          "step": 0.5,
          "default": "2.5"
        },
        {
          "name": "ac2-solenoid-hours",
          "type": "number",
          "label": "Solenoid Timer",
          "unit": "hrs/day",
          "min": 2,
          "max": 24,
          "step": 0.5,
          "default": "7.0"
        },
        {
          "name": "ac2-method",
          "type": "select-one",
          "label": "Diffuser Type",
          "unit": "",
          "options": [
            "in_tank",
            "inline",
            "reactor"
          ],
          "default": "in_tank"
        },
        {
          "name": "ac2-cyl-size",
          "type": "select-one",
          "label": "Cylinder Size",
          "unit": "",
          "options": [
            "567",
            "2000",
            "2268",
            "4536"
          ],
          "default": "2268"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=aquarium-co2-drop-checker-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=aquarium-co2-drop-checker-calculator&ac2-kh=4.0&ac2-ph-on=6.6&ac2-ph-off=7.6&ac2-bps=2.5&ac2-solenoid-hours=7.0&ac2-method=in_tank"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "aquarium",
        "co2",
        "drop",
        "checker",
        "aquatics",
        "fishkeeping",
        "dial",
        "high-tech",
        "planted",
        "tank"
      ],
      "popularity": 6865,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "aquarium-feeding-vacation-planner",
      "title": "🍤 Fish Feeding & Vacation Planner",
      "description": "Generate weekly nutrition schedules with gut-clearing fast days. Calculate safe vacation fasting limits, prevent the catastrophic \"neighbor overfeeding\" disaster, and generate foolproof pet-sitter ...",
      "category": "aquatics-and-fishkeeping",
      "categoryName": "Aquatics & Fishkeeping",
      "url": "https://www.themostusefulsiteintheworld.com/tool/aquarium-feeding-vacation-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=aquarium-feeding-vacation-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ad-days-away",
          "type": "number",
          "label": "Vacation Duration",
          "unit": "Days Away",
          "min": 1,
          "max": 30,
          "step": 1,
          "default": "7"
        },
        {
          "name": "ad-livestock-type",
          "type": "select-one",
          "label": "Livestock Profile",
          "unit": "",
          "options": [
            "community",
            "betta",
            "bottom",
            "cichlids",
            "discus",
            "axolotl"
          ],
          "default": "community"
        },
        {
          "name": "ad-planted",
          "type": "select-one",
          "label": "Live Plants & Microfauna",
          "unit": "",
          "options": [
            "dense",
            "mod",
            "bare"
          ],
          "default": "dense"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=aquarium-feeding-vacation-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=aquarium-feeding-vacation-planner&ad-days-away=7&ad-livestock-type=community&ad-planted=dense"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "aquarium",
        "feeding",
        "vacation",
        "planner",
        "fish",
        "aquatics",
        "fishkeeping",
        "generate",
        "weekly",
        "nutrition"
      ],
      "popularity": 4397,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "aquarium-heater-chiller-calculator",
      "title": "🌡️ Aquarium Heater & Chiller",
      "description": "Calculate precision heating wattage, evaporative surface loss, and cooling chiller ratings. Eliminates the catastrophic \"stuck heater\" disaster using fail-safe dual heater redundancy math.",
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        {
          "name": "at-room-cold",
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          "max": 95,
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        {
          "name": "at-room-hot",
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          "max": 110,
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        },
        {
          "name": "at-species",
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            "community",
            "betta",
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            "axolotl",
            "reef",
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        },
        {
          "name": "at-units",
          "type": "select-one",
          "label": "Units",
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          "options": [
            "f",
            "c"
          ],
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        },
        {
          "name": "at-lid",
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          "label": "Aquarium Top / Lid",
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            "lid",
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      },
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        "aquarium",
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        "chiller",
        "aquatics",
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        "heating",
        "wattage",
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      "featured": false,
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    },
    {
      "slug": "aquarium-lighting-par-calculator",
      "title": "💡 Aquarium PAR Lighting",
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      "category": "aquatics-and-fishkeeping",
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          "step": 1,
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        {
          "name": "al-hours",
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          "step": 0.5,
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        {
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            "sps_reef"
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        {
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        {
          "name": "al-dimming",
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          "label": "App Dimmer Setting",
          "unit": "",
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            "1.0",
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            "0.6",
            "0.4"
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        {
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          "options": [
            "1",
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          ],
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      ],
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        {
          "name": "al-schedule-display",
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      "featured": false,
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    },
    {
      "slug": "aquarium-medication-dosing-calculator",
      "title": "💊 Fish Medication Dosing",
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        {
          "name": "am-disease-select",
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            "ich",
            "velvet",
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            "columnaris",
            "finrot",
            "hexamita",
            "flukes"
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        },
        {
          "name": "am-units",
          "type": "select-one",
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          "unit": "",
          "options": [
            "gal",
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          ],
          "default": "gal"
        },
        {
          "name": "am-scaleless",
          "type": "select-one",
          "label": "Scaleless Fish Present?",
          "unit": "",
          "options": [
            "no",
            "yes"
          ],
          "default": "no"
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      ],
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      },
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        "aquarium",
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        "dosing",
        "fish",
        "aquatics",
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        "symptom",
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      ],
      "popularity": 4575,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "aquarium-nitrogen-cycle-tracker",
      "title": "🔄 Nitrogen Cycle Tracker",
      "description": "Master the nitrogen cycle without harming livestock. Calculate exact pure ammonia dosing, simulate bacterial colonisation curves (Nitrosomonas & Nitrospira), and validate your 24-hour clearance test.",
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      "categoryName": "Aquatics & Fishkeeping",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=aquarium-nitrogen-cycle-tracker&embed=1",
      "standaloneUrl": null,
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        },
        {
          "name": "ac-day-slider",
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        },
        {
          "name": "ac-test-nh3",
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          "label": "Ammonia 24h",
          "unit": "ppm",
          "min": 0,
          "max": 10,
          "step": 0.25,
          "default": "0.0"
        },
        {
          "name": "ac-test-no2",
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          "label": "Nitrite 24h",
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          "min": 0,
          "max": 10,
          "step": 0.25,
          "default": "0.0"
        },
        {
          "name": "ac-units",
          "type": "select-one",
          "label": "Volume Unit",
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          "options": [
            "gal",
            "l"
          ],
          "default": "gal"
        },
        {
          "name": "ac-target-nh3",
          "type": "select-one",
          "label": "Target Ammonia",
          "unit": "",
          "options": [
            "2.0",
            "3.0",
            "4.0"
          ],
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        },
        {
          "name": "ac-source",
          "type": "select-one",
          "label": "Ammonia Source",
          "unit": "",
          "options": [
            "drtims",
            "fritz",
            "household10"
          ],
          "default": "drtims"
        },
        {
          "name": "ac-bacteria",
          "type": "select-one",
          "label": "Bacteria Starter",
          "unit": "",
          "options": [
            "none",
            "bottled",
            "seeded"
          ],
          "default": "bottled"
        },
        {
          "name": "ac-temp",
          "type": "select-one",
          "label": "Cycle Water Temp",
          "unit": "",
          "options": [
            "opt",
            "cool",
            "cold"
          ],
          "default": "opt"
        },
        {
          "name": "ac-ph",
          "type": "select-one",
          "label": "Tank pH",
          "unit": "",
          "options": [
            "normal",
            "acidic",
            "crash"
          ],
          "default": "normal"
        }
      ],
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        {
          "name": "ac-dose-result",
          "type": "output"
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
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        "aquarium",
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      ],
      "popularity": 4720,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "aquarium-stocking-compatibility-calculator",
      "title": "🐠 Fish Stocking Compatibility",
      "description": "Build your community aquarium roster. Calculates true metabolic bioload, swimming strata distribution (top, mid, bottom), temperature and pH overlap, and flags aggression and schooling warnings.",
      "category": "aquatics-and-fishkeeping",
      "categoryName": "Aquatics & Fishkeeping",
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      "standaloneUrl": null,
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        {
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          "label": "Tank Size",
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        {
          "name": "as-filter-tier",
          "type": "select-one",
          "label": "Filtration Capacity",
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          "options": [
            "0.8",
            "1.0",
            "1.3",
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        {
          "name": "as-species-add",
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          "label": "Add Species",
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            "harlequin",
            "guppy",
            "platy",
            "betta",
            "cory",
            "pleco",
            "oto",
            "angel",
            "ram",
            "discus",
            "cherry",
            "amano",
            "snail",
            "goldfish",
            "axolotl"
          ],
          "default": "neon"
        }
      ],
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        "aquarium",
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        "aquatics",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "aquarium-substrate-hardscape-calculator",
      "title": "🪨 Aquarium Substrate Estimator",
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      "categoryName": "Aquatics & Fishkeeping",
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      "inputs": [
        {
          "name": "as2-len",
          "type": "number",
          "label": "Tank Length",
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          "min": 6,
          "max": 200,
          "step": 0.5,
          "default": "36"
        },
        {
          "name": "as2-wid",
          "type": "number",
          "label": "Tank Width / Depth",
          "unit": "in",
          "min": 6,
          "max": 200,
          "step": 0.5,
          "default": "18"
        },
        {
          "name": "as2-front-depth",
          "type": "number",
          "label": "Front Glass Depth",
          "unit": "in",
          "min": 0.5,
          "max": 10,
          "step": 0.25,
          "default": "1.5"
        },
        {
          "name": "as2-back-depth",
          "type": "number",
          "label": "Rear Wall Depth",
          "unit": "in",
          "min": 0.5,
          "max": 15,
          "step": 0.25,
          "default": "3.5"
        },
        {
          "name": "as2-units",
          "type": "select-one",
          "label": "Units",
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          "options": [
            "in",
            "cm"
          ],
          "default": "in"
        },
        {
          "name": "as2-profile",
          "type": "select-one",
          "label": "Layout Profile",
          "unit": "",
          "options": [
            "sloped",
            "flat",
            "walstad"
          ],
          "default": "sloped"
        },
        {
          "name": "as2-sub-type",
          "type": "select-one",
          "label": "Primary Substrate Type",
          "unit": "",
          "options": [
            "soil",
            "sand",
            "gravel"
          ],
          "default": "soil"
        },
        {
          "name": "as2-scape-style",
          "type": "select-one",
          "label": "scape style",
          "unit": "",
          "options": [
            "iwagumi",
            "nature",
            "cichlid",
            "minimal"
          ],
          "default": "iwagumi"
        }
      ],
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      "prefill": {
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
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        "aquarium",
        "substrate",
        "hardscape",
        "estimator",
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        "fishkeeping",
        "plan",
        "planted",
        "tank",
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      ],
      "popularity": 5274,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "aquarium-volume-weight-calculator",
      "title": "🌊 Aquarium Volume & Weight",
      "description": "Calculate gross and true net water volume, accounting for glass thickness, top water margin, substrate, and hardscape displacement. Computes total filled weight and structural floor joist loading.",
      "category": "aquatics-and-fishkeeping",
      "categoryName": "Aquatics & Fishkeeping",
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          "max": 200,
          "step": 0.5,
          "default": "30"
        },
        {
          "name": "av-wid",
          "type": "number",
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          "min": 4,
          "max": 200,
          "step": 0.5,
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        },
        {
          "name": "av-hgt",
          "type": "number",
          "label": "Height",
          "unit": "in",
          "min": 4,
          "max": 200,
          "step": 0.5,
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        },
        {
          "name": "av-margin",
          "type": "number",
          "label": "Waterline Gap",
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          "max": 6,
          "step": 0.25,
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        {
          "name": "av-sub-depth",
          "type": "number",
          "label": "Substrate Bed Depth",
          "unit": "in",
          "min": 0,
          "max": 10,
          "step": 0.25,
          "default": "1.5"
        },
        {
          "name": "av-preset",
          "type": "select-one",
          "label": "Tank Preset",
          "unit": "",
          "options": [
            "custom",
            "5g",
            "10g",
            "20l",
            "29g",
            "40b",
            "55g",
            "75g",
            "120g",
            "ada60p",
            "ada90p",
            "wb20c"
          ],
          "default": "20l"
        },
        {
          "name": "av-units",
          "type": "select-one",
          "label": "Measurement Units",
          "unit": "",
          "options": [
            "in",
            "cm"
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          "default": "in"
        },
        {
          "name": "av-water-type",
          "type": "select-one",
          "label": "Water Type",
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            "1.000",
            "1.010",
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          ],
          "default": "1.000"
        },
        {
          "name": "av-glass-thick",
          "type": "select-one",
          "label": "Glass / Acrylic Thickness",
          "unit": "",
          "options": [
            "6",
            "8",
            "10",
            "12",
            "15",
            "19"
          ],
          "default": "6"
        },
        {
          "name": "av-hardscape",
          "type": "select-one",
          "label": "Hardscape Level",
          "unit": "Rock/Wood",
          "options": [
            "0.02",
            "0.07",
            "0.15",
            "0.25"
          ],
          "default": "0.07"
        }
      ],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
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        "aquarium",
        "volume",
        "weight",
        "aquatics",
        "fishkeeping",
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        "water"
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      "popularity": 6378,
      "featured": false,
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    },
    {
      "slug": "aquarium-water-change-salinity-calculator",
      "title": "🧪 Water Change & Salinity",
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      "category": "aquatics-and-fishkeeping",
      "categoryName": "Aquatics & Fishkeeping",
      "url": "https://www.themostusefulsiteintheworld.com/tool/aquarium-water-change-salinity-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=aquarium-water-change-salinity-calculator&embed=1",
      "standaloneUrl": null,
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        {
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        {
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        {
          "name": "awc-d-tap",
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        {
          "name": "awc-d-target",
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        {
          "name": "awc-ro-vol",
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          "label": "RO Water Bucket Size",
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        },
        {
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        {
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        {
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            "neocaridina",
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        {
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        {
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            "gal",
            "l"
          ],
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        },
        {
          "name": "awc-s-target",
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            "1.020",
            "1.024",
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            "1.026"
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      ],
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      },
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        "aquarium",
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        "change",
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        "fishkeeping",
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    },
    {
      "slug": "archery-score-calculator",
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      "standaloneUrl": null,
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            "72",
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            "36",
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        {
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=archery-score-calculator&<id>=<value>",
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      "featured": false,
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    },
    {
      "slug": "architectural-orders-column",
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      "description": "Vitruvius counted in modules: the lower diameter of the column. Doric is stocky, Corinthian tall and leafy, Ionic the volute in between. Enter a diameter in metres; the plaque returns shaft, capita...",
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      "categoryName": "Museum & Collection",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=architectural-orders-column&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "min": 0.1,
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        },
        {
          "name": "arch-ord",
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      ],
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      ],
      "prefill": {
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      "tags": [
        "architectural",
        "orders",
        "column",
        "bench",
        "museum",
        "collection",
        "vitruvius",
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      "popularity": 5238,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "ascii-hex-binary-text-converter",
      "title": "🔤 Text ⇄ Hex ⇄ Binary",
      "description": "Encode UTF-8 text as hex or binary, or decode hex/binary back. Spaces in hex are ignored. Binary is 8-bit groups. Nothing is sent anywhere.",
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      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/ascii-hex-binary-text-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=ascii-hex-binary-text-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "textarea",
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        {
          "name": "ahbt-bin",
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          "label": "Binary",
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      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=ascii-hex-binary-text-converter&<id>=<value>",
        "runs": false
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
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        "ascii",
        "hex",
        "binary",
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      "popularity": 6594,
      "featured": false,
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    },
    {
      "slug": "ascii-text-banner-art-generator",
      "title": "🔤 ASCII Banner Generator",
      "description": "Generate retro ASCII text banners and terminal art for code headers, GitHub READMEs, Discord bots, and CLI scripts.",
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      "categoryName": "Productivity & Lifestyle",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=ascii-text-banner-art-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
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        {
          "name": "atb-font-style",
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            "block",
            "slant",
            "shadow",
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            "framed"
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        "ascii",
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      "featured": false,
      "updated": "2026-09-19"
    },
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      "slug": "aspect-ratio-resizer",
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      "standaloneUrl": null,
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        {
          "name": "ar-height-input",
          "type": "number",
          "label": "Height",
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          "default": "1080"
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=aspect-ratio-resizer&<id>=<value>",
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      "sources": [],
      "tags": [
        "aspect",
        "ratio",
        "resizer",
        "science",
        "engineering",
        "calculate",
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      "popularity": 6607,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "astronaut-artificial-gravity-calculator",
      "title": "🌀 Astronaut Artificial Gravity Calculator",
      "description": "Explore rotating habitats and short-arm centrifuges. Calculate floor gravity, rotation period, rim speed, target RPM, head-to-foot gravity gradient and Coriolis acceleration while moving.",
      "category": "astronomy-and-space",
      "categoryName": "Astronomy & Space",
      "url": "https://www.themostusefulsiteintheworld.com/tool/astronaut-artificial-gravity-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=astronaut-artificial-gravity-calculator&embed=1",
      "standaloneUrl": null,
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          "label": "Floor radius",
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          "step": 0.1,
          "default": "100"
        },
        {
          "name": "aagc-rpm",
          "type": "number",
          "label": "Operating rotation",
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          "min": 0.001,
          "step": 0.01,
          "default": "3.00"
        },
        {
          "name": "aagc-target",
          "type": "number",
          "label": "Target floor gravity",
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          "step": 0.01,
          "default": "1.00"
        },
        {
          "name": "aagc-height",
          "type": "number",
          "label": "Crew height",
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          "min": 0,
          "step": 0.01,
          "default": "1.75"
        },
        {
          "name": "aagc-motion",
          "type": "number",
          "label": "Radial movement speed",
          "unit": "m/s",
          "min": 0,
          "step": 0.1,
          "default": "1.0"
        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=astronaut-artificial-gravity-calculator&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "astronaut",
        "artificial",
        "gravity",
        "astronomy",
        "space",
        "explore",
        "rotating",
        "habitats",
        "short-arm",
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      "popularity": 5528,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "astronaut-cabin-atmosphere-planner",
      "title": "🫧 Spacecraft Cabin Atmosphere Planner",
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      "category": "astronomy-and-space",
      "categoryName": "Astronomy & Space",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=astronaut-cabin-atmosphere-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "acap-pressure",
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          "label": "Total cabin pressure",
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          "max": 500,
          "step": 0.01,
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        },
        {
          "name": "acap-o2",
          "type": "number",
          "label": "Oxygen fraction",
          "unit": "%",
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          "max": 100,
          "step": 0.01,
          "default": "20.946"
        },
        {
          "name": "acap-co2",
          "type": "number",
          "label": "Carbon dioxide",
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          "min": 0,
          "max": 1000000,
          "step": 1,
          "default": "1000"
        },
        {
          "name": "acap-water",
          "type": "number",
          "label": "Water vapour fraction",
          "unit": "%",
          "min": 0,
          "max": 100,
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          "default": "1.50"
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      ],
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      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=astronaut-cabin-atmosphere-planner&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
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        "astronaut",
        "cabin",
        "atmosphere",
        "planner",
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      "popularity": 4543,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "astronaut-crew-consumables-planner",
      "title": "📦 Astronaut Crew Consumables Planner",
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      "category": "astronomy-and-space",
      "categoryName": "Astronomy & Space",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=astronaut-crew-consumables-planner&embed=1",
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          "max": 100,
          "step": 1,
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        {
          "name": "acmp-days",
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          "max": 10000,
          "step": 0.1,
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        },
        {
          "name": "acmp-reserve",
          "type": "number",
          "label": "Contingency",
          "unit": "%",
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          "max": 300,
          "step": 1,
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        {
          "name": "acmp-recovery",
          "type": "number",
          "label": "Water recovered",
          "unit": "%",
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          "max": 100,
          "step": 1,
          "default": "85"
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        {
          "name": "acmp-water",
          "type": "number",
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          "unit": "",
          "min": 0,
          "step": 0.01,
          "default": "3.50"
        },
        {
          "name": "acmp-food",
          "type": "number",
          "label": "Food + packaging",
          "unit": "",
          "min": 0,
          "step": 0.01,
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        },
        {
          "name": "acmp-oxygen",
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          "label": "Oxygen make-up",
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          "step": 0.01,
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        {
          "name": "acmp-misc",
          "type": "number",
          "label": "Hygiene + other",
          "unit": "",
          "min": 0,
          "step": 0.01,
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      ],
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        {
          "name": "acmp-total",
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        {
          "name": "acmp-water-out",
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        },
        {
          "name": "acmp-food-out",
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        {
          "name": "acmp-oxygen-out",
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        {
          "name": "acmp-misc-out",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
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        "astronaut",
        "crew",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "astronaut-deep-space-communications",
      "title": "📡 Deep-Space Communications Planner",
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      "categoryName": "Astronomy & Space",
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        {
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          "label": "Range",
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          "step": 0.001,
          "default": "0.3844"
        },
        {
          "name": "adsc-rate",
          "type": "number",
          "label": "Data rate",
          "unit": "kb/s",
          "min": 0.001,
          "step": 1,
          "default": "256"
        },
        {
          "name": "adsc-file",
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      "title": "🥇 Athletics Decathlon & Heptathlon Points",
      "description": "The official World Athletics scoring tables: type a performance in any event and get its points, then watch the total build toward a world-class score. Times in seconds (or m:ss), jumps in centimet...",
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      "categoryName": "Sports",
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      "standaloneUrl": null,
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        {
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          "label": "Event list",
          "unit": "",
          "options": [
            "dec",
            "hep"
          ],
          "default": "dec"
        }
      ],
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        {
          "name": "dec-out",
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=athletics-decathlon-points-calculator&<id>=<value>",
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      },
      "formula": "The scoring formula Points = floor( A ×",
      "sources": [],
      "tags": [
        "athletics",
        "decathlon",
        "points",
        "heptathlon",
        "sports",
        "official",
        "world",
        "scoring",
        "tables",
        "type"
      ],
      "popularity": 6379,
      "featured": false,
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    },
    {
      "slug": "atmospheric-aurora-borealis-field",
      "title": "🌌 Aurora Solar Wind Chamber",
      "description": "Kristian Birkeland's Terrella experiment. Solar wind plasma streams channeled along geomagnetic dipole field lines excite shimmering atmospheric auroral ovals.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/atmospheric-aurora-borealis-field.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=atmospheric-aurora-borealis-field&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "label": "slider density",
          "unit": "",
          "min": 1,
          "max": 25,
          "default": "5"
        },
        {
          "name": "asw-slider-bz",
          "type": "range",
          "label": "slider bz",
          "unit": "",
          "min": -15,
          "max": 10,
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        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=atmospheric-aurora-borealis-field&<id>=<value>",
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      },
      "formula": "Geomagnetic Kp-Index Kp = 3.0 (Minor) Solar Wind Velocity 450 km/",
      "sources": [],
      "tags": [
        "atmospheric",
        "aurora",
        "borealis",
        "field",
        "solar",
        "wind",
        "chamber",
        "science",
        "engineering",
        "kristian"
      ],
      "popularity": 5025,
      "featured": false,
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    },
    {
      "slug": "atmospheric-plasma-globe",
      "title": "⚡ Tesla Atmospheric Plasma",
      "description": "High-frequency Tesla coil discharge globe. Noble gas ionization streamers branch from the central electrode and focus to your touch via capacitive coupling.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
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      "standaloneUrl": null,
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          "max": 25,
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          "name": "tap-slider-press",
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          "label": "slider press",
          "unit": "",
          "min": 0.2,
          "max": 5,
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      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=atmospheric-plasma-globe&<id>=<value>",
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      "sources": [],
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        "atmospheric",
        "plasma",
        "globe",
        "tesla",
        "science",
        "engineering",
        "high-frequency",
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        "noble"
      ],
      "popularity": 4282,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "audio-file-size-calculator",
      "title": "🎧 Audio File Size",
      "description": "Uncompressed WAV/AIFF size = sample rate × channels × (bit depth ÷ 8) × seconds. MP3/AAC size ≈ bitrate × seconds ÷ 8. Headers are a few kilobytes — ignored here.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/audio-file-size-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=audio-file-size-calculator&embed=1",
      "standaloneUrl": null,
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          "label": "Duration",
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        {
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          "type": "number",
          "label": "Compressed kbps",
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          "min": 32,
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        {
          "name": "afsz-sr",
          "type": "select-one",
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          "unit": "",
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            "44100",
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            "96000",
            "192000"
          ],
          "default": "44100"
        },
        {
          "name": "afsz-bit",
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            "16",
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            "32"
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          "name": "afsz-ch",
          "type": "select-one",
          "label": "Channels",
          "unit": "",
          "options": [
            "1",
            "2"
          ],
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      ],
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        {
          "name": "afsz-out",
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        }
      ],
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      },
      "formula": "Audio File Size Uncompressed WAV/AIFF size = sample rate × channels × (bit depth ÷ 8) × seconds. MP3/AAC size ≈ bitrate ×",
      "sources": [],
      "tags": [
        "audio",
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        "algorithms",
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      "popularity": 4236,
      "featured": false,
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    },
    {
      "slug": "audio-tone-frequency-generator",
      "title": "🎚️ Audio Tone Generator",
      "description": "Generate pure acoustic tones, test speaker frequency responses, and monitor live audio waveforms using the Web Audio API.",
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      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/audio-tone-frequency-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=audio-tone-frequency-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "atg-freq-num",
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          "unit": "",
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          "max": 20000,
          "step": 0.1,
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        {
          "name": "atg-freq-slider",
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          "label": "Frequency",
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          "max": 10000,
          "step": 1,
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        },
        {
          "name": "atg-slider-vol",
          "type": "range",
          "label": "Volume percentage",
          "unit": "",
          "min": 0,
          "max": 100,
          "default": "30"
        },
        {
          "name": "atg-slider-pan",
          "type": "range",
          "label": "Stereo pan",
          "unit": "",
          "min": -1,
          "max": 1,
          "step": 0.1,
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      ],
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      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=audio-tone-frequency-generator&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
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        "audio",
        "tone",
        "frequency",
        "music",
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      "featured": true,
      "updated": "2026-09-19"
    },
    {
      "slug": "awkward-silence-filler",
      "title": "🗣️ Awkward Silence Filler",
      "description": "The silence is deafening. Someone needs to say something. Let us help. (Results may make it worse.)",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=awkward-silence-filler&embed=1",
      "standaloneUrl": null,
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        {
          "name": "awksil-result",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=awkward-silence-filler&<id>=<value>",
        "runs": false
      },
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      "sources": [],
      "tags": [
        "awkward",
        "silence",
        "filler",
        "productivity",
        "lifestyle",
        "deafening",
        "someone",
        "needs",
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      ],
      "popularity": 6408,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "b2b-cold-email-sequence-generator",
      "title": "✉️ B2B Cold Email Generator",
      "description": "Generate high-converting 4-touch B2B cold email sequences. Features real-time spam keyword detection and an inbox deliverability health score. Replaces expensive monthly sales automation subscripti...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/b2b-cold-email-sequence-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=b2b-cold-email-sequence-generator&embed=1",
      "standaloneUrl": null,
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          "default": "VP of Engineering"
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        {
          "name": "ce-prospect-company",
          "type": "text",
          "label": "Target Company",
          "unit": "",
          "default": "Stripe"
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        {
          "name": "ce-core-pain",
          "type": "text",
          "label": "Core Pain Point Solved",
          "unit": "",
          "default": "API latency bottlenecks and microservice timeouts"
        },
        {
          "name": "ce-proof-metric",
          "type": "text",
          "label": "Metric Social Proof",
          "unit": "",
          "default": "reduced p99 latency by 44% for Vercel"
        },
        {
          "name": "ce-subject-line",
          "type": "text",
          "label": "subject line",
          "unit": "",
          "default": "quick question regarding API latency at Stripe"
        },
        {
          "name": "ce-email-body",
          "type": "textarea",
          "label": "email body",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "ce-deliverability-score",
          "type": "output"
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=b2b-cold-email-sequence-generator&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "b2b",
        "cold",
        "email",
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        "saas",
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      ],
      "popularity": 6474,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "baby-formula-mixing-calculator",
      "title": "🍼 Baby Formula Mixing",
      "description": "Most UK powders use 1 level scoop per 30 ml of water (check the tin). Water first, then powder. This is arithmetic — NHS mixing and sterilising steps still apply, and never microwave a bottle.",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=baby-formula-mixing-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "label": "Feed size",
          "unit": "ml",
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          "step": 30,
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        },
        {
          "name": "bfmx-n",
          "type": "number",
          "label": "Feeds per day",
          "unit": "",
          "min": 1,
          "max": 12,
          "default": "6"
        },
        {
          "name": "bfmx-ratio",
          "type": "number",
          "label": "ml water per scoop",
          "unit": "",
          "min": 20,
          "max": 60,
          "default": "30"
        },
        {
          "name": "bfmx-g",
          "type": "number",
          "label": "Grams per scoop",
          "unit": "",
          "min": 2,
          "max": 10,
          "default": "4.3"
        }
      ],
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        {
          "name": "bfmx-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=baby-formula-mixing-calculator&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "baby",
        "formula",
        "mixing",
        "health",
        "fitness",
        "most",
        "powders",
        "use",
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      ],
      "popularity": 5381,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "baby-sleep-planner",
      "title": "🍼 Baby Sleep & Feeding Day Planner",
      "description": "Babies run on wake windows — how long they can stay awake before they need to sleep again. It changes fast in the first year and getting it wrong by half an hour is usually the difference between a...",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/baby-sleep-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=baby-sleep-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bsp-wake",
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          "label": "Woke up at",
          "unit": "",
          "default": "07:00"
        },
        {
          "name": "bsp-bed",
          "type": "time",
          "label": "Aiming for bed at",
          "unit": "",
          "default": "19:00"
        },
        {
          "name": "bsp-weight",
          "type": "number",
          "label": "Weight (kg), optional",
          "unit": "",
          "min": 2,
          "max": 20,
          "step": 0.1
        },
        {
          "name": "bsp-age",
          "type": "select-one",
          "label": "Age",
          "unit": "",
          "options": [
            "0.25",
            "1.5",
            "2.5",
            "3.5",
            "4.5",
            "7",
            "9",
            "11",
            "15",
            "21",
            "30"
          ],
          "default": "3.5"
        }
      ],
      "outputs": [
        {
          "name": "bsp-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=baby-sleep-planner&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=baby-sleep-planner&bsp-wake=07%3A00&bsp-bed=19%3A00&bsp-age=3.5"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "baby",
        "sleep",
        "planner",
        "feeding",
        "day",
        "health",
        "fitness",
        "babies",
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      "popularity": 5875,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "backyard-bird-feeder-diet",
      "title": "🌻 Backyard Bird Feeder Nutrition",
      "description": "Avian nutritional formulation matrix. Matches seed types to bill morphology, prevents feeder pests (squirrels/starlings), and maintains disease-free feeding stations.",
      "category": "birdwatching-and-ornithology",
      "categoryName": "Birdwatching & Ornithology",
      "url": "https://www.themostusefulsiteintheworld.com/tool/backyard-bird-feeder-diet.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=backyard-bird-feeder-diet&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "feed-select",
          "type": "select-one",
          "label": "Select Seed / Food Type",
          "unit": "",
          "options": [
            "black_oil",
            "safflower",
            "nyjer",
            "suet",
            "peanuts",
            "mealworms"
          ],
          "default": "black_oil"
        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=backyard-bird-feeder-diet&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=backyard-bird-feeder-diet&feed-select=black_oil"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "backyard",
        "bird",
        "feeder",
        "diet",
        "nutrition",
        "birdwatching",
        "ornithology",
        "avian",
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        "formulation"
      ],
      "popularity": 4862,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "badminton-scorekeeper",
      "title": "🏸 Badminton Match Scorer",
      "description": "Rally scoring to 21, win by two — but a game can only go to 30. Tap a side to add their point and this handles the deuce, the game win, and the best-of-three match for you.",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/badminton-scorekeeper.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=badminton-scorekeeper&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [
        {
          "name": "bdm-board",
          "type": "live"
        },
        {
          "name": "bdm-score",
          "type": "output"
        }
      ],
      "prefill": {
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        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "badminton",
        "scorekeeper",
        "match",
        "scorer",
        "sports",
        "rally",
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        "win",
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      ],
      "popularity": 6771,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "bank-complaint-tracker",
      "title": "📅 Bank Complaint Deadline Tracker",
      "description": "Track your complaint deadlines — never miss a bank's response window, FOS deadline, or court limitation period",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/bank-complaint-tracker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-complaint-tracker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bt-name",
          "type": "text",
          "label": "Complaint name",
          "unit": ""
        },
        {
          "name": "bt-date",
          "type": "date",
          "label": "Complaint date",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-complaint-tracker&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "bank",
        "complaint",
        "tracker",
        "deadline",
        "finance",
        "money",
        "track",
        "deadlines",
        "never",
        "miss"
      ],
      "popularity": 4781,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "bank-credit-score-dispute",
      "title": "📊 Credit Score Dispute Letter Generator",
      "description": "Challenge incorrect entries on your credit report — generate dispute letters for credit agencies and banks",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/bank-credit-score-dispute.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-credit-score-dispute&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bcr-name",
          "type": "text",
          "label": "Your Name",
          "unit": "",
          "default": "Jane Smith"
        },
        {
          "name": "bcr-bank",
          "type": "text",
          "label": "Bank/Lender Name",
          "unit": "",
          "default": "Barclays"
        },
        {
          "name": "bcr-ref",
          "type": "text",
          "label": "Account reference / details",
          "unit": "",
          "default": "Account ending 1234"
        },
        {
          "name": "bcr-evidence",
          "type": "textarea",
          "label": "Additional evidence",
          "unit": ""
        },
        {
          "name": "bcr-agency",
          "type": "select-one",
          "label": "Credit Agency",
          "unit": "",
          "options": [
            "experian",
            "equifax",
            "transunion"
          ],
          "default": "experian"
        },
        {
          "name": "bcr-issue",
          "type": "select-one",
          "label": "What's wrong?",
          "unit": "",
          "options": [
            "wrongbalance",
            "wrongstatus",
            "notmine",
            "settled",
            "duplicate",
            "default",
            "old"
          ],
          "default": "wrongbalance"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-credit-score-dispute&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-credit-score-dispute&bcr-name=Jane%20Smith&bcr-bank=Barclays&bcr-ref=Account%20ending%201234&bcr-agency=experian&bcr-issue=wrongbalance"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "bank",
        "credit",
        "score",
        "dispute",
        "letter",
        "finance",
        "money",
        "challenge",
        "incorrect",
        "entries"
      ],
      "popularity": 4190,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "bank-dispute-letter",
      "title": "✉️ Bank Charge Dispute Letter Generator",
      "description": "Generate formal dispute letters for unauthorized charges, unfair fees, and billing errors — ready to send to your bank",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/bank-dispute-letter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-dispute-letter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bd-name",
          "type": "text",
          "label": "Your Name",
          "unit": "",
          "default": "Jane Smith"
        },
        {
          "name": "bd-addr",
          "type": "text",
          "label": "Your Address",
          "unit": "",
          "default": "123 Main Street, London"
        },
        {
          "name": "bd-bank",
          "type": "text",
          "label": "Bank Name",
          "unit": "",
          "default": "Barclays"
        },
        {
          "name": "bd-acct",
          "type": "text",
          "label": "Account Number",
          "unit": "",
          "default": "****1234"
        },
        {
          "name": "bd-amount",
          "type": "text",
          "label": "Amount Disputed",
          "unit": "",
          "default": "£35.00"
        },
        {
          "name": "bd-date",
          "type": "date",
          "label": "Date of Charge",
          "unit": ""
        },
        {
          "name": "bd-details",
          "type": "textarea",
          "label": "Additional Details",
          "unit": ""
        },
        {
          "name": "bd-type",
          "type": "select-one",
          "label": "Dispute Type",
          "unit": "",
          "options": [
            "unauthorized",
            "overdraft",
            "latefee",
            "billing",
            "closed",
            "hidden",
            "misold"
          ],
          "default": "unauthorized"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-dispute-letter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-dispute-letter&bd-name=Jane%20Smith&bd-addr=123%20Main%20Street%2C%20London&bd-bank=Barclays&bd-acct=****1234&bd-amount=%C2%A335.00&bd-type=unauthorized"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "bank",
        "dispute",
        "letter",
        "charge",
        "finance",
        "money",
        "generate",
        "formal",
        "letters",
        "unauthorized"
      ],
      "popularity": 6592,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "bank-fee-calculator",
      "title": "💰 Hidden Bank Fee Calculator",
      "description": "Calculate the TRUE cost of your bank account — overdraft fees, ATM charges, FX markups, and hidden costs that banks hope you won't notice",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/bank-fee-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-fee-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bf-acct",
          "type": "number",
          "label": "Monthly account fee",
          "unit": "",
          "default": "0"
        },
        {
          "name": "bf-od",
          "type": "number",
          "label": "Overdraft fees/month",
          "unit": "",
          "default": "0"
        },
        {
          "name": "bf-atm",
          "type": "number",
          "label": "ATM fees/month",
          "unit": "",
          "default": "0"
        },
        {
          "name": "bf-fx",
          "type": "number",
          "label": "FX/foreign tx fees",
          "unit": "",
          "default": "0"
        },
        {
          "name": "bf-late",
          "type": "number",
          "label": "Late payment fees",
          "unit": "",
          "default": "0"
        },
        {
          "name": "bf-return",
          "type": "number",
          "label": "Returned payment fees",
          "unit": "",
          "default": "0"
        },
        {
          "name": "bf-paper",
          "type": "number",
          "label": "Paper statement fee",
          "unit": "",
          "default": "0"
        },
        {
          "name": "bf-other",
          "type": "number",
          "label": "Other monthly fees",
          "unit": "",
          "default": "0"
        },
        {
          "name": "bf-od-bal",
          "type": "number",
          "label": "Average overdraft balance",
          "unit": "£",
          "default": "0"
        }
      ],
      "outputs": [
        {
          "name": "bf-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-fee-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-fee-calculator&bf-acct=0&bf-od=0&bf-atm=0&bf-fx=0&bf-late=0&bf-return=0"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "bank",
        "fee",
        "hidden",
        "finance",
        "money",
        "calculate",
        "true",
        "cost",
        "account",
        "overdraft"
      ],
      "popularity": 5446,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "bank-fos-complaint",
      "title": "⚖️ Financial Ombudsman Complaint Builder",
      "description": "Build a complete FOS complaint — step by step. Get your money back when the bank refuses to help",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/bank-fos-complaint.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-fos-complaint&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bf-name",
          "type": "text",
          "label": "Your Name",
          "unit": "",
          "default": "Jane Smith"
        },
        {
          "name": "bf-bank",
          "type": "text",
          "label": "Bank Name",
          "unit": "",
          "default": "Barclays"
        },
        {
          "name": "bf-ref",
          "type": "text",
          "label": "Bank Complaint Ref",
          "unit": "",
          "default": "CMP-123456"
        },
        {
          "name": "bf-amount",
          "type": "text",
          "label": "Amount Claimed",
          "unit": "",
          "default": "£500"
        },
        {
          "name": "bf-timeline",
          "type": "textarea",
          "label": "Timeline of Events",
          "unit": ""
        },
        {
          "name": "bf-outcome",
          "type": "textarea",
          "label": "What outcome do you want?",
          "unit": ""
        },
        {
          "name": "bf-what",
          "type": "select-one",
          "label": "What happened?",
          "unit": "",
          "options": [
            "fees",
            "unauthorized",
            "service",
            "misold",
            "discrimination",
            "credit",
            "fraud"
          ],
          "default": "fees"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-fos-complaint&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-fos-complaint&bf-name=Jane%20Smith&bf-bank=Barclays&bf-ref=CMP-123456&bf-amount=%C2%A3500&bf-what=fees"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "bank",
        "fos",
        "complaint",
        "financial",
        "ombudsman",
        "builder",
        "finance",
        "money",
        "build",
        "complete"
      ],
      "popularity": 6017,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "bank-interest-reclaim",
      "title": "📊 Overdraft & Interest Reclaim Calculator",
      "description": "Calculate how much you've been overcharged on overdraft interest and fees — then generate a reclaim letter",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/bank-interest-reclaim.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-interest-reclaim&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bi-months",
          "type": "range",
          "label": "How many months were you in overdraft?",
          "unit": "",
          "min": 1,
          "max": 72,
          "default": "12"
        },
        {
          "name": "bi-bal",
          "type": "number",
          "label": "Avg overdraft balance",
          "unit": "",
          "default": "500"
        },
        {
          "name": "bi-apr",
          "type": "number",
          "label": "Bank's overdraft APR",
          "unit": "",
          "step": 0.1,
          "default": "39.9"
        },
        {
          "name": "bi-fees",
          "type": "number",
          "label": "Monthly overdraft fees",
          "unit": "",
          "default": "0"
        },
        {
          "name": "bi-bank",
          "type": "text",
          "label": "Bank name",
          "unit": "",
          "default": "Lloyds"
        }
      ],
      "outputs": [
        {
          "name": "bi-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-interest-reclaim&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-interest-reclaim&bi-months=12&bi-bal=500&bi-apr=39.9&bi-fees=0&bi-bank=Lloyds"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "bank",
        "interest",
        "reclaim",
        "overdraft",
        "finance",
        "money",
        "calculate",
        "how",
        "much",
        "been"
      ],
      "popularity": 5375,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "bank-sar-request",
      "title": "🔍 Subject Access Request (SAR) Generator",
      "description": "Force your bank to reveal ALL data they hold on you — internal notes, decision records, credit scoring, and communications",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/bank-sar-request.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-sar-request&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bsar-name",
          "type": "text",
          "label": "Your Full Name",
          "unit": "",
          "default": "Jane Smith"
        },
        {
          "name": "bsar-addr",
          "type": "text",
          "label": "Your Address",
          "unit": "",
          "default": "123 Main St, London"
        },
        {
          "name": "bsar-bank",
          "type": "text",
          "label": "Bank Name",
          "unit": "",
          "default": "Barclays"
        },
        {
          "name": "bsar-acct",
          "type": "text",
          "label": "Account Number",
          "unit": "",
          "default": "****1234"
        },
        {
          "name": "bsar-dob",
          "type": "date",
          "label": "Date of Birth",
          "unit": ""
        },
        {
          "name": "bsar-notes",
          "type": "checkbox",
          "label": "Internal notes",
          "unit": "",
          "default": "1"
        },
        {
          "name": "bsar-score",
          "type": "checkbox",
          "label": "Credit scoring",
          "unit": "",
          "default": "1"
        },
        {
          "name": "bsar-comms",
          "type": "checkbox",
          "label": "Communications",
          "unit": "",
          "default": "1"
        },
        {
          "name": "bsar-decisions",
          "type": "checkbox",
          "label": "Decision records",
          "unit": "",
          "default": "1"
        },
        {
          "name": "bsar-third",
          "type": "checkbox",
          "label": "Third-party sharing",
          "unit": "",
          "default": "1"
        },
        {
          "name": "bsar-calls",
          "type": "checkbox",
          "label": "Call recordings",
          "unit": "",
          "default": "1"
        },
        {
          "name": "bsar-id",
          "type": "select-one",
          "label": "ID Type Provided",
          "unit": "",
          "options": [
            "Passport",
            "Driving Licence",
            "Utility Bill"
          ],
          "default": "Passport"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-sar-request&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-sar-request&bsar-name=Jane%20Smith&bsar-addr=123%20Main%20St%2C%20London&bsar-bank=Barclays&bsar-acct=****1234&bsar-notes=1&bsar-score=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "bank",
        "sar",
        "request",
        "subject",
        "access",
        "finance",
        "money",
        "force",
        "reveal",
        "all"
      ],
      "popularity": 4333,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "bank-section75-claim",
      "title": "🛡️ Section 75 Claim Calculator & Letter",
      "description": "Check if your credit card purchase is protected under Section 75 — calculate your claim and generate the letter",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/bank-section75-claim.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-section75-claim&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bs75-amt",
          "type": "number",
          "label": "Purchase Amount",
          "unit": "",
          "default": "500"
        },
        {
          "name": "bs75-cc",
          "type": "text",
          "label": "Credit Card Provider",
          "unit": "",
          "default": "Barclaycard"
        },
        {
          "name": "bs75-retail",
          "type": "text",
          "label": "Retailer",
          "unit": "",
          "default": "Online Store Ltd"
        },
        {
          "name": "bs75-date",
          "type": "date",
          "label": "Purchase Date",
          "unit": ""
        },
        {
          "name": "bs75-issue",
          "type": "select-one",
          "label": "What went wrong?",
          "unit": "",
          "options": [
            "notdelivered",
            "faulty",
            "company",
            "misrepresented",
            "breach"
          ],
          "default": "notdelivered"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-section75-claim&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-section75-claim&bs75-amt=500&bs75-cc=Barclaycard&bs75-retail=Online%20Store%20Ltd&bs75-issue=notdelivered"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "bank",
        "section75",
        "claim",
        "section",
        "letter",
        "finance",
        "money",
        "check",
        "credit",
        "card"
      ],
      "popularity": 5559,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "bank-small-claims",
      "title": "⚖️ Small Claims Court Guide & Cost Calculator",
      "description": "Calculate court costs, check eligibility, and generate your claim — the nuclear option when banks refuse to play fair",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/bank-small-claims.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-small-claims&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bcl-amt",
          "type": "number",
          "label": "Claim Amount",
          "unit": "£",
          "default": "2000"
        },
        {
          "name": "bcl-def",
          "type": "text",
          "label": "Defendant",
          "unit": "",
          "default": "Barclays Bank PLC"
        }
      ],
      "outputs": [
        {
          "name": "bcl-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-small-claims&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-small-claims&bcl-amt=2000&bcl-def=Barclays%20Bank%20PLC"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "bank",
        "small",
        "claims",
        "court",
        "guide",
        "cost",
        "finance",
        "money",
        "calculate",
        "costs"
      ],
      "popularity": 5486,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "bank-switching-calculator",
      "title": "🔄 Bank Switching Bonus Calculator",
      "description": "Compare bank switching bonuses, calculate total savings, and see how much your loyalty is costing you",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/bank-switching-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=bank-switching-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bss-cur-fee",
          "type": "number",
          "label": "Monthly fee",
          "unit": "",
          "default": "0"
        },
        {
          "name": "bss-cur-od",
          "type": "number",
          "label": "Avg overdraft cost",
          "unit": "",
          "default": "15"
        },
        {
          "name": "bss-cur-fx",
          "type": "number",
          "label": "FX fees/month",
          "unit": "",
          "default": "0"
        },
        {
          "name": "bss-cur-int",
          "type": "number",
          "label": "Interest earned",
          "unit": "",
          "default": "0"
        },
        {
          "name": "bss-new-bonus",
          "type": "number",
          "label": "Switching bonus",
          "unit": "",
          "default": "200"
        },
        {
          "name": "bss-new-fee",
          "type": "number",
          "label": "Monthly fee",
          "unit": "",
          "default": "0"
        },
        {
          "name": "bss-new-apr",
          "type": "number",
          "label": "Overdraft APR",
          "unit": "",
          "step": 0.1,
          "default": "35"
        },
        {
          "name": "bss-new-cb",
          "type": "number",
          "label": "Cashback/month",
          "unit": "",
          "default": "0"
        }
      ],
      "outputs": [
        {
          "name": "bss-results",
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      },
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      "sources": [],
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        "bank",
        "switching",
        "bonus",
        "finance",
        "money",
        "compare",
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        "savings"
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      "featured": false,
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    },
    {
      "slug": "bar-psi-kpa-pressure-converter",
      "title": "⏲️ Bar ⇄ PSI ⇄ kPa",
      "description": "Tyre, compressor and scuba pressures. 1 bar = 100 kPa = 14.5038 psi. Standard atmosphere is 101.325 kPa (14.696 psi). Gauge vs absolute is your problem — this is a unit convert only.",
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      "categoryName": "Science & Engineering",
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      "standaloneUrl": null,
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        {
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        },
        {
          "name": "bpsi-kpa",
          "type": "number",
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          "min": 0
        },
        {
          "name": "bpsi-atm",
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          "unit": "",
          "min": 0
        }
      ],
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=bar-psi-kpa-pressure-converter&<id>=<value>",
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      },
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      "sources": [],
      "tags": [
        "bar",
        "psi",
        "kpa",
        "pressure",
        "converter",
        "science",
        "engineering",
        "tyre",
        "compressor",
        "scuba"
      ],
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "barbell-plate-loader",
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      "category": "sports",
      "categoryName": "Sports",
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      "standaloneUrl": null,
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          "options": [
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            "lb"
          ],
          "default": "kg"
        },
        {
          "name": "bpl-bar",
          "type": "select-one",
          "label": "Bar",
          "unit": ""
        }
      ],
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          "name": "bpl-out",
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=barbell-plate-loader&<id>=<value>",
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      },
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      "sources": [],
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        "barbell",
        "plate",
        "loader",
        "warm-up",
        "ramp",
        "sports",
        "stop",
        "doing",
        "bar",
        "maths"
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "barcode-label-studio",
      "title": "🏷️ Barcode & Label Studio",
      "description": "Produce real, scanner-readable barcodes — Code 128, Code 39, EAN-13, UPC-A and ITF-14 — and download them as vector SVG or a print-resolution PNG. Barcode generator sites charge a subscription for ...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/barcode-label-studio.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=barcode-label-studio&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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        {
          "name": "bcls-mw",
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        },
        {
          "name": "bcls-h",
          "type": "number",
          "label": "Bar height",
          "unit": "px",
          "min": 20,
          "max": 400,
          "step": 5,
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        },
        {
          "name": "bcls-quiet",
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          "label": "Quiet zone",
          "unit": "modules",
          "min": 0,
          "max": 40,
          "step": 1,
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        },
        {
          "name": "bcls-fs",
          "type": "number",
          "label": "Text size",
          "unit": "px",
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          "max": 40,
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        {
          "name": "bcls-fg",
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          "unit": "",
          "default": "#000000"
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        {
          "name": "bcls-bg",
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        },
        {
          "name": "bcls-autocheck",
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          "label": "Add missing check digit",
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          "name": "bcls-showtext",
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        {
          "name": "bcls-mod43",
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          "label": "Code 39 mod-43 check",
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          "default": "0"
        },
        {
          "name": "bcls-symb",
          "type": "select-one",
          "label": "Symbology",
          "unit": "",
          "options": [
            "c128",
            "c39",
            "ean13",
            "upca",
            "itf14"
          ],
          "default": "c128"
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=barcode-label-studio&<id>=<value>",
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      },
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      "sources": [],
      "tags": [
        "barcode",
        "label",
        "studio",
        "saas",
        "business",
        "killers",
        "produce",
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        "scanner-readable",
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      ],
      "popularity": 6836,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "barnsley-fern-fractal",
      "title": "🌿 Barnsley Fern",
      "description": "Four simple rules, chosen at random, draw a perfect fern. No one programmed a leaf — the fern is the fixed point of the chaos, and every frond is a tiny copy of the whole.",
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      "categoryName": "Mind-Blowing Demos",
      "url": "https://www.themostusefulsiteintheworld.com/tool/barnsley-fern-fractal.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=barnsley-fern-fractal&embed=1",
      "standaloneUrl": null,
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        }
      ],
      "outputs": [
        {
          "name": "frn-out",
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        }
      ],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "barnsley",
        "fern",
        "fractal",
        "mind-blowing",
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        "rules",
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      "popularity": 6844,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "base64-text-encoder-decoder",
      "title": "🔐 Base64, Hex & Binary Text Encoder / Decoder",
      "description": "Encode text to Base64 (standard or URL-safe), hexadecimal, binary, HTML entities, Unicode escapes or ROT13 — and decode back. Full UTF-8 and emoji support. Live in both directions; nothing leaves y...",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/base64-text-encoder-decoder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=base64-text-encoder-decoder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bted-plain",
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          "label": "Plain text",
          "unit": ""
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        {
          "name": "bted-enc",
          "type": "textarea",
          "label": "Encoded",
          "unit": "Base64"
        },
        {
          "name": "bted-data-url",
          "type": "textarea",
          "label": "Data URL (ready for <img src=\"…\"> or CSS background)",
          "unit": ""
        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=base64-text-encoder-decoder&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "base64",
        "text",
        "encoder",
        "decoder",
        "hex",
        "binary",
        "algorithms",
        "computer",
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      "popularity": 6553,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "baseball-stats-calculator",
      "title": "⚾ Baseball Stats Calculator",
      "description": "The slash line every hitter lives by — batting average, on-base and slugging, plus OPS — and the pitching numbers (ERA and WHIP). Enter a box score and get the exact formulas and a read on what the...",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/baseball-stats-calculator.html",
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      "standaloneUrl": null,
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        {
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        {
          "name": "bsb-h",
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          "default": "150"
        },
        {
          "name": "bsb-2b",
          "type": "number",
          "label": "2B",
          "unit": "",
          "min": 0,
          "default": "30"
        },
        {
          "name": "bsb-3b",
          "type": "number",
          "label": "3B",
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          "min": 0,
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        {
          "name": "bsb-hr",
          "type": "number",
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        },
        {
          "name": "bsb-bb",
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          "unit": "",
          "min": 0,
          "default": "60"
        },
        {
          "name": "bsb-hbp",
          "type": "number",
          "label": "HBP",
          "unit": "",
          "min": 0,
          "default": "6"
        },
        {
          "name": "bsb-sf",
          "type": "number",
          "label": "SF",
          "unit": "",
          "min": 0,
          "default": "4"
        },
        {
          "name": "bsb-ip",
          "type": "number",
          "label": "IP (7.1 = 7&#8531;)",
          "unit": "",
          "min": 0,
          "step": 0.1,
          "default": "180.1"
        },
        {
          "name": "bsb-er",
          "type": "number",
          "label": "ER",
          "unit": "",
          "min": 0,
          "default": "70"
        },
        {
          "name": "bsb-ph",
          "type": "number",
          "label": "Hits allowed",
          "unit": "",
          "min": 0,
          "default": "160"
        },
        {
          "name": "bsb-pbb",
          "type": "number",
          "label": "BB allowed",
          "unit": "",
          "min": 0,
          "default": "50"
        },
        {
          "name": "bsb-so",
          "type": "number",
          "label": "Strikeouts",
          "unit": "",
          "min": 0,
          "default": "180"
        }
      ],
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        {
          "name": "bsb-out",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=baseball-stats-calculator&<id>=<value>",
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      },
      "formula": "Calculate The formulas BA = H ÷ AB. OBP = (H + BB + HBP) ÷ (AB + BB + HBP + SF). SLG = total bases ÷",
      "sources": [],
      "tags": [
        "baseball",
        "stats",
        "sports",
        "slash",
        "line",
        "every",
        "hitter",
        "lives",
        "batting",
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      ],
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "basketball-efficiency-calculator",
      "title": "🏀 Basketball Efficiency Calculator",
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      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/basketball-efficiency-calculator.html",
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      "standaloneUrl": null,
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        {
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        {
          "name": "bbp-reb",
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        {
          "name": "bbp-oreb",
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          "label": "OREB",
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        },
        {
          "name": "bbp-ast",
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          "label": "AST",
          "unit": "",
          "min": 0,
          "default": "7"
        },
        {
          "name": "bbp-stl",
          "type": "number",
          "label": "STL",
          "unit": "",
          "min": 0,
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        },
        {
          "name": "bbp-blk",
          "type": "number",
          "label": "BLK",
          "unit": "",
          "min": 0,
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        },
        {
          "name": "bbp-tov",
          "type": "number",
          "label": "TOV",
          "unit": "",
          "min": 0,
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        },
        {
          "name": "bbp-pf",
          "type": "number",
          "label": "PF",
          "unit": "",
          "min": 0,
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        },
        {
          "name": "bbp-fgm",
          "type": "number",
          "label": "FGM",
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          "min": 0,
          "default": "10"
        },
        {
          "name": "bbp-fga",
          "type": "number",
          "label": "FGA",
          "unit": "",
          "min": 0,
          "default": "18"
        },
        {
          "name": "bbp-3pm",
          "type": "number",
          "label": "3PM",
          "unit": "",
          "min": 0,
          "default": "3"
        },
        {
          "name": "bbp-3pa",
          "type": "number",
          "label": "3PA",
          "unit": "",
          "min": 0,
          "default": "7"
        },
        {
          "name": "bbp-ftm",
          "type": "number",
          "label": "FTM",
          "unit": "",
          "min": 0,
          "default": "5"
        },
        {
          "name": "bbp-fta",
          "type": "number",
          "label": "FTA",
          "unit": "",
          "min": 0,
          "default": "6"
        },
        {
          "name": "bbp-min",
          "type": "number",
          "label": "MIN",
          "unit": "",
          "min": 0,
          "default": "36"
        }
      ],
      "outputs": [
        {
          "name": "bbp-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=basketball-efficiency-calculator&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=basketball-efficiency-calculator&bbp-pts=28&bbp-reb=6&bbp-oreb=2&bbp-ast=7&bbp-stl=2&bbp-blk=1&run=1"
      },
      "formula": "The exact formulas Game Score = PTS + 0.4×FGM − 0.7×FGA − 0.4×(FTA − FTM) + 0.7×OREB + 0.3×DREB + STL + 0.7×",
      "sources": [],
      "tags": [
        "basketball",
        "efficiency",
        "sports",
        "type",
        "box",
        "score",
        "get",
        "metrics",
        "analysts",
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      ],
      "popularity": 4790,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "batch-link-cleaner",
      "title": "🔗 Batch Link Cleaner",
      "description": "Clean a list of links before sharing or archiving them. Removes recognized campaign trackers while keeping the destination, useful query parameters, and URL fragment. It does not open links, follow...",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/batch-link-cleaner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=batch-link-cleaner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "batch-link-cleaner-trackers",
          "type": "checkbox",
          "label": "Remove known campaign/ad trackers such as utm_* , gclid and fbclid",
          "unit": "",
          "default": "1"
        },
        {
          "name": "batch-link-cleaner-referrals",
          "type": "checkbox",
          "label": "Also remove generic referral/coupon keys such as ref , aff and coupon (may change how a link works)",
          "unit": "",
          "default": "0"
        },
        {
          "name": "batch-link-cleaner-input",
          "type": "textarea",
          "label": "Links — one per line",
          "unit": ""
        },
        {
          "name": "batch-link-cleaner-custom",
          "type": "textarea",
          "label": "Additional query keys to remove (optional, comma or newline separated)",
          "unit": ""
        },
        {
          "name": "batch-link-cleaner-output",
          "type": "textarea",
          "label": "Cleaned list",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "batch-link-cleaner-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=batch-link-cleaner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=batch-link-cleaner&batch-link-cleaner-trackers=1&batch-link-cleaner-referrals=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "batch",
        "link",
        "cleaner",
        "algorithms",
        "computer",
        "science",
        "clean",
        "list",
        "links",
        "before"
      ],
      "popularity": 5478,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "battery-runtime-mah-calculator",
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        {
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        "board",
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        "board-foot",
        "home",
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      "categoryName": "Arcade",
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      "slug": "boardgame-nine-mens-morris",
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      "categoryName": "Arcade",
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      "featured": false,
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    {
      "slug": "boardgame-othello",
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      "category": "mrprophecy-arcade",
      "categoryName": "Arcade",
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      "featured": false,
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    },
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      "slug": "boardgame-snakes-ladders",
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      "categoryName": "Arcade",
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      "featured": false,
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    {
      "slug": "boardgame-yahtzee",
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      "category": "mrprophecy-arcade",
      "categoryName": "Arcade",
      "url": "https://www.themostusefulsiteintheworld.com/tool/boardgame-yahtzee.html",
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      "popularity": 5105,
      "featured": false,
      "updated": "2026-09-19"
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      "categoryName": "Health & Fitness",
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      },
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      "featured": false,
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      "slug": "bodyfat",
      "title": "🏋️ Body Fat Calculator",
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      "categoryName": "Health & Fitness",
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      "formula": "US Navy: %fat from neck/waist/hip circumferences and height (log₁₀).",
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        "bodyfat",
        "body",
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        "health",
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      "popularity": 9520,
      "featured": true,
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    },
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      "slug": "boiling-point-finder",
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      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=boiling-point-finder&embed=1",
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          "type": "select-one",
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          "options": [
            "C",
            "F",
            "K"
          ],
          "default": "C"
        }
      ],
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        {
          "name": "bpf-results",
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          "name": "bpf-result-display",
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      "tags": [
        "boiling",
        "point",
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        "science",
        "engineering",
        "look",
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      "popularity": 5094,
      "featured": false,
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      "slug": "bouldering-score-calculator",
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      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/bouldering-score-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=bouldering-score-calculator&embed=1",
      "standaloneUrl": null,
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        {
          "name": "bld-aatt",
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        {
          "name": "bld-az",
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        {
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      ],
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        "bouldering",
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      "featured": false,
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      "slug": "bowling-score-calculator",
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      "categoryName": "Sports",
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        "bowling",
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        "enter",
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      "featured": false,
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        {
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          "label": "Completed",
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        {
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        {
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          "type": "number",
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        "boxing",
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        "decision",
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      "featured": false,
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      "slug": "boxing-judge-criteria-trainer",
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        {
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        "boxing",
        "judge",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "boxing-knockdown-count-rules",
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      "categoryName": "Sports",
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        "boxing",
        "knockdown",
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      "featured": false,
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    },
    {
      "slug": "boxing-punch-stat-tracker",
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      "category": "sports",
      "categoryName": "Sports",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=boxing-punch-stat-tracker&embed=1",
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        {
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      "sources": [],
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        "boxing",
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      "featured": false,
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    },
    {
      "slug": "boxing-round-by-round-analyzer",
      "title": "📈 Boxing Momentum & Swing Round Analyser",
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      "categoryName": "Sports",
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      "standaloneUrl": null,
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        {
          "name": "brba-in",
          "type": "textarea",
          "label": "Round winners ( A , B , E ) — one per round",
          "unit": ""
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      ],
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        {
          "name": "brba-score",
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        {
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      "sources": [],
      "tags": [
        "boxing",
        "round",
        "analyzer",
        "momentum",
        "swing",
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        "sports",
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      "popularity": 6030,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "boxing-round-timer-bell",
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      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/boxing-round-timer-bell.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=boxing-round-timer-bell&embed=1",
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        {
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          "label": "Rounds",
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          "default": "12"
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        {
          "name": "brtb-warn",
          "type": "number",
          "label": "Clapper",
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          "min": 0,
          "max": 60,
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        },
        {
          "name": "brtb-sound",
          "type": "checkbox",
          "label": "Bell & clapper sound (Web Audio — no files needed)",
          "unit": "",
          "default": "1"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=boxing-round-timer-bell&<id>=<value>",
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        "boxing",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "boxing-scorecard-comparator",
      "title": "🔍 Boxing Scorecard Comparator",
      "description": "Compare your card against the official judges round by round. Highlights exactly where you disagreed, measures your agreement rate, and flags the swing rounds that decided the fight.",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/boxing-scorecard-comparator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=boxing-scorecard-comparator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bsc-mine",
          "type": "textarea",
          "label": "Your card (one round per line: A , B or E )",
          "unit": ""
        },
        {
          "name": "bsc-off",
          "type": "textarea",
          "label": "Official / judge card",
          "unit": "same format"
        }
      ],
      "outputs": [
        {
          "name": "bsc-out",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=boxing-scorecard-comparator&<id>=<value>",
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "boxing",
        "scorecard",
        "comparator",
        "sports",
        "compare",
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      "popularity": 4017,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "boxing-ten-point-must-scorecard",
      "title": "🥊 Boxing 10-Point Must Scorecard",
      "description": "Score a fight round by round using the official 10-Point Must System. Knockdowns and point deductions are applied automatically, with a live running total and winner projection.",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/boxing-ten-point-must-scorecard.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=boxing-ten-point-must-scorecard&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "name": "btpm-red",
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          "default": "Boxer A"
        },
        {
          "name": "btpm-blue",
          "type": "text",
          "label": "Boxer B",
          "unit": "Blue Corner",
          "default": "Boxer B"
        },
        {
          "name": "btpm-rounds",
          "type": "select-one",
          "label": "Rounds",
          "unit": "",
          "options": [
            "4",
            "6",
            "8",
            "10",
            "12"
          ],
          "default": "12"
        }
      ],
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        {
          "name": "btpm-red-total",
          "type": "output"
        },
        {
          "name": "btpm-blue-total",
          "type": "output"
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          "name": "btpm-summary",
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      ],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "boxing",
        "ten",
        "point",
        "must",
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        "sports",
        "score",
        "fight",
        "round"
      ],
      "popularity": 5383,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "boxing-three-judge-simulator",
      "title": "👨‍⚖️ Boxing Three-Judge Decision Simulator",
      "description": "Enter three official cards and get the correct verdict — unanimous, split, majority, or draw. Handles every decision type including the frequently confused majority draw.",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/boxing-three-judge-simulator.html",
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      "standaloneUrl": null,
      "inputs": [
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          "name": "b3js-a",
          "type": "text",
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          "unit": "",
          "default": "Boxer A"
        },
        {
          "name": "b3js-b",
          "type": "text",
          "label": "b",
          "unit": "",
          "default": "Boxer B"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=boxing-three-judge-simulator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=boxing-three-judge-simulator&b3js-a=Boxer%20A&b3js-b=Boxer%20B"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "boxing",
        "three",
        "judge",
        "simulator",
        "three-judge",
        "decision",
        "sports",
        "enter",
        "official",
        "cards"
      ],
      "popularity": 5137,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "boxing-weight-class-checker",
      "title": "⚖️ Boxing Weight Class & Weigh-In Checker",
      "description": "Find the correct division for any weight, check whether a fighter has made the limit, and see rehydration-clause and catchweight implications. Covers all seventeen professional classes.",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/boxing-weight-class-checker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=boxing-weight-class-checker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bwcc-w",
          "type": "number",
          "label": "Scale weight",
          "unit": "",
          "min": 0,
          "step": 0.25,
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        },
        {
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          "type": "number",
          "label": "Stones",
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          "min": 0,
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        },
        {
          "name": "bwcc-stlb",
          "type": "number",
          "label": "Pounds",
          "unit": "",
          "min": 0,
          "max": 13.75,
          "step": 0.25,
          "default": "7"
        },
        {
          "name": "bwcc-u",
          "type": "select-one",
          "label": "Units",
          "unit": "",
          "options": [
            "lb",
            "kg",
            "st"
          ],
          "default": "lb"
        },
        {
          "name": "bwcc-target",
          "type": "select-one",
          "label": "Check against a specific division",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "bwcc-result",
          "type": "output"
        },
        {
          "name": "bwcc-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=boxing-weight-class-checker&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=boxing-weight-class-checker&bwcc-w=147&bwcc-st=10&bwcc-stlb=7&bwcc-u=lb"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "boxing",
        "weight",
        "class",
        "checker",
        "weigh-in",
        "sports",
        "find",
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        "any"
      ],
      "popularity": 6887,
      "featured": false,
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    },
    {
      "slug": "bpm-counter",
      "title": "BPM Tap Counter (Pro)",
      "description": "Instant, free online BPM Tap Counter (Pro) tool. No signup required.",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/bpm-counter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=bpm-counter&embed=1",
      "standaloneUrl": null,
      "inputs": [],
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        {
          "name": "btc-bpm-display",
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=bpm-counter&<id>=<value>",
        "runs": false
      },
      "formula": "Confidence Score Higher = more consistent tapping. Aim for 95%+",
      "sources": [],
      "tags": [
        "bpm",
        "counter",
        "tap",
        "pro",
        "music",
        "audio",
        "instant",
        "signup",
        "required"
      ],
      "popularity": 6422,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "bra-size-converter",
      "title": "🎀 Bra Size Converter",
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      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/bra-size-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=bra-size-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bras-sys",
          "type": "select-one",
          "label": "I have",
          "unit": "",
          "options": [
            "UK",
            "US",
            "EU",
            "FR",
            "AU"
          ],
          "default": "UK"
        },
        {
          "name": "bras-band",
          "type": "select-one",
          "label": "Band",
          "unit": ""
        },
        {
          "name": "bras-cup",
          "type": "select-one",
          "label": "Cup",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "bras-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=bra-size-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=bra-size-converter&bras-sys=UK"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "bra",
        "size",
        "converter",
        "productivity",
        "lifestyle",
        "convert",
        "band",
        "cup",
        "sister",
        "sizes"
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      "popularity": 4152,
      "featured": false,
      "updated": "2026-09-19"
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      "slug": "brachistochrone-tautochrone-gravity-race",
      "title": "⚡ Brachistochrone & Tautochrone: The Curve of Fastest Descent",
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      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/brachistochrone-tautochrone-gravity-race.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=brachistochrone-tautochrone-gravity-race&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "select-one",
          "label": "Experiment Mode",
          "unit": "",
          "options": [
            "race",
            "tautochrone"
          ],
          "default": "race"
        },
        {
          "name": "btg-gravity-select",
          "type": "select-one",
          "label": "Gravity Environment",
          "unit": "",
          "options": [
            "9.81",
            "1.62",
            "3.72",
            "24.79"
          ],
          "default": "9.81"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=brachistochrone-tautochrone-gravity-race&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=brachistochrone-tautochrone-gravity-race&btg-mode-select=race&btg-gravity-select=9.81"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "brachistochrone",
        "tautochrone",
        "gravity",
        "race",
        "curve",
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        "science",
        "engineering",
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      ],
      "popularity": 5154,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "braille-alphabet-trainer",
      "title": "🔵 Braille Alphabet Trainer",
      "description": "Learn the 26 letters of English Braille by building cells dot by dot and decoding them. Each letter is a 2×3 grid of raised dots — once you see the pattern, the whole alphabet unfolds. All local, n...",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/braille-alphabet-trainer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=braille-alphabet-trainer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "brl-answer",
          "type": "text",
          "label": "Your answer",
          "unit": "a–z"
        },
        {
          "name": "brl-mode",
          "type": "select-one",
          "label": "Mode",
          "unit": "",
          "options": [
            "l2d",
            "d2l"
          ],
          "default": "l2d"
        }
      ],
      "outputs": [
        {
          "name": "brl-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=braille-alphabet-trainer&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=braille-alphabet-trainer&brl-mode=l2d"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "braille",
        "alphabet",
        "trainer",
        "writing",
        "language",
        "learn",
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        "english",
        "building",
        "cells"
      ],
      "popularity": 5899,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "brand-logo-mark-generator",
      "title": "✒️ Brand Mark Forge",
      "description": "Design a real logo in the browser and leave with the vector file. Twenty-two hand-drawn icons, five type treatments, four container shapes, gradient or flat colour, and exports as SVG, a 1024px PNG...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/brand-logo-mark-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=brand-logo-mark-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "text",
          "label": "Wordmark",
          "unit": "",
          "default": "Northlight"
        },
        {
          "name": "lgf-tag",
          "type": "text",
          "label": "Tagline",
          "unit": "",
          "default": "instruments for makers"
        },
        {
          "name": "lgf-c1",
          "type": "color",
          "label": "Primary colour",
          "unit": "",
          "default": "#ffd700"
        },
        {
          "name": "lgf-c2",
          "type": "color",
          "label": "Secondary colour",
          "unit": "",
          "default": "#d4af37"
        },
        {
          "name": "lgf-ink",
          "type": "color",
          "label": "Text / icon colour",
          "unit": "",
          "default": "#04070a"
        },
        {
          "name": "lgf-gradient",
          "type": "checkbox",
          "label": "Gradient fill",
          "unit": "",
          "default": "1"
        },
        {
          "name": "lgf-ls",
          "type": "range",
          "label": "Letter spacing",
          "unit": "",
          "min": -4,
          "max": 14,
          "step": 0.5,
          "default": "1"
        },
        {
          "name": "lgf-weight",
          "type": "range",
          "label": "Font weight",
          "unit": "",
          "min": 300,
          "max": 900,
          "step": 100,
          "default": "800"
        },
        {
          "name": "lgf-scale",
          "type": "range",
          "label": "Icon scale",
          "unit": "",
          "min": 30,
          "max": 85,
          "step": 1,
          "default": "55"
        },
        {
          "name": "lgf-layout",
          "type": "select-one",
          "label": "Layout",
          "unit": "",
          "options": [
            "stack",
            "inline",
            "icon",
            "text"
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          "default": "stack"
        },
        {
          "name": "lgf-font",
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          "label": "Typeface",
          "unit": "",
          "options": [
            "system-ui, -apple-system, Segoe UI, Roboto, sans-serif",
            "Helvetica Neue, Helvetica, Arial, sans-serif",
            "Georgia, Times New Roman, serif",
            "ui-monospace, SFMono-Regular, Menlo, Consolas, monospace",
            "Trebuchet MS, Verdana, sans-serif"
          ],
          "default": "system-ui, -apple-system, Segoe UI, Roboto, sans-serif"
        },
        {
          "name": "lgf-shape",
          "type": "select-one",
          "label": "Container",
          "unit": "",
          "options": [
            "none",
            "circle",
            "square",
            "hex",
            "ring"
          ],
          "default": "circle"
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      ],
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        {
          "name": "lgf-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=brand-logo-mark-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=brand-logo-mark-generator&lgf-word=Northlight&lgf-tag=instruments%20for%20makers&lgf-c1=%23ffd700&lgf-c2=%23d4af37&lgf-ink=%2304070a&lgf-gradient=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "brand",
        "logo",
        "mark",
        "forge",
        "saas",
        "business",
        "killers",
        "design",
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      ],
      "popularity": 5337,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "break-even",
      "title": "Break‑Even Calculator",
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      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/break-even.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=break-even&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "unit": "£",
          "min": 0,
          "step": 100,
          "default": "10000"
        },
        {
          "name": "be-variable",
          "type": "number",
          "label": "Variable Cost per Unit",
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          "min": 0,
          "step": 0.01,
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        },
        {
          "name": "be-price",
          "type": "number",
          "label": "Selling Price per Unit",
          "unit": "£",
          "min": 0,
          "step": 0.01,
          "default": "10"
        },
        {
          "name": "be-simulation-units",
          "type": "number",
          "label": "Projected Sales Units",
          "unit": "",
          "min": 0,
          "step": 100,
          "default": "1500"
        }
      ],
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        {
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          "type": "output"
        },
        {
          "name": "be-simulation-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=break-even&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=break-even&be-fixed=10000&be-variable=5&be-price=10&be-simulation-units=1500&run=1"
      },
      "formula": "Formula: • Contribution Margin = Selling Price − Variable Cost • Break‑Even Units = Fixed Costs ÷",
      "sources": [],
      "tags": [
        "break",
        "even",
        "finance",
        "money",
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        "volume",
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      "popularity": 5088,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "breaker-sizing",
      "title": "⚡ Breaker Sizing Calculator",
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      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/breaker-sizing.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=breaker-sizing&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "label": "Load Current",
          "unit": "A",
          "min": 0.1,
          "step": 0.1
        },
        {
          "name": "bsc-conductor-ampacity",
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          "label": "Conductor Ampacity",
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          "min": 1,
          "step": 1
        },
        {
          "name": "bsc-load-type",
          "type": "select-one",
          "label": "Load Type",
          "unit": "",
          "options": [
            "continuous",
            "non-continuous",
            "motor",
            "heating",
            "lighting"
          ],
          "default": "non-continuous"
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      ],
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        {
          "name": "bsc-results",
          "type": "output"
        },
        {
          "name": "bsc-result-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=breaker-sizing&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=breaker-sizing&bsc-load-type=non-continuous&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "breaker",
        "sizing",
        "science",
        "engineering",
        "estimate",
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        "circuit",
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      "popularity": 5983,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "brick-calculator",
      "title": "🧱 Brick Calculator",
      "description": "Calculate how many bricks you need for any wall — including mortar joints, waste, and pallets to order. Works for UK standard, metric, and imperial bricks.",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/brick-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=brick-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "number",
          "label": "Wall Width",
          "unit": "m",
          "min": 0.5,
          "step": 0.1,
          "default": "6"
        },
        {
          "name": "brkcalc-h",
          "type": "number",
          "label": "Wall Height",
          "unit": "m",
          "min": 0.3,
          "step": 0.1,
          "default": "2.4"
        },
        {
          "name": "brkcalc-openings",
          "type": "number",
          "label": "Openings (doors/windows)",
          "unit": "",
          "min": 0,
          "step": 0.1,
          "default": "1.5"
        },
        {
          "name": "brkcalc-type",
          "type": "select-one",
          "label": "Brick Type",
          "unit": "",
          "options": [
            "uk",
            "metric",
            "imperial",
            "modular",
            "engineering"
          ],
          "default": "uk"
        },
        {
          "name": "brkcalc-bond",
          "type": "select-one",
          "label": "Bond Pattern",
          "unit": "",
          "options": [
            "stretcher",
            "english",
            "flemish",
            "header"
          ],
          "default": "stretcher"
        },
        {
          "name": "brkcalc-joint",
          "type": "select-one",
          "label": "Mortar Joint",
          "unit": "mm",
          "options": [
            "10",
            "8",
            "12"
          ],
          "default": "10"
        },
        {
          "name": "brkcalc-waste",
          "type": "select-one",
          "label": "Waste Allowance",
          "unit": "",
          "options": [
            "5",
            "10",
            "15"
          ],
          "default": "10"
        }
      ],
      "outputs": [
        {
          "name": "brkcalc-result",
          "type": "output"
        },
        {
          "name": "brkcalc-total",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=brick-calculator&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=brick-calculator&brkcalc-w=6&brkcalc-h=2.4&brkcalc-openings=1.5&brkcalc-type=uk&brkcalc-bond=stretcher&brkcalc-joint=10&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "brick",
        "home",
        "diy",
        "calculate",
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      ],
      "popularity": 4878,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "british-monarchs-quiz",
      "title": "👑 British Monarchs Quiz",
      "description": "Name the kings and queens of England, Scotland and the UK from 1066 to today — ten questions per round with streaks.",
      "category": "museum-and-collection",
      "categoryName": "Museum & Collection",
      "url": "https://www.themostusefulsiteintheworld.com/tool/british-monarchs-quiz.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=british-monarchs-quiz&embed=1",
      "standaloneUrl": null,
      "inputs": [],
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          "name": "bmq-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=british-monarchs-quiz&<id>=<value>",
        "runs": false
      },
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      "sources": [],
      "tags": [
        "british",
        "monarchs",
        "quiz",
        "museum",
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        "scotland"
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
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      "category": "museum-and-collection",
      "categoryName": "Museum & Collection",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=british-regnal-years&embed=1",
      "standaloneUrl": null,
      "inputs": [
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        },
        {
          "name": "regn-who",
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          "label": "Sovereign",
          "unit": ""
        }
      ],
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          "name": "regn-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=british-regnal-years&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=british-regnal-years&regn-y=1765"
      },
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      "sources": [],
      "tags": [
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        "years",
        "desk",
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      "popularity": 4336,
      "featured": false,
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    },
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      "slug": "budget",
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      "categoryName": "Finance & Money",
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        {
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        {
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        {
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        {
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        {
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          "min": 0,
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      ],
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        {
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        },
        {
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        }
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      "sources": [],
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        "financial",
        "dashboard",
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      "featured": false,
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      "standaloneUrl": null,
      "inputs": [
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          "max": 60,
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=buffons-needle-pi&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "buffons",
        "needle",
        "buffon",
        "mind-blowing",
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        "1777",
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      "popularity": 4453,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
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      "title": "🔨 Virtual Builder's Workmate",
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      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/builders-workmate.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=builders-workmate&embed=1",
      "standaloneUrl": null,
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            "protractor",
            "plumb",
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            "measure"
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        {
          "name": "workmate-unit",
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            "metric",
            "imperial"
          ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=builders-workmate&<id>=<value>",
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      "sources": [],
      "tags": [
        "builders",
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        "virtual",
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        "engineering",
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      "popularity": 6723,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "bulk-buy-coop-splitter",
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          "default": "Our Street Food Club"
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          "label": "Kitty float / order",
          "unit": "",
          "min": 0,
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      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=bulk-buy-coop-splitter&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "bulk",
        "buy",
        "coop",
        "splitter",
        "bulk-buy",
        "co-op",
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        "food",
        "bills",
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      "popularity": 6109,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "bulk-filename-preview",
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      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/bulk-filename-preview.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=bulk-filename-preview&embed=1",
      "standaloneUrl": null,
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        {
          "name": "bulk-filename-preview-padding",
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          "label": "Current filenames — one per line holiday beach.jpg holiday cafe.jpg holiday sunset.png",
          "unit": ""
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        {
          "name": "bulk-filename-preview-extension",
          "type": "select-one",
          "label": "Extension case Keep original Lowercase",
          "unit": "",
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            "keep",
            "lower"
          ],
          "default": "keep"
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=bulk-filename-preview&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=bulk-filename-preview&bulk-filename-preview-prefix=holiday-&bulk-filename-preview-start=1&bulk-filename-preview-padding=3&bulk-filename-preview-extension=keep"
      },
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      "sources": [],
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        "bulk",
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        "previewer",
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      "featured": false,
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        {
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          "max": 600,
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        {
          "name": "bcrd-where",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=business-card-size-guide&<id>=<value>",
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        "business",
        "card",
        "size",
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        "productivity",
        "lifestyle",
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        "pixels",
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      "popularity": 5016,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
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      "categoryName": "Finance & Money",
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        {
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          "unit": ""
        },
        {
          "name": "bdwk-inclusive",
          "type": "checkbox",
          "label": "Include both end dates",
          "unit": "",
          "default": "1"
        },
        {
          "name": "bdwk-start",
          "type": "date",
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        {
          "name": "bdwk-n",
          "type": "number",
          "label": "Working days to add",
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          "min": -3650,
          "max": 3650,
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        {
          "name": "bdwk-hols",
          "type": "textarea",
          "label": "Extra holidays (optional, YYYY-MM-DD, comma or newline)",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "bdwk-out",
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        {
          "name": "bdwk-result",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=business-days-working-days-calculator&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=business-days-working-days-calculator&bdwk-inclusive=1&bdwk-n=10&run=1"
      },
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      "tags": [
        "business",
        "days",
        "working",
        "finance",
        "money",
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        "between",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
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      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=business-model-canvas-builder&embed=1",
      "standaloneUrl": null,
      "inputs": [],
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        {
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      },
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      "sources": [],
      "tags": [
        "business",
        "model",
        "canvas",
        "builder",
        "saas",
        "killers",
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        "board",
        "consultants"
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      "popularity": 5247,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "business-name-generator",
      "title": "🏷️ Business & Domain Name Generator",
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      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/business-name-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=business-name-generator&embed=1",
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      "inputs": [
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          "unit": ""
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        {
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          "unit": ""
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        {
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          "type": "checkbox",
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        {
          "name": "bng-industry",
          "type": "select-one",
          "label": "What is it?",
          "unit": ""
        },
        {
          "name": "bng-style",
          "type": "select-one",
          "label": "Style",
          "unit": "",
          "options": [
            "all",
            "modern",
            "classic",
            "playful",
            "invented",
            "local"
          ],
          "default": "modern"
        },
        {
          "name": "bng-sort",
          "type": "select-one",
          "label": "Sort by best overall shortest A–Z fewest syllables",
          "unit": "",
          "options": [
            "score",
            "short",
            "az",
            "syllables"
          ],
          "default": "score"
        }
      ],
      "outputs": [
        {
          "name": "bng-msg",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=business-name-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=business-name-generator&bng-favonly=0&bng-style=modern&bng-sort=score"
      },
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      "sources": [],
      "tags": [
        "business",
        "name",
        "domain",
        "saas",
        "killers",
        "type",
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        "two",
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        "describe"
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      "popularity": 5942,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "business-writing",
      "title": "Business Writing Assistant",
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      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/business-writing.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=business-writing&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bw-purpose",
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          "label": "Purpose",
          "unit": "one sentence"
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        {
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      },
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        "cagr",
        "annual",
        "growth",
        "compound",
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      "updated": "2026-09-19"
    },
    {
      "slug": "candle-making-supplies-calculator",
      "title": "🕯️ Candle Making Supplies Calculator",
      "description": "Fill a jar with water, weigh it, and you’ve measured your candle. Enter vessel size and fragrance load — get wax grams, fragrance grams, wick guidance and a full batch shopping list.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/candle-making-supplies-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=candle-making-supplies-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "number",
          "label": "Diameter",
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          "max": 30,
          "step": 0.1,
          "default": "7"
        },
        {
          "name": "cndl-height",
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          "label": "Fill height",
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          "min": 1,
          "max": 30,
          "step": 0.1,
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        },
        {
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          "type": "number",
          "label": "Fill volume",
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          "min": 10,
          "max": 5000,
          "step": 5,
          "default": "300"
        },
        {
          "name": "cndl-count",
          "type": "number",
          "label": "Candles in batch",
          "unit": "",
          "min": 1,
          "max": 500,
          "step": 1,
          "default": "4"
        },
        {
          "name": "cndl-factor",
          "type": "number",
          "label": "Density factor (g per ml of fill)",
          "unit": "",
          "min": 0.5,
          "max": 1.1,
          "step": 0.01,
          "default": "0.88"
        },
        {
          "name": "cndl-load",
          "type": "number",
          "label": "Fragrance load",
          "unit": "%",
          "min": 0,
          "max": 12,
          "step": 0.5,
          "default": "8"
        },
        {
          "name": "cndl-waste",
          "type": "number",
          "label": "Waste buffer",
          "unit": "%",
          "min": 0,
          "max": 25,
          "step": 1,
          "default": "10"
        },
        {
          "name": "cndl-mode",
          "type": "select-one",
          "label": "Measure the vessel by",
          "unit": "",
          "options": [
            "dims",
            "vol"
          ],
          "default": "dims"
        },
        {
          "name": "cndl-wax",
          "type": "select-one",
          "label": "Wax",
          "unit": "",
          "options": [
            "soy",
            "paraffin",
            "coconut",
            "beeswax",
            "custom"
          ],
          "default": "soy"
        }
      ],
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        {
          "name": "cndl-out",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=candle-making-supplies-calculator&<id>=<value>",
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      },
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        "candle",
        "making",
        "supplies",
        "productivity",
        "lifestyle",
        "fill",
        "jar",
        "water",
        "weigh",
        "measured"
      ],
      "popularity": 5040,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "candy-sugar-stages-calculator",
      "title": "🍬 Candy & Sugar Stages Guide",
      "description": "Confectionery science & sugar crystallization guide. Features automatic boiling-point elevation correction, cold-water ball test simulations, and invert sugar balancing.",
      "category": "culinary-and-food-science",
      "categoryName": "Culinary & Food Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/candy-sugar-stages-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=candy-sugar-stages-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "max": 8000,
          "step": 500,
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        {
          "name": "cs-stage-select",
          "type": "select-one",
          "label": "Candy Stage Preset",
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            "thread",
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            "hard-ball",
            "soft-crack",
            "hard-crack",
            "light-caramel",
            "dark-caramel"
          ],
          "default": "soft-ball"
        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=candy-sugar-stages-calculator&<id>=<value>",
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      },
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      "sources": [],
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        "candy",
        "sugar",
        "stages",
        "guide",
        "culinary",
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        "confectionery",
        "crystallization",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "capacitor-calculator",
      "title": "Capacitor Calculator",
      "description": "Calculate capacitor values, RC time constants, impedance, and filter characteristics. ⚠️ Educational only — verify with datasheets and professional standards.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/capacitor-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=capacitor-calculator&embed=1",
      "standaloneUrl": null,
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        {
          "name": "cap-R",
          "type": "number",
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          "min": 0
        },
        {
          "name": "cap-C",
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          "label": "Capacitance",
          "unit": "",
          "min": 0
        },
        {
          "name": "cap-f",
          "type": "number",
          "label": "Frequency",
          "unit": "Hz",
          "min": 0
        },
        {
          "name": "cap-voltage",
          "type": "number",
          "label": "Voltage",
          "unit": "V",
          "min": 0
        },
        {
          "name": "cap-cap2",
          "type": "number",
          "label": "Capacitor 2 (for series/parallel)",
          "unit": "",
          "min": 0
        },
        {
          "name": "cap-temperature",
          "type": "number",
          "label": "Temperature",
          "unit": "°C",
          "default": "25"
        },
        {
          "name": "cap-esr",
          "type": "number",
          "label": "ESR",
          "unit": "Ω"
        },
        {
          "name": "cap-mode",
          "type": "select-one",
          "label": "Calculation Mode",
          "unit": "",
          "options": [
            "findC",
            "findF",
            "time-constant",
            "impedance",
            "filter-design",
            "series-parallel",
            "energy"
          ],
          "default": "findF"
        },
        {
          "name": "cap-C-multiplier",
          "type": "select-one",
          "label": "C multiplier",
          "unit": "",
          "options": [
            "1e-6",
            "1e-9",
            "1e-12",
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          ],
          "default": "1e-6"
        },
        {
          "name": "cap-show-advanced",
          "type": "select-one",
          "label": "Advanced Options",
          "unit": "",
          "options": [
            "no",
            "yes"
          ],
          "default": "no"
        },
        {
          "name": "cap-quality",
          "type": "select-one",
          "label": "Capacitor Type",
          "unit": "",
          "options": [
            "ceramic",
            "electrolytic",
            "film",
            "tantalum",
            "mica"
          ],
          "default": "ceramic"
        },
        {
          "name": "cap-tolerance",
          "type": "select-one",
          "label": "Tolerance",
          "unit": "%",
          "options": [
            "1",
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            "10",
            "20",
            "50"
          ],
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      ],
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        {
          "name": "cap-formula-display",
          "type": "output"
        },
        {
          "name": "cap-output",
          "type": "output"
        },
        {
          "name": "cap-mode-display",
          "type": "output"
        },
        {
          "name": "cap-tau-display",
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          "name": "cap-f0-display",
          "type": "output"
        }
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      },
      "formula": "Result Save Config Results f = 1/",
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        "capacitor",
        "science",
        "engineering",
        "calculate",
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        "impedance",
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      "featured": false,
      "updated": "2026-09-19"
    },
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      "slug": "capo-calculator",
      "title": "🎸 Capo Calculator",
      "description": "Find capo placement for key transposition, chord conversion, and song adaptation. Supports sharps/flats, multiple fret options, and tuning adjustments.",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=capo-calculator&embed=1",
      "standaloneUrl": null,
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          "name": "capo-chord",
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          "label": "Specific Chord",
          "unit": ""
        },
        {
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          "type": "select-one",
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          "unit": "",
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            "C",
            "C#",
            "D",
            "D#",
            "E",
            "F",
            "F#",
            "G",
            "G#",
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            "A#",
            "B"
          ],
          "default": "G"
        },
        {
          "name": "capo-target",
          "type": "select-one",
          "label": "Target Key",
          "unit": "",
          "options": [
            "C",
            "C#",
            "D",
            "D#",
            "E",
            "F",
            "F#",
            "G",
            "G#",
            "A",
            "A#",
            "B"
          ],
          "default": "C"
        },
        {
          "name": "capo-tuning",
          "type": "select-one",
          "label": "Tuning",
          "unit": "",
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            "standard",
            "dropD",
            "half-step",
            "full-step",
            "openG",
            "openD",
            "dadgad"
          ],
          "default": "standard"
        },
        {
          "name": "capo-type",
          "type": "select-one",
          "label": "Capo Type",
          "unit": "",
          "options": [
            "spring",
            "screw",
            "strap",
            "partial",
            "shubb"
          ],
          "default": "spring"
        },
        {
          "name": "capo-show-chords",
          "type": "select-one",
          "label": "Show Chord Conversion",
          "unit": "",
          "options": [
            "yes",
            "no"
          ],
          "default": "yes"
        },
        {
          "name": "capo-max-fret",
          "type": "select-one",
          "label": "Max Fret Display",
          "unit": "",
          "options": [
            "5",
            "7",
            "9",
            "12"
          ],
          "default": "7"
        }
      ],
      "outputs": [
        {
          "name": "capo-results",
          "type": "output"
        },
        {
          "name": "capo-interval-display",
          "type": "output"
        },
        {
          "name": "capo-result-display",
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        }
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=capo-calculator&<id>=<value>",
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      },
      "formula": "A capo raises pitch by one semitone per fret. Fret 1 = +1 semitone, Fret 2 = +",
      "sources": [],
      "tags": [
        "capo",
        "music",
        "audio",
        "find",
        "placement",
        "key",
        "transposition",
        "chord",
        "conversion",
        "song"
      ],
      "popularity": 6198,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "car-care-tracker",
      "title": "🚗 Car Care & MOT Due-Date Tracker",
      "description": "Keeps the dates that are easy to miss and expensive to miss in one place: MOT, tax, insurance, service intervals, and the four items that actually cause MOT failures. Saved in your browser only — n...",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/car-care-tracker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=car-care-tracker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cct-name",
          "type": "text",
          "label": "Car (for your own reference)",
          "unit": ""
        },
        {
          "name": "cct-reg",
          "type": "date",
          "label": "First registered",
          "unit": ""
        },
        {
          "name": "cct-lastmot",
          "type": "date",
          "label": "Last MOT passed",
          "unit": ""
        },
        {
          "name": "cct-mileage",
          "type": "number",
          "label": "Mileage now",
          "unit": "",
          "min": 0,
          "step": 100
        },
        {
          "name": "cct-lastservice",
          "type": "number",
          "label": "Mileage at last service",
          "unit": "",
          "min": 0,
          "step": 100
        },
        {
          "name": "cct-insurance",
          "type": "date",
          "label": "Insurance renews",
          "unit": ""
        },
        {
          "name": "cct-tax",
          "type": "date",
          "label": "Road tax renews",
          "unit": ""
        },
        {
          "name": "cct-motcost",
          "type": "number",
          "label": "Cost per mile",
          "unit": "p",
          "min": 0,
          "step": 0.5
        },
        {
          "name": "cct-annualmi",
          "type": "number",
          "label": "Miles driven a year",
          "unit": "",
          "min": 0,
          "step": 500
        },
        {
          "name": "cct-fl",
          "type": "number",
          "label": "Front left",
          "unit": "",
          "min": 0,
          "max": 12,
          "step": 0.1
        },
        {
          "name": "cct-fr",
          "type": "number",
          "label": "Front right",
          "unit": "",
          "min": 0,
          "max": 12,
          "step": 0.1
        },
        {
          "name": "cct-rl",
          "type": "number",
          "label": "Rear left",
          "unit": "",
          "min": 0,
          "max": 12,
          "step": 0.1
        },
        {
          "name": "cct-rr",
          "type": "number",
          "label": "Rear right",
          "unit": "",
          "min": 0,
          "max": 12,
          "step": 0.1
        },
        {
          "name": "cct-servicemi",
          "type": "select-one",
          "label": "Service interval",
          "unit": "miles",
          "options": [
            "8000",
            "10000",
            "12500",
            "18000"
          ],
          "default": "10000"
        }
      ],
      "outputs": [
        {
          "name": "cct-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=car-care-tracker&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "car",
        "care",
        "tracker",
        "mot",
        "due-date",
        "home",
        "diy",
        "keeps",
        "dates",
        "easy"
      ],
      "popularity": 6565,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "car-ownership-cost-calculator",
      "title": "🚗 Car Ownership Cost Calculator (UK)",
      "description": "Work out the true cost of running a car in the UK — depreciation, fuel or electricity, insurance, VED road tax, servicing, MOT, tyres and repairs — per month and per mile. Everything calculates loc...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/car-ownership-cost-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=car-ownership-cost-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "co-price",
          "type": "number",
          "label": "Purchase price",
          "unit": "£",
          "min": 0,
          "default": "18000"
        },
        {
          "name": "co-resale",
          "type": "number",
          "label": "Resale value after 3 yrs",
          "unit": "£",
          "min": 0,
          "default": "9000"
        },
        {
          "name": "co-years",
          "type": "number",
          "label": "Own it for",
          "unit": "years",
          "min": 1,
          "max": 12,
          "default": "3"
        },
        {
          "name": "co-miles",
          "type": "number",
          "label": "Annual miles",
          "unit": "",
          "min": 0,
          "default": "9000"
        },
        {
          "name": "co-mpg",
          "type": "number",
          "label": "MPG / kWh per 100 mi",
          "unit": "",
          "min": 1,
          "step": 0.1,
          "default": "40"
        },
        {
          "name": "co-price2",
          "type": "number",
          "label": "Fuel price",
          "unit": "£/L or £/kWh",
          "min": 0,
          "step": 0.01,
          "default": "1.45"
        },
        {
          "name": "co-ins",
          "type": "number",
          "label": "Insurance",
          "unit": "£/yr",
          "min": 0,
          "default": "650"
        },
        {
          "name": "co-ved",
          "type": "number",
          "label": "VED road tax",
          "unit": "£/yr",
          "min": 0,
          "default": "195"
        },
        {
          "name": "co-service",
          "type": "number",
          "label": "Servicing & repairs",
          "unit": "£/yr",
          "min": 0,
          "default": "450"
        },
        {
          "name": "co-fueltype",
          "type": "select-one",
          "label": "Fuel type",
          "unit": "",
          "options": [
            "petrol",
            "diesel",
            "ev",
            "hybrid"
          ],
          "default": "petrol"
        }
      ],
      "outputs": [
        {
          "name": "co-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=car-ownership-cost-calculator&<id>=<value>",
        "runs": true,
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "car",
        "ownership",
        "cost",
        "finance",
        "money",
        "work",
        "out",
        "true",
        "running",
        "depreciation"
      ],
      "popularity": 6883,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "care-handover-sheet",
      "title": "🤝 Care Handover Sheet",
      "description": "Make a clear, temporary handover for someone caring for a child, adult or pet: contacts, routines, practical preferences, access and instructions already agreed with the person or care team. Build ...",
      "category": "wellbeing-and-community",
      "categoryName": "Wellbeing & Community",
      "url": "https://www.themostusefulsiteintheworld.com/tool/care-handover-sheet.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=care-handover-sheet&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "care-handover-sheet-person",
          "type": "text",
          "label": "Person / pet this is for",
          "unit": ""
        },
        {
          "name": "care-handover-sheet-date",
          "type": "date",
          "label": "Handover date",
          "unit": ""
        },
        {
          "name": "care-handover-sheet-prepared-by",
          "type": "text",
          "label": "Prepared by",
          "unit": ""
        },
        {
          "name": "care-handover-sheet-carer",
          "type": "text",
          "label": "Caregiver / best way to reach them",
          "unit": ""
        },
        {
          "name": "care-handover-sheet-primary",
          "type": "text",
          "label": "Primary contact",
          "unit": ""
        },
        {
          "name": "care-handover-sheet-backup",
          "type": "text",
          "label": "Backup contact",
          "unit": ""
        },
        {
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          "label": "Where the current written care plan is kept",
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          "label": "Usual routine / timings",
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          "name": "care-handover-sheet-food",
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          "name": "care-handover-sheet-comfort",
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          "label": "What helps them feel comfortable",
          "unit": ""
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        {
          "name": "care-handover-sheet-collection",
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          "unit": ""
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          "unit": ""
        },
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          "name": "care-handover-sheet-escalation",
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          "label": "What to do if plans change or extra help is needed",
          "unit": ""
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        },
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          "type": "textarea",
          "label": "Generated handover",
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          "name": "care-handover-sheet-status",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=care-handover-sheet&<id>=<value>",
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      },
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      "sources": [],
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    },
    {
      "slug": "careerpath",
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      "category": "productivity-and-lifestyle",
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      "url": "https://www.themostusefulsiteintheworld.com/tool/careerpath.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=careerpath&embed=1",
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          "options": [
            "6",
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            "low",
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          "name": "careerpath-status",
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        {
          "name": "careerpath-filter-industry",
          "type": "select-one",
          "label": "careerpath filter industry",
          "unit": "",
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            "tech",
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        {
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          "type": "select-one",
          "label": "careerpath filter priority",
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        {
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          "unit": "",
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            "not-started",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=careerpath&<id>=<value>",
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        "careerpath",
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      "featured": false,
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    },
    {
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      "categoryName": "Wellbeing & Community",
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          "label": "What settles them",
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          "label": "What you do",
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        "carer",
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      "slug": "carol-karaoke",
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      "category": "music-and-audio",
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            "all-i-want",
            "last-christmas",
            "rockin-around",
            "wonderful-christmas",
            "hark-herald",
            "o-come",
            "o-holy-night",
            "away-in-manger"
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          "default": "jingle-bells"
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        {
          "name": "ck-difficulty",
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            "easy",
            "medium",
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            "expert"
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        }
      ],
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        {
          "name": "ck-key-display",
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        },
        {
          "name": "ck-tempo-display",
          "type": "output"
        },
        {
          "name": "ck-volume-display",
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        },
        {
          "name": "ck-stat-score",
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          "name": "ck-notes-display",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=carol-karaoke&<id>=<value>",
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
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        "carol",
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      "featured": false,
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      "slug": "cartographers-world-forge",
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      "categoryName": "Productivity & Lifestyle",
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        {
          "name": "cwf-civ",
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        {
          "name": "cwf-type",
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            "continent",
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            "pangaea",
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        {
          "name": "cwf-style",
          "type": "select-one",
          "label": "Map Style",
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          "options": [
            "parchment",
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            "relief"
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=cartographers-world-forge&<id>=<value>",
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      },
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      "sources": [],
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        "cartographers",
        "world",
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        "cartographer",
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      "slug": "cat-age-life-stage-calculator",
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        {
          "name": "cas-years",
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        },
        {
          "name": "cas-months",
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        },
        {
          "name": "cas-asat",
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          "label": "Age as at",
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        },
        {
          "name": "cas-mode",
          "type": "select-one",
          "label": "What do you know?",
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            "dob",
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      "sources": [],
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        "cat",
        "age",
        "life",
        "stage",
        "life-stage",
        "cats",
        "feline",
        "care",
        "turn",
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      "featured": false,
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    },
    {
      "slug": "cat-calorie-portion-calculator",
      "title": "🐈 Cat Calorie & Portion Calculator",
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      "category": "cats-and-feline-care",
      "categoryName": "Cats & Feline Care",
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        },
        {
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        },
        {
          "name": "ccp-dry-kcal",
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        },
        {
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          "step": 1,
          "default": "85"
        },
        {
          "name": "ccp-unit",
          "type": "select-one",
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          "options": [
            "kg",
            "lb"
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          "default": "kg"
        },
        {
          "name": "ccp-bcs",
          "type": "select-one",
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          "unit": "",
          "options": [
            "3",
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        {
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          "default": "neutered"
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        {
          "name": "ccp-meals",
          "type": "select-one",
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          "unit": "",
          "options": [
            "2",
            "3",
            "4",
            "5"
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        {
          "name": "ccp-mix",
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            "dry100",
            "dry75",
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            "wet75",
            "wet100"
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      },
      "formula": "The formula. Resting energy requirement (RER) = 70 × (body weight in kg) 0.75 . The daily target is RER multiplied by a life-",
      "sources": [],
      "tags": [
        "cat",
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        "cats",
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        "work",
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    },
    {
      "slug": "cat-litter-tray-planner",
      "title": "🧺 Cat Litter & Tray Planner",
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      "category": "cats-and-feline-care",
      "categoryName": "Cats & Feline Care",
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          "step": 1,
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        },
        {
          "name": "clt-length",
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          "label": "Largest cat, nose to tail base",
          "unit": "cm",
          "min": 20,
          "max": 90,
          "step": 1,
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        },
        {
          "name": "clt-bag",
          "type": "number",
          "label": "Bag size",
          "unit": "litres",
          "min": 1,
          "max": 30,
          "step": 1,
          "default": "10"
        },
        {
          "name": "clt-price",
          "type": "number",
          "label": "Price per bag",
          "unit": "£",
          "min": 0,
          "max": 60,
          "step": 0.5,
          "default": "8"
        },
        {
          "name": "clt-tray",
          "type": "select-one",
          "label": "Tray you use (or plan to buy)",
          "unit": "",
          "options": [
            "50x40",
            "58x45",
            "70x50",
            "84x50"
          ],
          "default": "70x50"
        },
        {
          "name": "clt-depth",
          "type": "select-one",
          "label": "Litter depth",
          "unit": "",
          "options": [
            "3",
            "4",
            "5"
          ],
          "default": "4"
        },
        {
          "name": "clt-litter",
          "type": "select-one",
          "label": "Litter type",
          "unit": "",
          "options": [
            "clay",
            "nonclay",
            "wood",
            "tofu",
            "silica"
          ],
          "default": "clay"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=cat-litter-tray-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=cat-litter-tray-planner&clt-cats=1&clt-length=45&clt-bag=10&clt-price=8&clt-tray=70x50&clt-depth=4"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "cat",
        "litter",
        "tray",
        "planner",
        "cats",
        "feline",
        "care",
        "work",
        "out",
        "how"
      ],
      "popularity": 5881,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "cat-photo-viewer",
      "title": "Cat Photo Viewer",
      "description": "Browse cat photos from free public APIs. Features infinite scrolling, favorites, and breed info.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/cat-photo-viewer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=cat-photo-viewer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cpv-breed",
          "type": "select-one",
          "label": "Breed",
          "unit": "",
          "options": [
            "all",
            "abys",
            "beng",
            "birm",
            "bsho",
            "pers",
            "mcoo",
            "siam",
            "ragd",
            "sphy",
            "norw"
          ],
          "default": "all"
        },
        {
          "name": "cpv-order",
          "type": "select-one",
          "label": "Order",
          "unit": "",
          "options": [
            "RANDOM",
            "ASC",
            "DESC"
          ],
          "default": "RANDOM"
        }
      ],
      "outputs": [
        {
          "name": "cpv-count-display",
          "type": "output"
        },
        {
          "name": "cpv-output",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=cat-photo-viewer&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=cat-photo-viewer&cpv-breed=all&cpv-order=RANDOM"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "cat",
        "photo",
        "viewer",
        "productivity",
        "lifestyle",
        "browse",
        "photos",
        "public",
        "apis",
        "features"
      ],
      "popularity": 6820,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "cat-poison-household-hazard-checker",
      "title": "🚨 Cat Poison & Household Hazard Checker",
      "description": "Search 50+ foods, medicines, plants and household products for how dangerous they are to cats, what to watch for and what to do first — with the UK emergency steps and helplines at the top.",
      "category": "cats-and-feline-care",
      "categoryName": "Cats & Feline Care",
      "url": "https://www.themostusefulsiteintheworld.com/tool/cat-poison-household-hazard-checker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=cat-poison-household-hazard-checker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cph-query",
          "type": "text",
          "label": "Search — name, brand or plant",
          "unit": ""
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        {
          "name": "cph-class",
          "type": "select-one",
          "label": "Category",
          "unit": "",
          "options": [
            "all",
            "Food &amp; drink",
            "Medicines",
            "Plants",
            "Household &amp; garden",
            "Pet products",
            "Hazards"
          ],
          "default": "all"
        }
      ],
      "outputs": [
        {
          "name": "cph-count",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=cat-poison-household-hazard-checker&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=cat-poison-household-hazard-checker&cph-class=all"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "cat",
        "poison",
        "household",
        "hazard",
        "checker",
        "cats",
        "feline",
        "care",
        "search",
        "foods"
      ],
      "popularity": 4518,
      "featured": false,
      "updated": "2026-09-19"
    },
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      "slug": "cat-pregnancy-kitten-timeline",
      "title": "🍼 Cat Pregnancy & Kitten Timeline",
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      "category": "cats-and-feline-care",
      "categoryName": "Cats & Feline Care",
      "url": "https://www.themostusefulsiteintheworld.com/tool/cat-pregnancy-kitten-timeline.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=cat-pregnancy-kitten-timeline&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cpk-mating",
          "type": "date",
          "label": "Date of the first mating",
          "unit": "day 0"
        },
        {
          "name": "cpk-birth",
          "type": "date",
          "label": "Date the kittens were born",
          "unit": ""
        },
        {
          "name": "cpk-mode",
          "type": "select-one",
          "label": "Track",
          "unit": "",
          "options": [
            "queen",
            "kittens"
          ],
          "default": "queen"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=cat-pregnancy-kitten-timeline&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=cat-pregnancy-kitten-timeline&cpk-mode=queen"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "cat",
        "pregnancy",
        "kitten",
        "timeline",
        "cats",
        "feline",
        "care",
        "date",
        "queen",
        "mating"
      ],
      "popularity": 5552,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "cellular-automata-explorer",
      "title": "🔲 Cellular Automata Explorer",
      "description": "One row of cells and one rule decides the next row from each cell's three neighbours. Rule 30 churns out pure randomness, Rule 90 grows a Sierpinski triangle, and Rule 110 is powerful enough to com...",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/cellular-automata-explorer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=cellular-automata-explorer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cel-rule",
          "type": "number",
          "label": "Custom",
          "unit": "",
          "min": 0,
          "max": 255,
          "default": "30"
        }
      ],
      "outputs": [
        {
          "name": "cel-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=cellular-automata-explorer&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=cellular-automata-explorer&cel-rule=30"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "cellular",
        "automata",
        "explorer",
        "algorithms",
        "computer",
        "science",
        "one",
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        "cells",
        "rule"
      ],
      "popularity": 6623,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "celsius-fahrenheit-kelvin-converter",
      "title": "🌡️ Celsius ⇄ Fahrenheit ⇄ Kelvin",
      "description": "°F = °C × 9/5 + 32. Kelvin = °C + 273.15. Absolute zero is 0 K (−273.15 °C). Edit any box — weather, ovens and science labs all use different scales.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/celsius-fahrenheit-kelvin-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=celsius-fahrenheit-kelvin-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tmpk-c",
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          "label": "Celsius",
          "unit": "",
          "default": "20"
        },
        {
          "name": "tmpk-f",
          "type": "number",
          "label": "Fahrenheit",
          "unit": ""
        },
        {
          "name": "tmpk-k",
          "type": "number",
          "label": "Kelvin",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "tmpk-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=celsius-fahrenheit-kelvin-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=celsius-fahrenheit-kelvin-converter&tmpk-c=20"
      },
      "formula": "Celsius ⇄ Fahrenheit ⇄ Kelvin °F = °C × 9/5 + 32. Kelvin = °C +",
      "sources": [],
      "tags": [
        "celsius",
        "fahrenheit",
        "kelvin",
        "converter",
        "science",
        "engineering",
        "273",
        "absolute",
        "zero",
        "edit"
      ],
      "popularity": 6460,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "censorship-monitor",
      "title": "🌐 Censorship Monitor",
      "description": "Monitor Wikipedia blocks and Reddit content moderation in real-time. ⚠️ Educational tool - uses public APIs",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/censorship-monitor.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=censorship-monitor&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "censor-keyword",
          "type": "text",
          "label": "Keyword Filter",
          "unit": ""
        },
        {
          "name": "censor-region",
          "type": "select-one",
          "label": "Filter by Country",
          "unit": "",
          "options": [
            "all",
            "us",
            "china",
            "russia",
            "india",
            "iran"
          ],
          "default": "all"
        },
        {
          "name": "censor-limit",
          "type": "select-one",
          "label": "Show Items",
          "unit": "",
          "options": [
            "5",
            "10",
            "15",
            "20"
          ],
          "default": "10"
        }
      ],
      "outputs": [
        {
          "name": "censor-output",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=censorship-monitor&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=censorship-monitor&censor-region=all&censor-limit=10"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "censorship",
        "monitor",
        "productivity",
        "lifestyle",
        "wikipedia",
        "blocks",
        "reddit",
        "content",
        "moderation",
        "real-time"
      ],
      "popularity": 5869,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "chads2vasc-hasbled-calculator",
      "title": "❤️ CHA₂DS₂-VASc & HAS-BLED Calculator",
      "description": "Stroke risk and bleeding risk for atrial fibrillation side by side, with the sex-adjusted anticoagulation thresholds, the Friberg annual stroke rates, and the modifiable-risk checklist that HAS-BLE...",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/chads2vasc-hasbled-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=chads2vasc-hasbled-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "number",
          "label": "Age",
          "unit": "years",
          "min": 0,
          "max": 120,
          "step": 1,
          "default": "72"
        },
        {
          "name": "chav-sex",
          "type": "select-one",
          "label": "Sex",
          "unit": "",
          "options": [
            "m",
            "f"
          ],
          "default": "m"
        }
      ],
      "outputs": [
        {
          "name": "chav-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=chads2vasc-hasbled-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=chads2vasc-hasbled-calculator&chav-age=72&chav-sex=m"
      },
      "formula": "TIA (2) + female (1) = 6 , annual stroke risk about 9.7 %, anticoagulation clearly indicated. HAS-",
      "sources": [],
      "tags": [
        "chads2vasc",
        "hasbled",
        "cha",
        "-vasc",
        "has-bled",
        "health",
        "fitness",
        "stroke",
        "risk",
        "bleeding"
      ],
      "popularity": 5473,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "chaotic-magnetic-pendulum",
      "title": "🧭 Chaotic Magnetic Pendulum",
      "description": "Nonlinear chaos theory exhibit. A metallic pendulum swings over three magnetic attractors, demonstrating sensitive dependence on initial conditions.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/chaotic-magnetic-pendulum.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=chaotic-magnetic-pendulum&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cmp-slider-mag",
          "type": "range",
          "label": "slider mag",
          "unit": "",
          "min": 0.5,
          "max": 3.5,
          "step": 0.1,
          "default": "1.8"
        },
        {
          "name": "cmp-slider-damp",
          "type": "range",
          "label": "slider damp",
          "unit": "",
          "min": 0.002,
          "max": 0.05,
          "step": 0.002,
          "default": "0.015"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=chaotic-magnetic-pendulum&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=chaotic-magnetic-pendulum&cmp-slider-mag=1.8&cmp-slider-damp=0.015"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "chaotic",
        "magnetic",
        "pendulum",
        "science",
        "engineering",
        "nonlinear",
        "chaos",
        "theory",
        "exhibit",
        "metallic"
      ],
      "popularity": 6649,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "character-limit-platform-counter",
      "title": "🔤 Platform Character Counter",
      "description": "Count characters against the live limits for X/Twitter, SMS, Google titles, Instagram, LinkedIn and more. Everything stays in this box — no draft is uploaded.",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/character-limit-platform-counter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=character-limit-platform-counter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "chlt-text",
          "type": "textarea",
          "label": "Your text",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=character-limit-platform-counter&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "character",
        "limit",
        "platform",
        "counter",
        "writing",
        "language",
        "count",
        "characters",
        "against",
        "live"
      ],
      "popularity": 5864,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "cheap-flight-fare-finder",
      "title": "✈️ Cheap Flight Fare Finder",
      "description": "Work out what a genuinely cheap fare looks like on your route, then jump straight into the right searches. Pick your airports, say when you want to travel and type the best price you have found: th...",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/cheap-flight-fare-finder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=cheap-flight-fare-finder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cff-from",
          "type": "text",
          "label": "From",
          "unit": "airport",
          "default": "LTN"
        },
        {
          "name": "cff-to",
          "type": "text",
          "label": "To",
          "unit": "airport",
          "default": "BCN"
        },
        {
          "name": "cff-out",
          "type": "date",
          "label": "Outbound date",
          "unit": ""
        },
        {
          "name": "cff-back",
          "type": "date",
          "label": "Return date",
          "unit": ""
        },
        {
          "name": "cff-pax",
          "type": "number",
          "label": "Passengers",
          "unit": "",
          "min": 1,
          "max": 9,
          "step": 1,
          "default": "1"
        },
        {
          "name": "cff-price",
          "type": "number",
          "label": "Best price found",
          "unit": "per person",
          "min": 0,
          "default": "120"
        },
        {
          "name": "cff-flex",
          "type": "checkbox",
          "label": "Dates are flexible",
          "unit": "±3 days",
          "default": "1"
        },
        {
          "name": "cff-bags",
          "type": "checkbox",
          "label": "I need a checked bag",
          "unit": "",
          "default": "0"
        },
        {
          "name": "cff-direct",
          "type": "checkbox",
          "label": "Direct flights only",
          "unit": "",
          "default": "0"
        },
        {
          "name": "cff-trip",
          "type": "select-one",
          "label": "Trip type",
          "unit": "",
          "options": [
            "round",
            "one"
          ],
          "default": "round"
        },
        {
          "name": "cff-cabin",
          "type": "select-one",
          "label": "Cabin",
          "unit": "",
          "options": [
            "1",
            "1.6",
            "3.2",
            "5.5"
          ],
          "default": "1"
        },
        {
          "name": "cff-cur",
          "type": "select-one",
          "label": "Currency",
          "unit": "",
          "options": [
            "GBP",
            "EUR",
            "USD"
          ],
          "default": "GBP"
        }
      ],
      "outputs": [
        {
          "name": "cff-out-panel",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=cheap-flight-fare-finder&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=cheap-flight-fare-finder&cff-from=LTN&cff-to=BCN&cff-pax=1&cff-price=120&cff-flex=1&cff-bags=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "cheap",
        "flight",
        "fare",
        "finder",
        "productivity",
        "lifestyle",
        "work",
        "out",
        "what",
        "genuinely"
      ],
      "popularity": 5214,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "chemical-solution-dilution",
      "title": "🧪 Solution Dilution Lab",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=christmas-naughty-list-quiz&<id>=<value>",
        "runs": false
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      "sources": [],
      "tags": [
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      "sources": [],
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        "chrono",
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    {
      "slug": "circuit-calculator",
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      "categoryName": "Science & Engineering",
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          "name": "cc-phase",
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        "circuit",
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      "slug": "citation",
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        {
          "name": "cg-results",
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        {
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      "slug": "classical-cipher-suite",
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      "category": "algorithms-and-computer-science",
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        {
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          "type": "textarea",
          "label": "input",
          "unit": ""
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        {
          "name": "cip-cipher",
          "type": "select-one",
          "label": "Cipher",
          "unit": "",
          "options": [
            "caesar",
            "atbash",
            "rot13",
            "vigenere"
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          "default": "caesar"
        },
        {
          "name": "cip-mode",
          "type": "select-one",
          "label": "Mode",
          "unit": "",
          "options": [
            "encrypt",
            "decrypt"
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          "default": "encrypt"
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=classical-cipher-suite&<id>=<value>",
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      "sources": [],
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        "classical",
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      "popularity": 5286,
      "featured": false,
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      "slug": "cleaning",
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      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/cleaning.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=cleaning&embed=1",
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          "label": "Room/Area",
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        {
          "name": "cleaning-date",
          "type": "date",
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          "unit": ""
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        {
          "name": "cleaning-priority",
          "type": "select-one",
          "label": "Priority",
          "unit": "",
          "options": [
            "low",
            "medium",
            "high",
            "urgent"
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          "default": "medium"
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        {
          "name": "cleaning-recurrence",
          "type": "select-one",
          "label": "Recurrence",
          "unit": "",
          "options": [
            "once",
            "daily",
            "weekly",
            "biweekly",
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          "default": "once"
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=cleaning&<id>=<value>",
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "cleaning",
        "schedule",
        "productivity",
        "lifestyle",
        "plan",
        "track",
        "manage",
        "tasks",
        "smart",
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      "popularity": 4281,
      "featured": false,
      "updated": "2026-09-19"
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    {
      "slug": "clientflow-pro",
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      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=clientflow-pro&embed=1",
      "standaloneUrl": null,
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          "default": "Studio North Ltd"
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          "name": "cfpro-biz-email",
          "type": "text",
          "label": "Email · phone",
          "unit": "",
          "default": "hello@studionorth.co · +44 7700 900123"
        },
        {
          "name": "cfpro-biz-addr",
          "type": "text",
          "label": "Address",
          "unit": "",
          "default": "12 Hoxton Street, London N1 6NG · VAT 123 4567 89"
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        {
          "name": "cfpro-biz-logo-text",
          "type": "text",
          "label": "Logo text (e.g. SN)",
          "unit": "",
          "default": "SN"
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        {
          "name": "cfpro-accent",
          "type": "color",
          "label": "Brand colour",
          "unit": "",
          "default": "#ffd700"
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          "name": "cfpro-client-name",
          "type": "text",
          "label": "Client name / company",
          "unit": "",
          "default": "Apex Global Technologies Inc."
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        {
          "name": "cfpro-client-email",
          "type": "text",
          "label": "Client email",
          "unit": "",
          "default": "finance@apexglobal.tech"
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        {
          "name": "cfpro-doc-no",
          "type": "text",
          "label": "Document number",
          "unit": "",
          "default": "Q-2026-0042"
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        {
          "name": "cfpro-date",
          "type": "date",
          "label": "Issue date",
          "unit": ""
        },
        {
          "name": "cfpro-due",
          "type": "date",
          "label": "Due / valid",
          "unit": ""
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        {
          "name": "cfpro-tax-rate",
          "type": "number",
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          "unit": "",
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          "max": 30,
          "step": 0.5,
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        {
          "name": "cfpro-discount",
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          "unit": "",
          "min": 0,
          "step": 10,
          "default": "0"
        },
        {
          "name": "cfpro-pay-link",
          "type": "text",
          "label": "PayPal.me / Stripe link — e.g. https://paypal.me/russellhead/500GBP",
          "unit": "",
          "default": "https://paypal.me/russellhead/"
        },
        {
          "name": "cfpro-sig-typed",
          "type": "text",
          "label": "Type",
          "unit": ""
        },
        {
          "name": "cfpro-sig-you-name",
          "type": "text",
          "label": "Your printed name",
          "unit": "",
          "default": "Alex Rivera — Studio North"
        },
        {
          "name": "cfpro-sig-you-date",
          "type": "date",
          "label": "Your signature date",
          "unit": ""
        },
        {
          "name": "cfpro-sig-client-name",
          "type": "text",
          "label": "Client printed name",
          "unit": ""
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        {
          "name": "cfpro-sig-client-date",
          "type": "date",
          "label": "Client signature date",
          "unit": ""
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        {
          "name": "cfpro-notes",
          "type": "textarea",
          "label": "Notes / payment instructions — e.g. Bank: 04-00-04 12345678 · PayPal: hello@studionorth.co · Solana: 7Nxu…",
          "unit": ""
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        {
          "name": "cfpro-doc-type",
          "type": "select-one",
          "label": "Document type",
          "unit": "",
          "options": [
            "quote",
            "invoice",
            "contract"
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          "default": "quote"
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        {
          "name": "cfpro-status",
          "type": "select-one",
          "label": "Status",
          "unit": "",
          "options": [
            "draft",
            "sent",
            "viewed",
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        {
          "name": "cfpro-total",
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=clientflow-pro&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=clientflow-pro&cfpro-biz-name=Studio%20North%20Ltd&cfpro-biz-email=hello%40studionorth.co%20%C2%B7%20%2B44%207700%20900123&cfpro-biz-addr=12%20Hoxton%20Street%2C%20London%20N1%206NG%20%C2%B7%20VAT%20123%204567%2089&cfpro-biz-logo-text=SN&cfpro-accent=%23ffd700&cfpro-client-name=Apex%20Global%20Technologies%20Inc."
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "clientflow",
        "pro",
        "quote",
        "invoice",
        "contract",
        "e-sign",
        "studio",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "climbing-anchor-force-calculator",
      "title": "🧗 Climbing Anchor Force & Fall Factor Calculator",
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      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/climbing-anchor-force-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=climbing-anchor-force-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cafc-mass",
          "type": "number",
          "label": "Climber mass, kitted",
          "unit": "kg",
          "min": 20,
          "max": 200,
          "step": 1,
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        },
        {
          "name": "cafc-out",
          "type": "number",
          "label": "Rope out from belayer",
          "unit": "m",
          "min": 0.5,
          "max": 120,
          "step": 0.5,
          "default": "12"
        },
        {
          "name": "cafc-above",
          "type": "number",
          "label": "Height above the last runner",
          "unit": "m",
          "min": 0,
          "max": 60,
          "step": 0.5,
          "default": "3"
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        {
          "name": "cafc-slack",
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          "label": "Slack in the system",
          "unit": "m",
          "min": 0,
          "max": 10,
          "step": 0.1,
          "default": "0.5"
        },
        {
          "name": "cafc-angle",
          "type": "range",
          "label": "Anchor V-angle: 45°",
          "unit": "",
          "min": 0,
          "max": 175,
          "step": 5,
          "default": "45"
        },
        {
          "name": "cafc-piece",
          "type": "number",
          "label": "Weakest placement rating",
          "unit": "kN",
          "min": 0.5,
          "max": 50,
          "step": 0.5,
          "default": "6"
        },
        {
          "name": "cafc-ground",
          "type": "number",
          "label": "Climber height above the ground",
          "unit": "m",
          "min": 1,
          "max": 300,
          "step": 0.5,
          "default": "18"
        },
        {
          "name": "cafc-rope",
          "type": "select-one",
          "label": "Rope type",
          "unit": "",
          "options": [
            "17",
            "20",
            "24",
            "14",
            "60",
            "300"
          ],
          "default": "20"
        },
        {
          "name": "cafc-belay",
          "type": "select-one",
          "label": "Belay behaviour",
          "unit": "",
          "options": [
            "1",
            "0.85",
            "0.72"
          ],
          "default": "0.85"
        },
        {
          "name": "cafc-legs",
          "type": "select-one",
          "label": "Anchor points sharing the load",
          "unit": "",
          "options": [
            "2",
            "3"
          ],
          "default": "2"
        }
      ],
      "outputs": [
        {
          "name": "cafc-verdict",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=climbing-anchor-force-calculator&<id>=<value>",
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "climbing",
        "anchor",
        "force",
        "fall",
        "factor",
        "science",
        "engineering",
        "falling",
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      "popularity": 5092,
      "featured": false,
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    },
    {
      "slug": "clinical-fluid-requirements-calculator",
      "title": "🚑 Clinical Fluid Requirements Calculator",
      "description": "Holliday-Segar maintenance, dehydration deficit replacement with the 8-hour split, and burn resuscitation with a Rule-of-Nines TBSA helper that counts down the first-8-hour window from the time of ...",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/clinical-fluid-requirements-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=clinical-fluid-requirements-calculator&embed=1",
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        },
        {
          "name": "clinfluid-dwt",
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        {
          "name": "clinfluid-bwt",
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        {
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        {
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        {
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            "child",
            "adult"
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            "3",
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            "2",
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        "clinical",
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      "slug": "clip-short",
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            "cover",
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        "clip",
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    },
    {
      "slug": "clock-angle-calculator",
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        "clock",
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        "hands",
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      "featured": false,
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      "slug": "clock-reading-trainer",
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        {
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          "name": "clk-ans",
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            "read",
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          "name": "clsz-sys",
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        },
        {
          "name": "clsz-val",
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        "size",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=coat-or-no-coat-weather&embed=1",
      "standaloneUrl": null,
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          "name": "wth-rain",
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            "none",
            "drizzle",
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        {
          "name": "wth-out",
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            "short",
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          ],
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      },
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        "coat",
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      "featured": false,
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      "slug": "coffee-brew-ratio-calculator",
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      "category": "culinary-and-food-science",
      "categoryName": "Culinary & Food Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/coffee-brew-ratio-calculator.html",
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      "standaloneUrl": null,
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        {
          "name": "cf-ratio",
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          "unit": "",
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          "step": 0.5,
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        {
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            "v60",
            "chemex",
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            "aeropress",
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      "sources": [],
      "tags": [
        "coffee",
        "brew",
        "ratio",
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      "featured": false,
      "updated": "2026-09-19"
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    {
      "slug": "cognitive-bias-detector",
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      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/cognitive-bias-detector.html",
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      "standaloneUrl": null,
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        {
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          "type": "textarea",
          "label": "Paste or Type Argument / Statement to Audit",
          "unit": ""
        }
      ],
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        {
          "name": "bias-audit-results",
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        {
          "name": "rigor-score-display",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
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        "cognitive",
        "bias",
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        "writing",
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        "interrogate",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "coincidence-finder",
      "title": "🔮 Coincidence Finder & Synchronicity Tracker",
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      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/coincidence-finder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=coincidence-finder&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "unit": ""
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        {
          "name": "cf-pattern-input",
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          "label": "Pattern or Symbol",
          "unit": ""
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        {
          "name": "cf-source-news",
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          "label": "News APIs",
          "unit": "",
          "default": "1"
        },
        {
          "name": "cf-source-wiki",
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          "label": "Wikipedia",
          "unit": "",
          "default": "1"
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        {
          "name": "cf-source-nasa",
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          "label": "NASA/ESA Data",
          "unit": "",
          "default": "1"
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          "name": "cf-source-weather",
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          "label": "Weather Data",
          "unit": "",
          "default": "1"
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        {
          "name": "cf-source-social",
          "type": "checkbox",
          "label": "Social Trends",
          "unit": "",
          "default": "0"
        },
        {
          "name": "cf-advanced-probability",
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          "label": "Calculate Probability",
          "unit": "",
          "default": "0"
        },
        {
          "name": "cf-advanced-timeline",
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          "label": "Show Timeline",
          "unit": "",
          "default": "1"
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        {
          "name": "cf-advanced-crossref",
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          "label": "Cross-Reference Sources",
          "unit": "",
          "default": "1"
        },
        {
          "name": "cf-number-type",
          "type": "select-one",
          "label": "Analysis Type",
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          "options": [
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            "angel",
            "date",
            "time",
            "math"
          ],
          "default": "numerology"
        },
        {
          "name": "cf-name-analysis",
          "type": "select-one",
          "label": "Analysis Method",
          "unit": "",
          "options": [
            "gematria",
            "synchronicity",
            "celebrity",
            "historical",
            "anagram"
          ],
          "default": "gematria"
        },
        {
          "name": "cf-event-source",
          "type": "select-one",
          "label": "Data Source",
          "unit": "",
          "options": [
            "news",
            "historical",
            "scientific",
            "cultural",
            "all"
          ],
          "default": "news"
        },
        {
          "name": "cf-probability",
          "type": "select-one",
          "label": "Probability Threshold",
          "unit": "",
          "options": [
            "0.001",
            "0.01",
            "0.05",
            "0.10",
            "0.25"
          ],
          "default": "0.01"
        },
        {
          "name": "cf-timeframe",
          "type": "select-one",
          "label": "Time Frame",
          "unit": "",
          "options": [
            "24h",
            "7d",
            "30d",
            "year",
            "all"
          ],
          "default": "7d"
        },
        {
          "name": "cf-significance",
          "type": "select-one",
          "label": "Significance Level",
          "unit": "",
          "options": [
            "high",
            "medium",
            "low"
          ],
          "default": "medium"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=coincidence-finder&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=coincidence-finder&cf-source-news=1&cf-source-wiki=1&cf-source-nasa=1&cf-source-weather=1&cf-source-social=0&cf-advanced-probability=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "coincidence",
        "finder",
        "synchronicity",
        "tracker",
        "productivity",
        "lifestyle",
        "discover",
        "meaningful",
        "coincidences",
        "synchronicities"
      ],
      "popularity": 4147,
      "featured": false,
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    },
    {
      "slug": "cold-flu-natural-remedy-hub",
      "title": "🍯 Cold & Flu Botanical Guide",
      "description": "Phase-specific botanical recovery matrix. Synchronizes natural remedies to viral replication curves—from neuraminidase inhibitors at hour zero to diaphoretic fever teas and expectorants.",
      "category": "natural-remedies-and-herbs",
      "categoryName": "Natural Remedies & Herbs",
      "url": "https://www.themostusefulsiteintheworld.com/tool/cold-flu-natural-remedy-hub.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=cold-flu-natural-remedy-hub&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cold-phase",
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          "label": "Current Illness Stage & Timeline",
          "unit": "",
          "options": [
            "onset",
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      },
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      "sources": [],
      "tags": [
        "cold",
        "flu",
        "natural",
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        "hub",
        "botanical",
        "guide",
        "remedies",
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        "phase-specific"
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      "popularity": 6461,
      "featured": false,
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    },
    {
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      "description": "Cold water kills strong swimmers in minutes, and it kills them long before hypothermia is even possible. Most people who die in UK waters were never trying to swim far — they fell in, gasped, and i...",
      "category": "survival-and-emergency-readiness",
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      "standaloneUrl": null,
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      ],
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        {
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        {
          "name": "cws-body",
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      ],
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      },
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        "cold",
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        "ice",
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      "featured": false,
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    },
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      "url": "https://www.themostusefulsiteintheworld.com/tool/collaboration.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=collaboration&embed=1",
      "standaloneUrl": null,
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        {
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          "max": 10,
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          "type": "select-one",
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          "options": [
            "backlog",
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            "inprogress",
            "review",
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      ],
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        {
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        {
          "name": "metric-total",
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=collaboration&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=collaboration&task-priority=5&task-status=todo"
      },
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        "collaboration",
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      "featured": false,
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      "category": "mathematics",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=collatz-conjecture-explorer&embed=1",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=collatz-conjecture-explorer&<id>=<value>",
        "runs": false,
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      },
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      "featured": false,
      "updated": "2026-09-19"
    },
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        {
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        },
        {
          "name": "wcag-bg-color",
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          "name": "wcag-bg-hex",
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          "label": "bg hex",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=color-contrast-checker&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=color-contrast-checker&wcag-fg-color=%2300ffcc&wcag-fg-hex=%2300ffcc&wcag-bg-color=%23080e14&wcag-bg-hex=%23080e14"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
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        "color",
        "contrast",
        "checker",
        "wcag",
        "vision",
        "algorithms",
        "computer",
        "science",
        "test",
        "ratios"
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      "popularity": 9110,
      "featured": true,
      "updated": "2026-09-19"
    },
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=color-converter-harmony-studio&embed=1",
      "standaloneUrl": null,
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          "unit": "",
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        {
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          "label": "HEX Color",
          "unit": "",
          "default": "#2dd4ff"
        },
        {
          "name": "cchs-in-rgb",
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          "default": "rgb(45, 212, 255)"
        },
        {
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          "type": "text",
          "label": "HSL",
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        {
          "name": "cchs-in-cmyk",
          "type": "text",
          "label": "CMYK (c%, m%, y%, k%)",
          "unit": "",
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        },
        {
          "name": "cchs-in-hsv",
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          "label": "HSV / HSB",
          "unit": "",
          "default": "hsv(192, 82%, 100%)"
        },
        {
          "name": "cchs-in-oklch",
          "type": "text",
          "label": "Modern CSS OKLCH",
          "unit": "",
          "default": "oklch(0.81 0.14 218)"
        }
      ],
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        {
          "name": "cchs-status",
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        }
      ],
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        "runs": false,
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "color",
        "converter",
        "harmony",
        "studio",
        "palette",
        "productivity",
        "lifestyle",
        "convert",
        "between",
        "hex"
      ],
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      "featured": false,
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    },
    {
      "slug": "color-palette-extractor",
      "title": "🎨 Color Palette Extractor",
      "description": "Generate algorithmic color harmonies (Complementary, Triadic, Analogous, Split) and verify accessibility with real-time WCAG 2.1 AA/AAA contrast ratio verification.",
      "category": "science-and-engineering",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=color-palette-extractor&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "unit": "",
          "default": "#00ffcc"
        },
        {
          "name": "base-color-hex",
          "type": "text",
          "label": "color hex",
          "unit": "",
          "default": "#00ffcc"
        },
        {
          "name": "harmony-mode-select",
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            "complementary",
            "triadic",
            "analogous",
            "split"
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          "default": "complementary"
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=color-palette-extractor&<id>=<value>",
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      },
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      "sources": [],
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        "color",
        "palette",
        "extractor",
        "science",
        "engineering",
        "generate",
        "algorithmic",
        "harmonies",
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      "featured": false,
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    },
    {
      "slug": "common-english-mistakes-trainer",
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      "categoryName": "Writing & Language",
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      "standaloneUrl": null,
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        {
          "name": "cem-score",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=common-english-mistakes-trainer&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "common",
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        "trainer",
        "writing",
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      "featured": false,
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    },
    {
      "slug": "community-apprenticeship-planner",
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      "categoryName": "Wellbeing & Community",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=community-apprenticeship-planner&embed=1",
      "standaloneUrl": null,
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          "name": "community-apprenticeship-planner-mentors",
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          "label": "Mentors",
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        },
        {
          "name": "community-apprenticeship-planner-courses",
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          "label": "Course requirements",
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        {
          "name": "community-apprenticeship-planner-learners",
          "type": "textarea",
          "label": "Interested learners",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "community-apprenticeship-planner-status",
          "type": "live"
        },
        {
          "name": "community-apprenticeship-planner-results",
          "type": "output"
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        {
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      ],
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        "runs": false
      },
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      "popularity": 4934,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "community-fridge-starter-kit",
      "title": "🧊 Community Fridge Starter Kit: Feed Your Street",
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      "category": "wellbeing-and-community",
      "categoryName": "Wellbeing & Community",
      "url": "https://www.themostusefulsiteintheworld.com/tool/community-fridge-starter-kit.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=community-fridge-starter-kit&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "text",
          "label": "Fridge / project name",
          "unit": "",
          "default": "Our Street Community Fridge"
        },
        {
          "name": "cfrs-place",
          "type": "text",
          "label": "Host venue",
          "unit": "",
          "default": "Community centre foyer"
        },
        {
          "name": "cfrs-li",
          "type": "text",
          "label": "Item",
          "unit": ""
        },
        {
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          "label": "Donated on",
          "unit": ""
        },
        {
          "name": "cfrs-le",
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          "label": "Eat by",
          "unit": ""
        },
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          "label": "Allergens in it",
          "unit": ""
        },
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          "type": "text",
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          "default": "Mon–Sat, 9am–6pm"
        },
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          "type": "text",
          "label": "Contact",
          "unit": "",
          "default": "Text Ana on 07000 000000"
        },
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          "label": "vols",
          "unit": ""
        },
        {
          "name": "cfrs-region",
          "type": "select-one",
          "label": "Your region (for legal notes)",
          "unit": "",
          "options": [
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            "us",
            "eu",
            "other"
          ],
          "default": "uk"
        },
        {
          "name": "cfrs-food",
          "type": "select-one",
          "label": "Food",
          "unit": ""
        },
        {
          "name": "cfrs-date",
          "type": "select-one",
          "label": "Date label",
          "unit": "",
          "options": [
            "ok",
            "useby",
            "bestbefore",
            "none"
          ],
          "default": "ok"
        },
        {
          "name": "cfrs-cond",
          "type": "select-one",
          "label": "Condition & packaging",
          "unit": "",
          "options": [
            "sealed",
            "openfresh",
            "home",
            "homebare",
            "dodgy"
          ],
          "default": "sealed"
        },
        {
          "name": "cfrs-which",
          "type": "select-one",
          "label": "Poster",
          "unit": "",
          "options": [
            "rules",
            "take",
            "shops",
            "vols"
          ],
          "default": "rules"
        }
      ],
      "outputs": [
        {
          "name": "cfrs-verdict",
          "type": "live"
        },
        {
          "name": "cfrs-labelout",
          "type": "live"
        },
        {
          "name": "cfrs-rotaout",
          "type": "live"
        },
        {
          "name": "cfrs-postout",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=community-fridge-starter-kit&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=community-fridge-starter-kit&cfrs-name=Our%20Street%20Community%20Fridge&cfrs-place=Community%20centre%20foyer&cfrs-hours=Mon%E2%80%93Sat%2C%209am%E2%80%936pm&cfrs-contact=Text%20Ana%20on%2007000%20000000&cfrs-region=uk&cfrs-date=ok"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "community",
        "fridge",
        "starter",
        "kit",
        "feed",
        "street",
        "wellbeing",
        "turns",
        "neighbourhood",
        "surplus"
      ],
      "popularity": 6252,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "community-project-budget-picker",
      "title": "Community Project Budget Picker",
      "description": "Explore which combination of community projects fits a shared budget. Use member-agreed support scores to compare the best affordable bundle with the projects it leaves out.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/community-project-budget-picker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=community-project-budget-picker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "community-project-budget-picker-unit",
          "type": "text",
          "label": "Currency / unit label (no conversion)",
          "unit": "",
          "default": "USD"
        },
        {
          "name": "community-project-budget-picker-budget",
          "type": "number",
          "label": "Available project budget",
          "unit": "",
          "min": 0,
          "max": 1000000000,
          "step": 0.01,
          "default": "1000"
        },
        {
          "name": "community-project-budget-picker-projects",
          "type": "textarea",
          "label": "Projects",
          "unit": "maximum 18"
        }
      ],
      "outputs": [
        {
          "name": "community-project-budget-picker-status",
          "type": "live"
        },
        {
          "name": "community-project-budget-picker-results",
          "type": "output"
        },
        {
          "name": "community-project-budget-picker-summary",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=community-project-budget-picker&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=community-project-budget-picker&community-project-budget-picker-unit=USD&community-project-budget-picker-budget=1000"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "community",
        "project",
        "budget",
        "picker",
        "finance",
        "money",
        "explore",
        "which",
        "combination",
        "projects"
      ],
      "popularity": 6486,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "community-skills-needs-matcher",
      "title": "Community Skills-to-Needs Matcher",
      "description": "Match neighbours’ offered skills and available hours to practical requests. See exactly who could help, which needs remain unmet, and where another volunteer would make the difference.",
      "category": "wellbeing-and-community",
      "categoryName": "Wellbeing & Community",
      "url": "https://www.themostusefulsiteintheworld.com/tool/community-skills-needs-matcher.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=community-skills-needs-matcher&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "community-skills-needs-matcher-offers",
          "type": "textarea",
          "label": "Offers",
          "unit": ""
        },
        {
          "name": "community-skills-needs-matcher-needs",
          "type": "textarea",
          "label": "Requests",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "community-skills-needs-matcher-status",
          "type": "live"
        },
        {
          "name": "community-skills-needs-matcher-results",
          "type": "output"
        },
        {
          "name": "community-skills-needs-matcher-summary",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=community-skills-needs-matcher&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "community",
        "skills",
        "needs",
        "matcher",
        "skills-to-needs",
        "wellbeing",
        "match",
        "neighbours",
        "offered",
        "available"
      ],
      "popularity": 4595,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "community-tool-library-scheduler",
      "title": "Community Tool Library Scheduler",
      "description": "Turn a shared equipment list and borrowing requests into a conflict-checked lending schedule. Track which items are available, flag double bookings, and leave time for return and inspection.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/community-tool-library-scheduler.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=community-tool-library-scheduler&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "community-tool-library-scheduler-buffer",
          "type": "number",
          "label": "Return / inspection buffer",
          "unit": "minutes",
          "min": 0,
          "max": 1440,
          "step": 1,
          "default": "60"
        },
        {
          "name": "community-tool-library-scheduler-items",
          "type": "textarea",
          "label": "Shared items",
          "unit": ""
        },
        {
          "name": "community-tool-library-scheduler-bookings",
          "type": "textarea",
          "label": "Borrowing requests",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "community-tool-library-scheduler-status",
          "type": "live"
        },
        {
          "name": "community-tool-library-scheduler-results",
          "type": "output"
        },
        {
          "name": "community-tool-library-scheduler-summary",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=community-tool-library-scheduler&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=community-tool-library-scheduler&community-tool-library-scheduler-buffer=60"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "community",
        "library",
        "scheduler",
        "productivity",
        "lifestyle",
        "turn",
        "shared",
        "equipment",
        "list",
        "borrowing"
      ],
      "popularity": 5888,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "commute",
      "title": "🚗 Commute Calculator",
      "description": "Calculate commute time, cost, and environmental impact. Compare different transportation modes. ✅ Tracks daily, weekly, monthly, and yearly totals",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/commute.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=commute&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "commute-distance",
          "type": "range",
          "label": "Distance",
          "unit": "km",
          "min": 1,
          "max": 100,
          "step": 1,
          "default": "20"
        },
        {
          "name": "commute-days",
          "type": "number",
          "label": "Trips per week",
          "unit": "",
          "min": 1,
          "max": 14,
          "default": "5"
        },
        {
          "name": "commute-fuel-price",
          "type": "number",
          "label": "Fuel price",
          "unit": "£/L",
          "step": 0.01,
          "default": "1.45"
        },
        {
          "name": "commute-fuel-efficiency",
          "type": "number",
          "label": "Fuel efficiency",
          "unit": "km/L",
          "step": 0.1,
          "default": "12.5"
        },
        {
          "name": "commute-car-speed",
          "type": "number",
          "label": "Average speed",
          "unit": "km/h",
          "min": 1,
          "max": 120,
          "default": "40"
        },
        {
          "name": "commute-car-cost",
          "type": "number",
          "label": "Cost per km",
          "unit": "£",
          "step": 0.01,
          "default": "0.20"
        }
      ],
      "outputs": [
        {
          "name": "distance-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=commute&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=commute&commute-distance=20&commute-days=5&commute-fuel-price=1.45&commute-fuel-efficiency=12.5&commute-car-speed=40&commute-car-cost=0.20&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "commute",
        "productivity",
        "lifestyle",
        "calculate",
        "time",
        "cost",
        "environmental",
        "impact",
        "compare",
        "different"
      ],
      "popularity": 6106,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "compare-two-lists",
      "title": "Compare Two Lists",
      "description": "Find missing items, overlaps and duplicates between two lists. Compare locally without uploading customer names, stock lists or other text.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/compare-two-lists.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=compare-two-lists&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "compare-two-lists-a",
          "type": "textarea",
          "label": "List A — one item per line Apples Pears Bananas Apples",
          "unit": ""
        },
        {
          "name": "compare-two-lists-b",
          "type": "textarea",
          "label": "List B — one item per line pears Oranges Bananas",
          "unit": ""
        },
        {
          "name": "compare-two-lists-case",
          "type": "select-one",
          "label": "Case matching Ignore uppercase / lowercase Match case exactly",
          "unit": "",
          "options": [
            "ignore",
            "exact"
          ],
          "default": "ignore"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=compare-two-lists&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=compare-two-lists&compare-two-lists-case=ignore"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "compare",
        "two",
        "lists",
        "productivity",
        "lifestyle",
        "find",
        "missing",
        "items",
        "overlaps",
        "duplicates"
      ],
      "popularity": 6604,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "compass-bearings-trainer",
      "title": "🧭 Compass Bearings Trainer",
      "description": "Learn the 16-point compass rose: convert between named bearings and degrees, then practise reading them on a marked compass — forward and back bearings, with instant feedback. Runs in your browser,...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/compass-bearings-trainer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=compass-bearings-trainer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cmp-deg",
          "type": "number",
          "label": "Degrees",
          "unit": "0–359",
          "min": 0,
          "max": 359,
          "default": "135"
        },
        {
          "name": "cmp-ans",
          "type": "number",
          "label": "degrees, e.g. 225",
          "unit": "",
          "min": 0,
          "max": 359
        }
      ],
      "outputs": [
        {
          "name": "cmp-out",
          "type": "output"
        },
        {
          "name": "cmp-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=compass-bearings-trainer&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=compass-bearings-trainer&cmp-deg=135&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "compass",
        "bearings",
        "trainer",
        "science",
        "engineering",
        "learn",
        "16-point",
        "rose",
        "convert",
        "between"
      ],
      "popularity": 5136,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "complex-function-landscape-3d",
      "title": "🌈 Complex Function Landscape 3D",
      "description": "Type any complex function f(z) and see it as a 3D landscape: height is |f(z)| or Re/Im, colour is the phase (domain colouring). Zeros become valleys, poles become towers. Evaluate f at any point, l...",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/complex-function-landscape-3d.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=complex-function-landscape-3d&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cfl-f",
          "type": "text",
          "label": "f(z) =",
          "unit": "",
          "default": "(z^2-1)/(z^2+1)"
        },
        {
          "name": "cfl-range",
          "type": "range",
          "label": "View half-width 2.5",
          "unit": "",
          "min": 0.5,
          "max": 8,
          "step": 0.1,
          "default": "2.5"
        },
        {
          "name": "cfl-res",
          "type": "range",
          "label": "Mesh resolution 70",
          "unit": "",
          "min": 30,
          "max": 120,
          "step": 5,
          "default": "70"
        },
        {
          "name": "cfl-zr",
          "type": "range",
          "label": "Re z₀ 0.5",
          "unit": "",
          "min": -8,
          "max": 8,
          "step": 0.01,
          "default": "0.5"
        },
        {
          "name": "cfl-zi",
          "type": "range",
          "label": "Im z₀ 0.5",
          "unit": "",
          "min": -8,
          "max": 8,
          "step": 0.01,
          "default": "0.5"
        },
        {
          "name": "cfl-cr",
          "type": "range",
          "label": "Contour radius 1.2",
          "unit": "",
          "min": 0.05,
          "max": 6,
          "step": 0.05,
          "default": "1.2"
        },
        {
          "name": "cfl-h",
          "type": "select-one",
          "label": "Height shows",
          "unit": "",
          "options": [
            "abs",
            "re",
            "im",
            "flat"
          ],
          "default": "abs"
        },
        {
          "name": "cfl-grid",
          "type": "select-one",
          "label": "Contours",
          "unit": "",
          "options": [
            "both",
            "mod",
            "none"
          ],
          "default": "both"
        }
      ],
      "outputs": [
        {
          "name": "cfl-hud",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=complex-function-landscape-3d&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=complex-function-landscape-3d&cfl-f=(z%5E2-1)%2F(z%5E2%2B1)&cfl-range=2.5&cfl-res=70&cfl-zr=0.5&cfl-zi=0.5&cfl-cr=1.2"
      },
      "formula": "N − P = (1/2πi) ∮ f′/",
      "sources": [],
      "tags": [
        "complex",
        "function",
        "landscape",
        "mathematics",
        "type",
        "any",
        "see",
        "height",
        "colour",
        "phase"
      ],
      "popularity": 4157,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "complex-numbers",
      "title": "🧮 Complex Numbers Calculator",
      "description": "Perform operations with complex numbers in rectangular (a+bi) and polar (r∠θ) forms. Visualize results on the complex plane with step-by-step solutions. ✅ Supports: + − × ÷ √ ^ log sin cos conjugat...",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/complex-numbers.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=complex-numbers&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cn-a",
          "type": "text",
          "label": "Complex Number A",
          "unit": ""
        },
        {
          "name": "cn-b",
          "type": "text",
          "label": "Complex Number B",
          "unit": ""
        },
        {
          "name": "cn-show-steps",
          "type": "checkbox",
          "label": "Show Steps",
          "unit": "",
          "default": "1"
        },
        {
          "name": "cn-show-polar",
          "type": "checkbox",
          "label": "Polar Form",
          "unit": "",
          "default": "1"
        },
        {
          "name": "cn-show-visual",
          "type": "checkbox",
          "label": "Visualize",
          "unit": "",
          "default": "1"
        },
        {
          "name": "cn-output",
          "type": "textarea",
          "label": "output",
          "unit": ""
        },
        {
          "name": "cn-operation",
          "type": "select-one",
          "label": "Operation",
          "unit": "",
          "options": [
            "add",
            "subtract",
            "multiply",
            "divide",
            "power",
            "conjugate",
            "modulus",
            "argument",
            "sqrt",
            "exp",
            "log",
            "sin",
            "cos"
          ],
          "default": "add"
        },
        {
          "name": "cn-precision",
          "type": "select-one",
          "label": "Decimal Precision",
          "unit": "",
          "options": [
            "2",
            "4",
            "6",
            "8",
            "10"
          ],
          "default": "4"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=complex-numbers&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=complex-numbers&cn-show-steps=1&cn-show-polar=1&cn-show-visual=1&cn-operation=add&cn-precision=4&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "complex",
        "numbers",
        "mathematics",
        "perform",
        "operations",
        "rectangular",
        "polar",
        "forms",
        "visualize",
        "results"
      ],
      "popularity": 5949,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "compost-carbon-nitrogen-balancer",
      "title": "🌱 Compost Carbon:Nitrogen Balancer",
      "description": "Slimy and smelly means too much nitrogen; dry and stubborn means too much carbon. Tell it what’s gone into the heap and it estimates your C:N ratio and exactly what to add next.",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/compost-carbon-nitrogen-balancer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=compost-carbon-nitrogen-balancer&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [
        {
          "name": "ccnb-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=compost-carbon-nitrogen-balancer&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "compost",
        "carbon",
        "nitrogen",
        "balancer",
        "home",
        "diy",
        "slimy",
        "smelly",
        "means",
        "too"
      ],
      "popularity": 5613,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "compoundinterest",
      "title": "💰 Compound Interest Calculator",
      "description": "Calculate future value, growth projections, and compare investment scenarios. Visualize wealth accumulation over time with detailed breakdowns. ✅ Features: Regular contributions, inflation adjustme...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/compoundinterest.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=compoundinterest&embed=1",
      "standaloneUrl": "https://www.themostusefulsiteintheworld.com/tools/compound-interest.html",
      "inputs": [
        {
          "name": "ci-principal",
          "type": "range",
          "label": "Initial Investment",
          "unit": "£",
          "min": 100,
          "max": 1000000,
          "step": 100,
          "default": "10000"
        },
        {
          "name": "ci-monthly-contribution",
          "type": "range",
          "label": "Monthly Contribution",
          "unit": "£",
          "min": 0,
          "max": 5000,
          "step": 50,
          "default": "100"
        },
        {
          "name": "ci-annual-rate",
          "type": "range",
          "label": "Annual Return Rate",
          "unit": "%",
          "min": 0,
          "max": 20,
          "step": 0.1,
          "default": "7"
        },
        {
          "name": "ci-years",
          "type": "range",
          "label": "Investment Period",
          "unit": "years",
          "min": 1,
          "max": 50,
          "step": 1,
          "default": "20"
        },
        {
          "name": "ci-inflation",
          "type": "number",
          "label": "Annual Inflation Rate",
          "unit": "%",
          "min": 0,
          "max": 10,
          "step": 0.1,
          "default": "2.5"
        },
        {
          "name": "ci-tax-rate",
          "type": "number",
          "label": "Annual Tax Rate",
          "unit": "%",
          "min": 0,
          "max": 50,
          "step": 0.1,
          "default": "20"
        },
        {
          "name": "ci-goal",
          "type": "number",
          "label": "Financial Goal",
          "unit": "£",
          "min": 0,
          "step": 1000,
          "default": "100000"
        },
        {
          "name": "ci-contribution-increase",
          "type": "number",
          "label": "Annual Contribution Increase",
          "unit": "%",
          "min": 0,
          "max": 20,
          "step": 0.1,
          "default": "3"
        },
        {
          "name": "ci-currency",
          "type": "select-one",
          "label": "Currency",
          "unit": "",
          "options": [
            "GBP",
            "USD",
            "EUR",
            "CAD",
            "AUD",
            "JPY",
            "INR"
          ],
          "default": "GBP"
        },
        {
          "name": "ci-frequency",
          "type": "select-one",
          "label": "Compounding Frequency",
          "unit": "",
          "options": [
            "1",
            "2",
            "4",
            "12",
            "52",
            "365",
            "continuous"
          ],
          "default": "12"
        }
      ],
      "outputs": [
        {
          "name": "ci-principal-display",
          "type": "output"
        },
        {
          "name": "ci-monthly-display",
          "type": "output"
        },
        {
          "name": "ci-rate-display",
          "type": "output"
        },
        {
          "name": "ci-years-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=compoundinterest&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=compoundinterest&ci-principal=10000&ci-monthly-contribution=100&ci-annual-rate=7&ci-years=20&ci-inflation=2.5&ci-tax-rate=20&run=1"
      },
      "formula": "A = P·(1 + r/n)^(n·t) — compound interest.",
      "sources": [],
      "tags": [
        "compoundinterest",
        "compound",
        "interest",
        "finance",
        "money",
        "calculate",
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        "value",
        "growth",
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      ],
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      "featured": true,
      "updated": "2026-09-19"
    },
    {
      "slug": "concrete-mix-calculator",
      "title": "🧱 Concrete Mix Calculator",
      "description": "Calculate cement, sand, gravel, and water for any concrete project — from fence posts to shed bases.",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/concrete-mix-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=concrete-mix-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "concmix-w",
          "type": "number",
          "label": "Width",
          "unit": "m",
          "min": 0.1,
          "step": 0.1,
          "default": "3"
        },
        {
          "name": "concmix-l",
          "type": "number",
          "label": "Length",
          "unit": "m",
          "min": 0.1,
          "step": 0.1,
          "default": "3"
        },
        {
          "name": "concmix-d",
          "type": "number",
          "label": "Depth",
          "unit": "cm",
          "min": 1,
          "step": 1,
          "default": "10"
        },
        {
          "name": "concmix-project",
          "type": "select-one",
          "label": "Project Type",
          "unit": "",
          "options": [
            "path",
            "base",
            "driveway",
            "structural",
            "post"
          ],
          "default": "base"
        },
        {
          "name": "concmix-method",
          "type": "select-one",
          "label": "Mix Method",
          "unit": "",
          "options": [
            "bags",
            "bulk"
          ],
          "default": "bags"
        }
      ],
      "outputs": [
        {
          "name": "concmix-result",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=concrete-mix-calculator&<id>=<value>",
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
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        "concrete",
        "mix",
        "home",
        "diy",
        "calculate",
        "cement",
        "sand",
        "gravel",
        "water",
        "any"
      ],
      "popularity": 4717,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "conduit-sizing",
      "title": "⚡ Conduit Sizing Calculator",
      "description": "Calculate conduit sizes based on NEC requirements, wire types, and installation conditions. ⚠️ Disclaimer: For educational purposes. Always consult NEC codebook and licensed electrician.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/conduit-sizing.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=conduit-sizing&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cond-count",
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          "label": "Number of Conductors",
          "unit": "",
          "min": 1,
          "max": 30,
          "step": 1,
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        },
        {
          "name": "cond-run-length",
          "type": "number",
          "label": "Run Length",
          "unit": "feet",
          "min": 1,
          "max": 500,
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        {
          "name": "cond-derating",
          "type": "range",
          "label": "Derating Factor",
          "unit": "",
          "min": 70,
          "max": 100,
          "step": 5,
          "default": "100"
        },
        {
          "name": "cond-output",
          "type": "textarea",
          "label": "output",
          "unit": ""
        },
        {
          "name": "cond-wire-type",
          "type": "select-one",
          "label": "Wire Type",
          "unit": "",
          "options": [
            "thhn",
            "xhhw",
            "uf",
            "nm",
            "service"
          ],
          "default": "thhn"
        },
        {
          "name": "cond-wire-size",
          "type": "select-one",
          "label": "Wire Gauge",
          "unit": "AWG/kcmil",
          "options": [
            "14",
            "12",
            "10",
            "8",
            "6",
            "4",
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            "3/0",
            "4/0",
            "250",
            "300",
            "350",
            "400",
            "500"
          ],
          "default": "12"
        },
        {
          "name": "cond-grounds",
          "type": "select-one",
          "label": "Ground Wires",
          "unit": "",
          "options": [
            "0",
            "1",
            "2",
            "3"
          ],
          "default": "1"
        },
        {
          "name": "cond-voltage",
          "type": "select-one",
          "label": "Voltage System",
          "unit": "",
          "options": [
            "120",
            "120240",
            "208",
            "240",
            "480"
          ],
          "default": "120240"
        },
        {
          "name": "cond-conduit-type",
          "type": "select-one",
          "label": "Conduit Material",
          "unit": "",
          "options": [
            "emt",
            "imc",
            "rigid",
            "pvc40",
            "pvc80",
            "flex",
            "lfmc"
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          "default": "emt"
        },
        {
          "name": "cond-fill-rule",
          "type": "select-one",
          "label": "NEC Fill Rule",
          "unit": "%",
          "options": [
            "53",
            "31",
            "40",
            "over40"
          ],
          "default": "40"
        },
        {
          "name": "cond-bends",
          "type": "select-one",
          "label": "Number of Bends",
          "unit": "",
          "options": [
            "0",
            "1",
            "2",
            "3"
          ],
          "default": "0"
        },
        {
          "name": "cond-temperature",
          "type": "select-one",
          "label": "Ambient Temperature",
          "unit": "°F",
          "options": [
            "30",
            "60",
            "86",
            "104",
            "122"
          ],
          "default": "86"
        },
        {
          "name": "cond-conductors-bundle",
          "type": "select-one",
          "label": "Conductors in Raceway",
          "unit": "",
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            "1-3",
            "4-6",
            "7-9",
            "10-20",
            "21-30"
          ],
          "default": "4-6"
        }
      ],
      "outputs": [
        {
          "name": "cond-count-display",
          "type": "output"
        },
        {
          "name": "cond-derating-display",
          "type": "output"
        }
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        "runs": true,
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      },
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      "sources": [],
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        "conduit",
        "sizing",
        "science",
        "engineering",
        "calculate",
        "sizes",
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        "nec",
        "requirements",
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      ],
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "consent-tech-watchlist",
      "title": "🛰️ Consent Tech Watchlist",
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      "categoryName": "Wellbeing & Community",
      "url": "https://www.themostusefulsiteintheworld.com/tool/consent-tech-watchlist.html",
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      "standaloneUrl": null,
      "inputs": [
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          "name": "ctw-c-work",
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          "unit": "",
          "default": "0"
        },
        {
          "name": "ctw-c-rent",
          "type": "checkbox",
          "label": "I rent my home",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ctw-c-study",
          "type": "checkbox",
          "label": "I study, or a child of mine does",
          "unit": "",
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        },
        {
          "name": "ctw-c-public",
          "type": "checkbox",
          "label": "Shops, gyms, venues, transport",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ctw-c-home",
          "type": "checkbox",
          "label": "A smart speaker, doorbell, meter or connected appliance",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ctw-c-car",
          "type": "checkbox",
          "label": "I drive a car built after about 2015",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ctw-c-family",
          "type": "checkbox",
          "label": "A relative has taken a consumer DNA test",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ctw-c-phone",
          "type": "checkbox",
          "label": "I carry a smartphone",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ctw-text",
          "type": "textarea",
          "label": "Plain text, for a note or a printout",
          "unit": ""
        }
      ],
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        {
          "name": "ctw-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=consent-tech-watchlist&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "consent",
        "tech",
        "watchlist",
        "wellbeing",
        "community",
        "thirteen",
        "technologies",
        "can",
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      ],
      "popularity": 4017,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "conservation-lux-hours",
      "title": "💡 The Light Budget",
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      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
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      "standaloneUrl": null,
      "inputs": [
        {
          "name": "clxh-lux",
          "type": "number",
          "label": "Gallery lux",
          "unit": "",
          "min": 1,
          "default": "150"
        },
        {
          "name": "clxh-h",
          "type": "number",
          "label": "Hours lit / week",
          "unit": "",
          "min": 0,
          "default": "42"
        },
        {
          "name": "clxh-w",
          "type": "number",
          "label": "Open weeks / year",
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          "min": 1,
          "max": 52,
          "step": 1,
          "default": "50"
        },
        {
          "name": "clxh-mat",
          "type": "select-one",
          "label": "Material class",
          "unit": "",
          "options": [
            "50|50000",
            "150|150000",
            "300|300000"
          ],
          "default": "150|150000"
        }
      ],
      "outputs": [
        {
          "name": "clxh-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=conservation-lux-hours&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=conservation-lux-hours&clxh-lux=150&clxh-h=42&clxh-w=50&clxh-mat=150%7C150000"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "conservation",
        "lux",
        "hours",
        "light",
        "budget",
        "science",
        "engineering",
        "loan",
        "interest",
        "museums"
      ],
      "popularity": 6321,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "conspiracy-theory-generator",
      "title": "🤡 Conspiracy Theory Generator",
      "description": "Generate absurd conspiracy theories that are somehow more believable than the real ones.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/conspiracy-theory-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=conspiracy-theory-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "conspgen-topic",
          "type": "select-one",
          "label": "Pick a topic to \"expose\"",
          "unit": "",
          "options": [
            "pigeons",
            "socks",
            "wifi",
            "cats",
            "mondays",
            "fridges",
            "stairs",
            "bubbles",
            "mirrors",
            "traffic"
          ],
          "default": "pigeons"
        }
      ],
      "outputs": [
        {
          "name": "conspgen-result",
          "type": "output"
        },
        {
          "name": "conspgen-title-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=conspiracy-theory-generator&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "conspiracy",
        "theory",
        "productivity",
        "lifestyle",
        "generate",
        "absurd",
        "theories",
        "somehow",
        "more",
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      ],
      "popularity": 5039,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "constant-treasury",
      "title": "📐 The Constant Treasury",
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      "category": "museum-and-collection",
      "categoryName": "Museum & Collection",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=constant-treasury&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ct-sl-d",
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          "label": "sl d",
          "unit": "",
          "min": 10,
          "max": 400,
          "step": 1,
          "default": "120"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=constant-treasury&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "constant",
        "treasury",
        "museum",
        "collection",
        "constants",
        "run",
        "universe",
        "numbered",
        "exhibits",
        "provenance"
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      "popularity": 4292,
      "featured": false,
      "updated": "2026-09-19"
    },
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      "slug": "constellation-chronicle-star-weaver",
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      "category": "interactive-art-and-living-worlds",
      "categoryName": "Interactive Art & Living Worlds",
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      "standaloneUrl": null,
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        {
          "name": "cc-constellation-name",
          "type": "text",
          "label": "Constellation Lore Name",
          "unit": "",
          "default": "The Astral Heron"
        },
        {
          "name": "cc-spectral-class",
          "type": "select-one",
          "label": "Star Spectral Class",
          "unit": "",
          "options": [
            "#9bb0ff",
            "#ffffff",
            "#ffd700",
            "#ff6b6b"
          ],
          "default": "#9bb0ff"
        },
        {
          "name": "cc-mode-select",
          "type": "select-one",
          "label": "Stargazing Tool",
          "unit": "",
          "options": [
            "line",
            "star",
            "pan"
          ],
          "default": "line"
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      ],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "constellation",
        "chronicle",
        "star",
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        "interactive",
        "art",
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      "popularity": 5483,
      "featured": false,
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      "slug": "continued-fraction-explorer",
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          "type": "number",
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        "continued",
        "fraction",
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            "supplier",
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        {
          "name": "cosentinel-type",
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          "label": "Contract type (helps detection)",
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            "saas",
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            "lease",
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        {
          "name": "cosentinel-results",
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        "contract",
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        "conways",
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      "slug": "cookie-consent-banner-builder",
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          "label": "Marketing",
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          "name": "ccbb-d-marketing",
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          "label": "d marketing",
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          "default": "Remember which adverts brought you here."
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        {
          "name": "ccbb-use-prefs",
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        {
          "name": "ccbb-layout",
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          "options": [
            "bar",
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          "default": "bar"
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        {
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          "label": "Theme",
          "unit": "",
          "options": [
            "light",
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          "default": "light"
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      ],
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        {
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      },
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      "sources": [],
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        "cookie",
        "consent",
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    {
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        },
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        },
        {
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        {
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        {
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        {
          "name": "cta-original-thickness",
          "type": "number",
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        },
        {
          "name": "cta-new-thickness",
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        {
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        {
          "name": "cta-time-unit",
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            "hours"
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        {
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          "type": "select-one",
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            "general",
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            "stew",
            "fish"
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        {
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      },
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      "sources": [],
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        "cooking",
        "time",
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        "culinary",
        "food",
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    },
    {
      "slug": "cooking-unit-converter",
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      "categoryName": "Culinary & Food Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/cooking-unit-converter.html",
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        },
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      "sources": [],
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        "cooking",
        "unit",
        "converter",
        "culinary",
        "food",
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    },
    {
      "slug": "cooperative-surplus-splitter",
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      "categoryName": "Finance & Money",
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        },
        {
          "name": "cooperative-surplus-splitter-surplus",
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          "unit": "",
          "min": 0,
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        },
        {
          "name": "cooperative-surplus-splitter-reserve",
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          "min": 0,
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          "step": 0.01,
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        },
        {
          "name": "cooperative-surplus-splitter-equal",
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          "unit": "%",
          "min": 0,
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          "step": 0.01,
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        },
        {
          "name": "cooperative-surplus-splitter-members",
          "type": "textarea",
          "label": "Members and agreed contribution weights",
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      ],
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        {
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        },
        {
          "name": "cooperative-surplus-splitter-results",
          "type": "output"
        },
        {
          "name": "cooperative-surplus-splitter-summary",
          "type": "output"
        }
      ],
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      },
      "formula": "How this works and what it cannot do Reserve = rounded surplus × reserve %. Remaining cents are split using equal share × (1 /",
      "sources": [],
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        "cooperative",
        "surplus",
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        "finance",
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    },
    {
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      "title": "🧭 3D Coordinate Converter — Cartesian, Cylindrical & Spherical",
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          "default": "iso"
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        {
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          "type": "select-one",
          "label": "Angles",
          "unit": "",
          "options": [
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            "rad"
          ],
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        }
      ],
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        {
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      },
      "formula": "Formulas & conventions Cylindrical (ρ, φ, z) : ρ = √(x² +",
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        "coordinate",
        "converter",
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        "spherical",
        "mathematics",
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    },
    {
      "slug": "coordinate-format-translator",
      "title": "🧭 Coordinate Format Translator",
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      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/coordinate-format-translator.html",
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          "label": "Paste any coordinate",
          "unit": ""
        },
        {
          "name": "ucrd-lat",
          "type": "number",
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        },
        {
          "name": "ucrd-place",
          "type": "select-one",
          "label": "…or jump to a landmark",
          "unit": ""
        }
      ],
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        {
          "name": "ucrd-parse",
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          "name": "ucrd-out",
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        "coordinate",
        "format",
        "translator",
        "science",
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      "slug": "coordinates-trainer",
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      "standaloneUrl": null,
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            "read",
            "plot"
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        "coordinates",
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        "read",
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        "plot",
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      "featured": false,
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        "coriolis",
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        "turntable",
        "storms",
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      "popularity": 6472,
      "featured": false,
      "updated": "2026-09-19"
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      "slug": "cors-header-builder",
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        {
          "name": "cors-headers",
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          "unit": "",
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        {
          "name": "cors-max",
          "type": "number",
          "label": "Max-Age",
          "unit": "s",
          "min": 0,
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        {
          "name": "cors-cred",
          "type": "checkbox",
          "label": "Allow-Credentials: true",
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          "default": "0"
        }
      ],
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        "cors",
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      "featured": false,
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      "categoryName": "Science & Engineering",
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          "type": "range",
          "label": "slider flux",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=cosmic-ray-cloud-chamber&<id>=<value>",
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      },
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        "cosmic",
        "ray",
        "cloud",
        "chamber",
        "wilson",
        "science",
        "engineering",
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      "featured": false,
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        {
          "name": "cpu-years",
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          "label": "Years you'll keep it",
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        {
          "name": "cpu-uses",
          "type": "range",
          "label": "uses",
          "unit": "",
          "min": 1,
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        },
        {
          "name": "cpu-hours",
          "type": "range",
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          "max": 8,
          "step": 0.1,
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        {
          "name": "cpu-joy",
          "type": "range",
          "label": "joy",
          "unit": "",
          "min": 1,
          "max": 5,
          "default": "3"
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        {
          "name": "cpu-out",
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      ],
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      },
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      "sources": [],
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        "cost",
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        "use",
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      "featured": false,
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      "categoryName": "Finance & Money",
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        {
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          "step": 10,
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        {
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        },
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          "name": "ctb-nation",
          "type": "select-one",
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            "england",
            "scotland",
            "wales"
          ],
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        {
          "name": "ctb-band",
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          "unit": ""
        }
      ],
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          "type": "output"
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=council-tax-band-checker&<id>=<value>",
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      },
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      "sources": [],
      "tags": [
        "council",
        "tax",
        "band",
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        "finance",
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      "featured": false,
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        {
          "name": "gct-date",
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          "name": "gct-time",
          "type": "time",
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          "unit": "",
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        },
        {
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          "type": "textarea",
          "label": "Days off to exclude from the working-day count (one YYYY-MM-DD per line)",
          "unit": ""
        }
      ],
      "outputs": [
        {
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      ],
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        "countdown",
        "date",
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      "featured": false,
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    {
      "slug": "country-flags-quiz",
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        {
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          "label": "Direction",
          "unit": "",
          "options": [
            "flag",
            "country"
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          "default": "flag"
        }
      ],
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          "name": "cfq-score",
          "type": "output"
        }
      ],
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      "sources": [],
      "tags": [
        "country",
        "flags",
        "quiz",
        "arcade",
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      "featured": false,
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    {
      "slug": "coupled-oscillators-normal-modes",
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          "step": 0.1,
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        {
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        {
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          "step": 1,
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        },
        {
          "name": "co-mode-select",
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          "label": "Initial Excitation",
          "unit": "",
          "options": [
            "beats",
            "symmetric",
            "antisymmetric"
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      "slug": "cover-letter",
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        {
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          "label": "Company Name",
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        {
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          "label": "Job Title",
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        {
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          "label": "Hiring Manager Name",
          "unit": ""
        },
        {
          "name": "cl-job-id",
          "type": "text",
          "label": "Job ID / Reference",
          "unit": ""
        },
        {
          "name": "cl-skills",
          "type": "text",
          "label": "Key Skills (comma separated)",
          "unit": ""
        },
        {
          "name": "cl-achievements",
          "type": "textarea",
          "label": "Key Achievements",
          "unit": "one per line"
        },
        {
          "name": "cl-why-role",
          "type": "textarea",
          "label": "Why You're Interested (2-3 sentences)",
          "unit": ""
        },
        {
          "name": "cl-tone",
          "type": "select-one",
          "label": "Tone & Style",
          "unit": "",
          "options": [
            "professional",
            "confident",
            "friendly",
            "innovative",
            "concise"
          ],
          "default": "professional"
        },
        {
          "name": "cl-length",
          "type": "select-one",
          "label": "Preferred Length",
          "unit": "",
          "options": [
            "short",
            "medium",
            "detailed"
          ],
          "default": "medium"
        },
        {
          "name": "cl-industry",
          "type": "select-one",
          "label": "Industry Focus",
          "unit": "",
          "options": [
            "general",
            "tech",
            "healthcare",
            "finance",
            "education",
            "creative",
            "nonprofit"
          ],
          "default": "general"
        }
      ],
      "outputs": [
        {
          "name": "coverlcl-results",
          "type": "output"
        },
        {
          "name": "cl-ats-score",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=cover-letter&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "cover",
        "letter",
        "builder",
        "writing",
        "language",
        "professional",
        "create",
        "tailored",
        "letters",
        "industry-specific"
      ],
      "popularity": 5420,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "cpr-service-deadline-calculator",
      "title": "📬 CPR Service & Response Deadline Calculator",
      "description": "Work out deemed service under CPR 6.14 and 6.26, then the acknowledgment, defence and reply deadlines, claim form validity and the CPR 2.8 court-office rule.",
      "category": "legal-and-professional",
      "categoryName": "Legal & Professional",
      "url": "https://www.themostusefulsiteintheworld.com/tool/cpr-service-deadline-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=cpr-service-deadline-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cpr-date",
          "type": "date",
          "label": "Date posted / sent / delivered",
          "unit": ""
        },
        {
          "name": "cpr-issue",
          "type": "date",
          "label": "Date the claim form was issued",
          "unit": ""
        },
        {
          "name": "cpr-pocdate",
          "type": "date",
          "label": "Date the particulars were served",
          "unit": ""
        },
        {
          "name": "cpr-abroad",
          "type": "checkbox",
          "label": "Claim form to be served out of the jurisdiction (6 months to serve, CPR 7.5(2))",
          "unit": "",
          "default": "0"
        },
        {
          "name": "cpr-doc",
          "type": "select-one",
          "label": "What was served",
          "unit": "",
          "options": [
            "other",
            "claim"
          ],
          "default": "other"
        },
        {
          "name": "cpr-method",
          "type": "select-one",
          "label": "Method of service",
          "unit": "",
          "options": [
            "post",
            "dx",
            "delivery",
            "email",
            "fax",
            "personal"
          ],
          "default": "post"
        },
        {
          "name": "cpr-time",
          "type": "select-one",
          "label": "Time of the step",
          "unit": "",
          "options": [
            "before",
            "after"
          ],
          "default": "before"
        },
        {
          "name": "cpr-poc",
          "type": "select-one",
          "label": "Particulars of claim",
          "unit": "",
          "options": [
            "with",
            "follow"
          ],
          "default": "with"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=cpr-service-deadline-calculator&<id>=<value>",
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "cpr",
        "service",
        "deadline",
        "response",
        "legal",
        "professional",
        "work",
        "out",
        "deemed",
        "under"
      ],
      "popularity": 5791,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "creative-writing",
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      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/creative-writing.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=creative-writing&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wordGoal",
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          "label": "wordGoal",
          "unit": "",
          "default": "1000"
        },
        {
          "name": "writingText",
          "type": "textarea",
          "label": "Start writing here... Your words will be saved automatically.",
          "unit": ""
        },
        {
          "name": "defaultTimer",
          "type": "select-one",
          "label": "defaultTimer",
          "unit": "",
          "options": [
            "5",
            "10",
            "15",
            "25",
            "45",
            "60"
          ],
          "default": "25"
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        {
          "name": "fontSize",
          "type": "select-one",
          "label": "fontSize",
          "unit": "",
          "options": [
            "12",
            "14",
            "16",
            "18"
          ],
          "default": "14"
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        {
          "name": "lineHeight",
          "type": "select-one",
          "label": "lineHeight",
          "unit": "",
          "options": [
            "1.4",
            "1.6",
            "1.8"
          ],
          "default": "1.6"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=creative-writing&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "creative",
        "writing",
        "studio",
        "language",
        "prompts",
        "character",
        "plot",
        "generators",
        "story",
        "ideas"
      ],
      "popularity": 6822,
      "featured": false,
      "updated": "2026-09-19"
    },
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      "slug": "cricket-chase-calculator",
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      "category": "sports",
      "categoryName": "Sports",
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      "standaloneUrl": null,
      "inputs": [
        {
          "name": "crc-target",
          "type": "number",
          "label": "Target",
          "unit": "runs",
          "min": 1,
          "default": "280"
        },
        {
          "name": "crc-score",
          "type": "number",
          "label": "Runs scored",
          "unit": "",
          "min": 0,
          "default": "154"
        },
        {
          "name": "crc-ov",
          "type": "number",
          "label": "Overs bowled",
          "unit": "",
          "min": 0,
          "default": "25"
        },
        {
          "name": "crc-balls",
          "type": "number",
          "label": "Balls",
          "unit": "",
          "min": 0,
          "max": 5,
          "default": "0"
        },
        {
          "name": "crc-wkts",
          "type": "number",
          "label": "Wickets lost",
          "unit": "",
          "min": 0,
          "max": 10,
          "default": "3"
        },
        {
          "name": "crc-overs",
          "type": "select-one",
          "label": "Match length",
          "unit": "",
          "options": [
            "20",
            "50",
            "40",
            "10",
            "90"
          ],
          "default": "50"
        }
      ],
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        {
          "name": "crc-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=cricket-chase-calculator&<id>=<value>",
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "cricket",
        "chase",
        "run-chase",
        "sports",
        "second",
        "innings",
        "chasing",
        "target",
        "enter",
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      "popularity": 5645,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "cricket-net-run-rate-calculator",
      "title": "🏏 Cricket Net Run Rate Calculator",
      "description": "The tie-breaker that decides tournaments. Add each match's runs and overs for and against, and this works out your aggregate Net Run Rate — applying the rule that a team bowled out is counted as fa...",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/cricket-net-run-rate-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=cricket-net-run-rate-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "nrr-quota",
          "type": "select-one",
          "label": "Overs per innings",
          "unit": "",
          "options": [
            "20",
            "50",
            "40",
            "10"
          ],
          "default": "50"
        }
      ],
      "outputs": [
        {
          "name": "nrr-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=cricket-net-run-rate-calculator&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=cricket-net-run-rate-calculator&nrr-quota=50"
      },
      "formula": "How NRR is worked out Net Run Rate = (total runs scored ÷ total overs faced) − (total runs conceded ÷",
      "sources": [],
      "tags": [
        "cricket",
        "net",
        "run",
        "rate",
        "sports",
        "tie-breaker",
        "decides",
        "tournaments",
        "add",
        "each"
      ],
      "popularity": 6185,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "crisis-offline-triage",
      "title": "🆘 Crisis Triage Guide",
      "description": "100% offline emergency triage protocols, acoustic CPR rhythm metronome, water survival calculator, and optical SOS distress beacon. Operates completely without internet during grid blackouts and na...",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/crisis-offline-triage.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=crisis-offline-triage&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "crisis-people-count",
          "type": "number",
          "label": "Number of People",
          "unit": "",
          "min": 1,
          "max": 50,
          "default": "3"
        },
        {
          "name": "crisis-days-count",
          "type": "number",
          "label": "Days Cut Off",
          "unit": "",
          "min": 1,
          "max": 90,
          "default": "14"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=crisis-offline-triage&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "crisis",
        "offline",
        "triage",
        "guide",
        "health",
        "fitness",
        "100",
        "emergency",
        "protocols",
        "acoustic"
      ],
      "popularity": 4920,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "cron-expression-builder",
      "title": "⏱️ Cron Schedule Builder",
      "description": "Construct cron expressions with interactive dials, read instant plain-English explanations, and preview the next 10 trigger times.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/cron-expression-builder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=cron-expression-builder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "csb-cron-str",
          "type": "text",
          "label": "cron str",
          "unit": "",
          "default": "0 9 * * 1-5"
        },
        {
          "name": "csb-f-min",
          "type": "text",
          "label": "Minute",
          "unit": "",
          "default": "0"
        },
        {
          "name": "csb-f-hour",
          "type": "text",
          "label": "Hour",
          "unit": "",
          "default": "9"
        },
        {
          "name": "csb-f-dom",
          "type": "text",
          "label": "Day",
          "unit": "Month",
          "default": "*"
        },
        {
          "name": "csb-f-mon",
          "type": "text",
          "label": "Month",
          "unit": "",
          "default": "*"
        },
        {
          "name": "csb-f-dow",
          "type": "text",
          "label": "Day",
          "unit": "Week",
          "default": "1-5"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=cron-expression-builder&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=cron-expression-builder&csb-cron-str=0%209%20*%20*%201-5&csb-f-min=0&csb-f-hour=9&csb-f-dom=*&csb-f-mon=*&csb-f-dow=1-5"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "cron",
        "expression",
        "builder",
        "schedule",
        "algorithms",
        "computer",
        "science",
        "construct",
        "expressions",
        "interactive"
      ],
      "popularity": 6787,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "crop-factor-35mm-equivalent",
      "title": "🖼️ Crop Factor & 35 mm Equivalent",
      "description": "35 mm-equivalent focal length = actual focal length × crop factor. Also shows equivalent f-number for depth of field (same framing). Field of view matches; light-gathering of the aperture does not ...",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/crop-factor-35mm-equivalent.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=crop-factor-35mm-equivalent&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cr35-f",
          "type": "number",
          "label": "Focal length",
          "unit": "mm",
          "min": 1,
          "max": 2000,
          "default": "50"
        },
        {
          "name": "cr35-n",
          "type": "number",
          "label": "Aperture f/",
          "unit": "",
          "min": 0.7,
          "max": 32,
          "default": "1.8"
        },
        {
          "name": "cr35-body",
          "type": "select-one",
          "label": "Sensor",
          "unit": "",
          "options": [
            "1",
            "1.5",
            "1.6",
            "2",
            "2.7",
            "5.6"
          ],
          "default": "1.5"
        }
      ],
      "outputs": [
        {
          "name": "cr35-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=crop-factor-35mm-equivalent&<id>=<value>",
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      },
      "formula": "Equivalent 35 mm-equivalent focal length = actual focal length × crop factor. Also shows equivalent f-",
      "sources": [],
      "tags": [
        "crop",
        "factor",
        "35mm",
        "equivalent",
        "productivity",
        "lifestyle",
        "mm-equivalent",
        "focal",
        "length",
        "actual"
      ],
      "popularity": 4196,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "crystal-lattice-unit-cell-3d",
      "title": "🔷 Crystal Lattice & Unit Cell 3D",
      "description": "Build simple cubic, BCC, FCC, diamond, rock-salt, CsCl and HCP crystals in 3D, slice them with any Miller plane (hkl), and calculate theoretical density, packing fraction, coordination number, d-sp...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/crystal-lattice-unit-cell-3d.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=crystal-lattice-unit-cell-3d&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "clu-a",
          "type": "number",
          "label": "Lattice constant a",
          "unit": "pm",
          "min": 1,
          "default": "361.49"
        },
        {
          "name": "clu-M",
          "type": "number",
          "label": "Molar mass per formula unit",
          "unit": "g/mol",
          "min": 0,
          "default": "63.546"
        },
        {
          "name": "clu-cells",
          "type": "range",
          "label": "Cells per side 1",
          "unit": "",
          "min": 1,
          "max": 3,
          "step": 1,
          "default": "1"
        },
        {
          "name": "clu-h",
          "type": "number",
          "label": "Miller h",
          "unit": "",
          "step": 1,
          "default": "1"
        },
        {
          "name": "clu-k",
          "type": "number",
          "label": "Miller k",
          "unit": "",
          "step": 1,
          "default": "1"
        },
        {
          "name": "clu-l",
          "type": "number",
          "label": "Miller l",
          "unit": "",
          "step": 1,
          "default": "1"
        },
        {
          "name": "clu-lam",
          "type": "number",
          "label": "X-ray λ",
          "unit": "pm",
          "min": 1,
          "default": "154.06"
        },
        {
          "name": "clu-plane",
          "type": "checkbox",
          "label": "Show (hkl) plane",
          "unit": "",
          "default": "1"
        },
        {
          "name": "clu-bonds",
          "type": "checkbox",
          "label": "Nearest-neighbour bonds",
          "unit": "",
          "default": "1"
        },
        {
          "name": "clu-full",
          "type": "checkbox",
          "label": "Space-filling atoms",
          "unit": "",
          "default": "0"
        },
        {
          "name": "clu-mat",
          "type": "select-one",
          "label": "Material preset",
          "unit": ""
        },
        {
          "name": "clu-src",
          "type": "select-one",
          "label": "X-ray tube",
          "unit": "",
          "options": [
            "154.06",
            "70.93",
            "178.90",
            "228.97"
          ],
          "default": "154.06"
        }
      ],
      "outputs": [
        {
          "name": "clu-hud",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=crystal-lattice-unit-cell-3d&<id>=<value>",
        "runs": false,
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      },
      "formula": "BCC 2, FCC 4 and diamond 8. Density : ρ = Z · M /",
      "sources": [],
      "tags": [
        "crystal",
        "lattice",
        "unit",
        "cell",
        "science",
        "engineering",
        "build",
        "simple",
        "cubic",
        "bcc"
      ],
      "popularity": 5409,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "csp-header-builder",
      "title": "🛡️ Content-Security-Policy Builder & Checker",
      "description": "Build a Content-Security-Policy header from plain fields, or paste an existing policy to find quoting mistakes and common weaknesses. Nothing is fetched or sent.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/csp-header-builder.html",
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      "standaloneUrl": null,
      "inputs": [
        {
          "name": "csp-header-builder-upgrade",
          "type": "checkbox",
          "label": "Add upgrade-insecure-requests (rewrite http:// sub-requests to https://)",
          "unit": "",
          "default": "0"
        },
        {
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          "min": 0,
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          "name": "cgg-tint-color",
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          "name": "cgg-border-color",
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          "name": "cgg-css-output",
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
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    {
      "slug": "css-grid-layout-generator",
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      "category": "saas-and-business-killers",
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          "name": "cgl-gap",
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          "default": "16"
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        {
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          "min": 1,
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        {
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      "featured": false,
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    },
    {
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      "category": "algorithms-and-computer-science",
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        {
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        {
          "name": "ccb-method",
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            "PUT",
            "PATCH",
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      },
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    {
      "slug": "curling-score-calculator",
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        {
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            "A",
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            "blank"
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      "featured": false,
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    },
    {
      "slug": "currency",
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        {
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          "name": "cx-to",
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        {
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        {
          "name": "cx-pair-display",
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=currency&<id>=<value>",
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      "featured": false,
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    {
      "slug": "curtain-width-drop-calculator",
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      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/curtain-width-drop-calculator.html",
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      "standaloneUrl": null,
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        {
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        {
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        {
          "name": "curtain-width-drop-calculator-side",
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          "label": "Total side-hem allowance per panel",
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        {
          "name": "curtain-width-drop-calculator-vertical",
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      ],
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        "curtain",
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      "slug": "cv-builder",
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          "label": "Professional Title",
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        {
          "name": "cv-email",
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        {
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        {
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          "label": "Location",
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        {
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        {
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        {
          "name": "cv-skills-technical",
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        {
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          "label": "Soft Skills (comma separated)",
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        {
          "name": "cv-summary",
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          "label": "Professional Summary (2-3 sentences)",
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        {
          "name": "cv-certifications",
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          "label": "Certifications",
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        },
        {
          "name": "cv-languages",
          "type": "textarea",
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          "unit": ""
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      ],
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        {
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      "sources": [],
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        "yield",
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      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "diving",
        "score",
        "sports",
        "dive",
        "way",
        "judges",
        "enter",
        "marks",
        "degree",
        "difficulty"
      ],
      "popularity": 4135,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "dna-helix-3d-builder",
      "title": "🧬 DNA Helix 3D Builder",
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      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/dna-helix-3d-builder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=dna-helix-3d-builder&embed=1",
      "standaloneUrl": null,
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        {
          "name": "dh3-seq",
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          "label": "DNA sequence, letters A T G C only",
          "unit": "",
          "default": "ATGGCCATTGTAATGGGCCGCTGAAAGGGTGCCCGATAG"
        },
        {
          "name": "dh3-spin",
          "type": "checkbox",
          "label": "spin",
          "unit": "",
          "default": "1"
        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=dna-helix-3d-builder&<id>=<value>",
        "runs": false,
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      },
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      "sources": [],
      "tags": [
        "dna",
        "helix",
        "builder",
        "science",
        "engineering",
        "type",
        "any",
        "sequence",
        "watch",
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      ],
      "popularity": 4780,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "dog-calorie-portion-calculator",
      "title": "🥩 Canine Daily Calorie Portioner",
      "description": "WSAVA metabolic energy calculator. Formulates exact Resting Energy Requirements (RER) and daily food cup portions to maintain ideal body condition.",
      "category": "dogs-and-canine-care",
      "categoryName": "Dogs & Canine Care",
      "url": "https://www.themostusefulsiteintheworld.com/tool/dog-calorie-portion-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-calorie-portion-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cal-dog-weight",
          "type": "number",
          "label": "Dog's Weight",
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          "min": 1,
          "max": 100,
          "step": 0.5,
          "default": "20"
        },
        {
          "name": "cal-kibble-density",
          "type": "number",
          "label": "Kibble / Wet Food Caloric Density",
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          "max": 600,
          "step": 5,
          "default": "375"
        },
        {
          "name": "cal-life-stage",
          "type": "select-one",
          "label": "Activity & Neutered Status",
          "unit": "",
          "options": [
            "1.6",
            "1.8",
            "1.0",
            "1.2",
            "2.5",
            "3.0",
            "2.0"
          ],
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-calorie-portion-calculator&<id>=<value>",
        "runs": false,
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      },
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      "sources": [],
      "tags": [
        "dog",
        "calorie",
        "portion",
        "canine",
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        "portioner",
        "dogs",
        "care",
        "wsava",
        "metabolic"
      ],
      "popularity": 6937,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "dog-chocolate-toxicity-calc",
      "title": "🍫 Dog Chocolate Toxicity Calc",
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      "category": "dogs-and-canine-care",
      "categoryName": "Dogs & Canine Care",
      "url": "https://www.themostusefulsiteintheworld.com/tool/dog-chocolate-toxicity-calc.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-chocolate-toxicity-calc&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "label": "Dog's Weight",
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          "min": 1,
          "max": 100,
          "step": 0.5,
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        },
        {
          "name": "choc-amount",
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          "max": 1500,
          "step": 5,
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        },
        {
          "name": "choc-type",
          "type": "select-one",
          "label": "Chocolate Type",
          "unit": "",
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            "milk",
            "dark",
            "dark85",
            "baker",
            "powder",
            "white"
          ],
          "default": "milk"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-chocolate-toxicity-calc&<id>=<value>",
        "runs": false,
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      },
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      "sources": [],
      "tags": [
        "dog",
        "chocolate",
        "toxicity",
        "calc",
        "dogs",
        "canine",
        "care",
        "emergency",
        "veterinary",
        "theobromine"
      ],
      "popularity": 6921,
      "featured": false,
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    },
    {
      "slug": "dog-clicker-trainer-cadence",
      "title": "🎯 Dog Clicker Trainer & Sound",
      "description": "Operant conditioning event marker. Features synthesized metallic clicker audio and a reaction-time latency game to calibrate your 0.8-second reward marking window.",
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      "categoryName": "Dogs & Canine Care",
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      "standaloneUrl": null,
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        {
          "name": "clicker-game-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-clicker-trainer-cadence&<id>=<value>",
        "runs": false
      },
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      "sources": [],
      "tags": [
        "dog",
        "clicker",
        "trainer",
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        "sound",
        "dogs",
        "canine",
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        "operant",
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      "popularity": 6664,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "dog-crate-sizing-den-blueprint",
      "title": "🏠 Dog Crate Sizing & Den Guide",
      "description": "Orthopedic crate sizing & housebreaking den blueprint. Computes exact crate length, height, and maximum continuous confinement hours by age.",
      "category": "dogs-and-canine-care",
      "categoryName": "Dogs & Canine Care",
      "url": "https://www.themostusefulsiteintheworld.com/tool/dog-crate-sizing-den-blueprint.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-crate-sizing-den-blueprint&embed=1",
      "standaloneUrl": null,
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        {
          "name": "crate-dog-len",
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          "unit": "Inches",
          "min": 10,
          "max": 60,
          "step": 1,
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        },
        {
          "name": "crate-dog-ht",
          "type": "number",
          "label": "Sitting Height to Ears",
          "unit": "Inches",
          "min": 10,
          "max": 50,
          "step": 1,
          "default": "22"
        },
        {
          "name": "crate-puppy-age",
          "type": "select-one",
          "label": "Puppy / Dog Age",
          "unit": "",
          "options": [
            "1",
            "2",
            "3",
            "4",
            "8"
          ],
          "default": "8"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-crate-sizing-den-blueprint&<id>=<value>",
        "runs": false,
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      },
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      "sources": [],
      "tags": [
        "dog",
        "crate",
        "sizing",
        "den",
        "blueprint",
        "guide",
        "dogs",
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        "orthopedic"
      ],
      "popularity": 5561,
      "featured": false,
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    },
    {
      "slug": "dog-daily-walk-exercise-calc",
      "title": "🦮 Dog Daily Walk & Activity Calc",
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      "category": "dogs-and-canine-care",
      "categoryName": "Dogs & Canine Care",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-daily-walk-exercise-calc&embed=1",
      "standaloneUrl": null,
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        {
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          "label": "Breed Energy Group",
          "unit": "",
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            "herding",
            "sporting",
            "terrier",
            "toy",
            "brachy"
          ],
          "default": "sporting"
        },
        {
          "name": "walk-age-months",
          "type": "select-one",
          "label": "Dog Age",
          "unit": "",
          "options": [
            "3",
            "5",
            "8",
            "adult",
            "senior"
          ],
          "default": "adult"
        },
        {
          "name": "walk-weather",
          "type": "select-one",
          "label": "Ambient Weather Condition",
          "unit": "",
          "options": [
            "moderate",
            "hot",
            "freezing"
          ],
          "default": "moderate"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-daily-walk-exercise-calc&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "dog",
        "daily",
        "walk",
        "exercise",
        "calc",
        "activity",
        "dogs",
        "canine",
        "care",
        "prescription"
      ],
      "popularity": 4013,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "dog-dehydration-vital-checker",
      "title": "🩺 Dog Vital Signs & Hydration",
      "description": "Clinical canine triage assessment. Evaluate skin turgor snapback, gum capillary refill time (CRT), normal body temperatures, and resting respiratory rates.",
      "category": "dogs-and-canine-care",
      "categoryName": "Dogs & Canine Care",
      "url": "https://www.themostusefulsiteintheworld.com/tool/dog-dehydration-vital-checker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-dehydration-vital-checker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "vital-skin-test",
          "type": "select-one",
          "label": "Skin Turgor",
          "unit": "Scruff Pinch",
          "options": [
            "normal",
            "mild",
            "severe"
          ],
          "default": "normal"
        },
        {
          "name": "vital-gum-color",
          "type": "select-one",
          "label": "Mucous Membrane",
          "unit": "Gum Color",
          "options": [
            "pink",
            "tacky",
            "brick",
            "white",
            "blue"
          ],
          "default": "pink"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-dehydration-vital-checker&<id>=<value>",
        "runs": false,
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      },
      "formula": "SLEEPING BREATHS 15–30 bpm (>30 = Heart Alert) The Life-",
      "sources": [],
      "tags": [
        "dog",
        "dehydration",
        "vital",
        "checker",
        "signs",
        "hydration",
        "dogs",
        "canine",
        "care",
        "clinical"
      ],
      "popularity": 4499,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "dog-human-age-epigenetic-calc",
      "title": "🐕 Dog Human Years Age Clock",
      "description": "UCSD School of Medicine DNA methylation epigenetic calculator (Wang et al., Cell Systems). Replaces the debunked 7-year myth with cellular age biology.",
      "category": "dogs-and-canine-care",
      "categoryName": "Dogs & Canine Care",
      "url": "https://www.themostusefulsiteintheworld.com/tool/dog-human-age-epigenetic-calc.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-human-age-epigenetic-calc&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "dog-calendar-age",
          "type": "number",
          "label": "Dog's Actual Age",
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          "max": 25,
          "step": 0.2,
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        },
        {
          "name": "dog-size-category",
          "type": "select-one",
          "label": "Breed Size Category",
          "unit": "",
          "options": [
            "small",
            "medium",
            "large",
            "giant"
          ],
          "default": "medium"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-human-age-epigenetic-calc&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "dog",
        "human",
        "age",
        "epigenetic",
        "calc",
        "years",
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        "dogs",
        "canine",
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      ],
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "dog-photo-viewer",
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      "description": "COMPLETE DOG VIEWER - Browse thousands of dog photos with breed information, favorites, and infinite scrolling. Multiple API sources for maximum reliability.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/dog-photo-viewer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-photo-viewer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "label": "Breed",
          "unit": "",
          "options": [
            "all",
            "african",
            "akita",
            "beagle",
            "boxer",
            "bulldog",
            "chihuahua",
            "collie",
            "corgi",
            "dachshund",
            "dalmatian",
            "germanshepherd",
            "goldenretriever",
            "husky",
            "labrador",
            "poodle",
            "pug",
            "rottweiler",
            "samoyed",
            "shiba",
            "terrier"
          ],
          "default": "all"
        },
        {
          "name": "dpv-order",
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          "label": "Order",
          "unit": "",
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            "random",
            "latest",
            "popular"
          ],
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        },
        {
          "name": "dpv-image-count",
          "type": "select-one",
          "label": "Images Per Load",
          "unit": "",
          "options": [
            "6",
            "12",
            "20",
            "30"
          ],
          "default": "12"
        }
      ],
      "outputs": [
        {
          "name": "dpv-count-display",
          "type": "output"
        },
        {
          "name": "dpv-output",
          "type": "output"
        }
      ],
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      },
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      "sources": [],
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        "dog",
        "photo",
        "viewer",
        "productivity",
        "lifestyle",
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      "featured": false,
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    },
    {
      "slug": "dog-safe-toxic-food-checker",
      "title": "🥩 Dog Food Safety & Toxicity Key",
      "description": "Emergency canine food safety encyclopedia. Search common household foods to identify lethal toxicities (Xylitol, grapes, alliums) versus safe nutrient-dense superfoods.",
      "category": "dogs-and-canine-care",
      "categoryName": "Dogs & Canine Care",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-safe-toxic-food-checker&embed=1",
      "standaloneUrl": null,
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        {
          "name": "food-search-input",
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          "unit": ""
        },
        {
          "name": "food-filter-select",
          "type": "select-one",
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          "unit": "",
          "options": [
            "all",
            "toxic",
            "caution",
            "safe"
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          "default": "all"
        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-safe-toxic-food-checker&<id>=<value>",
        "runs": false,
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      },
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      "sources": [],
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        "dog",
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        "toxic",
        "food",
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        "key",
        "dogs",
        "canine"
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      "featured": false,
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    },
    {
      "slug": "dog-ultrasonic-whistle-trainer",
      "title": "📯 Dog Ultrasonic Whistle Lab",
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      "category": "dogs-and-canine-care",
      "categoryName": "Dogs & Canine Care",
      "url": "https://www.themostusefulsiteintheworld.com/tool/dog-ultrasonic-whistle-trainer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-ultrasonic-whistle-trainer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "whis-freq-slider",
          "type": "range",
          "label": "Oscillator Frequency",
          "unit": "Hz",
          "min": 12000,
          "max": 22000,
          "step": 500,
          "default": "18000"
        }
      ],
      "outputs": [
        {
          "name": "whis-freq-display",
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        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=dog-ultrasonic-whistle-trainer&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "dog",
        "ultrasonic",
        "whistle",
        "trainer",
        "lab",
        "dogs",
        "canine",
        "care",
        "high-frequency",
        "acoustic"
      ],
      "popularity": 4770,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "doppler-effect-simulator",
      "title": "🔊 Doppler Effect Simulator",
      "description": "Simulate frequency shifts and wavefront compression for acoustic sound waves and relativistic light redshift ($z$). Features real-time wavefront propagation canvas and Web Audio tone simulation.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/doppler-effect-simulator.html",
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        {
          "name": "doppler-medium",
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            "343",
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        "doppler",
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        "engineering",
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    },
    {
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      "categoryName": "Science & Engineering",
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        {
          "name": "dp-mass-ratio",
          "type": "number",
          "label": "Mass Ratio",
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          "max": 5,
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        },
        {
          "name": "dp-gravity",
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          "label": "Gravity",
          "unit": "$g$",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=double-pendulum-chaos&<id>=<value>",
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        "double",
        "pendulum",
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    {
      "slug": "double-slit-quantum-eraser",
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      "categoryName": "Science & Engineering",
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      ],
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        "double",
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        "delayed-choice",
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      "popularity": 5757,
      "featured": false,
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    },
    {
      "slug": "downlight-spacing-calculator",
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      "categoryName": "Home & DIY",
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        "downlight",
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        },
        {
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        {
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        {
          "name": "drf-hg",
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        {
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          "label": "Intake hose length",
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        {
          "name": "drv-moving",
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        "driving",
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      "slug": "drone-sighting-safety-guide",
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        {
          "name": "drone-sighting-safety-guide-scenario",
          "type": "select-one",
          "label": "What is happening?",
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            "passing",
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            "landed",
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          "name": "drone-sighting-safety-guide-region",
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          "label": "Where are you?",
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            "other",
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          ],
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        {
          "name": "drone-sighting-safety-guide-advice",
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        {
          "name": "dwl-ceil",
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        },
        {
          "name": "dwl-waste",
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          "label": "Wastage",
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        },
        {
          "name": "dwl-size",
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            "32",
            "40",
            "48"
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      ],
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        {
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=drywall-calculator&<id>=<value>",
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        "drywall",
        "plasterboard",
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    {
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      "category": "productivity-and-lifestyle",
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      "standaloneUrl": null,
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        {
          "name": "dst-recurring-meeting-drift-time",
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          "default": "09:00"
        },
        {
          "name": "dst-recurring-meeting-drift-weeks",
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          "label": "Look ahead",
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        {
          "name": "dst-recurring-meeting-drift-people",
          "type": "textarea",
          "label": "Attendee time zones (one per line — IANA names such as America/New_York)",
          "unit": ""
        },
        {
          "name": "dst-recurring-meeting-drift-zone",
          "type": "select-one",
          "label": "Meeting is anchored to (organiser’s zone)",
          "unit": ""
        },
        {
          "name": "dst-recurring-meeting-drift-day",
          "type": "select-one",
          "label": "Repeats every Monday Tuesday Wednesday Thursday Friday Saturday Sunday",
          "unit": "",
          "options": [
            "1",
            "2",
            "3",
            "4",
            "5",
            "6",
            "0"
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      ],
      "outputs": [
        {
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        {
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        "dst",
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        {
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      "sources": [],
      "tags": [
        "duplicate",
        "line",
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      "category": "astronomy-and-space",
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        "earthquake",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=echo-pond-water-cymatics-soundscape&<id>=<value>",
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      "featured": false,
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    },
    {
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=edu-anatomy&<id>=<value>",
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    {
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    {
      "slug": "edu-country-data",
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        "data",
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          "options": [
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      "inputs": [],
      "outputs": [
        {
          "name": "primary-result",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=electricity&<id>=<value>",
        "runs": true
      },
      "formula": "Tool ⚡ Ohm's Law V = I × R 💡 Power P = V ×",
      "sources": [],
      "tags": [
        "electricity",
        "electrical",
        "engineering",
        "science",
        "comprehensive",
        "toolkit",
        "professionals",
        "students",
        "includes",
        "circuit"
      ],
      "popularity": 5849,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "electromagnetic-wave-polarization-3d",
      "title": "🌊 Electromagnetic Wave & Polarization 3D",
      "description": "Watch light travel as perpendicular E and B fields in 3D. Dial in linear, circular or elliptical polarization, send it through a polarizer to verify Malus's law, and convert between wavelength, fre...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/electromagnetic-wave-polarization-3d.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=electromagnetic-wave-polarization-3d&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "label": "Eₓ amplitude (vertical) 1.00",
          "unit": "",
          "min": 0,
          "max": 1,
          "step": 0.01,
          "default": "1"
        },
        {
          "name": "emw-ey",
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          "label": "E_y amplitude (horizontal) 0.00",
          "unit": "",
          "min": 0,
          "max": 1,
          "step": 0.01,
          "default": "0"
        },
        {
          "name": "emw-ph",
          "type": "range",
          "label": "Phase δ (y vs x) 0°",
          "unit": "",
          "min": -180,
          "max": 180,
          "step": 1,
          "default": "0"
        },
        {
          "name": "emw-pol",
          "type": "range",
          "label": "Polarizer axis θ 30°",
          "unit": "",
          "min": 0,
          "max": 180,
          "step": 1,
          "default": "30"
        },
        {
          "name": "emw-spd",
          "type": "range",
          "label": "Animation speed 1.0×",
          "unit": "",
          "min": 0,
          "max": 3,
          "step": 0.1,
          "default": "1"
        },
        {
          "name": "emw-cyc",
          "type": "range",
          "label": "Wavelengths shown 2.5",
          "unit": "",
          "min": 1,
          "max": 5,
          "step": 0.5,
          "default": "2.5"
        },
        {
          "name": "emw-b",
          "type": "checkbox",
          "label": "Magnetic field B",
          "unit": "",
          "default": "1"
        },
        {
          "name": "emw-usepol",
          "type": "checkbox",
          "label": "Polarizer in beam",
          "unit": "",
          "default": "1"
        },
        {
          "name": "emw-trace",
          "type": "checkbox",
          "label": "Polarization ellipse",
          "unit": "",
          "default": "1"
        },
        {
          "name": "emw-val",
          "type": "number",
          "label": "Value",
          "unit": "",
          "default": "532"
        },
        {
          "name": "emw-int",
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          "label": "Intensity",
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          "min": 0,
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        },
        {
          "name": "emw-n",
          "type": "number",
          "label": "Refractive index n",
          "unit": "medium",
          "min": 1,
          "default": "1"
        },
        {
          "name": "emw-unit",
          "type": "select-one",
          "label": "Unit",
          "unit": "",
          "options": [
            "nm",
            "um",
            "m",
            "THz",
            "GHz",
            "MHz",
            "eV",
            "cm-1"
          ],
          "default": "nm"
        }
      ],
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        {
          "name": "emw-hud",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=electromagnetic-wave-polarization-3d&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=electromagnetic-wave-polarization-3d&emw-ex=1&emw-ey=0&emw-ph=0&emw-pol=30&emw-spd=1&emw-cyc=2.5"
      },
      "formula": "In vacuum E ⟂ B ⟂ direction of travel, |B| = |E|/c , and they travel at c = 299,792,458 m/",
      "sources": [],
      "tags": [
        "electromagnetic",
        "wave",
        "polarization",
        "science",
        "engineering",
        "watch",
        "light",
        "travel",
        "perpendicular",
        "fields"
      ],
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      "featured": false,
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    },
    {
      "slug": "element-hall",
      "title": "⚗️ The Element Hall",
      "description": "All 118 elements as numbered museum exhibits: discovery year, discoverers, name origin, category, state at room temperature — plus curator's notes on two dozen showpieces and an honest word where d...",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/element-hall.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=element-hall&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "eh-q",
          "type": "text",
          "label": "Search elements",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=element-hall&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "element",
        "hall",
        "productivity",
        "lifestyle",
        "all",
        "118",
        "elements",
        "numbered",
        "museum",
        "exhibits"
      ],
      "popularity": 6694,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "email-header-inspector",
      "title": "🛡️ Email Header Inspector",
      "description": "Paste an email’s raw headers to inspect the visible From, Reply-To and Return-Path domains, reported SPF/DKIM/DMARC results, and the number of Received hops. Everything is checked in this page; no ...",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/email-header-inspector.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=email-header-inspector&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "email-header-inspector-input",
          "type": "textarea",
          "label": "Raw message headers",
          "unit": ""
        },
        {
          "name": "email-header-inspector-report",
          "type": "textarea",
          "label": "Plain-text report",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "email-header-inspector-status",
          "type": "live"
        },
        {
          "name": "email-header-inspector-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=email-header-inspector&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "email",
        "header",
        "inspector",
        "algorithms",
        "computer",
        "science",
        "paste",
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        "headers",
        "inspect"
      ],
      "popularity": 6744,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "email-signature-generator",
      "title": "📧 Signature Forge",
      "description": "Build an email signature that survives Gmail, Outlook and Apple Mail, then copy it with formatting intact and paste straight into your mail client. Table-based layout, inline styles only, no script...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/email-signature-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=email-signature-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "esg-name",
          "type": "text",
          "label": "Full name",
          "unit": "",
          "default": "Russell Head"
        },
        {
          "name": "esg-role",
          "type": "text",
          "label": "Job title",
          "unit": "",
          "default": "Founder"
        },
        {
          "name": "esg-company",
          "type": "text",
          "label": "Company",
          "unit": "",
          "default": "The Most Useful Site in the World"
        },
        {
          "name": "esg-pronouns",
          "type": "text",
          "label": "Pronouns",
          "unit": "",
          "default": "he/him"
        },
        {
          "name": "esg-phone",
          "type": "text",
          "label": "Phone",
          "unit": "",
          "default": "+44 1582 000000"
        },
        {
          "name": "esg-email",
          "type": "email",
          "label": "Email",
          "unit": "",
          "default": "hello@themostusefulsiteintheworld.com"
        },
        {
          "name": "esg-web",
          "type": "text",
          "label": "Website",
          "unit": "",
          "default": "https://www.themostusefulsiteintheworld.com"
        },
        {
          "name": "esg-addr",
          "type": "text",
          "label": "Address",
          "unit": "",
          "default": "Luton, Bedfordshire, United Kingdom"
        },
        {
          "name": "esg-linkedin",
          "type": "text",
          "label": "LinkedIn",
          "unit": "",
          "default": "https://www.linkedin.com/in/example"
        },
        {
          "name": "esg-x",
          "type": "text",
          "label": "X / Twitter",
          "unit": "",
          "default": "https://x.com/yourhandle"
        },
        {
          "name": "esg-github",
          "type": "text",
          "label": "GitHub",
          "unit": ""
        },
        {
          "name": "esg-logo",
          "type": "text",
          "label": "Logo URL",
          "unit": "hosted image"
        },
        {
          "name": "esg-accent",
          "type": "color",
          "label": "Accent colour",
          "unit": "",
          "default": "#1f6feb"
        },
        {
          "name": "esg-disclaim",
          "type": "checkbox",
          "label": "Confidentiality notice",
          "unit": "",
          "default": "1"
        },
        {
          "name": "esg-cta",
          "type": "checkbox",
          "label": "Call-to-action link",
          "unit": "",
          "default": "0"
        },
        {
          "name": "esg-ctatext",
          "type": "text",
          "label": "CTA text and URL",
          "unit": "text|url",
          "default": "Book a 15-minute call|https://example.com/book"
        },
        {
          "name": "esg-template",
          "type": "select-one",
          "label": "Layout",
          "unit": "",
          "options": [
            "classic",
            "stacked",
            "compact"
          ],
          "default": "classic"
        },
        {
          "name": "esg-font",
          "type": "select-one",
          "label": "Font family",
          "unit": "",
          "options": [
            "Helvetica, Arial, sans-serif",
            "Georgia, serif",
            "'Segoe UI', Tahoma, sans-serif",
            "'Courier New', monospace"
          ],
          "default": "Helvetica, Arial, sans-serif"
        }
      ],
      "outputs": [
        {
          "name": "esg-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=email-signature-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=email-signature-generator&esg-name=Russell%20Head&esg-role=Founder&esg-company=The%20Most%20Useful%20Site%20in%20the%20World&esg-pronouns=he%2Fhim&esg-phone=%2B44%201582%20000000&esg-email=hello%40themostusefulsiteintheworld.com"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "email",
        "signature",
        "forge",
        "saas",
        "business",
        "killers",
        "build",
        "survives",
        "gmail",
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      ],
      "popularity": 6867,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "email-subject-line-tester",
      "title": "✉️ Email Subject Line Tester",
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      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/email-subject-line-tester.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=email-subject-line-tester&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "est-sender",
          "type": "text",
          "label": "From name",
          "unit": "",
          "default": "The Most Useful Site"
        },
        {
          "name": "est-subject",
          "type": "text",
          "label": "Subject line",
          "unit": "",
          "default": "Ten practical tools for your next project"
        },
        {
          "name": "est-preheader",
          "type": "textarea",
          "label": "Preheader / preview text",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "est-tips",
          "type": "live"
        },
        {
          "name": "est-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=email-subject-line-tester&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=email-subject-line-tester&est-sender=The%20Most%20Useful%20Site&est-subject=Ten%20practical%20tools%20for%20your%20next%20project"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "email",
        "subject",
        "line",
        "tester",
        "saas",
        "business",
        "killers",
        "preview",
        "how",
        "preheader"
      ],
      "popularity": 4878,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "email-templates",
      "title": "📧 Email Template Generator",
      "description": "💼 Generate perfectly crafted professional emails, LinkedIn messages, and business communications. Includes tone analysis, etiquette tips, and productivity features.",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/email-templates.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=email-templates&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "et-recipient",
          "type": "text",
          "label": "→ Recipient",
          "unit": ""
        },
        {
          "name": "sig-name",
          "type": "text",
          "label": "Jane Smith",
          "unit": ""
        },
        {
          "name": "sig-title",
          "type": "text",
          "label": "Senior Project Manager",
          "unit": ""
        },
        {
          "name": "et-purpose",
          "type": "textarea",
          "label": "Purpose & Context",
          "unit": ""
        },
        {
          "name": "et-details",
          "type": "textarea",
          "label": "Key Details (Dates, Numbers, Specifics)",
          "unit": ""
        },
        {
          "name": "et-output",
          "type": "textarea",
          "label": "Your generated message will appear here...",
          "unit": ""
        },
        {
          "name": "et-relationship",
          "type": "select-one",
          "label": "Relationship",
          "unit": "",
          "options": [
            "new",
            "client",
            "colleague",
            "manager",
            "vendor",
            "recruiter"
          ],
          "default": "new"
        }
      ],
      "outputs": [
        {
          "name": "signature-output",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=email-templates&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=email-templates&et-relationship=new"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "email",
        "templates",
        "template",
        "writing",
        "language",
        "generate",
        "perfectly",
        "crafted",
        "professional",
        "emails"
      ],
      "popularity": 6736,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "emergency-comms-radio-planner",
      "title": "📡 Emergency Communications & Radio Planner",
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      "category": "survival-and-emergency-readiness",
      "categoryName": "Survival & Emergency Readiness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/emergency-comms-radio-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=emergency-comms-radio-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [
        {
          "name": "com-body",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=emergency-comms-radio-planner&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "emergency",
        "comms",
        "radio",
        "planner",
        "communications",
        "survival",
        "readiness",
        "every",
        "major",
        "incident"
      ],
      "popularity": 4570,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "emoji-meaning-decoder",
      "title": "🤔 What Does That Emoji *Actually* Mean?",
      "description": "The generational emoji gap, decoded. Search or tap an emoji to see what it really means, how your boss probably reads it, and whether it's safe for the work chat. You will never send 🙏 in the grou...",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/emoji-meaning-decoder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=emoji-meaning-decoder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "emd-search",
          "type": "text",
          "label": "Search an emoji or a word (e.g. skull, pray, smile)...",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "emd-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=emoji-meaning-decoder&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "emoji",
        "meaning",
        "decoder",
        "what",
        "does",
        "actually",
        "mean",
        "productivity",
        "lifestyle",
        "generational"
      ],
      "popularity": 6477,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "employee-true-cost-calculator",
      "title": "👥 Employee True Cost Calculator",
      "description": "Estimate the fully loaded annual and monthly cost of hiring beyond the headline salary. All calculations stay in your browser.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/employee-true-cost-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=employee-true-cost-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "employee-true-cost-calculator-salary",
          "type": "number",
          "label": "Annual salary",
          "unit": "£",
          "default": "35000"
        },
        {
          "name": "employee-true-cost-calculator-tax",
          "type": "number",
          "label": "Employer taxes/pension",
          "unit": "%",
          "default": "16"
        },
        {
          "name": "employee-true-cost-calculator-benefits",
          "type": "number",
          "label": "Annual benefits",
          "unit": "£",
          "default": "2500"
        },
        {
          "name": "employee-true-cost-calculator-overhead",
          "type": "number",
          "label": "Equipment/overhead",
          "unit": "£",
          "default": "4000"
        }
      ],
      "outputs": [
        {
          "name": "employee-true-cost-calculator-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=employee-true-cost-calculator&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=employee-true-cost-calculator&employee-true-cost-calculator-salary=35000&employee-true-cost-calculator-tax=16&employee-true-cost-calculator-benefits=2500&employee-true-cost-calculator-overhead=4000&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "employee",
        "true",
        "cost",
        "finance",
        "money",
        "estimate",
        "fully",
        "loaded",
        "annual",
        "monthly"
      ],
      "popularity": 4982,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "energy-tariff-comparator",
      "title": "⚡ Energy Tariff Comparator",
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      "url": "https://www.themostusefulsiteintheworld.com/tool/event-seating-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=event-seating-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "event-seating-planner-tables-input",
          "type": "text",
          "label": "Table sizes — e.g. “8, 8, 10” or “5x8” for five tables of eight",
          "unit": "",
          "default": "4x8"
        },
        {
          "name": "event-seating-planner-guests",
          "type": "textarea",
          "label": "Guests — one household or group per line; names on the same line always sit together",
          "unit": ""
        },
        {
          "name": "event-seating-planner-apart",
          "type": "textarea",
          "label": "Keep apart — one pair per line: Name / Name",
          "unit": ""
        },
        {
          "name": "event-seating-planner-near",
          "type": "textarea",
          "label": "Seat together if possible — Name / Name",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "event-seating-planner-status",
          "type": "live"
        },
        {
          "name": "event-seating-planner-result",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=event-seating-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=event-seating-planner&event-seating-planner-tables-input=4x8"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "event",
        "seating",
        "planner",
        "productivity",
        "lifestyle",
        "seat",
        "guests",
        "tables",
        "wedding",
        "party"
      ],
      "popularity": 4073,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "event",
      "title": "📅 Event Reminder",
      "description": "Set reminders for upcoming events with notifications, priorities, and recurrence options.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/event.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=event&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "er-name",
          "type": "text",
          "label": "Event Name",
          "unit": ""
        },
        {
          "name": "er-date",
          "type": "date",
          "label": "Date",
          "unit": ""
        },
        {
          "name": "er-time",
          "type": "time",
          "label": "Time",
          "unit": ""
        },
        {
          "name": "er-notes",
          "type": "textarea",
          "label": "Notes & Location",
          "unit": ""
        },
        {
          "name": "er-category",
          "type": "select-one",
          "label": "Category",
          "unit": "",
          "options": [
            "appointment",
            "meeting",
            "birthday",
            "deadline",
            "travel",
            "social",
            "work",
            "personal",
            "education",
            "health"
          ],
          "default": "appointment"
        },
        {
          "name": "er-priority",
          "type": "select-one",
          "label": "Priority",
          "unit": "",
          "options": [
            "low",
            "medium",
            "high",
            "urgent"
          ],
          "default": "medium"
        },
        {
          "name": "er-reminder",
          "type": "select-one",
          "label": "Reminder Before",
          "unit": "",
          "options": [
            "none",
            "15min",
            "1hour",
            "1day",
            "3days",
            "1week"
          ],
          "default": "1hour"
        },
        {
          "name": "er-recurrence",
          "type": "select-one",
          "label": "Recurrence",
          "unit": "",
          "options": [
            "none",
            "daily",
            "weekly",
            "monthly",
            "yearly",
            "weekdays",
            "custom"
          ],
          "default": "none"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=event&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=event&er-category=appointment&er-priority=medium&er-reminder=1hour&er-recurrence=none"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "event",
        "reminder",
        "productivity",
        "lifestyle",
        "set",
        "reminders",
        "upcoming",
        "events",
        "notifications",
        "priorities"
      ],
      "popularity": 4546,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "evidence-integrity-manifest",
      "title": "🔐 Evidence File Integrity Manifest",
      "description": "Create a local inventory of selected evidence files with file metadata and SHA-256 hashes for manageable files, then append handling events. This helps detect later file changes; it does not prove ...",
      "category": "field-investigation-and-evidence",
      "categoryName": "Field Investigation & Evidence",
      "url": "https://www.themostusefulsiteintheworld.com/tool/evidence-integrity-manifest.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=evidence-integrity-manifest&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "eim-operator",
          "type": "text",
          "label": "Operator code (not full name)",
          "unit": ""
        },
        {
          "name": "eim-note",
          "type": "text",
          "label": "Note",
          "unit": ""
        },
        {
          "name": "eim-target",
          "type": "select-one",
          "label": "Affected file / scope",
          "unit": "",
          "options": [
            "session"
          ]
        },
        {
          "name": "eim-action",
          "type": "select-one",
          "label": "Action",
          "unit": "",
          "options": [
            "Captured original",
            "Copied for review",
            "Transferred to another custodian",
            "Reviewed / played back",
            "Other handling event"
          ]
        }
      ],
      "outputs": [
        {
          "name": "eim-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=evidence-integrity-manifest&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "evidence",
        "integrity",
        "manifest",
        "file",
        "field",
        "investigation",
        "create",
        "local",
        "inventory",
        "selected"
      ],
      "popularity": 5115,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "evolution-arena-3d",
      "title": "🧬 Evolution Arena — 3D Creature Evolution",
      "description": "Evolve 3D creatures from scratch with a real genetic algorithm. Bodies of nodes and muscles are bred alongside their neural nets, then tested on walking, jumping, climbing, sumo and bridge combat.",
      "category": "mind-blowing-demos",
      "categoryName": "Mind-Blowing Demos",
      "url": "https://www.themostusefulsiteintheworld.com/tool/evolution-arena-3d.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=evolution-arena-3d&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=evolution-arena-3d&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "evolution",
        "arena",
        "creature",
        "mind-blowing",
        "demos",
        "evolve",
        "creatures",
        "scratch",
        "real",
        "genetic"
      ],
      "popularity": 6137,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "evolution-walker",
      "title": "Evolution AI Walker",
      "description": "Watch AI creatures evolve to walk, survive disasters, find food, and adapt! 10 terrain types, random events, food chains, achievements, and deep genetics. Creatures improve through natural selection.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/evolution-walker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=evolution-walker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "evo-mutation-slider",
          "type": "range",
          "label": "Mutation Rate",
          "unit": "",
          "min": 1,
          "max": 50,
          "default": "15"
        },
        {
          "name": "evo-population",
          "type": "select-one",
          "label": "Population Size",
          "unit": "",
          "options": [
            "8",
            "12",
            "16",
            "20",
            "30"
          ],
          "default": "12"
        },
        {
          "name": "evo-terrain",
          "type": "select-one",
          "label": "Terrain Type",
          "unit": "",
          "options": [
            "flat",
            "hills",
            "mountains",
            "obstacles",
            "swamp",
            "ice",
            "desert",
            "volcanic",
            "space",
            "stairs"
          ],
          "default": "flat"
        },
        {
          "name": "evo-events",
          "type": "select-one",
          "label": "Random Events",
          "unit": "",
          "options": [
            "off",
            "rare",
            "moderate",
            "extreme"
          ],
          "default": "rare"
        },
        {
          "name": "evo-gravity",
          "type": "select-one",
          "label": "Gravity",
          "unit": "",
          "options": [
            "0.3",
            "0.5",
            "1.0",
            "1.5",
            "2.0"
          ],
          "default": "1.0"
        },
        {
          "name": "evo-food",
          "type": "select-one",
          "label": "Food System",
          "unit": "",
          "options": [
            "off",
            "sparse",
            "moderate",
            "abundant"
          ],
          "default": "moderate"
        },
        {
          "name": "evo-bodytype",
          "type": "select-one",
          "label": "Starting Body Type",
          "unit": "",
          "options": [
            "random",
            "biped",
            "quadruped",
            "hexapod",
            "snake",
            "spider"
          ],
          "default": "random"
        }
      ],
      "outputs": [
        {
          "name": "evo-mutation-value",
          "type": "output"
        },
        {
          "name": "evo-bonus-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=evolution-walker&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=evolution-walker&evo-mutation-slider=15&evo-population=12&evo-terrain=flat&evo-events=rare&evo-gravity=1.0&evo-food=moderate"
      },
      "formula": "More creatures = faster evolution but lower FPS Challenging terrain +",
      "sources": [],
      "tags": [
        "evolution",
        "walker",
        "science",
        "engineering",
        "watch",
        "creatures",
        "evolve",
        "walk",
        "survive",
        "disasters"
      ],
      "popularity": 6784,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "evp-blind-listening-worksheet",
      "title": "🎧 Blind EVP Listening Worksheet",
      "description": "Capture an independent first-pass transcription before revealing the question or expected phrase. Then replay, record a second pass and compare the notes without the tool supplying words.",
      "category": "field-investigation-and-evidence",
      "categoryName": "Field Investigation & Evidence",
      "url": "https://www.themostusefulsiteintheworld.com/tool/evp-blind-listening-worksheet.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=evp-blind-listening-worksheet&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ebw-context",
          "type": "text",
          "label": "Prompt / expected phrase",
          "unit": ""
        },
        {
          "name": "ebw-confidence",
          "type": "range",
          "label": "Confidence (listener judgment): 25%",
          "unit": "",
          "min": 0,
          "max": 100,
          "default": "25"
        },
        {
          "name": "ebw-pass-two",
          "type": "textarea",
          "label": "Second-pass transcription / sound note",
          "unit": ""
        },
        {
          "name": "ebw-label",
          "type": "select-one",
          "label": "Listener's classification",
          "unit": "",
          "options": [
            "Unclear / no reliable words",
            "Possible speech",
            "Non-speech sound",
            "Ordinary sound likely"
          ],
          "default": "Unclear / no reliable words"
        }
      ],
      "outputs": [
        {
          "name": "ebw-status",
          "type": "live"
        },
        {
          "name": "ebw-confidence-out",
          "type": "output"
        },
        {
          "name": "ebw-pass-one-out",
          "type": "output"
        },
        {
          "name": "ebw-context-out",
          "type": "output"
        },
        {
          "name": "ebw-pass-two-out",
          "type": "output"
        },
        {
          "name": "ebw-label-out",
          "type": "output"
        },
        {
          "name": "ebw-score-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=evp-blind-listening-worksheet&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=evp-blind-listening-worksheet&ebw-confidence=25&ebw-label=Unclear%20%2F%20no%20reliable%20words"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "evp",
        "blind",
        "listening",
        "worksheet",
        "field",
        "investigation",
        "evidence",
        "capture",
        "independent",
        "first-pass"
      ],
      "popularity": 5262,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "evp-review-lab",
      "title": "🎙 EVP Audio Review Lab",
      "description": "Review an audio clip locally: scrub, slow playback, loop a short A/B section, and bookmark exact timecodes for later listening. Your selected file is never uploaded or saved by this tool.",
      "category": "horror-and-paranormal",
      "categoryName": "Horror & Paranormal",
      "url": "https://www.themostusefulsiteintheworld.com/tool/evp-review-lab.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=evp-review-lab&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "evp-note",
          "type": "text",
          "label": "Private listening note",
          "unit": ""
        },
        {
          "name": "evp-speed",
          "type": "select-one",
          "label": "Playback speed",
          "unit": "",
          "options": [
            "0.75",
            "0.9",
            "1",
            "1.15"
          ],
          "default": "1"
        },
        {
          "name": "evp-kind",
          "type": "select-one",
          "label": "Bookmark type",
          "unit": "",
          "options": [
            "Possible voice",
            "Background noise",
            "Uncertain",
            "Ordinary explanation"
          ],
          "default": "Possible voice"
        }
      ],
      "outputs": [
        {
          "name": "evp-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=evp-review-lab&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=evp-review-lab&evp-speed=1&evp-kind=Possible%20voice"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "evp",
        "review",
        "lab",
        "audio",
        "horror",
        "paranormal",
        "clip",
        "locally",
        "scrub",
        "slow"
      ],
      "popularity": 6710,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "exam-prep-maths",
      "title": "📚 Exam Prep - Mathematics",
      "description": "COMPLETE MATH PREP - Generate practice problems with step-by-step solutions. Track your progress across 500+ questions covering all major topics.",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/exam-prep-maths.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=exam-prep-maths&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "epm-user-answer",
          "type": "text",
          "label": "Your Answer",
          "unit": ""
        },
        {
          "name": "epm-difficulty",
          "type": "select-one",
          "label": "Difficulty Level",
          "unit": "",
          "options": [
            "easy",
            "medium",
            "hard",
            "exam"
          ],
          "default": "medium"
        },
        {
          "name": "epm-question-type",
          "type": "select-one",
          "label": "Question Type",
          "unit": "",
          "options": [
            "multiple",
            "short",
            "word",
            "proof",
            "mixed"
          ],
          "default": "mixed"
        },
        {
          "name": "epm-show-solution",
          "type": "select-one",
          "label": "Solution Display",
          "unit": "",
          "options": [
            "immediate",
            "hints",
            "hidden",
            "step"
          ],
          "default": "immediate"
        }
      ],
      "outputs": [
        {
          "name": "epm-correct-answer",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=exam-prep-maths&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=exam-prep-maths&epm-difficulty=medium&epm-question-type=mixed&epm-show-solution=immediate"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "exam",
        "prep",
        "maths",
        "mathematics",
        "complete",
        "math",
        "generate",
        "practice",
        "problems",
        "step-by-step"
      ],
      "popularity": 5119,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "exam",
      "title": "🎯 Exam & Study Planner",
      "description": "📚 A comprehensive exam planning and study management system for students and professionals. Track exams, create study schedules, set goals, and manage revision.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/exam.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=exam&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "exam-subject",
          "type": "text",
          "label": "Subject/Course",
          "unit": ""
        },
        {
          "name": "exam-date",
          "type": "datetime-local",
          "label": "Date & Time",
          "unit": ""
        },
        {
          "name": "exam-duration",
          "type": "number",
          "label": "Duration",
          "unit": "minutes",
          "min": 0,
          "step": 5
        },
        {
          "name": "exam-notes",
          "type": "textarea",
          "label": "Important Notes",
          "unit": ""
        },
        {
          "name": "study-hours-per-day",
          "type": "select-one",
          "label": "Daily Study Hours",
          "unit": "",
          "options": [
            "1",
            "2",
            "3",
            "4",
            "5"
          ],
          "default": "2"
        },
        {
          "name": "study-days-per-week",
          "type": "select-one",
          "label": "Study Days/Week",
          "unit": "",
          "options": [
            "5",
            "6",
            "7"
          ],
          "default": "6"
        },
        {
          "name": "study-weeks-before",
          "type": "select-one",
          "label": "Start Studying",
          "unit": "",
          "options": [
            "1",
            "2",
            "3",
            "4",
            "6"
          ],
          "default": "3"
        }
      ],
      "outputs": [
        {
          "name": "total-exams-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=exam&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=exam&study-hours-per-day=2&study-days-per-week=6&study-weeks-before=3"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "exam",
        "study",
        "planner",
        "productivity",
        "lifestyle",
        "comprehensive",
        "planning",
        "management",
        "system",
        "students"
      ],
      "popularity": 5327,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "excel-csv-corruption-guard",
      "title": "🛡️ Excel CSV Corruption Guard",
      "description": "Open a CSV in Excel and it silently eats leading zeros, turns long IDs into 1.23E+15, makes “1-2” into 2-Jan and gene names like MARCH1 into dates. This finds every cell Excel would mangle and expo...",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/excel-csv-corruption-guard.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=excel-csv-corruption-guard&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "excel-csv-corruption-guard-in",
          "type": "textarea",
          "label": "…or paste CSV",
          "unit": ""
        },
        {
          "name": "excel-csv-corruption-guard-mode",
          "type": "select-one",
          "label": "How to protect risky cells",
          "unit": "",
          "options": [
            "formula",
            "tab"
          ],
          "default": "formula"
        }
      ],
      "outputs": [
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      "title": "🧵 Fabric Yardage Estimator",
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        {
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        {
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          "default": "70"
        }
      ],
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        {
          "name": "ftic-out",
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=feet-inches-cm-height-converter&<id>=<value>",
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      },
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      "sources": [],
      "tags": [
        "feet",
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        "height",
        "converter",
        "science",
        "engineering",
        "convert",
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        "metres"
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "fence-calculator",
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      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/fence-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=fence-calculator&embed=1",
      "standaloneUrl": null,
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        {
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        },
        {
          "name": "fnccalc-gravel",
          "type": "checkbox",
          "label": "Include gravel boards",
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        },
        {
          "name": "fnccalc-height",
          "type": "select-one",
          "label": "Fence Height",
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            "0.9",
            "1.2",
            "1.5",
            "1.8",
            "2.0"
          ],
          "default": "1.5"
        },
        {
          "name": "fnccalc-type",
          "type": "select-one",
          "label": "Fence Type",
          "unit": "",
          "options": [
            "panel",
            "closeboard",
            "picket",
            "hit-miss"
          ],
          "default": "panel"
        },
        {
          "name": "fnccalc-post",
          "type": "select-one",
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          "unit": "",
          "options": [
            "75",
            "100",
            "125"
          ],
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        },
        {
          "name": "fnccalc-panel",
          "type": "select-one",
          "label": "Panel Width",
          "unit": "",
          "options": [
            "1.83",
            "1.8"
          ],
          "default": "1.83"
        }
      ],
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        {
          "name": "fnccalc-result",
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=fence-calculator&<id>=<value>",
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      },
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      "sources": [],
      "tags": [
        "fence",
        "home",
        "diy",
        "calculate",
        "posts",
        "panels",
        "gravel",
        "boards",
        "concrete",
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      "featured": false,
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    },
    {
      "slug": "fermentation-salt-brine-calc",
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      "category": "culinary-and-food-science",
      "categoryName": "Culinary & Food Science",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=fermentation-salt-brine-calc&embed=1",
      "standaloneUrl": null,
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        {
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        {
          "name": "fm-preset",
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            "sauerkraut",
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            "pickles",
            "hot-sauce",
            "garlic-honey",
            "mixed-veg"
          ],
          "default": "sauerkraut"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=fermentation-salt-brine-calc&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "fermentation",
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        "brine",
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        "culinary",
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        "science",
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      "featured": false,
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      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/fermi-estimator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=fermi-estimator&embed=1",
      "standaloneUrl": null,
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        {
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          "label": "choose a Fermi question",
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            "tuners",
            "stations",
            "heart",
            "bus",
            "rain",
            "custom"
          ],
          "default": "tuners"
        }
      ],
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        {
          "name": "fmi-answer",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=fermi-estimator&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "fermi",
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        "order-of-magnitude",
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        "mathematics",
        "enrico",
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      "popularity": 5114,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "ferrofluid-spike-sculpture",
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      "description": "Rosensweig normal-field magnetic instability simulator. Superparamagnetic liquid self-organizes into conical spikes balancing surface tension and magnetic stress.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/ferrofluid-spike-sculpture.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=ferrofluid-spike-sculpture&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "max": 10,
          "step": 0.1,
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        {
          "name": "ffs-slider-visc",
          "type": "range",
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          "min": 4,
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      ],
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        "runs": false,
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      },
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      "sources": [],
      "tags": [
        "ferrofluid",
        "spike",
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        "lab",
        "science",
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        "rosensweig",
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      "popularity": 5893,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "fiber-optic-total-internal-reflection",
      "title": "✨ Fiber Optic Light Guide Lab",
      "description": "Total internal reflection fiber optics lab. Explore critical angle guidance, acceptance cone numerical aperture (NA), and macro-bending radiation loss.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/fiber-optic-total-internal-reflection.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=fiber-optic-total-internal-reflection&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "min": 2,
          "max": 28,
          "step": 0.5,
          "default": "12"
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        {
          "name": "fot-slider-bend",
          "type": "range",
          "label": "slider bend",
          "unit": "",
          "min": -70,
          "max": 70,
          "default": "0"
        }
      ],
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      "sources": [],
      "tags": [
        "fiber",
        "optic",
        "total",
        "internal",
        "reflection",
        "light",
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        "lab",
        "science",
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      ],
      "popularity": 6377,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "fictional-planchette-board",
      "title": "🕯 Planchette Story Prop",
      "description": "A screen-friendly letter board that spells one prewritten horror line at a time. Choose the mood and reveal pace; use it as a fictional prop for a consenting cast on a controlled set.",
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      "categoryName": "Horror & Paranormal",
      "url": "https://www.themostusefulsiteintheworld.com/tool/fictional-planchette-board.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=fictional-planchette-board&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "fpb-mood",
          "type": "select-one",
          "label": "Scene mood",
          "unit": "",
          "options": [
            "quiet",
            "warning",
            "reveal"
          ],
          "default": "quiet"
        },
        {
          "name": "fpb-speed",
          "type": "select-one",
          "label": "Reveal pace",
          "unit": "",
          "options": [
            "780",
            "480",
            "260"
          ],
          "default": "480"
        }
      ],
      "outputs": [
        {
          "name": "fpb-line",
          "type": "live"
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        {
          "name": "fpb-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=fictional-planchette-board&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "fictional",
        "planchette",
        "board",
        "story",
        "prop",
        "horror",
        "paranormal",
        "screen-friendly",
        "letter",
        "spells"
      ],
      "popularity": 4389,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "field-protocol-control-planner",
      "title": "🧪 Field Protocol & Control Planner",
      "description": "Pre-register a small A/B field test before you start: define the question, conditions, repetition count and scoring rule, then generate a balanced random order. This helps separate an observation f...",
      "category": "field-investigation-and-evidence",
      "categoryName": "Field Investigation & Evidence",
      "url": "https://www.themostusefulsiteintheworld.com/tool/field-protocol-control-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=field-protocol-control-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "name": "ficp-question",
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          "unit": ""
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        {
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          "type": "text",
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          "unit": "",
          "default": "Control"
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        {
          "name": "ficp-b",
          "type": "text",
          "label": "Condition B",
          "unit": "",
          "default": "Comparison"
        },
        {
          "name": "ficp-pairs",
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          "unit": "",
          "min": 2,
          "max": 20,
          "default": "4"
        },
        {
          "name": "ficp-authorized",
          "type": "checkbox",
          "label": "Permission for this site and time is confirmed; exits and safe access are known.",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ficp-blind",
          "type": "checkbox",
          "label": "A separate schedule holder can keep condition order from the blind observer / scorer.",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ficp-rule",
          "type": "checkbox",
          "label": "The observation and scoring rule will be fixed before the first trial.",
          "unit": "",
          "default": "0"
        }
      ],
      "outputs": [
        {
          "name": "ficp-status",
          "type": "live"
        },
        {
          "name": "ficp-result",
          "type": "output"
        },
        {
          "name": "ficp-question-out",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=field-protocol-control-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=field-protocol-control-planner&ficp-a=Control&ficp-b=Comparison&ficp-pairs=4&ficp-authorized=0&ficp-blind=0&ficp-rule=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "field",
        "protocol",
        "control",
        "planner",
        "investigation",
        "evidence",
        "pre-register",
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      ],
      "popularity": 5800,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "filename-safety-checker",
      "title": "🗂️ Cross-Platform Filename Safety Checker",
      "description": "Paste names copied from a file list. Preview Windows-reserved characters and device names, trailing dots/spaces, Unicode normalization, and case-insensitive collisions before you share or move the ...",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/filename-safety-checker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=filename-safety-checker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "filename-safety-checker-unique",
          "type": "checkbox",
          "label": "Add “(2)”, “(3)” to duplicate destination names (case-insensitive)",
          "unit": "",
          "default": "1"
        },
        {
          "name": "filename-safety-checker-input",
          "type": "textarea",
          "label": "Filenames — one per line",
          "unit": ""
        },
        {
          "name": "filename-safety-checker-output",
          "type": "textarea",
          "label": "Safe names, one per line",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "filename-safety-checker-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=filename-safety-checker&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=filename-safety-checker&filename-safety-checker-unique=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "filename",
        "safety",
        "checker",
        "cross-platform",
        "algorithms",
        "computer",
        "science",
        "paste",
        "names",
        "copied"
      ],
      "popularity": 4840,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "fire-escape-smoke-safety-planner",
      "title": "🔥 Fire Escape & Smoke Safety Planner",
      "description": "Most fire deaths are not from flames — they are from smoke, at night, in homes where nobody had ever worked out a route. Answer twenty questions about your home and this builds a real escape plan, ...",
      "category": "survival-and-emergency-readiness",
      "categoryName": "Survival & Emergency Readiness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/fire-escape-smoke-safety-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=fire-escape-smoke-safety-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "fir-people",
          "type": "number",
          "label": "People asleep here at night",
          "unit": "",
          "min": 1,
          "default": "3"
        },
        {
          "name": "fir-home",
          "type": "select-one",
          "label": "Home type",
          "unit": "",
          "options": [
            "bungalow",
            "house",
            "terraced",
            "flat",
            "highrise",
            "hmo"
          ],
          "default": "bungalow"
        },
        {
          "name": "fir-needs",
          "type": "select-one",
          "label": "Anyone who would need help to escape?",
          "unit": "",
          "options": [
            "no",
            "child",
            "mobility",
            "sensory",
            "both"
          ],
          "default": "no"
        },
        {
          "name": "fir-alarm",
          "type": "select-one",
          "label": "Smoke alarms",
          "unit": "",
          "options": [
            "none",
            "one",
            "floor",
            "linked",
            "old"
          ],
          "default": "linked"
        },
        {
          "name": "fir-route",
          "type": "select-one",
          "label": "Routes out of every room",
          "unit": "",
          "options": [
            "two",
            "one",
            "none"
          ],
          "default": "two"
        },
        {
          "name": "fir-keys",
          "type": "select-one",
          "label": "Door and window keys",
          "unit": "",
          "options": [
            "place",
            "somewhere",
            "none"
          ],
          "default": "place"
        }
      ],
      "outputs": [
        {
          "name": "fir-score",
          "type": "live"
        },
        {
          "name": "fir-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=fire-escape-smoke-safety-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=fire-escape-smoke-safety-planner&fir-people=3&fir-home=bungalow&fir-needs=no&fir-alarm=linked&fir-route=two&fir-keys=place"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "fire",
        "escape",
        "smoke",
        "safety",
        "planner",
        "survival",
        "emergency",
        "readiness",
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        "deaths"
      ],
      "popularity": 6498,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "fire-financial-independence-calc",
      "title": "🔥 FIRE Retirement Planner",
      "description": "Estimate your Financial Independence number, years until retirement, and compound investment growth trajectory using the 4% Safe Withdrawal Rule. Illustrative projections, not financial advice.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/fire-financial-independence-calc.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=fire-financial-independence-calc&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "fire-cur-age",
          "type": "number",
          "label": "Current Age",
          "unit": "",
          "min": 16,
          "max": 90,
          "default": "28"
        },
        {
          "name": "fire-cur-networth",
          "type": "number",
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        {
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            "0.035",
            "0.04",
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        }
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      },
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        "fire",
        "financial",
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        "calc",
        "retirement",
        "planner",
        "finance",
        "money",
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      "featured": false,
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    },
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        {
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          "label": "Crew acclimatisation",
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            "1",
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        "fiscal",
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    },
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      "category": "health-and-fitness",
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            "poor",
            "average",
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        {
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        {
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        {
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        {
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      "sources": [],
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=flash-flood-lab&embed=1",
      "standaloneUrl": null,
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          "label": "slider amc",
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          "max": 100,
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      },
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        "flood",
        "lab",
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      "sources": [],
      "tags": [
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        },
        {
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          "max": 6,
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        {
          "name": "fpc-exp",
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          "label": "exp",
          "unit": "",
          "min": 1,
          "max": 5,
          "default": "3"
        },
        {
          "name": "fpc-helper",
          "type": "select-one",
          "label": "Who's helping",
          "unit": "",
          "options": [
            "alone",
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            "relative",
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          "default": "partner"
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        {
          "name": "fpc-manual",
          "type": "select-one",
          "label": "manual",
          "unit": "",
          "options": [
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            "skim",
            "ignore"
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=flat-pack-confidence-meter&<id>=<value>",
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      },
      "formula": "Methodology (the Leftover Screw Theorem) Forecast = pieces ÷ (experience ×",
      "sources": [],
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        "flat",
        "pack",
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        "flat-pack",
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      "featured": false,
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    },
    {
      "slug": "flavor-wine-pairing-matrix",
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      "slug": "fog-machine-calculator",
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      "standaloneUrl": null,
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=galton-board-central-limit&<id>=<value>",
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        "galton",
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        {
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            "auto",
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        {
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=gantt-project-timeline-studio&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=gantt-project-timeline-studio&gpts-deps=1&gpts-today=1&gpts-weekend=1&gpts-zoom=auto"
      },
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      "sources": [],
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        "gantt",
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      "slug": "garden-plant-spacing-calculator",
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      "url": "https://www.themostusefulsiteintheworld.com/tool/garden-plant-spacing-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=garden-plant-spacing-calculator&embed=1",
      "standaloneUrl": null,
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      ],
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        {
          "name": "plsp-out",
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        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=garden-plant-spacing-calculator&<id>=<value>",
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        "garden",
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      "categoryName": "Productivity & Lifestyle",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=garden-task&embed=1",
      "standaloneUrl": null,
      "inputs": [
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        {
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        {
          "name": "gtc-plant",
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        {
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=garden-task&<id>=<value>",
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            "garden",
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            "full",
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        "gardening",
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      "standaloneUrl": null,
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        "gas",
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      ],
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    {
      "slug": "gdpr-ccpa-privacy-policy-generator",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=gdpr-ccpa-privacy-policy-generator&embed=1",
      "standaloneUrl": null,
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        {
          "name": "pp-ch-payments",
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          "label": "Stripe / Crypto Payments",
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        },
        {
          "name": "pp-ch-cookies",
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          "default": "1"
        },
        {
          "name": "pp-ch-newsletter",
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          "label": "Newsletter / Email Subscriptions",
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          "default": "1"
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        {
          "name": "pp-ch-accounts",
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        },
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          "type": "checkbox",
          "label": "Ad Networks / Retargeting Pixels",
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          "default": "0"
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      ],
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=gdpr-ccpa-privacy-policy-generator&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=gdpr-ccpa-privacy-policy-generator&pp-app-name=The%20Most%20Useful%20Site%20in%20the%20World&pp-url=https%3A%2F%2Fthemostusefulsiteintheworld.com&pp-company=MrPr0phecy%20Ecosystem&pp-email=privacy%40themostusefulsiteintheworld.com&pp-ch-ga4=1&pp-ch-payments=1"
      },
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        "gdpr",
        "ccpa",
        "privacy",
        "policy",
        "saas",
        "business",
        "killers",
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        "legally-compliant",
        "policies"
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      "featured": false,
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    },
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=generative-joy-kaleidoscope&embed=1",
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            "6",
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        {
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            "ocean"
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        },
        {
          "name": "gjk-brush",
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            "ribbon",
            "sparkles",
            "geometric",
            "rings"
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        },
        {
          "name": "gjk-mode",
          "type": "select-one",
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          "unit": "",
          "options": [
            "interactive",
            "autoflow",
            "spiral"
          ],
          "default": "interactive"
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      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=generative-joy-kaleidoscope&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=generative-joy-kaleidoscope&gjk-symmetry=8&gjk-palette=solar&gjk-brush=ribbon&gjk-mode=interactive"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
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        "generative",
        "joy",
        "kaleidoscope",
        "luminous",
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        "interactive",
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    },
    {
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      "category": "science-and-engineering",
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      "url": "https://www.themostusefulsiteintheworld.com/tool/genetics.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=genetics&embed=1",
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      "inputs": [
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          "label": "Parent 1 Genotype",
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        },
        {
          "name": "gen-parent2-genotype",
          "type": "text",
          "label": "Parent 2 Genotype",
          "unit": ""
        },
        {
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        {
          "name": "gen-show-visual",
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          "label": "Show visual representation",
          "unit": "",
          "default": "1"
        },
        {
          "name": "gen-dna-sequence",
          "type": "textarea",
          "label": "DNA Sequence Human Example",
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        },
        {
          "name": "gen-tool",
          "type": "select-one",
          "label": "Genetics Tool",
          "unit": "",
          "options": [
            "dna-analyzer",
            "punnett-square",
            "gc-content",
            "molecular-weight",
            "codon-table",
            "pedigree",
            "mutation-simulator",
            "genetic-distance",
            "restriction-sites",
            "pcr-primer"
          ],
          "default": "dna-analyzer"
        },
        {
          "name": "gen-analysis-type",
          "type": "select-one",
          "label": "Analysis Type",
          "unit": "",
          "options": [
            "full",
            "composition",
            "orfs",
            "palindromes"
          ],
          "default": "full"
        },
        {
          "name": "gen-output-format",
          "type": "select-one",
          "label": "Output Format",
          "unit": "",
          "options": [
            "text",
            "json",
            "fasta"
          ],
          "default": "text"
        },
        {
          "name": "gen-cross-type",
          "type": "select-one",
          "label": "Cross Type",
          "unit": "",
          "options": [
            "monohybrid",
            "dihybrid",
            "trihybrid"
          ],
          "default": "dihybrid"
        },
        {
          "name": "gen-inheritance",
          "type": "select-one",
          "label": "Inheritance Pattern",
          "unit": "",
          "options": [
            "mendelian",
            "incomplete",
            "codominance",
            "sex-linked"
          ],
          "default": "mendelian"
        }
      ],
      "outputs": [
        {
          "name": "gen-results",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=genetics&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=genetics&gen-show-steps=1&gen-show-visual=1&gen-tool=dna-analyzer&gen-analysis-type=full&gen-output-format=text&gen-cross-type=dihybrid"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "genetics",
        "laboratory",
        "science",
        "engineering",
        "explore",
        "through",
        "interactive",
        "simulations",
        "dna",
        "analysis"
      ],
      "popularity": 5714,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "geodesic-area-parcel-calculator",
      "title": "📐 Geodesic Area & Parcel Calculator",
      "description": "Type or click out a boundary and get its true area on the curved Earth using the spherical-excess formula — the same maths GIS packages use — alongside the flat-map answer so you can see exactly ho...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/geodesic-area-parcel-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=geodesic-area-parcel-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "gapc-coords",
          "type": "textarea",
          "label": "Boundary vertices — one “latitude, longitude” per line, in order around the edge",
          "unit": ""
        },
        {
          "name": "gapc-preset",
          "type": "select-one",
          "label": "Load a boundary",
          "unit": ""
        },
        {
          "name": "gapc-unit",
          "type": "select-one",
          "label": "Headline unit",
          "unit": "",
          "options": [
            "auto",
            "m2",
            "ha",
            "ac",
            "km2",
            "mi2"
          ],
          "default": "auto"
        }
      ],
      "outputs": [
        {
          "name": "gapc-stats",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=geodesic-area-parcel-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=geodesic-area-parcel-calculator&gapc-unit=auto"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "geodesic",
        "area",
        "parcel",
        "science",
        "engineering",
        "type",
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        "out",
        "boundary",
        "get"
      ],
      "popularity": 5416,
      "featured": false,
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    },
    {
      "slug": "geography-flag-capital-quiz",
      "title": "🌍 Flag & Capital Quiz",
      "description": "Learn 40 countries with flip flashcards, then test yourself on capitals and flags. Streaks, scoring and fun facts make world geography stick.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/geography-flag-capital-quiz.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=geography-flag-capital-quiz&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [
        {
          "name": "gfl-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=geography-flag-capital-quiz&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "geography",
        "flag",
        "capital",
        "quiz",
        "science",
        "engineering",
        "learn",
        "countries",
        "flip",
        "flashcards"
      ],
      "popularity": 5238,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "geography",
      "title": "Geography Helper",
      "description": "Add countries, capitals, and notes to build your geography study list.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/geography.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=geography&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "geography-country",
          "type": "text",
          "label": "Country",
          "unit": ""
        },
        {
          "name": "geography-capital",
          "type": "text",
          "label": "Capital",
          "unit": ""
        },
        {
          "name": "geography-notes",
          "type": "text",
          "label": "Notes",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=geography&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "geography",
        "helper",
        "science",
        "engineering",
        "add",
        "countries",
        "capitals",
        "notes",
        "build",
        "study"
      ],
      "popularity": 5172,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "geology",
      "title": "Geology Tools & Facts",
      "description": "Explore geology concepts and discover fascinating facts about Earth's structure and processes.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/geology.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=geology&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "geo-output",
          "type": "textarea",
          "label": "output",
          "unit": ""
        },
        {
          "name": "geo-topic",
          "type": "select-one",
          "label": "Topic",
          "unit": "",
          "options": [
            "rock-cycle",
            "plate-tectonics",
            "earthquakes",
            "volcanoes",
            "minerals",
            "fossils",
            "geologic-time"
          ],
          "default": "rock-cycle"
        },
        {
          "name": "geo-show-facts",
          "type": "select-one",
          "label": "Show Geology Facts",
          "unit": "",
          "options": [
            "yes",
            "no"
          ],
          "default": "yes"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=geology&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=geology&geo-topic=rock-cycle&geo-show-facts=yes"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "geology",
        "tools",
        "facts",
        "science",
        "engineering",
        "explore",
        "concepts",
        "discover",
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      ],
      "popularity": 5874,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "geometric-size-illusion-lab",
      "title": "📏 Geometric Size Illusion Lab",
      "description": "Six classic length illusions — Müller-Lyer, Ponzo, Ebbinghaus, Delboeuf, vertical-horizontal and Jastrow — drawn live, with a strength slider, a measure-it overlay printing true pixel lengths and a...",
      "category": "mind-blowing-demos",
      "categoryName": "Mind-Blowing Demos",
      "url": "https://www.themostusefulsiteintheworld.com/tool/geometric-size-illusion-lab.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=geometric-size-illusion-lab&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "gis-strength",
          "type": "range",
          "label": "Trick strength",
          "unit": "",
          "min": 0,
          "max": 100,
          "default": "70"
        },
        {
          "name": "gis-match",
          "type": "range",
          "label": "Your match",
          "unit": "",
          "min": 55,
          "max": 145,
          "default": "100"
        }
      ],
      "outputs": [
        {
          "name": "gis-result",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=geometric-size-illusion-lab&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=geometric-size-illusion-lab&gis-strength=70&gis-match=100"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "geometric",
        "size",
        "illusion",
        "lab",
        "mind-blowing",
        "demos",
        "six",
        "classic",
        "length",
        "illusions"
      ],
      "popularity": 4231,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "geometry-calculator",
      "title": "📐 Geometry Calculator",
      "description": "Calculate the area, perimeter, or volume of common shapes.",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/geometry-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=geometry-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "g1",
          "type": "number",
          "label": "Width",
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          "default": "8"
        },
        {
          "name": "g2",
          "type": "number",
          "label": "Height",
          "unit": "",
          "default": "5"
        },
        {
          "name": "geo-shape",
          "type": "select-one",
          "label": "Shape Rectangle Circle Triangle Sphere",
          "unit": "",
          "options": [
            "rect",
            "circle",
            "tri",
            "sphere"
          ],
          "default": "rect"
        }
      ],
      "outputs": [
        {
          "name": "geo-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=geometry-calculator&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=geometry-calculator&g1=8&g2=5&geo-shape=rect&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "geometry",
        "mathematics",
        "calculate",
        "area",
        "perimeter",
        "volume",
        "common",
        "shapes"
      ],
      "popularity": 5763,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "geometry",
      "title": "Geometry Calculator",
      "description": "Calculate areas, perimeters, and volumes for common shapes. Choose a shape, enter dimensions, and get results with formulas shown.",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/geometry.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=geometry&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "geom-dimensions",
          "type": "text",
          "label": "Dimensions (e.g., radius=5, height=10)",
          "unit": ""
        },
        {
          "name": "geom-output",
          "type": "textarea",
          "label": "output",
          "unit": ""
        },
        {
          "name": "geom-shape",
          "type": "select-one",
          "label": "Shape",
          "unit": "",
          "options": [
            "circle",
            "rectangle",
            "triangle",
            "sphere",
            "cube",
            "cylinder",
            "cone",
            "trapezoid",
            "ellipse"
          ],
          "default": "circle"
        },
        {
          "name": "geom-show-steps",
          "type": "select-one",
          "label": "Show steps",
          "unit": "",
          "options": [
            "yes",
            "no"
          ],
          "default": "yes"
        },
        {
          "name": "geom-precision",
          "type": "select-one",
          "label": "precision",
          "unit": "",
          "options": [
            "2",
            "4",
            "6",
            "8"
          ],
          "default": "4"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=geometry&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=geometry&geom-shape=circle&geom-show-steps=yes&geom-precision=4&run=1"
      },
      "formula": "Circle Area = πr² Circumference = 2πr ▭ Rectangle Area = w ×",
      "sources": [],
      "tags": [
        "geometry",
        "mathematics",
        "calculate",
        "areas",
        "perimeters",
        "volumes",
        "common",
        "shapes",
        "choose",
        "shape"
      ],
      "popularity": 4210,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "german-cases-gender",
      "title": "🇩🇪 German Cases & Gender",
      "description": "Conquer the 4 German grammatical cases (Nominativ, Akkusativ, Dativ, Genitiv) and understand exactly how der, die, das shift based on subject, direct object, indirect recipient, or possession.",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/german-cases-gender.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=german-cases-gender&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=german-cases-gender&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "german",
        "cases",
        "gender",
        "writing",
        "language",
        "conquer",
        "grammatical",
        "nominativ",
        "akkusativ",
        "dativ"
      ],
      "popularity": 5398,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "ghost-radar-prop",
      "title": "📡 Ghost Radar Video Prop",
      "description": "A recordable, full-screen-style radar graphic for a staged horror segment. Choose how many synthetic contacts appear and how quickly the sweep moves; save a still or capture your screen using your ...",
      "category": "horror-and-paranormal",
      "categoryName": "Horror & Paranormal",
      "url": "https://www.themostusefulsiteintheworld.com/tool/ghost-radar-prop.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=ghost-radar-prop&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "grp-speed",
          "type": "range",
          "label": "Sweep speed: 4",
          "unit": "",
          "min": 1,
          "max": 10,
          "default": "4"
        },
        {
          "name": "grp-contacts",
          "type": "select-one",
          "label": "Synthetic contacts",
          "unit": "",
          "options": [
            "1",
            "2",
            "3",
            "4",
            "5"
          ],
          "default": "2"
        }
      ],
      "outputs": [
        {
          "name": "grp-status",
          "type": "live"
        },
        {
          "name": "grp-speed-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=ghost-radar-prop&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=ghost-radar-prop&grp-speed=4&grp-contacts=2"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "ghost",
        "radar",
        "prop",
        "video",
        "horror",
        "paranormal",
        "recordable",
        "full-screen-style",
        "graphic",
        "staged"
      ],
      "popularity": 4520,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "gift-aid-calculator",
      "title": "🎁 Gift Aid Calculator",
      "description": "Gift Aid is the rare tax relief where everybody wins: the charity gets 25p more for every pound you give, at no cost to you, and if you pay tax above the basic rate you can claim some of it back pe...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/gift-aid-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=gift-aid-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "gaac-amount",
          "type": "number",
          "label": "You give",
          "unit": "£",
          "min": 0,
          "max": 1000000,
          "step": 1,
          "default": "100"
        },
        {
          "name": "gaac-tax",
          "type": "number",
          "label": "Income/CGT paid this year",
          "unit": "£",
          "min": 0,
          "max": 10000000,
          "step": 100,
          "default": "6000"
        },
        {
          "name": "gaac-other",
          "type": "number",
          "label": "Already Gift Aided elsewhere",
          "unit": "£/yr",
          "min": 0,
          "max": 1000000,
          "step": 10,
          "default": "0"
        },
        {
          "name": "gaac-small",
          "type": "number",
          "label": "Small donations of £30 or less",
          "unit": "£/yr",
          "min": 0,
          "max": 100000,
          "step": 10,
          "default": "1200"
        },
        {
          "name": "gaac-claimed",
          "type": "number",
          "label": "Your other Gift Aid claimed",
          "unit": "£/yr",
          "min": 0,
          "max": 10000000,
          "step": 100,
          "default": "4000"
        },
        {
          "name": "gaac-freq",
          "type": "select-one",
          "label": "How often",
          "unit": "",
          "options": [
            "1",
            "12",
            "52",
            "4"
          ],
          "default": "12"
        },
        {
          "name": "gaac-band",
          "type": "select-one",
          "label": "Your tax band",
          "unit": "",
          "options": [
            "20",
            "40",
            "45",
            "0"
          ],
          "default": "20"
        }
      ],
      "outputs": [
        {
          "name": "gaac-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=gift-aid-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=gift-aid-calculator&gaac-amount=100&gaac-tax=6000&gaac-other=0&gaac-small=1200&gaac-claimed=4000&gaac-freq=12"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "gift",
        "aid",
        "finance",
        "money",
        "rare",
        "tax",
        "relief",
        "where",
        "everybody",
        "wins"
      ],
      "popularity": 6640,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "gift",
      "title": "Gift Helper 🎁",
      "description": "Find the perfect gift with smart suggestions, reminders, and inspiration for every occasion.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/gift.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=gift&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "gh-recipient",
          "type": "text",
          "label": "Recipient",
          "unit": ""
        },
        {
          "name": "gh-year",
          "type": "number",
          "label": "Year (anniversary only)",
          "unit": "",
          "min": 1,
          "max": 100
        },
        {
          "name": "gh-budget",
          "type": "number",
          "label": "Budget",
          "unit": "£",
          "min": 0,
          "step": 0.01
        },
        {
          "name": "gh-occasion",
          "type": "select-one",
          "label": "Occasion",
          "unit": "",
          "options": [
            "Birthday",
            "Anniversary",
            "Wedding",
            "Graduation",
            "Holiday",
            "Baby Shower",
            "Housewarming",
            "Retirement",
            "Thank You",
            "Just Because"
          ],
          "default": "Birthday"
        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=gift&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=gift&gh-occasion=Birthday"
      },
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      "sources": [],
      "tags": [
        "gift",
        "helper",
        "productivity",
        "lifestyle",
        "find",
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        "smart",
        "suggestions",
        "reminders",
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      "popularity": 5656,
      "featured": false,
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    },
    {
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      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/gitignore-template-builder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=gitignore-template-builder&embed=1",
      "standaloneUrl": null,
      "inputs": [],
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          "name": "gign-out",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=gitignore-template-builder&<id>=<value>",
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      "sources": [],
      "tags": [
        "gitignore",
        "template",
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      "popularity": 4073,
      "featured": false,
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    },
    {
      "slug": "glasgow-coma-scale-calculator",
      "title": "🧠 Glasgow Coma Scale Calculator",
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      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/glasgow-coma-scale-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=glasgow-coma-scale-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "label": "Scale",
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            "adult",
            "paed"
          ],
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        {
          "name": "gcsx-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=glasgow-coma-scale-calculator&<id>=<value>",
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      },
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      "sources": [],
      "tags": [
        "glasgow",
        "coma",
        "scale",
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        "adult",
        "pre-verbal",
        "paediatric",
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      "popularity": 4869,
      "featured": false,
      "updated": "2026-09-19"
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    {
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=go-outsideometer&embed=1",
      "standaloneUrl": null,
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        {
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      ],
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          "name": "goo-out",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=go-outsideometer&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "outsideometer",
        "productivity",
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      "featured": false,
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=goaltracker&embed=1",
      "standaloneUrl": null,
      "inputs": [
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        {
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        {
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        {
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=goaltracker&<id>=<value>",
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        "goaltracker",
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      "featured": false,
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    },
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      "url": "https://www.themostusefulsiteintheworld.com/tool/golden-ratio-crop-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=golden-ratio-crop-calculator&embed=1",
      "standaloneUrl": null,
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        {
          "name": "grcc-h",
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        },
        {
          "name": "grcc-len",
          "type": "number",
          "label": "Any length → pair",
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          "min": 0,
          "default": "100"
        }
      ],
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        {
          "name": "grcc-out",
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=golden-ratio-crop-calculator&<id>=<value>",
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      },
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      "sources": [],
      "tags": [
        "golden",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "golf-stableford-scorecard-calculator",
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      "url": "https://www.themostusefulsiteintheworld.com/tool/golf-stableford-scorecard-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=golf-stableford-scorecard-calculator&embed=1",
      "standaloneUrl": null,
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      ],
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        {
          "name": "stf-out",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=golf-stableford-scorecard-calculator&<id>=<value>",
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      },
      "formula": "Net score = gross − shots. Points: net double-",
      "sources": [],
      "tags": [
        "golf",
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      "featured": false,
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      "slug": "golf-whs-handicap-calculator",
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      "category": "sports",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=golf-whs-handicap-calculator&embed=1",
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        {
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        {
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          "label": "Playing allowance",
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            "90",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=golf-whs-handicap-calculator&<id>=<value>",
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      },
      "formula": "The WHS formulas behind it Score Differential = (113 ÷ Slope) ×",
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    {
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      "url": "https://www.themostusefulsiteintheworld.com/tool/gpa.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=gpa&embed=1",
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        {
          "name": "gpa-grade",
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      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=gpa&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=gpa&gpa-country=us&run=1"
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      "sources": [],
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      "popularity": 4552,
      "featured": false,
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    },
    {
      "slug": "grade",
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      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/grade.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=grade&embed=1",
      "standaloneUrl": null,
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          "min": 0,
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        {
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          "max": 100,
          "step": 0.1
        },
        {
          "name": "gc-target-grade",
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        {
          "name": "gc-category",
          "type": "select-one",
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          "options": [
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          "name": "gc-target-result",
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=grade&<id>=<value>",
        "runs": true,
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
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      "featured": false,
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    {
      "slug": "graphing-calculator",
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      "category": "mathematics",
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      "url": "https://www.themostusefulsiteintheworld.com/tool/graphing-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=graphing-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "type": "text",
          "label": "Enter Mathematical Expression",
          "unit": ""
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        {
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          "type": "number",
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        {
          "name": "gc-xmax",
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          "default": "10"
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        {
          "name": "gc-quality",
          "type": "range",
          "label": "Quality",
          "unit": "",
          "min": 100,
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        {
          "name": "gc-deriv",
          "type": "checkbox",
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          "default": "0"
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        {
          "name": "gc-integral",
          "type": "checkbox",
          "label": "Integral",
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          "default": "0"
        },
        {
          "name": "gc-roots",
          "type": "checkbox",
          "label": "Find Roots",
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          "default": "0"
        },
        {
          "name": "gc-tangent",
          "type": "checkbox",
          "label": "Tangent Line",
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          "default": "0"
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        {
          "name": "gc-integral-a",
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          "label": "a",
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          "default": "-2"
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        {
          "name": "gc-integral-b",
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          "label": "b",
          "unit": "",
          "default": "2"
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        {
          "name": "gc-root-x",
          "type": "number",
          "label": "Initial x",
          "unit": "",
          "default": "0"
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        {
          "name": "gc-animation-speed",
          "type": "range",
          "label": "Animation speed",
          "unit": "",
          "min": 1,
          "max": 100,
          "default": "50"
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        {
          "name": "gc-lang",
          "type": "select-one",
          "label": "Language",
          "unit": "",
          "options": [
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          "default": "en"
        },
        {
          "name": "gc-mode",
          "type": "select-one",
          "label": "Plot Type",
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          "options": [
            "explicit",
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            "polar"
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      ],
      "outputs": [
        {
          "name": "gc-output",
          "type": "live"
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        {
          "name": "gc-quality-value",
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      ],
      "prefill": {
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      "slug": "ground-ladder-placement-reach",
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      "description": "Quarter rule, climbing angle from where the butt actually sits, the height a given ladder reaches, the ladder you need for a given objective, and the collapse zone for the building.",
      "category": "fire-and-rescue-service",
      "categoryName": "Fire & Rescue Service",
      "url": "https://www.themostusefulsiteintheworld.com/tool/ground-ladder-placement-reach.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=ground-ladder-placement-reach&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "lad-len",
          "type": "number",
          "label": "Working length",
          "unit": "ft",
          "min": 0,
          "default": "24"
        },
        {
          "name": "lad-hgt",
          "type": "number",
          "label": "Height to reach",
          "unit": "ft",
          "min": 0,
          "default": "20"
        },
        {
          "name": "lad-butt",
          "type": "number",
          "label": "Actual butt distance",
          "unit": "ft",
          "min": 0
        },
        {
          "name": "lad-bldg",
          "type": "number",
          "label": "Building height (ft) — collapse zone",
          "unit": "",
          "min": 0
        },
        {
          "name": "lad-mode",
          "type": "select-one",
          "label": "Work from",
          "unit": "",
          "options": [
            "len",
            "hgt"
          ],
          "default": "len"
        },
        {
          "name": "lad-use",
          "type": "select-one",
          "label": "What the ladder is for",
          "unit": "",
          "options": [
            "roof",
            "window",
            "egress",
            "work"
          ],
          "default": "roof"
        }
      ],
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        {
          "name": "lad-out",
          "type": "live"
        }
      ],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "ground",
        "ladder",
        "placement",
        "reach",
        "fire",
        "rescue",
        "service",
        "quarter",
        "rule",
        "climbing"
      ],
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "grounding-breathing-coach",
      "title": "🫁 Grounding & Breathing Coach",
      "description": "For the moments when your body has decided there is an emergency and your head knows there is not one. Nothing here needs signing up to, nothing is recorded, and it works offline once the page is o...",
      "category": "wellbeing-and-community",
      "categoryName": "Wellbeing & Community",
      "url": "https://www.themostusefulsiteintheworld.com/tool/grounding-breathing-coach.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=grounding-breathing-coach&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "gbc-pattern",
          "type": "select-one",
          "label": "Breathing pattern",
          "unit": "",
          "options": [
            "phys",
            "coherent",
            "box",
            "478",
            "calm"
          ],
          "default": "calm"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=grounding-breathing-coach&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=grounding-breathing-coach&gbc-pattern=calm"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "grounding",
        "breathing",
        "coach",
        "wellbeing",
        "community",
        "moments",
        "when",
        "body",
        "decided",
        "there"
      ],
      "popularity": 4123,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "group-expense-splitter",
      "title": "🧾 Group Expense Splitter & Settle Up",
      "description": "Shared house, road trip, group holiday or a flat's running costs: log who paid what and who it was for, and this works out everyone's balance and the fewest transfers that settle the whole group. E...",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/group-expense-splitter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=group-expense-splitter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ges-people",
          "type": "text",
          "label": "People in the group",
          "unit": "",
          "default": "Alex, Sam, Jordan, Riley"
        },
        {
          "name": "ges-e-desc",
          "type": "text",
          "label": "What was it for?",
          "unit": ""
        },
        {
          "name": "ges-e-amt",
          "type": "number",
          "label": "Amount",
          "unit": "",
          "min": 0,
          "step": 0.01
        },
        {
          "name": "ges-currency",
          "type": "select-one",
          "label": "Currency",
          "unit": "",
          "options": [
            "£",
            "€",
            "$",
            "A$",
            "C$",
            "kr",
            "CHF",
            "zł"
          ],
          "default": "£"
        },
        {
          "name": "ges-e-paid",
          "type": "select-one",
          "label": "Paid by",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "ges-msg",
          "type": "live"
        },
        {
          "name": "ges-s-total",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=group-expense-splitter&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "group",
        "expense",
        "splitter",
        "settle",
        "productivity",
        "lifestyle",
        "shared",
        "house",
        "road",
        "trip"
      ],
      "popularity": 6494,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "grout-adhesive-calculator",
      "title": "🧱 Grout & Tile Adhesive Calculator",
      "description": "The tiles are one thing — the grout and adhesive to fix them are another. Enter the tiled area, tile size and joint width to work out how much grout and thinset to mix.",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/grout-adhesive-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=grout-adhesive-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "label": "Tiled area",
          "unit": "sq ft",
          "min": 1,
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        },
        {
          "name": "grw-tl",
          "type": "number",
          "label": "Tile length",
          "unit": "cm",
          "min": 1,
          "default": "30"
        },
        {
          "name": "grw-tw",
          "type": "number",
          "label": "Tile width",
          "unit": "cm",
          "min": 1,
          "default": "30"
        },
        {
          "name": "grw-gap",
          "type": "number",
          "label": "Joint width",
          "unit": "mm",
          "min": 1,
          "max": 15,
          "default": "3"
        },
        {
          "name": "grw-depth",
          "type": "number",
          "label": "Tile thickness",
          "unit": "mm",
          "min": 1,
          "default": "8"
        }
      ],
      "outputs": [
        {
          "name": "grw-out",
          "type": "live"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=grout-adhesive-calculator&<id>=<value>",
        "runs": true,
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "grout",
        "adhesive",
        "tile",
        "home",
        "diy",
        "tiles",
        "one",
        "thing",
        "fix",
        "them"
      ],
      "popularity": 4536,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "grow-your-calories",
      "title": "🌾 Grow Your Calories",
      "description": "How much of your own food could your patch actually grow? Give it your household and your soil, and this plans a real crop mix — staples, protein and high-value veg — with yields, calories, money s...",
      "category": "culinary-and-food-science",
      "categoryName": "Culinary & Food Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/grow-your-calories.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=grow-your-calories&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "gyc-people",
          "type": "number",
          "label": "Mouths to feed",
          "unit": "",
          "min": 1,
          "max": 12,
          "step": 1,
          "default": "2"
        },
        {
          "name": "gyc-area",
          "type": "number",
          "label": "Growing area",
          "unit": "m² of beds",
          "min": 1,
          "max": 5000,
          "step": 1,
          "default": "50"
        },
        {
          "name": "gyc-cost",
          "type": "number",
          "label": "Setup cost (£ per m², seeds & compost)",
          "unit": "",
          "min": 0,
          "max": 50,
          "step": 0.5,
          "default": "2"
        },
        {
          "name": "gyc-climate",
          "type": "select-one",
          "label": "Season you get",
          "unit": "",
          "options": [
            "temperate",
            "mild",
            "cold"
          ],
          "default": "temperate"
        },
        {
          "name": "gyc-effort",
          "type": "select-one",
          "label": "Effort you'll put in",
          "unit": "",
          "options": [
            "0.65",
            "1",
            "1.3"
          ],
          "default": "1"
        },
        {
          "name": "gyc-goal",
          "type": "select-one",
          "label": "Plan the beds for…",
          "unit": "",
          "options": [
            "calories",
            "money",
            "balanced"
          ],
          "default": "calories"
        },
        {
          "name": "gyc-vegprice",
          "type": "select-one",
          "label": "Your veg price level",
          "unit": "",
          "options": [
            "0.8",
            "1",
            "1.5"
          ],
          "default": "1"
        }
      ],
      "outputs": [
        {
          "name": "gyc-out",
          "type": "live"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=grow-your-calories&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "grow",
        "calories",
        "culinary",
        "food",
        "science",
        "how",
        "much",
        "own",
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      ],
      "popularity": 5510,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "guitar-fret-calculator",
      "title": "🎸 Guitar Fret Position Calculator",
      "description": "Equal-temperament fret rule: distance from nut to fret n = L × (1 − 1/2^(n/12)) where L is scale length. 12th fret is the octave (halfway). Not a CNC file.",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/guitar-fret-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=guitar-fret-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "gfrt-l",
          "type": "number",
          "label": "Scale length mm",
          "unit": "",
          "min": 100,
          "default": "648"
        },
        {
          "name": "gfrt-n",
          "type": "number",
          "label": "Frets",
          "unit": "",
          "min": 12,
          "max": 27,
          "step": 1,
          "default": "22"
        }
      ],
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        {
          "name": "gfrt-out",
          "type": "output"
        }
      ],
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=guitar-fret-calculator&gfrt-l=648&gfrt-n=22"
      },
      "formula": "Equal-temperament fret rule: distance from nut to fret n = L × (1 − 1/2^(n/",
      "sources": [],
      "tags": [
        "guitar",
        "fret",
        "position",
        "music",
        "audio",
        "equal-temperament",
        "rule",
        "distance",
        "nut",
        "where"
      ],
      "popularity": 5049,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "gymnastics-score-calculator",
      "title": "🤸 Gymnastics Score Calculator",
      "description": "A gymnastics score is difficulty plus execution. Enter the D-score, tick the deductions, and this works out the E-score (out of 10) and the final total.",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/gymnastics-score-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=gymnastics-score-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "gym-d",
          "type": "number",
          "label": "D-score",
          "unit": "difficulty",
          "min": 0,
          "step": 0.1,
          "default": "5.8"
        },
        {
          "name": "gym-e",
          "type": "number",
          "label": "E-score override",
          "unit": "",
          "min": 0,
          "max": 10,
          "step": 0.1
        }
      ],
      "outputs": [
        {
          "name": "gym-out",
          "type": "live"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=gymnastics-score-calculator&<id>=<value>",
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "gymnastics",
        "score",
        "sports",
        "difficulty",
        "plus",
        "execution",
        "enter",
        "d-score",
        "tick",
        "deductions"
      ],
      "popularity": 4816,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "gyroscopic-precession-dynamics",
      "title": "🧭 Gyroscopic Precession Lab",
      "description": "Explore rigid body rotational mechanics ($\\boldsymbol{\\tau} = \\boldsymbol{\\Omega}_p \\times \\mathbf{L}$). Calculate steady precession velocity ($\\Omega_p = \\frac{mgr}{I_z \\omega_s}$), nutation frequ...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/gyroscopic-precession-dynamics.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=gyroscopic-precession-dynamics&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "gyro-rpm",
          "type": "number",
          "label": "Spin Speed",
          "unit": "$N_s$",
          "min": 100,
          "max": 50000,
          "step": 100,
          "default": "3000"
        },
        {
          "name": "gyro-rotor-mass",
          "type": "number",
          "label": "Rotor Mass",
          "unit": "$m$",
          "min": 0.05,
          "max": 20,
          "step": 0.05,
          "default": "0.8"
        },
        {
          "name": "gyro-radius",
          "type": "number",
          "label": "Flywheel Radius",
          "unit": "$R$",
          "min": 0.01,
          "max": 0.5,
          "step": 0.005,
          "default": "0.06"
        },
        {
          "name": "gyro-arm-dist",
          "type": "number",
          "label": "Pivot Arm",
          "unit": "$r_{cm}$",
          "min": 0.01,
          "max": 0.5,
          "step": 0.01,
          "default": "0.12"
        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=gyroscopic-precession-dynamics&<id>=<value>",
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      },
      "formula": "Speed ($\\Omega_p$) 2.08 rad/s Period T = 3.02 s /",
      "sources": [],
      "tags": [
        "gyroscopic",
        "precession",
        "dynamics",
        "lab",
        "science",
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        "explore",
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      "popularity": 6683,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "habit",
      "title": "📈 Habit Tracker",
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      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/habit.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=habit&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ht-name",
          "type": "text",
          "label": "Habit Name",
          "unit": ""
        },
        {
          "name": "ht-date",
          "type": "date",
          "label": "Log Date",
          "unit": ""
        },
        {
          "name": "habitht-category",
          "type": "select-one",
          "label": "Category",
          "unit": "",
          "options": [
            "health",
            "learning",
            "productivity",
            "mindfulness",
            "creative",
            "other"
          ],
          "default": "health"
        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=habit&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=habit&habitht-category=health"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "habit",
        "tracker",
        "productivity",
        "lifestyle",
        "build",
        "consistent",
        "habits",
        "visual",
        "streaks",
        "daily"
      ],
      "popularity": 4460,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-candy-calculator",
      "title": "🍫 Halloween Candy Calculator",
      "description": "Buy the right amount of sweets: estimate the door traffic from your street, allow for the late rush, and see exactly when the bowl runs out.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-candy-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-candy-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "number",
          "label": "Trick-or-treaters expected",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "60"
        },
        {
          "name": "hcc-pieces",
          "type": "number",
          "label": "Sweets per visitor",
          "unit": "handful",
          "min": 1,
          "step": 1,
          "default": "3"
        },
        {
          "name": "hcc-bag",
          "type": "number",
          "label": "Sweets per bag",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "60"
        },
        {
          "name": "hcc-cost",
          "type": "number",
          "label": "Cost per bag",
          "unit": "£",
          "min": 0,
          "step": 0.01,
          "default": "5.00"
        },
        {
          "name": "hcc-margin",
          "type": "number",
          "label": "Spare for latecomers",
          "unit": "%",
          "min": 0,
          "max": 100,
          "step": 5,
          "default": "15"
        },
        {
          "name": "hcc-peak",
          "type": "number",
          "label": "Share arriving in the peak hour",
          "unit": "%",
          "min": 10,
          "max": 90,
          "step": 5,
          "default": "40"
        },
        {
          "name": "hcc-houses",
          "type": "number",
          "label": "Households within walking distance",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "120"
        },
        {
          "name": "hcc-kids",
          "type": "number",
          "label": "Children per household",
          "unit": "",
          "min": 0,
          "step": 0.1,
          "default": "0.8"
        },
        {
          "name": "hcc-share",
          "type": "number",
          "label": "Share who come to your door",
          "unit": "%",
          "min": 0,
          "max": 100,
          "step": 5,
          "default": "55"
        }
      ],
      "outputs": [
        {
          "name": "hcc-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-candy-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-candy-calculator&hcc-visitors=60&hcc-pieces=3&hcc-bag=60&hcc-cost=5.00&hcc-margin=15&hcc-peak=40"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "halloween",
        "candy",
        "buy",
        "right",
        "amount",
        "sweets",
        "estimate",
        "door",
        "traffic",
        "street"
      ],
      "popularity": 6870,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-costume-generator",
      "title": "🎃 Halloween Costume Generator",
      "description": "Halloween costume ideas in seconds: pick who it is for, the vibe and the budget, and get three complete costumes with everything you need.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-costume-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-costume-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hcg-seed",
          "type": "number",
          "label": "Seed",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "31"
        },
        {
          "name": "hcg-who",
          "type": "select-one",
          "label": "Who is it for?",
          "unit": "",
          "options": [
            "child",
            "teen",
            "adult",
            "group"
          ],
          "default": "child"
        },
        {
          "name": "hcg-vibe",
          "type": "select-one",
          "label": "Vibe",
          "unit": "",
          "options": [
            "any",
            "funny",
            "scary",
            "cute",
            "classic"
          ],
          "default": "any"
        },
        {
          "name": "hcg-effort",
          "type": "select-one",
          "label": "Time to make it",
          "unit": "",
          "options": [
            "any",
            "1",
            "2",
            "3"
          ],
          "default": "any"
        },
        {
          "name": "hcg-budget",
          "type": "select-one",
          "label": "Budget",
          "unit": "",
          "options": [
            "any",
            "1",
            "2",
            "3"
          ],
          "default": "any"
        },
        {
          "name": "hcg-weather",
          "type": "select-one",
          "label": "Evening weather",
          "unit": "",
          "options": [
            "any",
            "cold",
            "mild"
          ],
          "default": "any"
        }
      ],
      "outputs": [
        {
          "name": "hcg-count",
          "type": "live"
        },
        {
          "name": "hcg-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-costume-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-costume-generator&hcg-seed=31&hcg-who=child&hcg-vibe=any&hcg-effort=any&hcg-budget=any&hcg-weather=any"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "halloween",
        "costume",
        "ideas",
        "seconds",
        "pick",
        "who",
        "vibe",
        "budget",
        "get",
        "three"
      ],
      "popularity": 4706,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-costume-weather-planner",
      "title": "🧥 Halloween Costume Weather Planner",
      "description": "Will that costume survive the evening? Add the forecast, the wind and the layers underneath, and get an honest read on comfort, exposed skin and rain before anyone leaves the house.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-costume-weather-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-costume-weather-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hcw-temp",
          "type": "number",
          "label": "Air temperature",
          "unit": "°C",
          "min": -15,
          "max": 25,
          "step": 0.5,
          "default": "8"
        },
        {
          "name": "hcw-wind",
          "type": "number",
          "label": "Wind",
          "unit": "km/h",
          "min": 0,
          "max": 80,
          "step": 1,
          "default": "15"
        },
        {
          "name": "hcw-rain",
          "type": "number",
          "label": "Rain",
          "unit": "mm/h",
          "min": 0,
          "max": 20,
          "step": 0.5,
          "default": "0"
        },
        {
          "name": "hcw-duration",
          "type": "number",
          "label": "Time outside",
          "unit": "min",
          "min": 10,
          "max": 300,
          "step": 10,
          "default": "90"
        },
        {
          "name": "hcw-costume",
          "type": "select-one",
          "label": "Costume coverage",
          "unit": "",
          "options": [
            "thin",
            "covered",
            "padded"
          ],
          "default": "covered"
        },
        {
          "name": "hcw-layers",
          "type": "select-one",
          "label": "Layers underneath",
          "unit": "",
          "options": [
            "0",
            "1",
            "2",
            "3"
          ],
          "default": "1"
        },
        {
          "name": "hcw-activity",
          "type": "select-one",
          "label": "Activity",
          "unit": "",
          "options": [
            "walk",
            "door",
            "party"
          ],
          "default": "walk"
        }
      ],
      "outputs": [
        {
          "name": "hcw-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-costume-weather-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-costume-weather-planner&hcw-temp=8&hcw-wind=15&hcw-rain=0&hcw-duration=90&hcw-costume=covered&hcw-layers=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "halloween",
        "costume",
        "weather",
        "planner",
        "survive",
        "evening",
        "add",
        "forecast",
        "wind",
        "layers"
      ],
      "popularity": 4212,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-couple-costume-matcher",
      "title": "💑 Couple Halloween Costume Ideas",
      "description": "Match a couple Halloween costume in seconds: pick a vibe, effort and budget, and get paired ideas with what each person wears and the build time.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-couple-costume-matcher.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-couple-costume-matcher&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hcm-seed",
          "type": "number",
          "label": "Seed",
          "unit": "",
          "min": 1,
          "max": 9999,
          "step": 1,
          "default": "31"
        },
        {
          "name": "hcm-vibe",
          "type": "select-one",
          "label": "Vibe",
          "unit": "",
          "options": [
            "any",
            "spooky",
            "funny",
            "film",
            "pun",
            "glam",
            "classic"
          ],
          "default": "any"
        },
        {
          "name": "hcm-effort",
          "type": "select-one",
          "label": "Effort",
          "unit": "",
          "options": [
            "1",
            "2",
            "3"
          ],
          "default": "2"
        },
        {
          "name": "hcm-budget",
          "type": "select-one",
          "label": "Budget for two",
          "unit": "",
          "options": [
            "1",
            "2",
            "3"
          ],
          "default": "2"
        }
      ],
      "outputs": [
        {
          "name": "hcm-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-couple-costume-matcher&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-couple-costume-matcher&hcm-seed=31&hcm-vibe=any&hcm-effort=2&hcm-budget=2"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "halloween",
        "couple",
        "costume",
        "matcher",
        "ideas",
        "match",
        "seconds",
        "pick",
        "vibe",
        "effort"
      ],
      "popularity": 6872,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-decoration-power-budget",
      "title": "🔌 Halloween Decoration Power Budget",
      "description": "Add up every prop on the circuit, check the breaker and the extension lead, and see what the display costs to run each night.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-decoration-power-budget.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-decoration-power-budget&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "dpb-lights",
          "type": "number",
          "label": "Lights",
          "unit": "W",
          "min": 0,
          "step": 5,
          "default": "180"
        },
        {
          "name": "dpb-inflate",
          "type": "number",
          "label": "Inflatables & blowers",
          "unit": "W",
          "min": 0,
          "step": 10,
          "default": "240"
        },
        {
          "name": "dpb-fog",
          "type": "number",
          "label": "Fog machine",
          "unit": "W",
          "min": 0,
          "step": 10,
          "default": "700"
        },
        {
          "name": "dpb-proj",
          "type": "number",
          "label": "Projector",
          "unit": "W",
          "min": 0,
          "step": 10,
          "default": "300"
        },
        {
          "name": "dpb-audio",
          "type": "number",
          "label": "Sound",
          "unit": "W",
          "min": 0,
          "step": 5,
          "default": "120"
        },
        {
          "name": "dpb-other",
          "type": "number",
          "label": "Other props",
          "unit": "W",
          "min": 0,
          "step": 5,
          "default": "60"
        },
        {
          "name": "dpb-hours",
          "type": "number",
          "label": "Hours per night",
          "unit": "",
          "min": 0.5,
          "max": 12,
          "step": 0.5,
          "default": "5"
        },
        {
          "name": "dpb-nights",
          "type": "number",
          "label": "Nights on display",
          "unit": "",
          "min": 1,
          "max": 60,
          "step": 1,
          "default": "12"
        },
        {
          "name": "dpb-tariff",
          "type": "number",
          "label": "Electricity",
          "unit": "p/kWh",
          "min": 0,
          "max": 100,
          "step": 0.1,
          "default": "24.9"
        },
        {
          "name": "dpb-breaker",
          "type": "number",
          "label": "Breaker / socket rating",
          "unit": "A",
          "min": 1,
          "max": 63,
          "step": 1,
          "default": "13"
        },
        {
          "name": "dpb-existing",
          "type": "number",
          "label": "Other load on circuit",
          "unit": "A",
          "min": 0,
          "max": 60,
          "step": 0.5,
          "default": "2"
        },
        {
          "name": "dpb-cable",
          "type": "number",
          "label": "Lead length",
          "unit": "m",
          "min": 1,
          "max": 100,
          "step": 1,
          "default": "20"
        },
        {
          "name": "dpb-duty",
          "type": "number",
          "label": "Proportion running at once",
          "unit": "%",
          "min": 10,
          "max": 100,
          "step": 5,
          "default": "100"
        },
        {
          "name": "dpb-voltage",
          "type": "select-one",
          "label": "Supply voltage",
          "unit": "",
          "options": [
            "230",
            "120"
          ],
          "default": "230"
        },
        {
          "name": "dpb-gauge",
          "type": "select-one",
          "label": "Lead cross-section",
          "unit": "",
          "options": [
            "0.75",
            "1",
            "1.5",
            "2.5"
          ],
          "default": "1.5"
        }
      ],
      "outputs": [
        {
          "name": "dpb-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-decoration-power-budget&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-decoration-power-budget&dpb-lights=180&dpb-inflate=240&dpb-fog=700&dpb-proj=300&dpb-audio=120&dpb-other=60"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "halloween",
        "decoration",
        "power",
        "budget",
        "add",
        "every",
        "prop",
        "circuit",
        "check",
        "breaker"
      ],
      "popularity": 6286,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-face-paint-planner",
      "title": "🎨 Halloween Face Paint Planner",
      "description": "Plan Halloween face paint: pick a design, skin tone and time budget, and get the colours, steps, drying time and enough paint for the group.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-face-paint-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-face-paint-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hfp-people",
          "type": "number",
          "label": "People",
          "unit": "",
          "min": 1,
          "max": 30,
          "step": 1,
          "default": "4"
        },
        {
          "name": "hfp-minutes",
          "type": "number",
          "label": "Minutes per face",
          "unit": "",
          "min": 5,
          "max": 60,
          "step": 1,
          "default": "25"
        },
        {
          "name": "hfp-design",
          "type": "select-one",
          "label": "Design",
          "unit": "",
          "options": [
            "skeleton",
            "cat",
            "vampire",
            "zombie",
            "witch",
            "pumpkin",
            "sugar",
            "spider"
          ],
          "default": "skeleton"
        },
        {
          "name": "hfp-tone",
          "type": "select-one",
          "label": "Skin tone",
          "unit": "",
          "options": [
            "fair",
            "medium",
            "deep"
          ],
          "default": "fair"
        },
        {
          "name": "hfp-cover",
          "type": "select-one",
          "label": "Coverage",
          "unit": "",
          "options": [
            "half",
            "full"
          ],
          "default": "full"
        }
      ],
      "outputs": [
        {
          "name": "hfp-out",
          "type": "live"
        },
        {
          "name": "hfp-total",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-face-paint-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-face-paint-planner&hfp-people=4&hfp-minutes=25&hfp-design=skeleton&hfp-tone=fair&hfp-cover=full"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "halloween",
        "face",
        "paint",
        "planner",
        "plan",
        "pick",
        "design",
        "skin",
        "tone",
        "time"
      ],
      "popularity": 4539,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-group-costume-planner",
      "title": "👯 Group Halloween Costume Planner",
      "description": "Plan a group Halloween costume that works for your headcount: matched themes, a role for every person, per-person costs and a group build schedule.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-group-costume-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-group-costume-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hgp-size",
          "type": "number",
          "label": "People in the group",
          "unit": "",
          "min": 2,
          "max": 24,
          "step": 1,
          "default": "6"
        },
        {
          "name": "hgp-seed",
          "type": "number",
          "label": "Seed",
          "unit": "",
          "min": 1,
          "max": 9999,
          "step": 1,
          "default": "31"
        },
        {
          "name": "hgp-vibe",
          "type": "select-one",
          "label": "Vibe",
          "unit": "",
          "options": [
            "any",
            "film",
            "spooky",
            "funny",
            "classic",
            "games"
          ],
          "default": "any"
        },
        {
          "name": "hgp-effort",
          "type": "select-one",
          "label": "Effort",
          "unit": "",
          "options": [
            "1",
            "2",
            "3"
          ],
          "default": "2"
        },
        {
          "name": "hgp-budget",
          "type": "select-one",
          "label": "Budget per person",
          "unit": "",
          "options": [
            "1",
            "2",
            "3"
          ],
          "default": "2"
        }
      ],
      "outputs": [
        {
          "name": "hgp-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-group-costume-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-group-costume-planner&hgp-size=6&hgp-seed=31&hgp-vibe=any&hgp-effort=2&hgp-budget=2"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "halloween",
        "group",
        "costume",
        "planner",
        "plan",
        "works",
        "headcount",
        "matched",
        "themes",
        "role"
      ],
      "popularity": 6945,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-movie-marathon-planner",
      "title": "🍿 Halloween Movie Marathon Planner",
      "description": "Plan a Halloween movie marathon that ends on time: pick the start, the hours and who is watching, and get a running order with runtimes and breaks.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-movie-marathon-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-movie-marathon-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hmm-start",
          "type": "time",
          "label": "Start time",
          "unit": "",
          "default": "19:00"
        },
        {
          "name": "hmm-seed",
          "type": "number",
          "label": "Seed",
          "unit": "",
          "min": 1,
          "max": 9999,
          "step": 1,
          "default": "31"
        },
        {
          "name": "hmm-hours",
          "type": "select-one",
          "label": "Hours available",
          "unit": "",
          "options": [
            "2",
            "3",
            "4",
            "5",
            "6"
          ],
          "default": "3"
        },
        {
          "name": "hmm-audience",
          "type": "select-one",
          "label": "Watching",
          "unit": "",
          "options": [
            "1",
            "2",
            "3",
            "4"
          ],
          "default": "2"
        },
        {
          "name": "hmm-scare",
          "type": "select-one",
          "label": "Scare level",
          "unit": "",
          "options": [
            "1",
            "2",
            "3"
          ],
          "default": "2"
        },
        {
          "name": "hmm-break",
          "type": "select-one",
          "label": "Break between films",
          "unit": "",
          "options": [
            "5",
            "10",
            "15",
            "20"
          ],
          "default": "15"
        }
      ],
      "outputs": [
        {
          "name": "hmm-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-movie-marathon-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-movie-marathon-planner&hmm-start=19%3A00&hmm-seed=31&hmm-hours=3&hmm-audience=2&hmm-scare=2&hmm-break=15"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "halloween",
        "movie",
        "marathon",
        "planner",
        "plan",
        "ends",
        "time",
        "pick",
        "start",
        "hours"
      ],
      "popularity": 5536,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-name-generator",
      "title": "🦇 Halloween Name Generator",
      "description": "Turn your own name into a Halloween name: pick a style and a spookiness, and get three witch, vampire, ghost or monster names with a backstory.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-name-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-name-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hng-name",
          "type": "text",
          "label": "Your name",
          "unit": "",
          "default": "Sam"
        },
        {
          "name": "hng-spook",
          "type": "range",
          "label": "Spookiness 3",
          "unit": "",
          "min": 1,
          "max": 5,
          "step": 1,
          "default": "3"
        },
        {
          "name": "hng-seed",
          "type": "number",
          "label": "Seed",
          "unit": "",
          "min": 1,
          "max": 9999,
          "step": 1,
          "default": "31"
        },
        {
          "name": "hng-style",
          "type": "select-one",
          "label": "Style",
          "unit": "",
          "options": [
            "witch",
            "vampire",
            "monster",
            "ghost",
            "pumpkin"
          ],
          "default": "witch"
        }
      ],
      "outputs": [
        {
          "name": "hng-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-name-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-name-generator&hng-name=Sam&hng-spook=3&hng-seed=31&hng-style=witch"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "halloween",
        "name",
        "turn",
        "own",
        "into",
        "pick",
        "style",
        "spookiness",
        "get",
        "three"
      ],
      "popularity": 4481,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-night-visibility-check",
      "title": "🔦 Halloween Night Visibility Check",
      "description": "Compare how far a driver can see a child with how far the car needs to stop — then find the reflective area that closes the gap.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-night-visibility-check.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-night-visibility-check&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hnv-speed",
          "type": "number",
          "label": "Traffic speed",
          "unit": "km/h",
          "min": 10,
          "max": 110,
          "step": 5,
          "default": "30"
        },
        {
          "name": "hnv-react",
          "type": "number",
          "label": "Driver reaction time",
          "unit": "s",
          "min": 0.5,
          "max": 3,
          "step": 0.1,
          "default": "1.5"
        },
        {
          "name": "hnv-area",
          "type": "number",
          "label": "Reflective area",
          "unit": "cm²",
          "min": 0,
          "max": 600,
          "step": 5,
          "default": "20"
        },
        {
          "name": "hnv-surface",
          "type": "select-one",
          "label": "Road surface",
          "unit": "",
          "options": [
            "dry",
            "wet",
            "icy"
          ],
          "default": "dry"
        },
        {
          "name": "hnv-light",
          "type": "select-one",
          "label": "Street lighting",
          "unit": "",
          "options": [
            "no",
            "yes"
          ],
          "default": "no"
        },
        {
          "name": "hnv-costume",
          "type": "select-one",
          "label": "Costume tone",
          "unit": "",
          "options": [
            "dark",
            "light",
            "reflective"
          ],
          "default": "dark"
        },
        {
          "name": "hnv-torch",
          "type": "select-one",
          "label": "Carrying a torch",
          "unit": "",
          "options": [
            "no",
            "yes"
          ],
          "default": "no"
        }
      ],
      "outputs": [
        {
          "name": "hnv-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-night-visibility-check&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-night-visibility-check&hnv-speed=30&hnv-react=1.5&hnv-area=20&hnv-surface=dry&hnv-light=no&hnv-costume=dark"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "halloween",
        "night",
        "visibility",
        "check",
        "compare",
        "how",
        "far",
        "driver",
        "can",
        "see"
      ],
      "popularity": 5526,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-party-games-planner",
      "title": "🎉 Halloween Party Games Planner",
      "description": "Fill a Halloween party with games that fit the age group, room and time — with durations, supplies and a running order that works.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-party-games-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-party-games-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hpg-guests",
          "type": "number",
          "label": "Guests",
          "unit": "",
          "min": 3,
          "max": 40,
          "step": 1,
          "default": "12"
        },
        {
          "name": "hpg-minutes",
          "type": "number",
          "label": "Party length",
          "unit": "min",
          "min": 30,
          "max": 300,
          "step": 5,
          "default": "120"
        },
        {
          "name": "hpg-ages",
          "type": "select-one",
          "label": "Ages",
          "unit": "",
          "options": [
            "3",
            "6",
            "9",
            "13",
            "18",
            "6"
          ],
          "default": "6"
        },
        {
          "name": "hpg-space",
          "type": "select-one",
          "label": "Space",
          "unit": "",
          "options": [
            "room",
            "hall",
            "garden"
          ],
          "default": "room"
        },
        {
          "name": "hpg-energy",
          "type": "select-one",
          "label": "Energy",
          "unit": "",
          "options": [
            "2",
            "1",
            "3"
          ],
          "default": "2"
        }
      ],
      "outputs": [
        {
          "name": "hpg-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-party-games-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-party-games-planner&hpg-guests=12&hpg-minutes=120&hpg-ages=6&hpg-space=room&hpg-energy=2"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "halloween",
        "party",
        "games",
        "planner",
        "fill",
        "fit",
        "age",
        "group",
        "room",
        "time"
      ],
      "popularity": 4895,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-party-playlist-planner",
      "title": "🎵 Halloween Party Playlist Planner",
      "description": "Build a Halloween party playlist that fits the night: pick the hours, the guests and the energy curve, and get a timed song list block by block.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-party-playlist-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-party-playlist-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hpl-start",
          "type": "time",
          "label": "Music starts",
          "unit": "",
          "default": "18:30"
        },
        {
          "name": "hpl-seed",
          "type": "number",
          "label": "Seed",
          "unit": "",
          "min": 1,
          "max": 9999,
          "step": 1,
          "default": "31"
        },
        {
          "name": "hpl-hours",
          "type": "select-one",
          "label": "Party length",
          "unit": "hours",
          "options": [
            "1.5",
            "2",
            "3",
            "4",
            "5"
          ],
          "default": "2"
        },
        {
          "name": "hpl-guests",
          "type": "select-one",
          "label": "Guests",
          "unit": "",
          "options": [
            "kids",
            "family",
            "teens",
            "adults"
          ],
          "default": "family"
        },
        {
          "name": "hpl-energy",
          "type": "select-one",
          "label": "Energy",
          "unit": "",
          "options": [
            "1",
            "2",
            "3"
          ],
          "default": "2"
        }
      ],
      "outputs": [
        {
          "name": "hpl-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-party-playlist-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-party-playlist-planner&hpl-start=18%3A30&hpl-seed=31&hpl-hours=2&hpl-guests=family&hpl-energy=2"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "halloween",
        "party",
        "playlist",
        "planner",
        "build",
        "fits",
        "night",
        "pick",
        "hours",
        "guests"
      ],
      "popularity": 4642,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-pumpkin-stencil-generator",
      "title": "🎃 Pumpkin Stencil Generator",
      "description": "Free pumpkin stencil generator: choose a face, size and difficulty, and get a printable pattern with cut order and bridge widths.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-pumpkin-stencil-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-pumpkin-stencil-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hps-width",
          "type": "number",
          "label": "Pumpkin width",
          "unit": "cm",
          "min": 12,
          "max": 60,
          "step": 1,
          "default": "24"
        },
        {
          "name": "hps-seed",
          "type": "number",
          "label": "Variation",
          "unit": "",
          "min": 1,
          "max": 9999,
          "step": 1,
          "default": "31"
        },
        {
          "name": "hps-pattern",
          "type": "select-one",
          "label": "Pattern",
          "unit": "",
          "options": [
            "classic",
            "cat",
            "bat",
            "ghost",
            "spider",
            "moon",
            "skull",
            "smile"
          ],
          "default": "classic"
        },
        {
          "name": "hps-diff",
          "type": "select-one",
          "label": "Difficulty",
          "unit": "",
          "options": [
            "1",
            "2",
            "3"
          ],
          "default": "2"
        }
      ],
      "outputs": [
        {
          "name": "hps-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-pumpkin-stencil-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-pumpkin-stencil-generator&hps-width=24&hps-seed=31&hps-pattern=classic&hps-diff=2"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "halloween",
        "pumpkin",
        "stencil",
        "choose",
        "face",
        "size",
        "difficulty",
        "get",
        "printable",
        "pattern"
      ],
      "popularity": 5715,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-scavenger-hunt-generator",
      "title": "🔍 Halloween Scavenger Hunt Generator",
      "description": "Generate a printable Halloween scavenger hunt: choose the age, the area and the number of clues, and get riddle cards, a route and an answer key.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-scavenger-hunt-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-scavenger-hunt-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hsh-seed",
          "type": "number",
          "label": "Seed",
          "unit": "",
          "min": 1,
          "max": 9999,
          "step": 1,
          "default": "31"
        },
        {
          "name": "hsh-place",
          "type": "select-one",
          "label": "Where",
          "unit": "",
          "options": [
            "home",
            "garden",
            "street",
            "park"
          ],
          "default": "home"
        },
        {
          "name": "hsh-age",
          "type": "select-one",
          "label": "Ages",
          "unit": "",
          "options": [
            "1",
            "2",
            "3"
          ],
          "default": "2"
        },
        {
          "name": "hsh-count",
          "type": "select-one",
          "label": "Clues",
          "unit": "",
          "options": [
            "6",
            "8",
            "10",
            "12"
          ],
          "default": "8"
        },
        {
          "name": "hsh-diff",
          "type": "select-one",
          "label": "Difficulty",
          "unit": "",
          "options": [
            "1",
            "2",
            "3"
          ],
          "default": "2"
        }
      ],
      "outputs": [
        {
          "name": "hsh-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-scavenger-hunt-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-scavenger-hunt-generator&hsh-seed=31&hsh-place=home&hsh-age=2&hsh-count=8&hsh-diff=2"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "halloween",
        "scavenger",
        "hunt",
        "generate",
        "printable",
        "choose",
        "age",
        "area",
        "number",
        "clues"
      ],
      "popularity": 5280,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "halloween-trivia-questions",
      "title": "🧠 Halloween Trivia Questions",
      "description": "Generate Halloween trivia questions and answers for a party quiz — rounds, difficulty, teams, a printable score sheet and a tiebreaker.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/halloween-trivia-questions.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-trivia-questions&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hqt-teams",
          "type": "number",
          "label": "Teams",
          "unit": "",
          "min": 2,
          "max": 8,
          "step": 1,
          "default": "4"
        },
        {
          "name": "hqt-seed",
          "type": "number",
          "label": "Seed",
          "unit": "",
          "min": 1,
          "max": 9999,
          "step": 1,
          "default": "31"
        },
        {
          "name": "hqt-rounds",
          "type": "select-one",
          "label": "Rounds",
          "unit": "",
          "options": [
            "1",
            "2",
            "3",
            "4",
            "5"
          ],
          "default": "3"
        },
        {
          "name": "hqt-per",
          "type": "select-one",
          "label": "Questions per round",
          "unit": "",
          "options": [
            "5",
            "10",
            "15"
          ],
          "default": "10"
        },
        {
          "name": "hqt-diff",
          "type": "select-one",
          "label": "Difficulty",
          "unit": "",
          "options": [
            "1",
            "2",
            "3"
          ],
          "default": "2"
        }
      ],
      "outputs": [
        {
          "name": "hqt-out",
          "type": "live"
        },
        {
          "name": "hqt-teams-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-trivia-questions&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=halloween-trivia-questions&hqt-teams=4&hqt-seed=31&hqt-rounds=3&hqt-per=10&hqt-diff=2"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "halloween",
        "trivia",
        "questions",
        "generate",
        "answers",
        "party",
        "quiz",
        "rounds",
        "difficulty",
        "teams"
      ],
      "popularity": 6077,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "handball-scorekeeper",
      "title": "🤾 Handball Scorekeeper",
      "description": "Two halves, goals, and the two-minute suspensions that define the game. Tap to score, track each team's suspensions, and keep the running total.",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/handball-scorekeeper.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=handball-scorekeeper&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [
        {
          "name": "hnb-board",
          "type": "live"
        },
        {
          "name": "hnb-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=handball-scorekeeper&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "handball",
        "scorekeeper",
        "sports",
        "two",
        "halves",
        "goals",
        "two-minute",
        "suspensions",
        "define",
        "game"
      ],
      "popularity": 6149,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "hard-times-help-navigator",
      "title": "🧭 Hard Times Navigator: No Food, No Money — Start Here",
      "description": "If you are out of food or money, start here. A calm step-by-step triage that builds your personal action plan for today and this week, shows how to find food aid anywhere in the world, and gives yo...",
      "category": "wellbeing-and-community",
      "categoryName": "Wellbeing & Community",
      "url": "https://www.themostusefulsiteintheworld.com/tool/hard-times-help-navigator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hard-times-help-navigator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hthn-name",
          "type": "text",
          "label": "Your first name",
          "unit": ""
        },
        {
          "name": "hthn-need",
          "type": "text",
          "label": "Who needs feeding",
          "unit": ""
        },
        {
          "name": "hthn-cname",
          "type": "text",
          "label": "Place name",
          "unit": ""
        },
        {
          "name": "hthn-cwhat",
          "type": "text",
          "label": "What they give",
          "unit": ""
        },
        {
          "name": "hthn-caddr",
          "type": "text",
          "label": "Address or hours",
          "unit": ""
        },
        {
          "name": "hthn-cphone",
          "type": "text",
          "label": "Phone or contact",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "hthn-plan",
          "type": "live"
        },
        {
          "name": "hthn-contacts",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=hard-times-help-navigator&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "hard",
        "times",
        "help",
        "navigator",
        "food",
        "money",
        "start",
        "here",
        "wellbeing",
        "community"
      ],
      "popularity": 6596,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "hardship-letter-writer",
      "title": "✉️ Hardship Letter Writer: Ask for Breathing Space",
      "description": "Falling behind on rent, energy or debts? Silence makes everything worse. Build a calm, formal hardship letter with a budget summary that asks for a payment plan, freeze or reduction — in UK, US or ...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/hardship-letter-writer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hardship-letter-writer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hdlw-name",
          "type": "text",
          "label": "Your full name",
          "unit": ""
        },
        {
          "name": "hdlw-addr",
          "type": "text",
          "label": "Your address",
          "unit": ""
        },
        {
          "name": "hdlw-ref",
          "type": "text",
          "label": "Account / tenancy ref",
          "unit": ""
        },
        {
          "name": "hdlw-owed",
          "type": "number",
          "label": "Amount owed / behind",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "450"
        },
        {
          "name": "hdlw-cur",
          "type": "text",
          "label": "Currency",
          "unit": "",
          "default": "£"
        },
        {
          "name": "hdlw-date",
          "type": "text",
          "label": "Letter date",
          "unit": ""
        },
        {
          "name": "hdlw-inc",
          "type": "number",
          "label": "Monthly income",
          "unit": "all in",
          "min": 0,
          "step": 1,
          "default": "1400"
        },
        {
          "name": "hdlw-rent",
          "type": "number",
          "label": "Rent / mortgage",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "700"
        },
        {
          "name": "hdlw-bills",
          "type": "number",
          "label": "Energy + water + council",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "260"
        },
        {
          "name": "hdlw-food",
          "type": "number",
          "label": "Food + essentials",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "280"
        },
        {
          "name": "hdlw-travel",
          "type": "number",
          "label": "Travel to work/school",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "90"
        },
        {
          "name": "hdlw-other",
          "type": "number",
          "label": "Other essentials",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "60"
        },
        {
          "name": "hdlw-who",
          "type": "select-one",
          "label": "Recipient",
          "unit": "",
          "options": [
            "landlord",
            "energy",
            "council",
            "lender",
            "collector",
            "water"
          ],
          "default": "landlord"
        },
        {
          "name": "hdlw-region",
          "type": "select-one",
          "label": "Wording",
          "unit": "",
          "options": [
            "uk",
            "us",
            "intl"
          ],
          "default": "uk"
        },
        {
          "name": "hdlw-reason",
          "type": "select-one",
          "label": "Why you are struggling",
          "unit": "",
          "options": [
            "hours",
            "jobloss",
            "illness",
            "benefit",
            "prices",
            "family",
            "split"
          ],
          "default": "hours"
        },
        {
          "name": "hdlw-ask",
          "type": "select-one",
          "label": "What you are asking for",
          "unit": "",
          "options": [
            "plan",
            "freeze",
            "reduce",
            "charges",
            "writeoff"
          ],
          "default": "plan"
        }
      ],
      "outputs": [
        {
          "name": "hdlw-afford",
          "type": "live"
        },
        {
          "name": "hdlw-out",
          "type": "live"
        }
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      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=hardship-letter-writer&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "hardship",
        "letter",
        "writer",
        "ask",
        "breathing",
        "space",
        "finance",
        "money",
        "falling",
        "behind"
      ],
      "popularity": 6628,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "harmonic-orbit-gravitational-soundscape",
      "title": "🪐 HarmonicOrbit Loom",
      "description": "An evolving celestial music box. Launch orbiting planets into gravitational fields. As orbital bodies cross harmonic resonance spokes, they trigger soothing mathematical melodies synthesized in rea...",
      "category": "interactive-art-and-living-worlds",
      "categoryName": "Interactive Art & Living Worlds",
      "url": "https://www.themostusefulsiteintheworld.com/tool/harmonic-orbit-gravitational-soundscape.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=harmonic-orbit-gravitational-soundscape&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ho-gravity",
          "type": "range",
          "label": "Central Mass Gravity",
          "unit": "",
          "min": 500,
          "max": 3500,
          "step": 50,
          "default": "1800"
        },
        {
          "name": "ho-scale",
          "type": "select-one",
          "label": "Musical Tuning Scale",
          "unit": "",
          "options": [
            "celestial",
            "pentatonic",
            "dorian",
            "major7"
          ],
          "default": "celestial"
        },
        {
          "name": "ho-trails",
          "type": "select-one",
          "label": "Orbital Trail Echo",
          "unit": "",
          "options": [
            "0.08",
            "0.2",
            "0.5"
          ],
          "default": "0.2"
        },
        {
          "name": "ho-spokes",
          "type": "select-one",
          "label": "Harmonic Trigger Spokes",
          "unit": "",
          "options": [
            "4",
            "6",
            "8",
            "12"
          ],
          "default": "8"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=harmonic-orbit-gravitational-soundscape&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "harmonic",
        "orbit",
        "gravitational",
        "soundscape",
        "harmonicorbit",
        "loom",
        "interactive",
        "art",
        "living",
        "worlds"
      ],
      "popularity": 5702,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "hash-checker",
      "title": "🔐 File Hash Checker",
      "description": "Verify file integrity and calculate cryptographic hashes. Compare hashes to verify file authenticity!",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/hash-checker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hash-checker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "fh-md5",
          "type": "checkbox",
          "label": "MD5",
          "unit": "",
          "default": "1"
        },
        {
          "name": "fh-sha1",
          "type": "checkbox",
          "label": "SHA-1",
          "unit": "",
          "default": "1"
        },
        {
          "name": "fh-sha256",
          "type": "checkbox",
          "label": "SHA-256",
          "unit": "",
          "default": "1"
        },
        {
          "name": "fh-sha512",
          "type": "checkbox",
          "label": "SHA-512",
          "unit": "",
          "default": "0"
        },
        {
          "name": "fh-sha3",
          "type": "checkbox",
          "label": "SHA3-256",
          "unit": "",
          "default": "0"
        },
        {
          "name": "fh-compare-hash",
          "type": "text",
          "label": "Paste hash to compare...",
          "unit": ""
        },
        {
          "name": "fh-compare-algo",
          "type": "select-one",
          "label": "compare algo",
          "unit": "",
          "options": [
            "md5",
            "sha1",
            "sha256",
            "sha512"
          ],
          "default": "sha256"
        }
      ],
      "outputs": [
        {
          "name": "fh-comparison-result",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=hash-checker&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=hash-checker&fh-md5=1&fh-sha1=1&fh-sha256=1&fh-sha512=0&fh-sha3=0&fh-compare-algo=sha256&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "hash",
        "checker",
        "file",
        "productivity",
        "lifestyle",
        "verify",
        "integrity",
        "calculate",
        "cryptographic",
        "hashes"
      ],
      "popularity": 6162,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "hash-crypto-encoder-suite",
      "title": "🔐 Crypto & Hash Suite",
      "description": "Generate cryptographic hashes (SHA-256, SHA-512, MD5), HMAC signatures, and multi-format encodings (Base64, Hex, URL). Fast, client-side, and zero-knowledge.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/hash-crypto-encoder-suite.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hash-crypto-encoder-suite&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "has-hmac-key",
          "type": "text",
          "label": "Optional Secret",
          "unit": "HMAC"
        },
        {
          "name": "has-input-text",
          "type": "textarea",
          "label": "Plaintext Input",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=hash-crypto-encoder-suite&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "hash",
        "crypto",
        "encoder",
        "suite",
        "productivity",
        "lifestyle",
        "generate",
        "cryptographic",
        "hashes",
        "sha-256"
      ],
      "popularity": 6378,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "hash-generator",
      "title": "🔒 Hash Generator",
      "description": "Generate cryptographic hashes instantly. Supports MD5, SHA-1, SHA-256, SHA-384, SHA-512. All processing happens in your browser — nothing is sent to any server.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/hash-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hash-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hashGenCompare",
          "type": "text",
          "label": "Paste a hash to compare...",
          "unit": ""
        },
        {
          "name": "hashGenInput",
          "type": "textarea",
          "label": "Enter text to hash...",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=hash-generator&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "hash",
        "algorithms",
        "computer",
        "science",
        "generate",
        "cryptographic",
        "hashes",
        "instantly",
        "supports",
        "md5"
      ],
      "popularity": 6244,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "hat-size-converter",
      "title": "🎩 Hat Size Converter",
      "description": "Convert head circumference to UK, US and cm hat sizes. US size ≈ circumference in inches ÷ π. Measure just above the ears, level around the widest part. Felt hats often want a snug fit; straw can r...",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/hat-size-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hat-size-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hatz-cm",
          "type": "number",
          "label": "Head circumference",
          "unit": "cm",
          "min": 40,
          "max": 70,
          "default": "57"
        },
        {
          "name": "hatz-in",
          "type": "number",
          "label": "Inches",
          "unit": "",
          "min": 15,
          "max": 28
        },
        {
          "name": "hatz-us",
          "type": "number",
          "label": "US size",
          "unit": "",
          "min": 6,
          "max": 8.5,
          "step": 0.125
        }
      ],
      "outputs": [
        {
          "name": "hatz-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=hat-size-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=hat-size-converter&hatz-cm=57"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "hat",
        "size",
        "converter",
        "productivity",
        "lifestyle",
        "convert",
        "head",
        "circumference",
        "sizes",
        "inches"
      ],
      "popularity": 6818,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "haunt-atmosphere-generator",
      "title": "🌫 Haunted Atmosphere Generator",
      "description": "Make a gentle, continuous horror sound bed from synthesized wind-like noise and low tones. Pick a room, mix the layers, and start or stop it yourself—no recordings or sound files are used.",
      "category": "horror-and-paranormal",
      "categoryName": "Horror & Paranormal",
      "url": "https://www.themostusefulsiteintheworld.com/tool/haunt-atmosphere-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=haunt-atmosphere-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hag-volume",
          "type": "range",
          "label": "Master level: 7%",
          "unit": "",
          "min": 0,
          "max": 20,
          "default": "7"
        },
        {
          "name": "hag-wind",
          "type": "checkbox",
          "label": "Air / soft static texture",
          "unit": "",
          "default": "1"
        },
        {
          "name": "hag-drone",
          "type": "checkbox",
          "label": "Low harmonic drone",
          "unit": "",
          "default": "1"
        },
        {
          "name": "hag-scene",
          "type": "select-one",
          "label": "Room tone",
          "unit": "",
          "options": [
            "hall",
            "cellar",
            "corridor"
          ],
          "default": "hall"
        }
      ],
      "outputs": [
        {
          "name": "hag-status",
          "type": "live"
        },
        {
          "name": "hag-volume-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=haunt-atmosphere-generator&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=haunt-atmosphere-generator&hag-volume=7&hag-wind=1&hag-drone=1&hag-scene=hall"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "haunt",
        "atmosphere",
        "haunted",
        "horror",
        "paranormal",
        "make",
        "gentle",
        "continuous",
        "sound",
        "bed"
      ],
      "popularity": 6123,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "haunt-cue-sequencer",
      "title": "🎬 Haunted Shoot Cue Sequencer",
      "description": "Run a calm, predictable cue list for a permissioned horror shoot: room tone, camera holds, cast lines and resets. The tool only displays crew prompts—no lights, speakers, or devices are triggered.",
      "category": "horror-and-paranormal",
      "categoryName": "Horror & Paranormal",
      "url": "https://www.themostusefulsiteintheworld.com/tool/haunt-cue-sequencer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=haunt-cue-sequencer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hcs-interval",
          "type": "number",
          "label": "Time between prompts",
          "unit": "seconds",
          "min": 15,
          "max": 180,
          "step": 5,
          "default": "30"
        },
        {
          "name": "hcs-custom",
          "type": "text",
          "label": "Add a crew cue",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "hcs-cue",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=haunt-cue-sequencer&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=haunt-cue-sequencer&hcs-interval=30"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "haunt",
        "cue",
        "sequencer",
        "haunted",
        "shoot",
        "horror",
        "paranormal",
        "run",
        "calm",
        "predictable"
      ],
      "popularity": 6084,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "haunted-house-throughput-planner",
      "title": "🎪 Haunted House Throughput Planner",
      "description": "Find the scene that sets the pace, work out how many groups an hour the attraction can pass, and see the queue that builds when arrivals outrun it.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/haunted-house-throughput-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=haunted-house-throughput-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hht-times",
          "type": "text",
          "label": "Scene times (s, comma separated)",
          "unit": "",
          "default": "90, 75, 110, 80, 60"
        },
        {
          "name": "hht-walk",
          "type": "number",
          "label": "Walk between scenes",
          "unit": "s",
          "min": 0,
          "max": 180,
          "step": 5,
          "default": "20"
        },
        {
          "name": "hht-entry",
          "type": "number",
          "label": "Entry and briefing",
          "unit": "s",
          "min": 0,
          "max": 300,
          "step": 10,
          "default": "60"
        },
        {
          "name": "hht-group",
          "type": "number",
          "label": "Group size",
          "unit": "",
          "min": 1,
          "max": 30,
          "step": 1,
          "default": "8"
        },
        {
          "name": "hht-arrivals",
          "type": "number",
          "label": "Arrivals (visitors/hour)",
          "unit": "",
          "min": 1,
          "max": 600,
          "step": 5,
          "default": "180"
        },
        {
          "name": "hht-hours",
          "type": "number",
          "label": "Open for",
          "unit": "hours",
          "min": 0.5,
          "max": 12,
          "step": 0.5,
          "default": "4"
        },
        {
          "name": "hht-actors",
          "type": "number",
          "label": "Actors per scene",
          "unit": "",
          "min": 1,
          "max": 10,
          "step": 1,
          "default": "1"
        }
      ],
      "outputs": [
        {
          "name": "hht-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=haunted-house-throughput-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=haunted-house-throughput-planner&hht-times=90%2C%2075%2C%20110%2C%2080%2C%2060&hht-walk=20&hht-entry=60&hht-group=8&hht-arrivals=180&hht-hours=4"
      },
      "formula": "Poisson stream and uses the M/D/1 waiting-time formula: wait = ρ ÷",
      "sources": [],
      "tags": [
        "haunted",
        "house",
        "throughput",
        "planner",
        "halloween",
        "find",
        "scene",
        "sets",
        "pace",
        "work"
      ],
      "popularity": 5840,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "haunted-photo-fx-studio",
      "title": "📷 Haunted Photo FX Studio",
      "description": "Build a still-frame look for a horror video: green night-vision-style grading, heat-map colors, noir or analog-tape texture, optional grain and an optional orb overlay. Import and export stay on th...",
      "category": "horror-and-paranormal",
      "categoryName": "Horror & Paranormal",
      "url": "https://www.themostusefulsiteintheworld.com/tool/haunted-photo-fx-studio.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=haunted-photo-fx-studio&embed=1",
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          "name": "hfx-mix",
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        {
          "name": "hfx-grain",
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          "label": "Film grain: 18%",
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        {
          "name": "hfx-scanlines",
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        {
          "name": "hfx-orb",
          "type": "checkbox",
          "label": "Add one staged orb overlay",
          "unit": "",
          "default": "0"
        },
        {
          "name": "hfx-watermark",
          "type": "checkbox",
          "label": "Mark export “FICTIONAL FX”",
          "unit": "",
          "default": "1"
        },
        {
          "name": "hfx-look",
          "type": "select-one",
          "label": "Color grade",
          "unit": "",
          "options": [
            "night",
            "thermal",
            "noir",
            "tape"
          ],
          "default": "night"
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      ],
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        {
          "name": "hfx-status",
          "type": "live"
        },
        {
          "name": "hfx-mix-out",
          "type": "output"
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        {
          "name": "hfx-grain-out",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "haunted",
        "photo",
        "studio",
        "horror",
        "paranormal",
        "build",
        "still-frame",
        "look",
        "video",
        "green"
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      "popularity": 5998,
      "featured": false,
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    },
    {
      "slug": "hazmat-concentration-exposure-converter",
      "title": "☣️ Hazmat Concentration Converter",
      "description": "ppm to mg/m³ and back at the temperature and pressure you are actually working at, ppm to percent by volume, percent LEL to ppm, and what an oxygen reading means.",
      "category": "fire-and-rescue-service",
      "categoryName": "Fire & Rescue Service",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hazmat-concentration-exposure-converter&embed=1",
      "standaloneUrl": null,
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        {
          "name": "haz-val",
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        {
          "name": "haz-mw",
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          "label": "Or: molecular weight",
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          "min": 0
        },
        {
          "name": "haz-temp",
          "type": "number",
          "label": "Temperature",
          "unit": "°C",
          "default": "25"
        },
        {
          "name": "haz-pres",
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          "label": "Pressure",
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        {
          "name": "haz-lel",
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          "label": "Lower explosive limit",
          "unit": "% vol",
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        },
        {
          "name": "haz-o2",
          "type": "number",
          "label": "Oxygen reading",
          "unit": "% vol",
          "min": 0,
          "max": 100
        },
        {
          "name": "haz-mode",
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          "label": "Convert",
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            "p2m",
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        },
        {
          "name": "haz-gas",
          "type": "select-one",
          "label": "Gas",
          "unit": ""
        }
      ],
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        {
          "name": "haz-out",
          "type": "live"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=hazmat-concentration-exposure-converter&<id>=<value>",
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      },
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        "hazmat",
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        "exposure",
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        "fire",
        "rescue",
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        "ppm",
        "back",
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      ],
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      "featured": false,
      "updated": "2026-09-19"
    },
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      "slug": "heartrate",
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        {
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        },
        {
          "name": "hr-known-max",
          "type": "number",
          "label": "Known Max HR",
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        },
        {
          "name": "hr-weight",
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        },
        {
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        },
        {
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          "type": "select-one",
          "label": "Fitness Level",
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            "sedentary",
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            "athlete",
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        },
        {
          "name": "hr-gender",
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          "label": "Gender",
          "unit": "",
          "options": [
            "male",
            "female",
            "other"
          ],
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        }
      ],
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          "name": "hr-pulse-results",
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      ],
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      "sources": [],
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        "heartrate",
        "heart",
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    },
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      "slug": "heat-cold-exposure-survival-calc",
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            "2.5",
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          "name": "hcx-state",
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            "3"
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      },
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      "sources": [],
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        "heat",
        "cold",
        "exposure",
        "survival",
        "calc",
        "emergency",
        "readiness",
        "temperature",
        "alone",
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      "popularity": 5138,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "heat-index-calculator",
      "title": "🥵 Heat Index Calculator",
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      "categoryName": "Science & Engineering",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=heat-index-calculator&embed=1",
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        },
        {
          "name": "htix-rh",
          "type": "number",
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          "unit": "",
          "min": 0,
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        }
      ],
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          "name": "htix-out",
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      "sources": [],
      "tags": [
        "heat",
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        "science",
        "engineering",
        "nws",
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        "shade",
        "air",
        "temperature",
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      "popularity": 5030,
      "featured": false,
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    },
    {
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      "categoryName": "Interactive Art & Living Worlds",
      "url": "https://www.themostusefulsiteintheworld.com/tool/heightmap-3d-sculptor.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=heightmap-3d-sculptor&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "unit": "",
          "min": 4,
          "max": 40,
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        },
        {
          "name": "hm3-sea",
          "type": "range",
          "label": "Sea level: 35%",
          "unit": "",
          "min": 0,
          "max": 70,
          "default": "35"
        },
        {
          "name": "hm3-spin",
          "type": "checkbox",
          "label": "spin",
          "unit": "",
          "default": "1"
        },
        {
          "name": "hm3-wire",
          "type": "checkbox",
          "label": "wireframe",
          "unit": "",
          "default": "0"
        }
      ],
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      "sources": [],
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        "heightmap",
        "sculptor",
        "interactive",
        "art",
        "living",
        "worlds",
        "paint",
        "mountains",
        "pointer",
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      ],
      "popularity": 4790,
      "featured": false,
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    },
    {
      "slug": "heraldry-blazon-workshop",
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      "categoryName": "Museum & Collection",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=heraldry-blazon-workshop&embed=1",
      "standaloneUrl": null,
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          "unit": ""
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        {
          "name": "hrld-ord",
          "type": "select-one",
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          "unit": ""
        },
        {
          "name": "hrld-ot",
          "type": "select-one",
          "label": "Ordinary tincture",
          "unit": ""
        },
        {
          "name": "hrld-ch",
          "type": "select-one",
          "label": "Charge",
          "unit": ""
        },
        {
          "name": "hrld-ct",
          "type": "select-one",
          "label": "Charge tincture",
          "unit": ""
        }
      ],
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        {
          "name": "hrld-out",
          "type": "output"
        }
      ],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "heraldry",
        "blazon",
        "workshop",
        "museum",
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        "teaching",
        "coat",
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      ],
      "popularity": 5480,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "herb-drug-interaction-checker",
      "title": "⚠️ Herb & Prescription Safety",
      "description": "Clinical botanical pharmacodynamics checker. Cross-references herbal compounds against prescription drug classes to prevent CYP450 enzyme conflicts and adverse events.",
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      "categoryName": "Natural Remedies & Herbs",
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      "standaloneUrl": null,
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        {
          "name": "hdi-herb",
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          "unit": "",
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            "sjw",
            "ginkgo",
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            "ashwagandha",
            "garlic",
            "berberine",
            "valerian"
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          "default": "sjw"
        },
        {
          "name": "hdi-drug",
          "type": "select-one",
          "label": "Prescription Drug Class",
          "unit": "",
          "options": [
            "ssri",
            "thinner",
            "bp",
            "bc",
            "sedative",
            "diabetes"
          ],
          "default": "ssri"
        }
      ],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "herb",
        "drug",
        "interaction",
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        "natural",
        "remedies",
        "herbs",
        "clinical"
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      "featured": false,
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    },
    {
      "slug": "herbal-infusion-decoction-timer",
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      "categoryName": "Natural Remedies & Herbs",
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      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tea-method",
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          "label": "Extraction Method & Plant Part",
          "unit": "",
          "options": [
            "hot_infusion",
            "decoction",
            "cold_infusion",
            "nourishing"
          ],
          "default": "hot_infusion"
        }
      ],
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        {
          "name": "tea-time-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=herbal-infusion-decoction-timer&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "herbal",
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        "decoction",
        "timer",
        "tea",
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        "natural",
        "remedies",
        "herbs",
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      ],
      "popularity": 5181,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "herbal-salve-beeswax-ratio",
      "title": "🧴 Herbal Salve & Balm Crafter",
      "description": "Formulate medicinal balms and herbal salves. Calculates exact beeswax-to-infused-oil ratios for soft rubs, standard tins, or heat-resistant summer lip balms.",
      "category": "natural-remedies-and-herbs",
      "categoryName": "Natural Remedies & Herbs",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=herbal-salve-beeswax-ratio&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "min": 20,
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          "step": 10,
          "default": "120"
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        {
          "name": "salve-consistency",
          "type": "select-one",
          "label": "Salve Consistency",
          "unit": "",
          "options": [
            "soft",
            "standard",
            "firm"
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          "default": "standard"
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      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=herbal-salve-beeswax-ratio&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=herbal-salve-beeswax-ratio&salve-batch-size=120&salve-consistency=standard"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "herbal",
        "salve",
        "beeswax",
        "ratio",
        "balm",
        "crafter",
        "natural",
        "remedies",
        "herbs",
        "formulate"
      ],
      "popularity": 5922,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "herbal-tincture-ratio-calc",
      "title": "🌿 Herbal Tincture Ratio Calc",
      "description": "Pharmacopoeial weight-to-volume maceration calculator. Formulates herb-to-solvent ratios (1:5 dry / 1:2 fresh) and calculates alcohol-to-water dilution for target phytochemical solubility.",
      "category": "natural-remedies-and-herbs",
      "categoryName": "Natural Remedies & Herbs",
      "url": "https://www.themostusefulsiteintheworld.com/tool/herbal-tincture-ratio-calc.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=herbal-tincture-ratio-calc&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tinc-herb-weight",
          "type": "number",
          "label": "Herb Weight",
          "unit": "g",
          "min": 10,
          "max": 2000,
          "step": 5,
          "default": "100"
        },
        {
          "name": "tinc-herb-type",
          "type": "select-one",
          "label": "Herb Material",
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          "options": [
            "dry_1_5",
            "fresh_1_2",
            "potent_1_1",
            "roots_1_4"
          ],
          "default": "dry_1_5"
        },
        {
          "name": "tinc-target-abv",
          "type": "select-one",
          "label": "Target Menstruum ABV",
          "unit": "",
          "options": [
            "40",
            "50",
            "65",
            "85"
          ],
          "default": "50"
        },
        {
          "name": "tinc-source-abv",
          "type": "select-one",
          "label": "Base Alcohol Available",
          "unit": "",
          "options": [
            "95",
            "75",
            "50",
            "40"
          ],
          "default": "95"
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=herbal-tincture-ratio-calc&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "herbal",
        "tincture",
        "ratio",
        "calc",
        "natural",
        "remedies",
        "herbs",
        "pharmacopoeial",
        "weight-to-volume",
        "maceration"
      ],
      "popularity": 6465,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "hex-decimal",
      "title": "🔢 Hex & Decimal Converter",
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      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/hex-decimal.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hex-decimal&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hx-hex-input",
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          "label": "Hexadecimal",
          "unit": ""
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          "name": "hx-dec-input",
          "type": "number",
          "label": "Decimal",
          "unit": ""
        },
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          "type": "text",
          "label": "Binary",
          "unit": ""
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        {
          "name": "hx-oct-input",
          "type": "text",
          "label": "Octal",
          "unit": ""
        },
        {
          "name": "hx-ascii-input",
          "type": "text",
          "label": "ASCII Character",
          "unit": ""
        },
        {
          "name": "hx-operand",
          "type": "text",
          "label": "Operand",
          "unit": "Hex"
        },
        {
          "name": "hx-bits",
          "type": "select-one",
          "label": "Bit Size",
          "unit": "",
          "options": [
            "8",
            "16",
            "32",
            "64"
          ],
          "default": "32"
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      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=hex-decimal&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=hex-decimal&hx-bits=32&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "hex",
        "decimal",
        "converter",
        "mathematics",
        "convert",
        "between",
        "hexadecimal",
        "binary",
        "octal",
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      "popularity": 6513,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "hike-time-planner",
      "title": "🥾 Hike & Walk Time Planner",
      "description": "Built on Naismith's Rule, the estimate mountain rescue has used for a century: allow an hour for every 5 km, plus a minute for every 10 m climbed. Then it adds the two things that actually decide w...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/hike-time-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hike-time-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
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        {
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          "type": "number",
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          "unit": "m",
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          "step": 10,
          "default": "650"
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        {
          "name": "htp-stops",
          "type": "number",
          "label": "Stops",
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          "default": "45"
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        {
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        {
          "name": "htp-start",
          "type": "time",
          "label": "Setting off at",
          "unit": "",
          "default": "09:00"
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        {
          "name": "htp-lat",
          "type": "number",
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          "unit": "",
          "step": 0.1,
          "default": "57.0"
        },
        {
          "name": "htp-lon",
          "type": "number",
          "label": "Longitude",
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          "step": 0.1,
          "default": "-4.0"
        },
        {
          "name": "htp-fit",
          "type": "select-one",
          "label": "How you walk",
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          "options": [
            "1.4",
            "1.15",
            "1",
            "0.85",
            "0.72"
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          "default": "1"
        },
        {
          "name": "htp-terrain",
          "type": "select-one",
          "label": "Underfoot",
          "unit": "",
          "options": [
            "1",
            "1.15",
            "1.35",
            "1.6"
          ],
          "default": "1"
        },
        {
          "name": "htp-tz",
          "type": "select-one",
          "label": "Clock at the location",
          "unit": "",
          "options": [
            "auto",
            "0",
            "60",
            "120",
            "180",
            "-300",
            "-480",
            "600"
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          "default": "auto"
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      ],
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        {
          "name": "htp-out",
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        }
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=hike-time-planner&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "hike",
        "time",
        "planner",
        "walk",
        "science",
        "engineering",
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      ],
      "popularity": 6972,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "hip-hop-drum-groove-swing-quantizer",
      "title": "🥁 MPC & SP Swing Groove Quantize Calculator",
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      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/hip-hop-drum-groove-swing-quantizer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hip-hop-drum-groove-swing-quantizer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "min": 60,
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          "default": "90"
        },
        {
          "name": "sgq-groove-preset",
          "type": "select-one",
          "label": "Groove Template",
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          "options": [
            "58",
            "66",
            "50",
            "dilla",
            "drill"
          ],
          "default": "58"
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        {
          "name": "sgq-ppq-select",
          "type": "select-one",
          "label": "DAW / Sampler PPQ",
          "unit": "",
          "options": [
            "96",
            "480",
            "960"
          ],
          "default": "960"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=hip-hop-drum-groove-swing-quantizer&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "hip",
        "hop",
        "drum",
        "groove",
        "swing",
        "quantizer",
        "mpc",
        "quantize",
        "music",
        "audio"
      ],
      "popularity": 5052,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "history",
      "title": "📜 Advanced History Timeline Builder",
      "description": "Create interactive timelines, explore historical databases, and visualize events across civilizations. Perfect for students, educators, and history enthusiasts!",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/history.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=history&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ht-event",
          "type": "text",
          "label": "Event Title",
          "unit": ""
        },
        {
          "name": "ht-year",
          "type": "number",
          "label": "Year",
          "unit": "",
          "min": -3500,
          "max": 2100
        },
        {
          "name": "ht-sources",
          "type": "text",
          "label": "Sources",
          "unit": ""
        },
        {
          "name": "ht-search",
          "type": "text",
          "label": "Search events... (e.g., 'revolution', 'discovery')",
          "unit": ""
        },
        {
          "name": "ht-range-start",
          "type": "number",
          "label": "Start year",
          "unit": ""
        },
        {
          "name": "ht-range-end",
          "type": "number",
          "label": "End year",
          "unit": ""
        },
        {
          "name": "ht-description",
          "type": "textarea",
          "label": "Description",
          "unit": ""
        },
        {
          "name": "ht-month",
          "type": "select-one",
          "label": "Month",
          "unit": "",
          "options": [
            "01",
            "02",
            "03",
            "04",
            "05",
            "06",
            "07",
            "08",
            "09",
            "10",
            "11",
            "12"
          ],
          "default": "01"
        },
        {
          "name": "ht-category",
          "type": "select-one",
          "label": "Category",
          "unit": "",
          "options": [
            "politics",
            "war",
            "science",
            "culture",
            "religion",
            "economics",
            "exploration",
            "social",
            "sports",
            "other"
          ],
          "default": "politics"
        },
        {
          "name": "ht-region",
          "type": "select-one",
          "label": "Region",
          "unit": "",
          "options": [
            "global",
            "europe",
            "asia",
            "africa",
            "americas",
            "middle-east",
            "oceania"
          ],
          "default": "global"
        },
        {
          "name": "ht-significance",
          "type": "select-one",
          "label": "Significance",
          "unit": "",
          "options": [
            "1",
            "2",
            "3",
            "4",
            "5"
          ],
          "default": "3"
        },
        {
          "name": "ht-filter-category",
          "type": "select-one",
          "label": "filter category",
          "unit": "",
          "options": [
            "all",
            "politics",
            "war",
            "science",
            "culture",
            "religion"
          ],
          "default": "all"
        },
        {
          "name": "ht-sort-by",
          "type": "select-one",
          "label": "sort by",
          "unit": "",
          "options": [
            "year",
            "year-desc",
            "significance",
            "category"
          ],
          "default": "year"
        }
      ],
      "outputs": [
        {
          "name": "ht-timeline-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=history&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=history&ht-month=01&ht-category=politics&ht-region=global&ht-significance=3&ht-filter-category=all&ht-sort-by=year"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "history",
        "advanced",
        "timeline",
        "builder",
        "productivity",
        "lifestyle",
        "create",
        "interactive",
        "timelines",
        "explore"
      ],
      "popularity": 4164,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "hmrc-mileage-allowance-calculator",
      "title": "🚗 HMRC Mileage Allowance",
      "description": "Tax-free Approved Mileage Allowance Payments for 2026/27: cars and vans 55p for the first 10,000 business miles then 25p; motorcycles 24p; bicycles 20p; plus 5p per passenger per mile. Rates from G...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/hmrc-mileage-allowance-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hmrc-mileage-allowance-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hmrc-miles",
          "type": "number",
          "label": "Business miles this tax year",
          "unit": "",
          "min": 0,
          "default": "8500"
        },
        {
          "name": "hmrc-pass",
          "type": "number",
          "label": "Passenger miles",
          "unit": "car/van",
          "min": 0,
          "default": "0"
        },
        {
          "name": "hmrc-paid",
          "type": "number",
          "label": "Already paid by employer £",
          "unit": "",
          "min": 0,
          "default": "0"
        },
        {
          "name": "hmrc-veh",
          "type": "select-one",
          "label": "Vehicle",
          "unit": "",
          "options": [
            "car",
            "moto",
            "bike"
          ],
          "default": "car"
        }
      ],
      "outputs": [
        {
          "name": "hmrc-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=hmrc-mileage-allowance-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=hmrc-mileage-allowance-calculator&hmrc-miles=8500&hmrc-pass=0&hmrc-paid=0&hmrc-veh=car"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "hmrc",
        "mileage",
        "allowance",
        "finance",
        "money",
        "tax-free",
        "approved",
        "payments",
        "2026",
        "cars"
      ],
      "popularity": 4129,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "home-inventory-worksheet",
      "title": "🏠 Home Inventory & Insurance Worksheet",
      "description": "Create a clear room-by-room record of belongings, quantities, serial numbers and replacement values for a move or an insurance review. Add, search, export, and re-import a JSON backup. Entries stay...",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/home-inventory-worksheet.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=home-inventory-worksheet&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "home-inventory-worksheet-name",
          "type": "text",
          "label": "Item name",
          "unit": ""
        },
        {
          "name": "home-inventory-worksheet-room",
          "type": "text",
          "label": "Room or location",
          "unit": ""
        },
        {
          "name": "home-inventory-worksheet-quantity",
          "type": "number",
          "label": "Quantity",
          "unit": "",
          "min": 1,
          "max": 9999,
          "step": 1,
          "default": "1"
        },
        {
          "name": "home-inventory-worksheet-value",
          "type": "number",
          "label": "Replacement value per item",
          "unit": "0 if unknown",
          "min": 0,
          "max": 100000000,
          "step": 0.01
        },
        {
          "name": "home-inventory-worksheet-date",
          "type": "date",
          "label": "Purchase date",
          "unit": ""
        },
        {
          "name": "home-inventory-worksheet-serial",
          "type": "text",
          "label": "Serial or asset number",
          "unit": ""
        },
        {
          "name": "home-inventory-worksheet-notes",
          "type": "text",
          "label": "Notes",
          "unit": ""
        },
        {
          "name": "home-inventory-worksheet-search",
          "type": "search",
          "label": "Find an item",
          "unit": ""
        },
        {
          "name": "home-inventory-worksheet-category",
          "type": "select-one",
          "label": "Category",
          "unit": "",
          "options": [
            "Electronics",
            "Furniture",
            "Kitchen",
            "Clothing",
            "Jewellery",
            "Tools",
            "Collectables",
            "Other"
          ],
          "default": "Electronics"
        },
        {
          "name": "home-inventory-worksheet-currency",
          "type": "select-one",
          "label": "Currency for this inventory",
          "unit": "",
          "options": [
            "GBP",
            "USD",
            "EUR",
            "CAD",
            "AUD",
            "NZD",
            "INR"
          ],
          "default": "GBP"
        }
      ],
      "outputs": [
        {
          "name": "home-inventory-worksheet-status",
          "type": "live"
        },
        {
          "name": "home-inventory-worksheet-total",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=home-inventory-worksheet&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=home-inventory-worksheet&home-inventory-worksheet-quantity=1&home-inventory-worksheet-category=Electronics&home-inventory-worksheet-currency=GBP"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "home",
        "inventory",
        "worksheet",
        "insurance",
        "diy",
        "create",
        "clear",
        "room-by-room",
        "record",
        "belongings"
      ],
      "popularity": 5385,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "home-maintenance-planner",
      "title": "🏠 Home Maintenance Planner & Service Log",
      "description": "Keep routine home jobs, appliance servicing and the last-completed dates together. Sort upcoming work, log a completion, and export a backup or spreadsheet-friendly service log. It saves in this br...",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/home-maintenance-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=home-maintenance-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "home-maintenance-planner-task",
          "type": "text",
          "label": "Maintenance task",
          "unit": ""
        },
        {
          "name": "home-maintenance-planner-area",
          "type": "text",
          "label": "Room, system or item",
          "unit": ""
        },
        {
          "name": "home-maintenance-planner-due",
          "type": "date",
          "label": "Next due date",
          "unit": ""
        },
        {
          "name": "home-maintenance-planner-notes",
          "type": "text",
          "label": "Notes",
          "unit": ""
        },
        {
          "name": "home-maintenance-planner-search",
          "type": "search",
          "label": "Search tasks",
          "unit": ""
        },
        {
          "name": "home-maintenance-planner-category",
          "type": "select-one",
          "label": "Category",
          "unit": "",
          "options": [
            "Safety",
            "Heating & ventilation",
            "Water & plumbing",
            "Appliances",
            "Exterior & structure",
            "Other"
          ],
          "default": "Safety"
        },
        {
          "name": "home-maintenance-planner-repeat",
          "type": "select-one",
          "label": "Repeat after completion",
          "unit": "",
          "options": [
            "0",
            "1",
            "3",
            "6",
            "12",
            "24"
          ],
          "default": "0"
        },
        {
          "name": "home-maintenance-planner-filter",
          "type": "select-one",
          "label": "Show",
          "unit": "",
          "options": [
            "open",
            "all",
            "overdue",
            "soon",
            "completed"
          ],
          "default": "open"
        }
      ],
      "outputs": [
        {
          "name": "home-maintenance-planner-status",
          "type": "live"
        },
        {
          "name": "home-maintenance-planner-tasks",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=home-maintenance-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=home-maintenance-planner&home-maintenance-planner-category=Safety&home-maintenance-planner-repeat=0&home-maintenance-planner-filter=open"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "home",
        "maintenance",
        "planner",
        "service",
        "log",
        "diy",
        "keep",
        "routine",
        "jobs",
        "appliance"
      ],
      "popularity": 5182,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "home-project-quote-comparator",
      "title": "🧾 Home Project Quote Comparator",
      "description": "Compare up to three contractor estimates on a more like-for-like basis. Record each quote’s total, known extras, included work, exclusions, schedule, payment terms and guarantee notes—without prete...",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/home-project-quote-comparator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=home-project-quote-comparator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "home-project-quote-comparator-name-a",
          "type": "text",
          "label": "Contractor / quote label",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-total-a",
          "type": "number",
          "label": "Quoted total, tax included",
          "unit": "",
          "min": 0,
          "max": 100000000,
          "step": 0.01
        },
        {
          "name": "home-project-quote-comparator-extras-a",
          "type": "number",
          "label": "Known extra costs",
          "unit": "",
          "min": 0,
          "max": 100000000,
          "step": 0.01
        },
        {
          "name": "home-project-quote-comparator-schedule-a",
          "type": "text",
          "label": "Start date / duration",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-payment-a",
          "type": "text",
          "label": "Deposit and payment milestones",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-guarantee-a",
          "type": "text",
          "label": "Guarantee / aftercare notes",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-name-b",
          "type": "text",
          "label": "Contractor / quote label",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-total-b",
          "type": "number",
          "label": "Quoted total, tax included",
          "unit": "",
          "min": 0,
          "max": 100000000,
          "step": 0.01
        },
        {
          "name": "home-project-quote-comparator-extras-b",
          "type": "number",
          "label": "Known extra costs",
          "unit": "",
          "min": 0,
          "max": 100000000,
          "step": 0.01
        },
        {
          "name": "home-project-quote-comparator-schedule-b",
          "type": "text",
          "label": "Start date / duration",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-payment-b",
          "type": "text",
          "label": "Deposit and payment milestones",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-guarantee-b",
          "type": "text",
          "label": "Guarantee / aftercare notes",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-name-c",
          "type": "text",
          "label": "Contractor / quote label",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-total-c",
          "type": "number",
          "label": "Quoted total, tax included",
          "unit": "",
          "min": 0,
          "max": 100000000,
          "step": 0.01
        },
        {
          "name": "home-project-quote-comparator-extras-c",
          "type": "number",
          "label": "Known extra costs",
          "unit": "",
          "min": 0,
          "max": 100000000,
          "step": 0.01
        },
        {
          "name": "home-project-quote-comparator-schedule-c",
          "type": "text",
          "label": "Start date / duration",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-payment-c",
          "type": "text",
          "label": "Deposit and payment milestones",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-guarantee-c",
          "type": "text",
          "label": "Guarantee / aftercare notes",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-scope-a",
          "type": "textarea",
          "label": "Work included",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-exclusions-a",
          "type": "textarea",
          "label": "Exclusions / provisional allowances",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-scope-b",
          "type": "textarea",
          "label": "Work included",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-exclusions-b",
          "type": "textarea",
          "label": "Exclusions / provisional allowances",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-scope-c",
          "type": "textarea",
          "label": "Work included",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-exclusions-c",
          "type": "textarea",
          "label": "Exclusions / provisional allowances",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-report",
          "type": "textarea",
          "label": "Copyable comparison summary",
          "unit": ""
        },
        {
          "name": "home-project-quote-comparator-currency",
          "type": "select-one",
          "label": "Currency for all quotes",
          "unit": "",
          "options": [
            "GBP",
            "USD",
            "EUR",
            "CAD",
            "AUD",
            "NZD",
            "INR"
          ],
          "default": "GBP"
        }
      ],
      "outputs": [
        {
          "name": "home-project-quote-comparator-status",
          "type": "live"
        },
        {
          "name": "home-project-quote-comparator-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=home-project-quote-comparator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=home-project-quote-comparator&home-project-quote-comparator-currency=GBP"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "home",
        "project",
        "quote",
        "comparator",
        "diy",
        "compare",
        "three",
        "contractor",
        "estimates",
        "more"
      ],
      "popularity": 5657,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "hominin-timeline-hall",
      "title": "🧬 The Hominin Corridor",
      "description": "Not a ladder. A bush of species, several of which overlapped. Brain volumes are typical adult means; dates are first-to-last fossil appearances as currently argued. The corridor will not tell you w...",
      "category": "museum-and-collection",
      "categoryName": "Museum & Collection",
      "url": "https://www.themostusefulsiteintheworld.com/tool/hominin-timeline-hall.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hominin-timeline-hall&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [
        {
          "name": "homin-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=hominin-timeline-hall&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "hominin",
        "timeline",
        "hall",
        "corridor",
        "museum",
        "collection",
        "not",
        "ladder",
        "bush",
        "species"
      ],
      "popularity": 4936,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "horizon-line-of-sight-calculator",
      "title": "🌅 Horizon & Line-of-Sight Calculator",
      "description": "How far can you actually see, and how much of that distant hill, ship or radio mast is hidden behind the bulge of the Earth? Enter two heights and a distance and get the geometric answer, the refra...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/horizon-line-of-sight-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=horizon-line-of-sight-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hlos-h1",
          "type": "number",
          "label": "Your eye height (m above sea level)",
          "unit": "",
          "min": 0,
          "step": 0.1,
          "default": "1.7"
        },
        {
          "name": "hlos-h2",
          "type": "number",
          "label": "Target height",
          "unit": "m",
          "min": 0,
          "step": 0.1,
          "default": "60"
        },
        {
          "name": "hlos-d",
          "type": "number",
          "label": "Distance to target",
          "unit": "km",
          "min": 0,
          "step": 0.1,
          "default": "40"
        },
        {
          "name": "hlos-preset",
          "type": "select-one",
          "label": "Quick scenario",
          "unit": ""
        },
        {
          "name": "hlos-model",
          "type": "select-one",
          "label": "Refraction model",
          "unit": "",
          "options": [
            "1.17",
            "1",
            "1.33",
            "1.4"
          ],
          "default": "1.17"
        }
      ],
      "outputs": [
        {
          "name": "hlos-verdict",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=horizon-line-of-sight-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=horizon-line-of-sight-calculator&hlos-h1=1.7&hlos-h2=60&hlos-d=40&hlos-model=1.17"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "horizon",
        "line",
        "sight",
        "line-of-sight",
        "science",
        "engineering",
        "how",
        "far",
        "can",
        "actually"
      ],
      "popularity": 5767,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "horsepower-kw-torque-converter",
      "title": "🏎️ Horsepower, kW & Torque",
      "description": "Convert mechanical horsepower, metric PS and kilowatts, and compute power from torque × RPM. 1 hp = 745.7 W; 1 PS = 735.5 W. Power (kW) = torque (N·m) × RPM / 9549.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/horsepower-kw-torque-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=horsepower-kw-torque-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hpkw-hp",
          "type": "number",
          "label": "hp",
          "unit": "mechanical",
          "min": 0,
          "default": "150"
        },
        {
          "name": "hpkw-ps",
          "type": "number",
          "label": "PS",
          "unit": "metric",
          "min": 0,
          "default": "152.1"
        },
        {
          "name": "hpkw-kw",
          "type": "number",
          "label": "kW",
          "unit": "",
          "min": 0,
          "default": "111.9"
        },
        {
          "name": "hpkw-nm",
          "type": "number",
          "label": "Torque N·m",
          "unit": "",
          "min": 0,
          "default": "250"
        },
        {
          "name": "hpkw-lbft",
          "type": "number",
          "label": "Torque lb·ft",
          "unit": "",
          "min": 0,
          "default": "184.4"
        },
        {
          "name": "hpkw-rpm",
          "type": "number",
          "label": "RPM",
          "unit": "",
          "min": 1,
          "default": "5500"
        }
      ],
      "outputs": [
        {
          "name": "hpkw-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=horsepower-kw-torque-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=horsepower-kw-torque-converter&hpkw-hp=150&hpkw-ps=152.1&hpkw-kw=111.9&hpkw-nm=250&hpkw-lbft=184.4&hpkw-rpm=5500"
      },
      "formula": "PS and kilowatts, and compute power from torque × RPM. 1 hp = 745.7 W; 1 PS = 735.5 W. Power (kW) = torque (N·m) × RPM /",
      "sources": [],
      "tags": [
        "horsepower",
        "torque",
        "converter",
        "science",
        "engineering",
        "convert",
        "mechanical",
        "metric",
        "kilowatts",
        "compute"
      ],
      "popularity": 4063,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "hourly-to-annual-salary-converter",
      "title": "💷 Hourly ⇄ Annual Salary",
      "description": "Convert an hourly rate to a yearly salary (and back) using your hours per week and weeks per year. Defaults match a UK full-time week. Gross pay only — tax is not deducted.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/hourly-to-annual-salary-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hourly-to-annual-salary-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hsal-hourly",
          "type": "number",
          "label": "Hourly rate",
          "unit": "",
          "min": 0,
          "default": "15"
        },
        {
          "name": "hsal-annual",
          "type": "number",
          "label": "Annual salary",
          "unit": "",
          "min": 0,
          "default": "29250"
        },
        {
          "name": "hsal-hpw",
          "type": "number",
          "label": "Hours / week",
          "unit": "",
          "min": 1,
          "max": 168,
          "default": "37.5"
        },
        {
          "name": "hsal-wpy",
          "type": "number",
          "label": "Paid weeks / year",
          "unit": "",
          "min": 1,
          "max": 52,
          "default": "52"
        }
      ],
      "outputs": [
        {
          "name": "hsal-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=hourly-to-annual-salary-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=hourly-to-annual-salary-converter&hsal-hourly=15&hsal-annual=29250&hsal-hpw=37.5&hsal-wpy=52"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "hourly",
        "annual",
        "salary",
        "converter",
        "finance",
        "money",
        "convert",
        "rate",
        "yearly",
        "back"
      ],
      "popularity": 5979,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "household-chore-rota",
      "title": "Household Chore Rota Generator",
      "description": "Share recurring jobs fairly: rotate a weekly list of chores across housemates and generate a copyable multi-week rota.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/household-chore-rota.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=household-chore-rota&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "household-chore-rota-weeks",
          "type": "number",
          "label": "Number of weeks",
          "unit": "",
          "min": 1,
          "max": 52,
          "step": 1,
          "default": "4"
        },
        {
          "name": "household-chore-rota-start",
          "type": "date",
          "label": "Week 1 starts",
          "unit": "",
          "default": "2026-09-28"
        },
        {
          "name": "household-chore-rota-people",
          "type": "textarea",
          "label": "People — one per line Alex Sam Charlie",
          "unit": ""
        },
        {
          "name": "household-chore-rota-jobs",
          "type": "textarea",
          "label": "Weekly chores — one per line Kitchen Bathroom Bins Vacuuming",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=household-chore-rota&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=household-chore-rota&household-chore-rota-weeks=4&household-chore-rota-start=2026-09-28"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "household",
        "chore",
        "rota",
        "productivity",
        "lifestyle",
        "share",
        "recurring",
        "jobs",
        "fairly",
        "rotate"
      ],
      "popularity": 6600,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "household-emergency-plan",
      "title": "🚨 Household Emergency Plan",
      "description": "Fill this in once on a calm afternoon and it turns a frightening night into a set of steps everyone already knows. It stays on your device, and you can print or copy it to stick on the fridge — whi...",
      "category": "wellbeing-and-community",
      "categoryName": "Wellbeing & Community",
      "url": "https://www.themostusefulsiteintheworld.com/tool/household-emergency-plan.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=household-emergency-plan&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hep-pets",
          "type": "text",
          "label": "Animals",
          "unit": ""
        },
        {
          "name": "hep-near",
          "type": "text",
          "label": "Meeting point near home",
          "unit": ""
        },
        {
          "name": "hep-far",
          "type": "text",
          "label": "Meeting point outside the area",
          "unit": ""
        },
        {
          "name": "hep-docs",
          "type": "text",
          "label": "Documents and keys",
          "unit": ""
        },
        {
          "name": "hep-people",
          "type": "textarea",
          "label": "Who lives here",
          "unit": ""
        },
        {
          "name": "hep-contacts",
          "type": "textarea",
          "label": "Two people to call",
          "unit": ""
        },
        {
          "name": "hep-meds",
          "type": "textarea",
          "label": "Medicines and equipment",
          "unit": ""
        },
        {
          "name": "hep-shutoff",
          "type": "textarea",
          "label": "Where the gas, water and electrics turn off",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "hep-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=household-emergency-plan&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "household",
        "emergency",
        "plan",
        "wellbeing",
        "community",
        "fill",
        "once",
        "calm",
        "afternoon",
        "turns"
      ],
      "popularity": 4827,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "household",
      "title": "🏠 Advanced Household Chore Tracker",
      "description": "Manage household chores, assign tasks, set schedules, and track completion with reminders. Perfect for families and shared living!",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/household.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=household&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hh-task",
          "type": "text",
          "label": "Chore Name",
          "unit": ""
        },
        {
          "name": "hh-other-person",
          "type": "text",
          "label": "Custom Name",
          "unit": ""
        },
        {
          "name": "hh-notes",
          "type": "textarea",
          "label": "Notes",
          "unit": ""
        },
        {
          "name": "hh-person",
          "type": "select-one",
          "label": "Assigned To",
          "unit": "",
          "options": [
            "Alex",
            "Jordan",
            "Taylor",
            "Casey",
            "Everyone",
            "Other"
          ],
          "default": "Alex"
        },
        {
          "name": "hh-category",
          "type": "select-one",
          "label": "Category",
          "unit": "",
          "options": [
            "cleaning",
            "kitchen",
            "bathroom",
            "laundry",
            "outdoor",
            "pet",
            "maintenance",
            "shopping",
            "other"
          ],
          "default": "cleaning"
        },
        {
          "name": "hh-frequency",
          "type": "select-one",
          "label": "Frequency",
          "unit": "",
          "options": [
            "daily",
            "weekly",
            "biweekly",
            "monthly",
            "as-needed"
          ],
          "default": "daily"
        },
        {
          "name": "hh-priority",
          "type": "select-one",
          "label": "Priority",
          "unit": "",
          "options": [
            "1",
            "2",
            "3",
            "4"
          ],
          "default": "2"
        },
        {
          "name": "hh-filter-category",
          "type": "select-one",
          "label": "filter category",
          "unit": "",
          "options": [
            "all",
            "cleaning",
            "kitchen",
            "bathroom",
            "laundry",
            "outdoor"
          ],
          "default": "all"
        },
        {
          "name": "hh-filter-person",
          "type": "select-one",
          "label": "filter person",
          "unit": "",
          "options": [
            "all",
            "Alex",
            "Jordan",
            "Taylor",
            "Casey",
            "Everyone"
          ],
          "default": "all"
        },
        {
          "name": "hh-filter-status",
          "type": "select-one",
          "label": "filter status",
          "unit": "",
          "options": [
            "all",
            "pending",
            "completed",
            "overdue"
          ],
          "default": "all"
        },
        {
          "name": "hh-reminder-time",
          "type": "select-one",
          "label": "reminder time",
          "unit": "",
          "options": [
            "18:00",
            "19:00",
            "20:00",
            "21:00"
          ],
          "default": "18:00"
        }
      ],
      "outputs": [
        {
          "name": "hh-chores-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=household&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=household&hh-person=Alex&hh-category=cleaning&hh-frequency=daily&hh-priority=2&hh-filter-category=all&hh-filter-person=all"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "household",
        "advanced",
        "chore",
        "tracker",
        "productivity",
        "lifestyle",
        "manage",
        "chores",
        "assign",
        "tasks"
      ],
      "popularity": 6383,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "houseplant-matchmaker",
      "title": "🪴 Houseplant Matchmaker",
      "description": "The dating app for you and a plant. Answer honestly about your light, your watering habits and your pets, and it will set you up with a houseplant that can actually survive you.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/houseplant-matchmaker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=houseplant-matchmaker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hpm-drama",
          "type": "range",
          "label": "drama",
          "unit": "",
          "min": 1,
          "max": 5,
          "default": "3"
        },
        {
          "name": "hpm-light",
          "type": "select-one",
          "label": "Light in the room",
          "unit": "",
          "options": [
            "bright",
            "indirect",
            "low",
            "none"
          ],
          "default": "indirect"
        },
        {
          "name": "hpm-water",
          "type": "select-one",
          "label": "Your watering style",
          "unit": "",
          "options": [
            "drowner",
            "regular",
            "forgetful",
            "never"
          ],
          "default": "regular"
        },
        {
          "name": "hpm-pets",
          "type": "select-one",
          "label": "Pets & kids in the house?",
          "unit": "",
          "options": [
            "safe",
            "shelf",
            "none"
          ],
          "default": "safe"
        }
      ],
      "outputs": [
        {
          "name": "hpm-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=houseplant-matchmaker&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=houseplant-matchmaker&hpm-drama=3&hpm-light=indirect&hpm-water=regular&hpm-pets=safe"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "houseplant",
        "matchmaker",
        "productivity",
        "lifestyle",
        "dating",
        "app",
        "plant",
        "answer",
        "honestly",
        "about"
      ],
      "popularity": 4145,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "htaccess-redirect-generator",
      "title": "🔀 Apache & Nginx Redirect Generator",
      "description": "Build 301/302 redirect snippets for Apache (.htaccess) or Nginx (server { }): HTTP→HTTPS, www/apex canonical hosts and page redirects. Review before deploying — a bad rule loops a site (test Nginx ...",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/htaccess-redirect-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=htaccess-redirect-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "htxr-from",
          "type": "text",
          "label": "From path or URL",
          "unit": ""
        },
        {
          "name": "htxr-to",
          "type": "text",
          "label": "To URL",
          "unit": ""
        },
        {
          "name": "htxr-https",
          "type": "checkbox",
          "label": "Force HTTPS",
          "unit": "",
          "default": "1"
        },
        {
          "name": "htxr-www",
          "type": "checkbox",
          "label": "Force www",
          "unit": "",
          "default": "0"
        },
        {
          "name": "htxr-apex",
          "type": "checkbox",
          "label": "Force apex",
          "unit": "no www",
          "default": "0"
        },
        {
          "name": "htxr-host",
          "type": "text",
          "label": "Canonical host",
          "unit": "for www/apex"
        },
        {
          "name": "htxr-server",
          "type": "select-one",
          "label": "Server",
          "unit": "",
          "options": [
            "apache",
            "nginx"
          ],
          "default": "apache"
        },
        {
          "name": "htxr-code",
          "type": "select-one",
          "label": "Status",
          "unit": "",
          "options": [
            "301",
            "302"
          ],
          "default": "301"
        }
      ],
      "outputs": [
        {
          "name": "htxr-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=htaccess-redirect-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=htaccess-redirect-generator&htxr-https=1&htxr-www=0&htxr-apex=0&htxr-server=apache&htxr-code=301"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "htaccess",
        "redirect",
        "apache",
        "nginx",
        "algorithms",
        "computer",
        "science",
        "build",
        "301",
        "302"
      ],
      "popularity": 6465,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "html-css-minifier",
      "title": "📦 HTML / CSS Minifier",
      "description": "Strip comments and collapse idle whitespace in HTML or CSS. Not a full parser — keep <pre> and <textarea> out of the input, and do not minify JavaScript here. Local only.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/html-css-minifier.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=html-css-minifier&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "minf-in",
          "type": "textarea",
          "label": "Source",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "minf-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=html-css-minifier&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "html",
        "css",
        "minifier",
        "algorithms",
        "computer",
        "science",
        "strip",
        "comments",
        "collapse",
        "idle"
      ],
      "popularity": 4069,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "html-entity-encoder",
      "title": "🔤 HTML Entity Encoder & Decoder",
      "description": "Escape text for safe HTML display, decode named or numeric entities, and inspect the characters in a string. Choose readable entities for the five HTML-sensitive characters or numeric entities for ...",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/html-entity-encoder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=html-entity-encoder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hed-numeric",
          "type": "checkbox",
          "label": "Encode non-ASCII too",
          "unit": "",
          "default": "0"
        },
        {
          "name": "hed-input",
          "type": "textarea",
          "label": "Input",
          "unit": ""
        },
        {
          "name": "hed-output",
          "type": "textarea",
          "label": "Output",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "hed-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=html-entity-encoder&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=html-entity-encoder&hed-numeric=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "html",
        "entity",
        "encoder",
        "decoder",
        "algorithms",
        "computer",
        "science",
        "escape",
        "text",
        "safe"
      ],
      "popularity": 4412,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "html-table-generator",
      "title": "📋 HTML Table Generator",
      "description": "Turn a quick list of headers and rows into accessible, escaped HTML table markup with a live preview. Paste pipe- or comma-separated data, add an optional caption, and copy code that works cleanly ...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/html-table-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=html-table-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "htg-headers",
          "type": "text",
          "label": "Column headers (comma-separated)",
          "unit": "",
          "default": "Name, Role, Location"
        },
        {
          "name": "htg-caption",
          "type": "text",
          "label": "Table caption",
          "unit": "",
          "default": "Project team"
        },
        {
          "name": "htg-striped",
          "type": "checkbox",
          "label": "Stripe preview rows",
          "unit": "",
          "default": "1"
        },
        {
          "name": "htg-rows",
          "type": "textarea",
          "label": "Rows — one per line; use | or commas between cells",
          "unit": ""
        },
        {
          "name": "htg-output",
          "type": "textarea",
          "label": "Accessible HTML markup",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "htg-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=html-table-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=html-table-generator&htg-headers=Name%2C%20Role%2C%20Location&htg-caption=Project%20team&htg-striped=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "html",
        "table",
        "saas",
        "business",
        "killers",
        "turn",
        "quick",
        "list",
        "headers",
        "rows"
      ],
      "popularity": 4050,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "html-to-markdown-converter",
      "title": "📝 HTML to Markdown Converter",
      "description": "A practical subset: headings, paragraphs, links, images, lists, bold/italic, code, blockquotes, hr. Scripts and styles are dropped. Not a full CommonMark round-trip.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/html-to-markdown-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=html-to-markdown-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "h2md-in",
          "type": "textarea",
          "label": "HTML",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "h2md-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=html-to-markdown-converter&<id>=<value>",
        "runs": true
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "html",
        "markdown",
        "converter",
        "algorithms",
        "computer",
        "science",
        "practical",
        "subset",
        "headings",
        "paragraphs"
      ],
      "popularity": 5950,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "http-status-codes",
      "title": "📡 HTTP Status Code Encyclopedia",
      "description": "Look up any HTTP status code, filter by class, and copy a one-line explanation. Covers the registered 1xx–5xx codes developers hit in the wild. Entirely offline.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/http-status-codes.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=http-status-codes&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "htsc-q",
          "type": "search",
          "label": "Search code or phrase",
          "unit": ""
        },
        {
          "name": "htsc-class",
          "type": "select-one",
          "label": "Class",
          "unit": "",
          "options": [
            "all",
            "1",
            "2",
            "3",
            "4",
            "5"
          ],
          "default": "all"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=http-status-codes&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=http-status-codes&htsc-class=all"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "http",
        "status",
        "codes",
        "code",
        "encyclopedia",
        "algorithms",
        "computer",
        "science",
        "look",
        "any"
      ],
      "popularity": 4168,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "huffman-coding-compression",
      "title": "🗜️ Huffman Coding: How Compression Works",
      "description": "Type any text and watch it get smaller: common letters get short codes, rare ones get long codes, and the result is the exact same idea behind ZIP, PNG and MP3. The tree is the codebook, drawn for ...",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/huffman-coding-compression.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=huffman-coding-compression&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "huf-input",
          "type": "textarea",
          "label": "input",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "huf-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=huffman-coding-compression&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "huffman",
        "coding",
        "compression",
        "how",
        "works",
        "algorithms",
        "computer",
        "science",
        "type",
        "any"
      ],
      "popularity": 6597,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "hummingbird-nectar-spoilage",
      "title": "🌸 Hummingbird Nectar & Spoilage",
      "description": "Formulate natural 20% sucrose syrup and monitor microbial fermentation rates. Calculates exact water-to-cane-sugar ratios and temperature-driven spoilage limits.",
      "category": "birdwatching-and-ornithology",
      "categoryName": "Birdwatching & Ornithology",
      "url": "https://www.themostusefulsiteintheworld.com/tool/hummingbird-nectar-spoilage.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hummingbird-nectar-spoilage&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hum-ratio",
          "type": "select-one",
          "label": "Nectar Formulation",
          "unit": "",
          "options": [
            "4",
            "3"
          ],
          "default": "4"
        },
        {
          "name": "hum-volume",
          "type": "select-one",
          "label": "Feeder Water",
          "unit": "Cups",
          "options": [
            "1",
            "2",
            "4"
          ],
          "default": "2"
        },
        {
          "name": "hum-temp",
          "type": "select-one",
          "label": "Outdoor Ambient Air Temperature",
          "unit": "",
          "options": [
            "hot",
            "warm",
            "mild",
            "cool"
          ],
          "default": "warm"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=hummingbird-nectar-spoilage&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=hummingbird-nectar-spoilage&hum-ratio=4&hum-volume=2&hum-temp=warm"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "hummingbird",
        "nectar",
        "spoilage",
        "birdwatching",
        "ornithology",
        "formulate",
        "natural",
        "sucrose",
        "syrup",
        "monitor"
      ],
      "popularity": 6223,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "hurricane-engine",
      "title": "🌀 Hurricane Engine",
      "description": "A rotating tropical cyclone whose intensity is set by Emanuel's maximum potential intensity: sea-surface temperature, Coriolis (latitude) and vertical wind shear. Warm water and a spinning Earth bu...",
      "category": "interactive-art-and-living-worlds",
      "categoryName": "Interactive Art & Living Worlds",
      "url": "https://www.themostusefulsiteintheworld.com/tool/hurricane-engine.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=hurricane-engine&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hur-sst",
          "type": "range",
          "label": "SST 28.5 °C",
          "unit": "",
          "min": 24,
          "max": 32,
          "step": 0.1,
          "default": "28.5"
        },
        {
          "name": "hur-lat",
          "type": "range",
          "label": "Latitude 18°N",
          "unit": "",
          "min": 0,
          "max": 40,
          "default": "18"
        },
        {
          "name": "hur-shear",
          "type": "range",
          "label": "Wind shear 8 m/s",
          "unit": "",
          "min": 0,
          "max": 30,
          "default": "8"
        },
        {
          "name": "hur-hum",
          "type": "range",
          "label": "Mid-level RH 70%",
          "unit": "",
          "min": 30,
          "max": 95,
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      "sources": [],
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        "hurricane",
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        {
          "name": "hft-residual",
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        {
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        },
        {
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          "label": "Pitot reading",
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          "min": 0
        },
        {
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        "hydrant",
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            "sedentary",
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            "active",
            "athlete"
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            "young",
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        {
          "name": "hydration-climate",
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            "temperate",
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        "hydrogen",
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      "featured": false,
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          "label": "IBAN",
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      ],
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        {
          "name": "iban-out",
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        "iban",
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      "featured": false,
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        {
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        {
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          "name": "hky-otl",
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        {
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          "label": "Shutouts",
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    {
      "slug": "ics-event-builder",
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        {
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          "name": "icsf-loc",
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        {
          "name": "icsf-all",
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      "categoryName": "Health & Fitness",
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          "name": "idealweight-current",
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        {
          "name": "iw-target-weight",
          "type": "number",
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        "idealweight",
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      "featured": false,
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        "ieee",
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      "slug": "image-base64-data-url-converter",
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        {
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      ],
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        "image",
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      "featured": false,
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      "standaloneUrl": null,
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        {
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            "4",
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            "10",
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        "image",
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      "featured": false,
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          "name": "iopt-status",
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        "image",
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      "slug": "impossible-object-viewer",
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          "name": "iov-explode",
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      ],
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      "tags": [
        "impossible",
        "object",
        "viewer",
        "mind-blowing",
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      "popularity": 4856,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "inductance-calculator",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=inductance-calculator&embed=1",
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        },
        {
          "name": "ind-length",
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        {
          "name": "ind-area",
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          "step": 0.000001,
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        {
          "name": "ind-mu",
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        {
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        },
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          "name": "ind-output",
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          "name": "ind-wire-gauge",
          "type": "select-one",
          "label": "Wire Gauge",
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            "18",
            "22",
            "26",
            "30",
            "36"
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        {
          "name": "ind-inductance-value",
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        },
        {
          "name": "ind-reactance-value",
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        },
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          "name": "ind-energy-value",
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          "name": "ind-freq-display",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=inductance-calculator&<id>=<value>",
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      },
      "formula": "Core Formulas L = (µ₀ × µr × N² × A) / l - Basic formula XL = 2πfL -",
      "sources": [],
      "tags": [
        "inductance",
        "science",
        "engineering",
        "professional",
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        "multiple",
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      "featured": false,
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    },
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      "slug": "inflation",
      "title": "📉 Inflation Impact Calculator",
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          "min": 0,
          "max": 100,
          "step": 0.1,
          "default": "3"
        },
        {
          "name": "inflation-years",
          "type": "number",
          "label": "Time Period",
          "unit": "",
          "min": 1,
          "max": 100,
          "default": "10"
        },
        {
          "name": "infl-investment-return",
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          "label": "Annual Investment Return",
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          "min": 0,
          "max": 100,
          "step": 0.1,
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        {
          "name": "infl-retirement-income",
          "type": "number",
          "label": "retirement income",
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          "min": 0,
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        },
        {
          "name": "infl-currency",
          "type": "select-one",
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            "GBP",
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            "EUR",
            "JPY",
            "CAD",
            "AUD"
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        {
          "name": "infl-ppl-value",
          "type": "output"
        },
        {
          "name": "infl-invest-rate-display",
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        },
        {
          "name": "infl-retirement-result",
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      },
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      "sources": [],
      "tags": [
        "inflation",
        "impact",
        "finance",
        "money",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "ingredient-label-allergen-decoder",
      "title": "🏷️ Ingredient Label Allergen Decoder",
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      "standaloneUrl": null,
      "inputs": [
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          "default": "0"
        },
        {
          "name": "ilad-halal",
          "type": "checkbox",
          "label": "Also flag possible pork & alcohol",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ilad-text",
          "type": "textarea",
          "label": "Paste the ingredient list",
          "unit": ""
        }
      ],
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        {
          "name": "ilad-out",
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=ingredient-label-allergen-decoder&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "ingredient",
        "label",
        "allergen",
        "decoder",
        "health",
        "fitness",
        "allergens",
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      ],
      "popularity": 5066,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "ingredient-scaler",
      "title": "🧮 Recipe Ingredient Scaler",
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      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/ingredient-scaler.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=ingredient-scaler&embed=1",
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          "type": "number",
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          "default": "4"
        },
        {
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          "min": 1,
          "max": 1000,
          "default": "8"
        },
        {
          "name": "is-baker-flour",
          "type": "number",
          "label": "baker flour",
          "unit": "",
          "min": 0,
          "step": 10,
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        },
        {
          "name": "is-ingredients",
          "type": "textarea",
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          "unit": ""
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        {
          "name": "is-rounding",
          "type": "select-one",
          "label": "Rounding Precision",
          "unit": "",
          "options": [
            "none",
            "kitchen",
            "decimal1",
            "decimal2",
            "whole"
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          "default": "kitchen"
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        {
          "name": "is-factor-value",
          "type": "output"
        },
        {
          "name": "is-original-display",
          "type": "output"
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        {
          "name": "is-desired-display",
          "type": "output"
        },
        {
          "name": "is-factor-display",
          "type": "output"
        },
        {
          "name": "is-output",
          "type": "output"
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          "name": "is-bakers-result",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "ingredient",
        "scaler",
        "recipe",
        "productivity",
        "lifestyle",
        "perfectly",
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      "popularity": 4268,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "instrument-care",
      "title": "🎶 Instrument Care Guide",
      "description": "Get detailed care instructions with maintenance schedules, required tools, and professional tips for your specific instrument.",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/instrument-care.html",
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        {
          "name": "care-last-maintenance",
          "type": "date",
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          "unit": ""
        },
        {
          "name": "care-instrument",
          "type": "select-one",
          "label": "Specific Instrument",
          "unit": "",
          "options": [
            "acoustic_guitar",
            "electric_guitar",
            "violin",
            "viola",
            "cello",
            "bass_guitar",
            "ukulele"
          ],
          "default": "acoustic_guitar"
        }
      ],
      "outputs": [
        {
          "name": "care-instrument-display",
          "type": "output"
        },
        {
          "name": "care-experience-display",
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          "name": "care-output",
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      },
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        "instrument",
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      "category": "music-and-audio",
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      "featured": false,
      "updated": "2026-09-19"
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      "slug": "interview-star-answer-builder",
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      "category": "writing-and-language",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=interview-star-answer-builder&embed=1",
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      ],
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      "featured": false,
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    },
    {
      "slug": "inventory-reorder-point-planner",
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        {
          "name": "inventory-reorder-point-planner-lead",
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          "label": "Supplier lead time",
          "unit": "days",
          "default": "14"
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        {
          "name": "inventory-reorder-point-planner-safety",
          "type": "number",
          "label": "Safety stock",
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          "default": "7"
        },
        {
          "name": "inventory-reorder-point-planner-stock",
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          "unit": "",
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      "categoryName": "Science & Engineering",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=inverter-sizing&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "step": 0.1,
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          "label": "eff",
          "unit": "",
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          "max": 98,
          "step": 1,
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        {
          "name": "inv-voltage",
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          "max": 240,
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        },
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          "max": 48,
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        {
          "name": "inv-output",
          "type": "textarea",
          "label": "Inverter specification report",
          "unit": ""
        },
        {
          "name": "battery-type",
          "type": "select-one",
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          "unit": "",
          "options": [
            "leadacid",
            "agm",
            "lifepo4",
            "lithium"
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          "default": "lifepo4"
        }
      ],
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        {
          "name": "surge-value",
          "type": "output"
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        {
          "name": "efficiency-value",
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      },
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      "sources": [],
      "tags": [
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        "sizing",
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        "science",
        "engineering",
        "essential",
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      "featured": false,
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      "slug": "investigation-report-builder",
      "title": "📝 Structured Investigation Report Builder",
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      "category": "field-investigation-and-evidence",
      "categoryName": "Field Investigation & Evidence",
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        {
          "name": "irb-site",
          "type": "text",
          "label": "Site label (no exact address)",
          "unit": ""
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        {
          "name": "irb-team",
          "type": "text",
          "label": "Investigator codes",
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        {
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          "label": "Limitations / missing data",
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          "type": "textarea",
          "label": "Objective / question (pre-set where possible)",
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          "name": "irb-controls",
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          "unit": ""
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        {
          "name": "irb-alternatives",
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          "unit": ""
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        {
          "name": "irb-interpretation",
          "type": "textarea",
          "label": "Interpretation (clearly labeled as tentative)",
          "unit": ""
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        {
          "name": "irb-outcome",
          "type": "select-one",
          "label": "Session outcome",
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            "Inconclusive / insufficient data",
            "No anomaly noted in recorded session",
            "Observation recorded; cause unknown",
            "Ordinary explanation supported by checks"
          ],
          "default": "Inconclusive / insufficient data"
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          "name": "irb-status",
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=investigation-report-builder&<id>=<value>",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "investigation-timeline-logger",
      "title": "⏱ Investigation Timeline Logger",
      "description": "Keep a neutral, timestamped field log while a permitted investigation is underway. The clock is manual; observations are written by your team, not inferred from sensors.",
      "category": "field-investigation-and-evidence",
      "categoryName": "Field Investigation & Evidence",
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      "inputs": [
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        },
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          "type": "text",
          "label": "What happened? (brief, factual)",
          "unit": ""
        },
        {
          "name": "itl-kind",
          "type": "select-one",
          "label": "Event type",
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            "Direct observation",
            "Manual instrument reading",
            "Witness note",
            "Environmental change",
            "Equipment / handling event",
            "Control / room tone",
            "Interpretation (keep separate)"
          ],
          "default": "Direct observation"
        }
      ],
      "outputs": [
        {
          "name": "itl-status",
          "type": "live"
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=investigation-timeline-logger&<id>=<value>",
        "runs": false,
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      },
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        "investigation",
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        "timestamped",
        "log",
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      ],
      "popularity": 5457,
      "featured": false,
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    },
    {
      "slug": "investment",
      "title": "📈 Investment Growth Calculator",
      "description": "Watch your money multiply: Calculate how small investments today can grow into significant wealth over time through compounding. Illustrative estimates only — not financial advice; markets can fall...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/investment.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=investment&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "inv-principal",
          "type": "range",
          "label": "Initial Investment",
          "unit": "",
          "min": 0,
          "max": 100000,
          "step": 100,
          "default": "5000"
        },
        {
          "name": "inv-monthly",
          "type": "range",
          "label": "Monthly Contribution",
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          "min": 0,
          "max": 5000,
          "step": 10,
          "default": "200"
        },
        {
          "name": "inv-rate",
          "type": "range",
          "label": "Annual Return",
          "unit": "",
          "min": 0,
          "max": 20,
          "step": 0.1,
          "default": "7"
        },
        {
          "name": "inv-years",
          "type": "range",
          "label": "Investment Period",
          "unit": "",
          "min": 1,
          "max": 50,
          "step": 1,
          "default": "20"
        }
      ],
      "outputs": [
        {
          "name": "principal-value",
          "type": "output"
        },
        {
          "name": "monthly-value",
          "type": "output"
        },
        {
          "name": "rate-value",
          "type": "output"
        },
        {
          "name": "years-value",
          "type": "output"
        },
        {
          "name": "years-display",
          "type": "output"
        },
        {
          "name": "inv-total",
          "type": "output"
        },
        {
          "name": "principal-amount",
          "type": "output"
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        {
          "name": "growth-amount",
          "type": "output"
        }
      ],
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      },
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      "sources": [],
      "tags": [
        "investment",
        "growth",
        "finance",
        "money",
        "watch",
        "multiply",
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      "featured": false,
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    },
    {
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      "title": "👻 Invisible Character & Lookalike Detector",
      "description": "Code that won’t compile, a password that “is definitely right”, a search that finds nothing, a spreadsheet match that fails: the culprit is often a character you cannot see. Reveals zero-width spac...",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=invisible-character-detector&embed=1",
      "standaloneUrl": null,
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        {
          "name": "invisible-character-detector-o-zw",
          "type": "checkbox",
          "label": "Remove invisible / control characters",
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          "default": "1"
        },
        {
          "name": "invisible-character-detector-o-sp",
          "type": "checkbox",
          "label": "Unusual spaces → normal space",
          "unit": "",
          "default": "1"
        },
        {
          "name": "invisible-character-detector-o-gl",
          "type": "checkbox",
          "label": "Lookalike letters → Latin",
          "unit": "",
          "default": "1"
        },
        {
          "name": "invisible-character-detector-o-q",
          "type": "checkbox",
          "label": "Smart quotes & dashes → ASCII",
          "unit": "",
          "default": "0"
        },
        {
          "name": "invisible-character-detector-in",
          "type": "textarea",
          "label": "Text to inspect",
          "unit": ""
        }
      ],
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        {
          "name": "invisible-character-detector-status",
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=invisible-character-detector&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "invisible",
        "character",
        "detector",
        "lookalike",
        "algorithms",
        "computer",
        "science",
        "code",
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        "compile"
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      "popularity": 6366,
      "featured": false,
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    },
    {
      "slug": "invoice-billing-pdf-generator",
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      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/invoice-billing-pdf-generator.html",
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      "standaloneUrl": null,
      "inputs": [
        {
          "name": "inv-biz-name",
          "type": "text",
          "label": "Your Business / Full Name",
          "unit": "",
          "default": "ACME STUDIO DESIGN LLC"
        },
        {
          "name": "inv-biz-email",
          "type": "text",
          "label": "Email & Phone",
          "unit": "",
          "default": "billing@acmestudio.com"
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          "type": "text",
          "label": "Address, City, Country",
          "unit": "",
          "default": "100 Innovation Way, Suite 400"
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        {
          "name": "inv-num",
          "type": "text",
          "label": "Invoice #",
          "unit": "",
          "default": "INV-2026-0042"
        },
        {
          "name": "inv-date",
          "type": "date",
          "label": "Date",
          "unit": "",
          "default": "2026-08-29"
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        {
          "name": "inv-due",
          "type": "date",
          "label": "Due",
          "unit": "",
          "default": "2026-09-15"
        },
        {
          "name": "inv-client-name",
          "type": "text",
          "label": "Client Company or Individual Name",
          "unit": "",
          "default": "Apex Global Technologies Inc."
        },
        {
          "name": "inv-client-attn",
          "type": "text",
          "label": "Contact Person / Department",
          "unit": "",
          "default": "Attn: Accounts Payable"
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        {
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          "type": "text",
          "label": "Client Email",
          "unit": "",
          "default": "finance@apexglobal.tech"
        },
        {
          "name": "inv-tax-rate",
          "type": "number",
          "label": "Tax Rate",
          "unit": "%",
          "min": 0,
          "max": 50,
          "step": 0.25,
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        },
        {
          "name": "inv-discount",
          "type": "number",
          "label": "Discount",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "0"
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        {
          "name": "inv-payment-notes",
          "type": "textarea",
          "label": "Bank Wire / ACH / PayPal / Crypto Address...",
          "unit": ""
        },
        {
          "name": "inv-currency",
          "type": "select-one",
          "label": "Currency",
          "unit": "",
          "options": [
            "$",
            "€",
            "£",
            "¥",
            "CA$",
            "AU$",
            "CHF",
            "SOL",
            "USDC"
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          "default": "$"
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      ],
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        {
          "name": "inv-grand-total",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=invoice-billing-pdf-generator&<id>=<value>",
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      },
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      "sources": [],
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        "invoice",
        "billing",
        "pdf",
        "invoiceforge",
        "saas",
        "business",
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      "featured": false,
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    },
    {
      "slug": "invoice-late-fee-calculator",
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      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/invoice-late-fee-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=invoice-late-fee-calculator&embed=1",
      "standaloneUrl": null,
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        {
          "name": "invoice-late-fee-calculator-amount",
          "type": "number",
          "label": "Overdue invoice",
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          "default": "2500"
        },
        {
          "name": "invoice-late-fee-calculator-rate",
          "type": "number",
          "label": "Annual interest rate",
          "unit": "%",
          "default": "8"
        },
        {
          "name": "invoice-late-fee-calculator-days",
          "type": "number",
          "label": "Days overdue",
          "unit": "",
          "default": "45"
        },
        {
          "name": "invoice-late-fee-calculator-fee",
          "type": "number",
          "label": "Fixed recovery fee",
          "unit": "£",
          "default": "40"
        }
      ],
      "outputs": [
        {
          "name": "invoice-late-fee-calculator-out",
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        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=invoice-late-fee-calculator&<id>=<value>",
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "invoice",
        "late",
        "fee",
        "finance",
        "money",
        "calculate",
        "statutory",
        "agreed",
        "late-payment",
        "interest"
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      "popularity": 4368,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "ir35-comparator",
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      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/ir35-comparator.html",
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      "inputs": [
        {
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          "type": "number",
          "label": "Day rate",
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        {
          "name": "ic-days",
          "type": "number",
          "label": "Chargeable days/yr",
          "unit": "",
          "min": 1,
          "max": 365,
          "default": "212"
        },
        {
          "name": "ic-margin",
          "type": "number",
          "label": "Umbrella margin",
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          "step": 0.5,
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        },
        {
          "name": "ic-pension",
          "type": "number",
          "label": "Pension",
          "unit": "% of gross",
          "min": 0,
          "step": 0.5,
          "default": "3"
        },
        {
          "name": "ic-ltdcost",
          "type": "number",
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          "min": 0,
          "default": "250"
        },
        {
          "name": "ic-salary",
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          "label": "Ltd salary",
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          "min": 0,
          "default": "12570"
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        {
          "name": "ic-pa",
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          "unit": "",
          "default": "12570"
        },
        {
          "name": "ic-basic",
          "type": "number",
          "label": "Basic band upper",
          "unit": "£",
          "default": "50270"
        },
        {
          "name": "ic-tb",
          "type": "number",
          "label": "Basic tax %",
          "unit": "",
          "default": "20"
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        {
          "name": "ic-th",
          "type": "number",
          "label": "Higher tax %",
          "unit": "",
          "default": "40"
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        {
          "name": "ic-ta",
          "type": "number",
          "label": "Additional tax %",
          "unit": "",
          "default": "45"
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        {
          "name": "ic-nim",
          "type": "number",
          "label": "Employee NI main %",
          "unit": "",
          "default": "8"
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        {
          "name": "ic-nih",
          "type": "number",
          "label": "Employee NI higher %",
          "unit": "",
          "default": "2"
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        {
          "name": "ic-ct",
          "type": "number",
          "label": "Corporation tax %",
          "unit": "",
          "default": "19"
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        {
          "name": "ic-dva",
          "type": "number",
          "label": "Dividend allowance",
          "unit": "",
          "default": "500"
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        {
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          "type": "number",
          "label": "Div basic %",
          "unit": "",
          "default": "8.75"
        },
        {
          "name": "ic-dvh",
          "type": "number",
          "label": "Div higher %",
          "unit": "",
          "default": "33.75"
        },
        {
          "name": "ic-dva2",
          "type": "number",
          "label": "Div additional %",
          "unit": "",
          "default": "39.35"
        }
      ],
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        {
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=ir35-comparator&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
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        "ir35",
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    {
      "slug": "irregular-verbs-trainer",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=irregular-verbs-trainer&embed=1",
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          "name": "ivb-past",
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          "unit": "yesterday I…"
        },
        {
          "name": "ivb-part",
          "type": "text",
          "label": "Past participle",
          "unit": "I have…"
        }
      ],
      "outputs": [
        {
          "name": "ivb-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=irregular-verbs-trainer&<id>=<value>",
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "irregular",
        "verbs",
        "trainer",
        "writing",
        "language",
        "drill",
        "english",
        "refuse",
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      "popularity": 6246,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "isbn-10-13-converter",
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      "url": "https://www.themostusefulsiteintheworld.com/tool/isbn-10-13-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=isbn-10-13-converter&embed=1",
      "standaloneUrl": null,
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          "label": "ISBN",
          "unit": ""
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        {
          "name": "isbx-out",
          "type": "output"
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=isbn-10-13-converter&<id>=<value>",
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      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
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        "isbn",
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        "isbn-10",
        "isbn-13",
        "algorithms",
        "computer",
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      "popularity": 5284,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "iso-week-number-finder",
      "title": "📆 ISO Week Number Finder",
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      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/iso-week-number-finder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=iso-week-number-finder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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        },
        {
          "name": "isow-year",
          "type": "number",
          "label": "ISO year",
          "unit": "",
          "min": 1970,
          "max": 2100,
          "default": "2026"
        },
        {
          "name": "isow-week",
          "type": "number",
          "label": "Week 1–53",
          "unit": "",
          "min": 1,
          "max": 53,
          "default": "1"
        },
        {
          "name": "isow-day",
          "type": "select-one",
          "label": "Weekday",
          "unit": "",
          "options": [
            "1",
            "2",
            "3",
            "4",
            "5",
            "6",
            "7"
          ],
          "default": "1"
        }
      ],
      "outputs": [
        {
          "name": "isow-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=iso-week-number-finder&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=iso-week-number-finder&isow-year=2026&isow-week=1&isow-day=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "iso",
        "week",
        "number",
        "finder",
        "productivity",
        "lifestyle",
        "convert",
        "date",
        "iso-8601",
        "yyyy-www-d"
      ],
      "popularity": 6919,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "iv-drip-rate-infusion-calculator",
      "title": "💧 IV Drip Rate & Infusion Calculator",
      "description": "mL/h ⇄ drops/min for any giving set, weight-based dose rates from the concentration in the bag, and time-to-empty with the clock time it finishes. Everything works out on your device.",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/iv-drip-rate-infusion-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=iv-drip-rate-infusion-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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        },
        {
          "name": "ivdrip-hours",
          "type": "number",
          "label": "Time",
          "unit": "hours",
          "min": 0,
          "default": "4"
        },
        {
          "name": "ivdrip-damt",
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          "label": "Drug in the bag",
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        },
        {
          "name": "ivdrip-dil",
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          "min": 0,
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        },
        {
          "name": "ivdrip-dose",
          "type": "number",
          "label": "Prescribed dose",
          "unit": "",
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          "default": "5"
        },
        {
          "name": "ivdrip-wt",
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          "label": "Patient weight",
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        },
        {
          "name": "ivdrip-remain",
          "type": "number",
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          "min": 0,
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        },
        {
          "name": "ivdrip-rate",
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          "label": "Rate",
          "unit": "mL/hour",
          "min": 0,
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        },
        {
          "name": "ivdrip-drop",
          "type": "select-one",
          "label": "Giving set",
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            "20",
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            "60"
          ],
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        },
        {
          "name": "ivdrip-dunit",
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            "mg",
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            "unit"
          ],
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        },
        {
          "name": "ivdrip-drate",
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            "mcg-kg-min",
            "mg-kg-h",
            "mcg-kg-h",
            "mg-h",
            "unit-h",
            "unit-kg-h"
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          "default": "mcg-kg-min"
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      ],
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        {
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      },
      "formula": "Volume over time. mL/hour = volume ÷ hours. Drops per minute = (volume in mL × drop factor) ÷",
      "sources": [],
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        "drip",
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    },
    {
      "slug": "jack-o-lantern-carve-planner",
      "title": "🎃 Jack-o'-Lantern Carve Planner",
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      "standaloneUrl": null,
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        },
        {
          "name": "jlp-wall",
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          "label": "Wall thickness",
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          "max": 8,
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          "default": "2.5"
        },
        {
          "name": "jlp-size",
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          "unit": "% of pumpkin",
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        },
        {
          "name": "jlp-pattern",
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            "simple",
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            "detailed"
          ],
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        },
        {
          "name": "jlp-tool",
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          "label": "Cutting tool",
          "unit": "",
          "options": [
            "saw",
            "craft",
            "paring"
          ],
          "default": "saw"
        },
        {
          "name": "jlp-exp",
          "type": "select-one",
          "label": "Experience",
          "unit": "",
          "options": [
            "first",
            "some",
            "confident"
          ],
          "default": "some"
        },
        {
          "name": "jlp-light",
          "type": "select-one",
          "label": "Light",
          "unit": "",
          "options": [
            "tea",
            "pillar",
            "led"
          ],
          "default": "tea"
        }
      ],
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        {
          "name": "jlp-out",
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      },
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      "sources": [],
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        "jack",
        "lantern",
        "carve",
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        "halloween",
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      ],
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    },
    {
      "slug": "japanese-era-nengo",
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      "standaloneUrl": null,
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        {
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          "unit": "",
          "step": 1,
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        },
        {
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          "unit": "",
          "min": 1,
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        },
        {
          "name": "neng-era",
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          "unit": ""
        }
      ],
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        {
          "name": "neng-out",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=japanese-era-nengo&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "japanese",
        "era",
        "nengo",
        "neng",
        "desk",
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        "objects",
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    },
    {
      "slug": "japanese-jlpt-vocabulary",
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      "standaloneUrl": null,
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=japanese-jlpt-vocabulary&<id>=<value>",
        "runs": false
      },
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        "japanese",
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    },
    {
      "slug": "japanese-kana-trainer",
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      "categoryName": "Writing & Language",
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      "standaloneUrl": null,
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=japanese-kana-trainer&<id>=<value>",
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        "japanese",
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      "featured": false,
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    },
    {
      "slug": "japanese-keigo-politeness",
      "title": "👑 Japanese Keigo Master",
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      "category": "writing-and-language",
      "categoryName": "Writing & Language",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=japanese-keigo-politeness&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "keigo-verb-select",
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          "label": "Select Core Action / Business Concept",
          "unit": "",
          "options": [
            "iku",
            "iu",
            "taberu",
            "miru",
            "shiru",
            "suru",
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          ],
          "default": "iku"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=japanese-keigo-politeness&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
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        "japanese",
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      "featured": false,
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    },
    {
      "slug": "japanese-numbers-counters",
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      "category": "writing-and-language",
      "categoryName": "Writing & Language",
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      "standaloneUrl": null,
      "inputs": [
        {
          "name": "counter-num-slider",
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          "max": 10,
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        },
        {
          "name": "counter-category-select",
          "type": "select-one",
          "label": "Select Object Type to Count",
          "unit": "",
          "options": [
            "tsu",
            "nin",
            "hon",
            "mai",
            "hiki",
            "satsu",
            "nichi",
            "hai"
          ],
          "default": "tsu"
        }
      ],
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        {
          "name": "counter-num-display",
          "type": "output"
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=japanese-numbers-counters&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
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        "japanese",
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      "featured": false,
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    },
    {
      "slug": "japanese-particles-master",
      "title": "🧩 Japanese Particles Master",
      "description": "Master the grammatical glue of Japanese sentences (助詞 - Joshi). Practice tricky distinctions like は vs が (topic vs subject) and に vs で (time/target vs location of action) with interactive fill-in-t...",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
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      "standaloneUrl": null,
      "inputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=japanese-particles-master&<id>=<value>",
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      },
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      "sources": [],
      "tags": [
        "japanese",
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      ],
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      "featured": false,
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    },
    {
      "slug": "japanese-romaji-converter",
      "title": "🔄 Romaji & Kana Converter",
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      "categoryName": "Writing & Language",
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      "standaloneUrl": null,
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        {
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          "label": "Type Romaji or Japanese Text",
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          "default": "arigatou gozaimasu"
        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=japanese-romaji-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=japanese-romaji-converter&romaji-input-text=arigatou%20gozaimasu"
      },
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      "sources": [],
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        "japanese",
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      "featured": false,
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    },
    {
      "slug": "japanese-verb-conjugator",
      "title": "⚡ Japanese Verb Conjugator",
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      "category": "writing-and-language",
      "categoryName": "Writing & Language",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=japanese-verb-conjugator&embed=1",
      "standaloneUrl": null,
      "inputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=japanese-verb-conjugator&<id>=<value>",
        "runs": false
      },
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      "sources": [],
      "tags": [
        "japanese",
        "verb",
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        "writing",
        "language",
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      ],
      "popularity": 5906,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "jet-lag-sleep-shift-planner",
      "title": "✈️ Jet Lag Sleep Shift Planner",
      "description": "Plan a sleep shift for a timezone jump. Eastbound is harder (phase advance ~1 h/day); westbound is easier (~1.5 h/day). Times are a circadian rule of thumb, not a flight-medicine consult.",
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      "categoryName": "Lucid Dreaming & Sleep",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=jet-lag-sleep-shift-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "jlag-home",
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          "label": "Home UTC offset",
          "unit": "",
          "step": 0.5,
          "default": "0"
        },
        {
          "name": "jlag-dest",
          "type": "number",
          "label": "Destination UTC offset",
          "unit": "",
          "step": 0.5,
          "default": "9"
        },
        {
          "name": "jlag-sleep",
          "type": "time",
          "label": "Usual bedtime",
          "unit": "home",
          "default": "23:00"
        },
        {
          "name": "jlag-wake",
          "type": "time",
          "label": "Usual wake",
          "unit": "home",
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        },
        {
          "name": "jlag-days",
          "type": "number",
          "label": "Days until departure",
          "unit": "",
          "min": 0,
          "max": 14,
          "default": "4"
        }
      ],
      "outputs": [
        {
          "name": "jlag-out",
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        }
      ],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "jet",
        "lag",
        "sleep",
        "shift",
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        "lucid",
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        "timezone",
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      ],
      "popularity": 5006,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "job-offer-comparator",
      "title": "💼 Job Offer Comparator",
      "description": "Put up to three roles side by side: base pay, expected bonus, employer pension, your estimate of other benefits, commuting costs and time, contracted hours, and paid leave. No offer is ranked for you.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=job-offer-comparator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "job-offer-comparator-name-a",
          "type": "text",
          "label": "Role / employer label",
          "unit": ""
        },
        {
          "name": "job-offer-comparator-base-a",
          "type": "number",
          "label": "Annual base pay",
          "unit": "",
          "min": 0,
          "max": 100000000,
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        },
        {
          "name": "job-offer-comparator-bonus-a",
          "type": "number",
          "label": "Expected annual bonus",
          "unit": "",
          "min": 0,
          "max": 100000000,
          "step": 0.01
        },
        {
          "name": "job-offer-comparator-pension-a",
          "type": "number",
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          "max": 100000000,
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        },
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        {
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        },
        {
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        },
        {
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          "max": 168,
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        },
        {
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          "max": 366,
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        },
        {
          "name": "job-offer-comparator-name-b",
          "type": "text",
          "label": "Role / employer label",
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        },
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          "max": 100000000,
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        },
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          "step": 1
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        },
        {
          "name": "job-offer-comparator-name-c",
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          "label": "Role / employer label",
          "unit": ""
        },
        {
          "name": "job-offer-comparator-base-c",
          "type": "number",
          "label": "Annual base pay",
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          "min": 0,
          "max": 100000000,
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        },
        {
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          "max": 100000000,
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        },
        {
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          "max": 1000000,
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          "unit": "",
          "min": 0,
          "max": 366,
          "step": 0.5
        },
        {
          "name": "job-offer-comparator-report",
          "type": "textarea",
          "label": "Copyable comparison summary",
          "unit": ""
        },
        {
          "name": "job-offer-comparator-currency",
          "type": "select-one",
          "label": "Currency for every offer",
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            "GBP",
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            "EUR",
            "CAD",
            "AUD",
            "NZD",
            "INR"
          ],
          "default": "GBP"
        }
      ],
      "outputs": [
        {
          "name": "job-offer-comparator-status",
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        {
          "name": "job-offer-comparator-results",
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      },
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        "job",
        "offer",
        "comparator",
        "finance",
        "money",
        "put",
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        "side",
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      "featured": false,
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    {
      "slug": "joy-spark-micro-celebrations",
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      "category": "wellbeing-and-community",
      "categoryName": "Wellbeing & Community",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=joy-spark-micro-celebrations&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "text",
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          "unit": ""
        },
        {
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          "type": "select-one",
          "label": "Pick a Micro-Victory (or type your own below)",
          "unit": "",
          "options": [
            "I drank a full glass of cold, fresh water!",
            "I sent that email I was quietly dreading all day!",
            "I stood up, rolled my shoulders, and took 3 deep breaths!",
            "I got out of bed and showed up today!",
            "I chose peace instead of engaging in an unnecessary argument!",
            "I did 5 minutes of focused work without checking my phone!",
            "I washed the dishes and cleared the sink!",
            "I forgave myself for not being 100% perfect today!",
            "I stepped outside and felt the sun & breeze on my face!",
            "I ate a nourishing meal to fuel my wonderful body!",
            "I asked for help when I needed it!",
            "I laughed genuinely at something silly!"
          ],
          "default": "I drank a full glass of cold, fresh water!"
        },
        {
          "name": "jmc-intensity",
          "type": "select-one",
          "label": "Celebration Blast",
          "unit": "",
          "options": [
            "medium",
            "mega",
            "gentle",
            "fireworks"
          ],
          "default": "medium"
        },
        {
          "name": "jmc-audio-fanfare",
          "type": "select-one",
          "label": "Audio Fanfare",
          "unit": "",
          "options": [
            "brass",
            "harp",
            "arcade",
            "chimes",
            "mute"
          ],
          "default": "brass"
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=joy-spark-micro-celebrations&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "joy",
        "spark",
        "micro",
        "celebrations",
        "joyspark",
        "micro-victory",
        "celebration",
        "cannon",
        "wellbeing",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
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      "category": "interactive-art-and-living-worlds",
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            "fine-rake",
            "wave-rake",
            "swirl",
            "smooth",
            "sakura"
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          "default": "fine-rake"
        },
        {
          "name": "zrg-place-item",
          "type": "select-one",
          "label": "Place Element",
          "unit": "",
          "options": [
            "none",
            "granite",
            "jade",
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            "lantern"
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        },
        {
          "name": "zrg-preset-pattern",
          "type": "select-one",
          "label": "Auto-Pattern",
          "unit": "",
          "options": [
            "concentric",
            "fibonacci",
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            "yinyang"
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        {
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          "type": "select-one",
          "label": "Lighting",
          "unit": "",
          "options": [
            "day",
            "dusk",
            "moonlight"
          ],
          "default": "day"
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      ],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
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        "joyful",
        "zen",
        "sand",
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        "raker",
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      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "textarea",
          "label": "JSON",
          "unit": ""
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        "json",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=json-ld-structured-data-generator&embed=1",
      "standaloneUrl": null,
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        {
          "name": "jld-context",
          "type": "checkbox",
          "label": "Include @context",
          "unit": "",
          "default": "1"
        },
        {
          "name": "jld-out",
          "type": "textarea",
          "label": "Generated JSON-LD",
          "unit": ""
        },
        {
          "name": "jld-type",
          "type": "select-one",
          "label": "Schema type",
          "unit": ""
        }
      ],
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        {
          "name": "jld-status",
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        }
      ],
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        "json",
        "structured",
        "data",
        "rich",
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        "forge",
        "saas",
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      "popularity": 4420,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "json-to-typescript-interface-generator",
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      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=json-to-typescript-interface-generator&embed=1",
      "standaloneUrl": null,
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          "unit": "",
          "default": "ApiResponse"
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          "name": "jts-literals",
          "type": "checkbox",
          "label": "Infer literal unions",
          "unit": "",
          "default": "1"
        },
        {
          "name": "jts-readonly",
          "type": "checkbox",
          "label": "Mark TS props readonly",
          "unit": "",
          "default": "0"
        },
        {
          "name": "jts-input",
          "type": "textarea",
          "label": "JSON input",
          "unit": ""
        },
        {
          "name": "jts-out",
          "type": "textarea",
          "label": "Generated types",
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        }
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      "sources": [],
      "tags": [
        "json",
        "typescript",
        "interface",
        "schema",
        "forge",
        "saas",
        "business",
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      "popularity": 6804,
      "featured": false,
      "updated": "2026-09-19"
    },
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      "slug": "json-yaml-diff-validator",
      "title": "🔧 JSON & YAML Studio",
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          "label": "Paste JSON or YAML here...",
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        {
          "name": "jyd-diff-a",
          "type": "textarea",
          "label": "{\"version\": 1, \"name\": \"app\", \"debug\": false}",
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        },
        {
          "name": "jyd-diff-b",
          "type": "textarea",
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          "unit": ""
        },
        {
          "name": "jyd-indent",
          "type": "select-one",
          "label": "indent",
          "unit": "",
          "options": [
            "2",
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            "tab"
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          "name": "jyd-diff-output",
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        }
      ],
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      },
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      "sources": [],
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        "json",
        "yaml",
        "diff",
        "validator",
        "studio",
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        "lifestyle",
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      "popularity": 5027,
      "featured": false,
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    },
    {
      "slug": "julian-day-date-converter",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=julian-day-date-converter&embed=1",
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          "type": "date",
          "label": "Date",
          "unit": "UTC"
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          "type": "time",
          "label": "Time UTC",
          "unit": "",
          "step": 1,
          "default": "12:00"
        },
        {
          "name": "jday-jd",
          "type": "number",
          "label": "Julian Day",
          "unit": ""
        }
      ],
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        {
          "name": "jday-out",
          "type": "output"
        }
      ],
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        "julian",
        "day",
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        "converter",
        "productivity",
        "lifestyle",
        "convert",
        "calendar",
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        "jdn"
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      "featured": false,
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          "max": 9999,
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          "default": "31"
        },
        {
          "name": "hlm-own-black",
          "type": "checkbox",
          "label": "Black clothes",
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          "default": "1"
        },
        {
          "name": "hlm-own-white",
          "type": "checkbox",
          "label": "White clothes",
          "unit": "",
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        },
        {
          "name": "hlm-own-sheet",
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          "label": "An old sheet",
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        },
        {
          "name": "hlm-own-paint",
          "type": "checkbox",
          "label": "Face paint",
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        {
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          "type": "checkbox",
          "label": "Tape",
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          "default": "1"
        },
        {
          "name": "hlm-own-cardboard",
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          "default": "0"
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        {
          "name": "hlm-own-bags",
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          "default": "0"
        },
        {
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          "type": "checkbox",
          "label": "A hat",
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          "default": "0"
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        {
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          "default": "0"
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        {
          "name": "hlm-own-check",
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          "label": "Checked shirt",
          "unit": "",
          "default": "0"
        },
        {
          "name": "hlm-own-foil",
          "type": "checkbox",
          "label": "Foil",
          "unit": "",
          "default": "0"
        },
        {
          "name": "hlm-minutes",
          "type": "select-one",
          "label": "Minutes you have",
          "unit": "",
          "options": [
            "5",
            "15",
            "30",
            "60",
            "120"
          ],
          "default": "15"
        },
        {
          "name": "hlm-vibe",
          "type": "select-one",
          "label": "Vibe",
          "unit": "",
          "options": [
            "any",
            "spooky",
            "funny",
            "film"
          ],
          "default": "any"
        }
      ],
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        {
          "name": "hlm-out",
          "type": "live"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=last-minute-halloween-costume-finder&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "last",
        "minute",
        "halloween",
        "costume",
        "finder",
        "last-minute",
        "what",
        "already",
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        "pick"
      ],
      "popularity": 4957,
      "featured": false,
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    },
    {
      "slug": "late-payment-interest-chaser",
      "title": "⏰ Late Payment Interest & Chaser Letter",
      "description": "Unpaid invoice? UK law lets you charge 8% above the Bank of England base rate plus fixed compensation on overdue business invoices — automatically, even if your contract never mentioned it. Calcula...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=late-payment-interest-chaser&embed=1",
      "standaloneUrl": null,
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        {
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        },
        {
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          "unit": "",
          "min": 0,
          "max": 2200,
          "default": "45"
        },
        {
          "name": "lpi-base",
          "type": "number",
          "label": "BoE base rate for the period",
          "unit": "%",
          "min": 0,
          "max": 20,
          "step": 0.05,
          "default": "3.75"
        },
        {
          "name": "lpi-costs",
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          "min": 0,
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        },
        {
          "name": "lpi-client",
          "type": "text",
          "label": "Client / debtor name",
          "unit": "",
          "default": "Client Ltd"
        },
        {
          "name": "lpi-ref",
          "type": "text",
          "label": "Invoice reference",
          "unit": "",
          "default": "INV-1042"
        },
        {
          "name": "lpi-letter",
          "type": "textarea",
          "label": "Generated letter — edit before sending",
          "unit": ""
        },
        {
          "name": "lpi-tone",
          "type": "select-one",
          "label": "Letter stage",
          "unit": "",
          "options": [
            "polite",
            "firm",
            "lba"
          ],
          "default": "polite"
        }
      ],
      "outputs": [
        {
          "name": "lpi-res-total",
          "type": "output"
        }
      ],
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        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=late-payment-interest-chaser&lpi-amount=4500&lpi-days=45&lpi-base=3.75&lpi-costs=0&lpi-client=Client%20Ltd&lpi-ref=INV-1042"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "late",
        "payment",
        "interest",
        "chaser",
        "letter",
        "finance",
        "money",
        "unpaid",
        "invoice",
        "law"
      ],
      "popularity": 4663,
      "featured": false,
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    },
    {
      "slug": "latex-table-maths-studio",
      "title": "📐 LaTeX Table & Maths Studio",
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        },
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          "type": "text",
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        {
          "name": "ltms-booktabs",
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          "label": "booktabs rules (no vertical lines)",
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          "default": "1"
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        {
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          "label": "First row is a header",
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        },
        {
          "name": "ltms-maths",
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        {
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          "label": "Shrink to text width",
          "unit": "",
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        {
          "name": "ltms-in",
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          "label": "Paste your table — tab, comma or pipe separated, one row per line",
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        },
        {
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          "label": "Paste prose, a filename, a URL or a bit of code",
          "unit": ""
        },
        {
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          "unit": "",
          "options": [
            "auto",
            "l",
            "c",
            "r"
          ],
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        }
      ],
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        "runs": false,
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      },
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      "sources": [],
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        "latex",
        "table",
        "maths",
        "studio",
        "writing",
        "language",
        "building",
        "tabular",
        "hand",
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      "featured": false,
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    },
    {
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      "title": "📜 The Kalends Desk",
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      "category": "museum-and-collection",
      "categoryName": "Museum & Collection",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=latin-date-kalends-nones&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "kald-d",
          "type": "number",
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          "min": 1,
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        },
        {
          "name": "kald-m",
          "type": "select-one",
          "label": "Month",
          "unit": ""
        },
        {
          "name": "kald-leap",
          "type": "select-one",
          "label": "February",
          "unit": "",
          "options": [
            "0",
            "1"
          ],
          "default": "0"
        }
      ],
      "outputs": [
        {
          "name": "kald-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=latin-date-kalends-nones&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=latin-date-kalends-nones&kald-d=15&kald-leap=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "latin",
        "date",
        "kalends",
        "nones",
        "desk",
        "museum",
        "collection",
        "romans",
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      ],
      "popularity": 5334,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "laugh-laboratory-chuckle-box",
      "title": "😄 The Laugh Laboratory & Mood Prescription",
      "description": "Laughter reduces cortisol by 39% and floods the bloodstream with feel-good endorphins. Explore the Emergency Chuckle Dispenser, trigger classic synthesized cartoon sound effects, reframe overthinki...",
      "category": "wellbeing-and-community",
      "categoryName": "Wellbeing & Community",
      "url": "https://www.themostusefulsiteintheworld.com/tool/laugh-laboratory-chuckle-box.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=laugh-laboratory-chuckle-box&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "llc-melo-input",
          "type": "text",
          "label": "Enter your small daily annoyance or overthinking thought",
          "unit": ""
        },
        {
          "name": "llc-joke-type",
          "type": "select-one",
          "label": "Humor Category",
          "unit": "",
          "options": [
            "all",
            "dad",
            "shower",
            "animal"
          ],
          "default": "all"
        }
      ],
      "outputs": [
        {
          "name": "llc-melo-result",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=laugh-laboratory-chuckle-box&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=laugh-laboratory-chuckle-box&llc-joke-type=all"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "laugh",
        "laboratory",
        "chuckle",
        "box",
        "mood",
        "prescription",
        "wellbeing",
        "community",
        "laughter",
        "reduces"
      ],
      "popularity": 6807,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "laundry-care-label-stain-solver",
      "title": "🧺 Laundry Care & Stain Solver",
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      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/laundry-care-label-stain-solver.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=laundry-care-label-stain-solver&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "lcr-fabric",
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          "label": "Fabric",
          "unit": "",
          "options": [
            "cotton",
            "polyester",
            "wool",
            "silk",
            "denim",
            "activewear",
            "towels",
            "mixed"
          ],
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        },
        {
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          "label": "Colour group",
          "unit": "",
          "options": [
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            "lights",
            "darks"
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          "default": "whites"
        },
        {
          "name": "lcr-soil",
          "type": "select-one",
          "label": "How dirty?",
          "unit": "",
          "options": [
            "light",
            "normal",
            "heavy"
          ],
          "default": "normal"
        },
        {
          "name": "lcr-stain",
          "type": "select-one",
          "label": "The stain",
          "unit": "",
          "options": [
            "red-wine",
            "coffee-tea",
            "grease-oil",
            "blood",
            "sweat",
            "ink",
            "grass",
            "chocolate",
            "tomato",
            "mud",
            "gum",
            "turmeric"
          ],
          "default": "red-wine"
        },
        {
          "name": "lcr-sfabric",
          "type": "select-one",
          "label": "On fabric",
          "unit": "",
          "options": [
            "robust",
            "delicate",
            "coloured"
          ],
          "default": "robust"
        }
      ],
      "outputs": [
        {
          "name": "lcr-washout",
          "type": "live"
        },
        {
          "name": "lcr-stainout",
          "type": "live"
        },
        {
          "name": "lcr-symout",
          "type": "live"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=laundry-care-label-stain-solver&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=laundry-care-label-stain-solver&lcr-fabric=mixed&lcr-colour=whites&lcr-soil=normal&lcr-stain=red-wine&lcr-sfabric=robust"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "laundry",
        "care",
        "label",
        "stain",
        "solver",
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        "complete",
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      ],
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      "featured": false,
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    },
    {
      "slug": "laundry",
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      "inputs": [
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          "unit": ""
        },
        {
          "name": "laundry-type",
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          "label": "Load Type",
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          "options": [
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            "darks",
            "colors",
            "delicates",
            "towels",
            "workout",
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          ]
        },
        {
          "name": "laundry-cycle",
          "type": "select-one",
          "label": "Wash Cycle",
          "unit": "",
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            "normal",
            "quick",
            "heavy",
            "delicate",
            "cold",
            "sanitize"
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        {
          "name": "laundry-status",
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          "options": [
            "pending",
            "washing",
            "drying",
            "folded",
            "complete"
          ],
          "default": "pending"
        },
        {
          "name": "laundry-filter",
          "type": "select-one",
          "label": "laundry filter",
          "unit": "",
          "options": [
            "all",
            "pending",
            "complete",
            "today",
            "week"
          ],
          "default": "all"
        }
      ],
      "outputs": [
        {
          "name": "laundry-summary",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=laundry&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=laundry&laundry-cycle=normal&laundry-status=pending&laundry-filter=all"
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      "sources": [],
      "tags": [
        "laundry",
        "tracker",
        "productivity",
        "lifestyle",
        "log",
        "loads",
        "track",
        "completion",
        "monitor",
        "habits"
      ],
      "popularity": 4891,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "leanbodymass",
      "title": "Lean Body Mass Calculator",
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      "categoryName": "Health & Fitness",
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      "standaloneUrl": null,
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        {
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        },
        {
          "name": "lbm-height",
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          "max": 250,
          "step": 0.1,
          "default": "175"
        },
        {
          "name": "lbm-bodyfat",
          "type": "range",
          "label": "Body Fat Percentage",
          "unit": "",
          "min": 3,
          "max": 60,
          "step": 0.5,
          "default": "20"
        },
        {
          "name": "lbm-bodyfat-value",
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          "min": 3,
          "max": 60,
          "step": 0.1,
          "default": "20"
        },
        {
          "name": "lbm-gender",
          "type": "select-one",
          "label": "Gender",
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          "options": [
            "male",
            "female"
          ],
          "default": "male"
        },
        {
          "name": "lbm-formula",
          "type": "select-one",
          "label": "Calculation Formula",
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          "options": [
            "bodyfat",
            "boer",
            "james",
            "hume"
          ],
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        }
      ],
      "outputs": [
        {
          "name": "lbm-lean-value",
          "type": "output"
        },
        {
          "name": "lbm-fat-value",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=leanbodymass&<id>=<value>",
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      },
      "formula": "Quick Formulas: 1. Body Fat Method: LBM = Weight × (1 - BodyFat%) 2. Boer Formula (Men): 0.407×Weight + 0.267×",
      "sources": [],
      "tags": [
        "leanbodymass",
        "lean",
        "body",
        "mass",
        "health",
        "fitness",
        "estimate",
        "using",
        "multiple",
        "formulas"
      ],
      "popularity": 6148,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "leap-year-weekday-finder",
      "title": "📆 Leap Year & Weekday",
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      "standaloneUrl": null,
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        },
        {
          "name": "leap-date",
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          "name": "leap-out",
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        }
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        "leap",
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        "lifestyle",
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      "updated": "2026-09-19"
    },
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      "slug": "learning-style",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=learning-style&embed=1",
      "standaloneUrl": null,
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        "learning",
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        "productivity",
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      "featured": false,
      "updated": "2026-09-19"
    },
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      "description": "Compare the true cost of leasing a vehicle against buying it outright or on finance, over the same term. Accounts for deposit, monthly payments, residual value and what the car is worth at the end.",
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          "step": 100,
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        {
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        {
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          "step": 50,
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        {
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        {
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        {
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          "name": "lvsb-maint",
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          "label": "Buy servicing total",
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          "min": 0,
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        }
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        {
          "name": "lvsb-out",
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        "lease",
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      "categoryName": "Productivity & Lifestyle",
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        {
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        },
        {
          "name": "leave-on-time-planner-buffer",
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          "label": "Arrive early by",
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          "min": 0,
          "max": 1440,
          "step": 1,
          "default": "15"
        },
        {
          "name": "leave-on-time-planner-prep",
          "type": "number",
          "label": "Getting ready",
          "unit": "minutes",
          "min": 0,
          "max": 1440,
          "step": 1,
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      ],
      "outputs": [],
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      "sources": [],
      "tags": [
        "leave",
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        "planner",
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      "featured": false,
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    },
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        {
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        },
        {
          "name": "ledr-ma",
          "type": "number",
          "label": "Current mA",
          "unit": "",
          "min": 0.1,
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        },
        {
          "name": "ledr-n",
          "type": "number",
          "label": "LEDs in series",
          "unit": "",
          "min": 1,
          "max": 20,
          "step": 1,
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        }
      ],
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          "name": "ledr-out",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=led-current-limiting-resistor&<id>=<value>",
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      },
      "formula": "LED Current-Limiting Resistor R = (supply − LED V f ) / current. Typical V f : red ~1.8–2.2 V, green/blue/",
      "sources": [],
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        "led",
        "current",
        "limiting",
        "resistor",
        "current-limiting",
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        "engineering",
        "supply",
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      ],
      "popularity": 5691,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "led-watt-equivalent-calculator",
      "title": "💡 LED Watt Equivalent Calculator",
      "description": "Rough incandescent, halogen and CFL wattage versus LED lumens. Packaging lumens win over “60 W equivalent” marketing. Efficacy defaults to typical household LEDs (~90 lm/W).",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/led-watt-equivalent-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=led-watt-equivalent-calculator&embed=1",
      "standaloneUrl": null,
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          "name": "ledw-v",
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          "unit": "",
          "min": 0,
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        },
        {
          "name": "ledw-eff",
          "type": "number",
          "label": "LED lm / W",
          "unit": "",
          "min": 1,
          "default": "90"
        },
        {
          "name": "ledw-mode",
          "type": "select-one",
          "label": "I know",
          "unit": "",
          "options": [
            "inc",
            "lm",
            "led"
          ],
          "default": "inc"
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      ],
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        {
          "name": "ledw-out",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=led-watt-equivalent-calculator&<id>=<value>",
        "runs": false,
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      "sources": [],
      "tags": [
        "led",
        "watt",
        "equivalent",
        "science",
        "engineering",
        "rough",
        "incandescent",
        "halogen",
        "cfl",
        "wattage"
      ],
      "popularity": 5788,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "leftover-rescue-kitchen",
      "title": "♻️ Leftover Rescue Kitchen: Waste Nothing",
      "description": "A third of all food is wasted while people go hungry. Tick what you have and get rescue recipes, check whether it is still safe to eat, stretch one portion into a family meal, and track your use-fi...",
      "category": "culinary-and-food-science",
      "categoryName": "Culinary & Food Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/leftover-rescue-kitchen.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=leftover-rescue-kitchen&embed=1",
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          "min": 0,
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          "step": 0.5,
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        },
        {
          "name": "lrsk-fridge",
          "type": "number",
          "label": "Days in fridge",
          "unit": "0 = none",
          "min": 0,
          "max": 14,
          "step": 0.5,
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        },
        {
          "name": "lrsk-have",
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          "label": "Portions you have",
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          "step": 0.5,
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        {
          "name": "lrsk-need",
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          "label": "Portions you need",
          "unit": "",
          "min": 1,
          "max": 30,
          "step": 0.5,
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        },
        {
          "name": "lrsk-fname",
          "type": "text",
          "label": "Food that must be used",
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        {
          "name": "lrsk-item",
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        },
        {
          "name": "lrsk-ext",
          "type": "select-one",
          "label": "Stretch with",
          "unit": "",
          "options": [
            "rice",
            "redlent",
            "pasta",
            "oats",
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            "bread"
          ],
          "default": "rice"
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        {
          "name": "lrsk-fdays",
          "type": "select-one",
          "label": "Use within",
          "unit": "",
          "options": [
            "0",
            "1",
            "2",
            "3",
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        }
      ],
      "outputs": [
        {
          "name": "lrsk-recipes",
          "type": "live"
        },
        {
          "name": "lrsk-verdict",
          "type": "live"
        },
        {
          "name": "lrsk-stretchout",
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          "name": "lrsk-flist",
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      },
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      "sources": [],
      "tags": [
        "leftover",
        "rescue",
        "kitchen",
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        "culinary",
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      "popularity": 5628,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "lighting-design",
      "title": "💡 Lighting Design Calculator",
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      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/lighting-design.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=lighting-design&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "number",
          "label": "Room Length",
          "unit": "m",
          "min": 1,
          "max": 100,
          "step": 0.1,
          "default": "5"
        },
        {
          "name": "light-width",
          "type": "number",
          "label": "Room Width",
          "unit": "m",
          "min": 1,
          "max": 100,
          "step": 0.1,
          "default": "4"
        },
        {
          "name": "light-height",
          "type": "number",
          "label": "Ceiling Height",
          "unit": "m",
          "min": 2,
          "max": 20,
          "step": 0.1,
          "default": "2.7"
        },
        {
          "name": "light-ceiling-reflectance",
          "type": "range",
          "label": "Ceiling Reflectance",
          "unit": "%",
          "min": 10,
          "max": 90,
          "step": 5,
          "default": "70"
        },
        {
          "name": "light-ceiling-reflectance-value",
          "type": "number",
          "label": "ceiling reflectance value",
          "unit": "",
          "min": 10,
          "max": 90,
          "step": 5,
          "default": "70"
        },
        {
          "name": "light-wall-reflectance",
          "type": "range",
          "label": "Wall Reflectance",
          "unit": "%",
          "min": 10,
          "max": 90,
          "step": 5,
          "default": "50"
        },
        {
          "name": "light-wall-reflectance-value",
          "type": "number",
          "label": "wall reflectance value",
          "unit": "",
          "min": 10,
          "max": 90,
          "step": 5,
          "default": "50"
        },
        {
          "name": "light-floor-reflectance",
          "type": "range",
          "label": "Floor Reflectance",
          "unit": "%",
          "min": 10,
          "max": 90,
          "step": 5,
          "default": "20"
        },
        {
          "name": "light-floor-reflectance-value",
          "type": "number",
          "label": "floor reflectance value",
          "unit": "",
          "min": 10,
          "max": 90,
          "step": 5,
          "default": "20"
        },
        {
          "name": "light-lamp-lumens",
          "type": "number",
          "label": "Fixture Lumen Output",
          "unit": "",
          "min": 100,
          "max": 50000,
          "step": 100,
          "default": "800"
        },
        {
          "name": "light-lamp-wattage",
          "type": "number",
          "label": "Fixture Wattage",
          "unit": "W",
          "min": 1,
          "max": 1000,
          "step": 1,
          "default": "10"
        },
        {
          "name": "light-lamp-efficacy",
          "type": "number",
          "label": "Luminous Efficacy",
          "unit": "lm/W",
          "min": 1,
          "max": 200,
          "step": 1,
          "default": "80"
        },
        {
          "name": "light-room-type",
          "type": "select-one",
          "label": "Room Type",
          "unit": "",
          "options": [
            "custom",
            "office",
            "living",
            "kitchen",
            "bedroom",
            "bathroom",
            "classroom",
            "retail",
            "hospital",
            "warehouse",
            "gym"
          ],
          "default": "custom"
        },
        {
          "name": "light-lighting-type",
          "type": "select-one",
          "label": "Lighting Type",
          "unit": "",
          "options": [
            "general",
            "task",
            "accent",
            "emergency",
            "decorative"
          ],
          "default": "general"
        },
        {
          "name": "light-fixture-type",
          "type": "select-one",
          "label": "Fixture Type",
          "unit": "",
          "options": [
            "custom",
            "led_panel",
            "led_downlight",
            "fluorescent",
            "incandescent",
            "halogen",
            "high_bay",
            "track",
            "pendant"
          ],
          "default": "custom"
        }
      ],
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        {
          "name": "light-detailed-results",
          "type": "output"
        }
      ],
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      },
      "formula": "Lumen Method Formula: N = (E × A) ÷ (F × UF ×",
      "sources": [],
      "tags": [
        "lighting",
        "design",
        "science",
        "engineering",
        "professional",
        "comprehensive",
        "room",
        "analysis",
        "fixture",
        "selection"
      ],
      "popularity": 6057,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "lightning-charge-anatomy",
      "title": "⚡ Lightning — Storm Anatomy in 5 Steps",
      "description": "Follow a flash from charge separation to thunder: colliding ice makes charge, a stepped leader feels its way down, a streamer connects, and a 30,000 A return stroke heats the air hotter than the Su...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/lightning-charge-anatomy.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=lightning-charge-anatomy&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ltn-dist",
          "type": "range",
          "label": "Storm distance 3.0 km",
          "unit": "",
          "min": 1,
          "max": 40,
          "default": "6"
        }
      ],
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        {
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        {
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      "formula": "Monthly Base Payment $1,580.17 + $100.00 extra = $1,680.17/",
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            "sp1200",
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        "loop",
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        "checker",
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      "slug": "lorenz-attractor",
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          "unit": "",
          "min": 1,
          "max": 30,
          "default": "8"
        }
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        {
          "name": "lrz-out",
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      },
      "formula": "Lorenz simplified a weather model to three equations: dx/dt = σ(y−x), dy/dt = x(&rho;−z)−y, dz/dt = xy−βz, with σ=10, &rho;=28, β=8/",
      "sources": [],
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        "lorenz",
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      "featured": false,
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    },
    {
      "slug": "ltv-mortgage-calculator",
      "title": "🏦 LTV Mortgage Calculator",
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      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/ltv-mortgage-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=ltv-mortgage-calculator&embed=1",
      "standaloneUrl": null,
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        {
          "name": "ltvm-price",
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          "label": "Property price £",
          "unit": "",
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        },
        {
          "name": "ltvm-x",
          "type": "number",
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          "unit": "",
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        },
        {
          "name": "ltvm-mode",
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          "label": "I know",
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          "options": [
            "price",
            "ltv",
            "loan"
          ],
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        }
      ],
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        {
          "name": "ltvm-out",
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      },
      "formula": "LTV Mortgage Calculator Loan-to-value = mortgage ÷",
      "sources": [],
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        "ltv",
        "mortgage",
        "finance",
        "money",
        "loan-to-value",
        "property",
        "price",
        "product",
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      "featured": false,
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    },
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      "slug": "lucid-dream-quest-taskboard",
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      "category": "lucid-dreaming-and-sleep",
      "categoryName": "Lucid Dreaming & Sleep",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=lucid-dream-quest-taskboard&embed=1",
      "standaloneUrl": null,
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      "tags": [
        "lucid",
        "dream",
        "quest",
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      "popularity": 4852,
      "featured": false,
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    },
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      "slug": "lucid-dream-stabilizer-sim",
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        "lucid",
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      "popularity": 4377,
      "featured": false,
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    },
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      "slug": "lucid-reality-check-trainer",
      "title": "👁️ Lucid Reality Check Trainer",
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      "category": "lucid-dreaming-and-sleep",
      "categoryName": "Lucid Dreaming & Sleep",
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            "clock",
            "nose",
            "hands",
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        {
          "name": "rc-timer-interval",
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          "unit": "",
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            "0",
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      "featured": false,
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    },
    {
      "slug": "lucid-supplements-timing-calc",
      "title": "💊 Lucid Dream Supplement Clock",
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      "categoryName": "Lucid Dreaming & Sleep",
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      "standaloneUrl": null,
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        {
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        },
        {
          "name": "supp-stack",
          "type": "select-one",
          "label": "Oneirogen Protocol",
          "unit": "",
          "options": [
            "galantamine",
            "huperzine",
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            "rebound"
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        }
      ],
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      },
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      "sources": [],
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        "lucid",
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        "dream",
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        "pharmacokinetic"
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      "popularity": 4683,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "lufs-target-headroom-planner",
      "title": "LUFS Target & Headroom Planner",
      "description": "Use measured integrated LUFS and true peak to plan a gain change and see whether your chosen peak ceiling permits it.",
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      "categoryName": "Music & Audio",
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          "label": "Measured integrated LUFS",
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          "min": -70,
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        },
        {
          "name": "lthp-peak",
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        {
          "name": "lthp-target",
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          "label": "Desired integrated LUFS",
          "unit": "",
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        {
          "name": "lthp-ceiling",
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          "unit": "dBTP",
          "min": -24,
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          "default": "-1"
        }
      ],
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          "name": "lthp-result",
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      ],
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=lufs-target-headroom-planner&lthp-current=-18&lthp-peak=-3&lthp-target=-14&lthp-ceiling=-1"
      },
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      "sources": [],
      "tags": [
        "lufs",
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        "headroom",
        "planner",
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      "popularity": 4029,
      "featured": false,
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      "slug": "luhn-check-digit-validator",
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      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=luhn-check-digit-validator&embed=1",
      "standaloneUrl": null,
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        {
          "name": "luhn-in",
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          "label": "Number",
          "unit": ""
        }
      ],
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        {
          "name": "luhn-out",
          "type": "output"
        }
      ],
      "prefill": {
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        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "luhn",
        "check",
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        "algorithms",
        "computer",
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      ],
      "popularity": 4737,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "lumen-lux-calculator",
      "title": "💡 Lumens ⇄ Lux",
      "description": "Lux = lumens ÷ area (m²) when light is spread evenly. A 800 lm bulb over a 10 m² desk is 80 lux — offices often want 300–500 lux. Beam angle and bounce are ignored.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/lumen-lux-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=lumen-lux-calculator&embed=1",
      "standaloneUrl": null,
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          "min": 0,
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        {
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          "type": "number",
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        },
        {
          "name": "lmlx-cd",
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          "label": "Candela",
          "unit": "",
          "min": 0
        },
        {
          "name": "lmlx-d",
          "type": "number",
          "label": "Distance",
          "unit": "m",
          "min": 0.1,
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        }
      ],
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      ],
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      },
      "formula": "Lumens ⇄ Lux Lux = lumens ÷",
      "sources": [],
      "tags": [
        "lumen",
        "lux",
        "lumens",
        "science",
        "engineering",
        "area",
        "when",
        "light",
        "spread",
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      ],
      "popularity": 5320,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "lunar-phase-illuminator",
      "title": "🌙 Lunar Phase & Illumination",
      "description": "Phase, illumination fraction, age and a drawn disc for any date and time — plus the next new and full Moons and how much moonlight is washing out the sky. Runs entirely offline.",
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      "categoryName": "Astronomy & Space",
      "url": "https://www.themostusefulsiteintheworld.com/tool/lunar-phase-illuminator.html",
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      "standaloneUrl": null,
      "inputs": [
        {
          "name": "lpi-date",
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          "label": "Date",
          "unit": ""
        },
        {
          "name": "lpi-time",
          "type": "time",
          "label": "Time",
          "unit": "UTC",
          "default": "22:00"
        }
      ],
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        {
          "name": "lpi-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=lunar-phase-illuminator&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "lunar",
        "phase",
        "illuminator",
        "illumination",
        "astronomy",
        "space",
        "fraction",
        "age",
        "drawn",
        "disc"
      ],
      "popularity": 5483,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "lunar-tide-simulator",
      "title": "🌕 Lunar Tide Simulator",
      "description": "The equilibrium tide, live: Moon and Sun each raise two opposing bulges (H ∝ cos²θ), Earth rotates beneath them, and the 24h50m lunar day makes the tide arrive 50 minutes later every day. Set the l...",
      "category": "interactive-art-and-living-worlds",
      "categoryName": "Interactive Art & Living Worlds",
      "url": "https://www.themostusefulsiteintheworld.com/tool/lunar-tide-simulator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=lunar-tide-simulator&embed=1",
      "standaloneUrl": null,
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          "max": 29.5,
          "step": 0.1,
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          "name": "tid-slider-mdist",
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          "name": "tid-slider-sdist",
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        },
        {
          "name": "tid-slider-amp",
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          "label": "slider amp",
          "unit": "",
          "min": 1,
          "max": 12,
          "step": 0.5,
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        },
        {
          "name": "tid-slider-clock",
          "type": "range",
          "label": "slider clock",
          "unit": "",
          "min": 0,
          "max": 25,
          "step": 0.05,
          "default": "0"
        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=lunar-tide-simulator&<id>=<value>",
        "runs": false,
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      },
      "formula": "Equilibrium tide: H = A_m·cos²(θ_m) +",
      "sources": [],
      "tags": [
        "lunar",
        "tide",
        "simulator",
        "interactive",
        "art",
        "living",
        "worlds",
        "equilibrium",
        "live",
        "moon"
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "macros",
      "title": "🥗 Smart Macros Calculator",
      "description": "🏋️ Achieve your goals: Calculate protein, carbs, and fats for weight loss, muscle gain, or maintenance. Get personalized meal plans and food suggestions.",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/macros.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=macros&embed=1",
      "standaloneUrl": null,
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          "min": 15,
          "max": 100,
          "default": "30"
        },
        {
          "name": "mc-weight",
          "type": "number",
          "label": "Weight",
          "unit": "kg",
          "min": 40,
          "max": 200,
          "step": 0.5,
          "default": "70"
        },
        {
          "name": "mc-height",
          "type": "number",
          "label": "Height",
          "unit": "cm",
          "min": 140,
          "max": 220,
          "default": "175"
        },
        {
          "name": "mc-protein-slider",
          "type": "range",
          "label": "protein slider",
          "unit": "",
          "min": 10,
          "max": 50,
          "step": 1,
          "default": "30"
        },
        {
          "name": "mc-carbs-slider",
          "type": "range",
          "label": "carbs slider",
          "unit": "",
          "min": 20,
          "max": 60,
          "step": 1,
          "default": "40"
        },
        {
          "name": "mc-fat-slider",
          "type": "range",
          "label": "fat slider",
          "unit": "",
          "min": 15,
          "max": 40,
          "step": 1,
          "default": "30"
        },
        {
          "name": "mc-custom-calories",
          "type": "number",
          "label": "custom calories",
          "unit": "",
          "min": 1200,
          "max": 5000,
          "step": 50,
          "default": "2000"
        },
        {
          "name": "mc-activity",
          "type": "select-one",
          "label": "Activity Level",
          "unit": "",
          "options": [
            "1.2",
            "1.375",
            "1.55",
            "1.725",
            "1.9"
          ],
          "default": "1.375"
        }
      ],
      "outputs": [
        {
          "name": "mc-ratio-total",
          "type": "output"
        },
        {
          "name": "mc-protein-value",
          "type": "output"
        },
        {
          "name": "mc-carbs-value",
          "type": "output"
        },
        {
          "name": "mc-fat-value",
          "type": "output"
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        {
          "name": "mc-goal-display",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=macros&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=macros&mc-age=30&mc-weight=70&mc-height=175&mc-protein-slider=30&mc-carbs-slider=40&mc-fat-slider=30&run=1"
      },
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      "sources": [],
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        "macros",
        "smart",
        "health",
        "fitness",
        "achieve",
        "goals",
        "calculate",
        "protein",
        "carbs",
        "fats"
      ],
      "popularity": 6881,
      "featured": false,
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    },
    {
      "slug": "magic-background-eraser-pro",
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      "description": "One-tap background removal, chroma key, edge feathering and 2×/4× upscaling — the offline replacement for remove.bg & Let's Enhance. Flood-fill magic wand, color distance, and canvas compositing. E...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=magic-background-eraser-pro&embed=1",
      "standaloneUrl": null,
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        {
          "name": "mberaser-tol",
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          "min": 4,
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        },
        {
          "name": "mberaser-feather",
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        {
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        {
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        {
          "name": "mberaser-bg-mode",
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            "transparent",
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        {
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            "png",
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            "jpeg"
          ],
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      ],
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        {
          "name": "mberaser-zoom-out",
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=magic-background-eraser-pro&<id>=<value>",
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      },
      "formula": "Upscaling uses imageSmoothingQuality = 'high' bicubic via an offscreen canvas (2× / 4×",
      "sources": [],
      "tags": [
        "magic",
        "background",
        "eraser",
        "pro",
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        "saas",
        "business",
        "killers",
        "one-tap",
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      ],
      "popularity": 4459,
      "featured": false,
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    },
    {
      "slug": "magic-square-lab",
      "title": "🔮 Magic Square Lab — Generate & Verify",
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      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/magic-square-lab.html",
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      "standaloneUrl": null,
      "inputs": [
        {
          "name": "msl-order",
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            "3",
            "4",
            "5",
            "6",
            "7",
            "8",
            "9",
            "10",
            "11",
            "12",
            "13",
            "14"
          ]
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=magic-square-lab&<id>=<value>",
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      },
      "formula": "Magic constant for order 4 : 34 = n(n² + 1)/",
      "sources": [],
      "tags": [
        "magic",
        "square",
        "lab",
        "generate",
        "verify",
        "mathematics",
        "fill",
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        "every",
        "row"
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      "popularity": 4981,
      "featured": false,
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    },
    {
      "slug": "magnetic-eddy-current-brake",
      "title": "🧲 Lenz's Law Eddy Current Tube",
      "description": "Lenz's law electromagnetic braking exhibit. Drop a strong neodymium magnet down metal tubes; circulating eddy currents oppose motion, creating levitation-like terminal float.",
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      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/magnetic-eddy-current-brake.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=magnetic-eddy-current-brake&embed=1",
      "standaloneUrl": null,
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        {
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          "type": "range",
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          "min": 20,
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        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=magnetic-eddy-current-brake&<id>=<value>",
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      },
      "formula": "Terminal Velocity vt = 0.08 m/",
      "sources": [],
      "tags": [
        "magnetic",
        "eddy",
        "current",
        "brake",
        "lenz",
        "law",
        "tube",
        "finance",
        "money",
        "electromagnetic"
      ],
      "popularity": 5567,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "magnetic-levitation-meissner-lab",
      "title": "🧲 Superconductor Flux Pinning",
      "description": "Type-II high-temperature superconductor cryogenic lab. Explore Meissner effect magnetic field expulsion and quantum flux pinning levitation.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/magnetic-levitation-meissner-lab.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=magnetic-levitation-meissner-lab&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sfp-slider-temp",
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          "label": "slider temp",
          "unit": "",
          "min": 60,
          "max": 130,
          "default": "77"
        },
        {
          "name": "sfp-slider-field",
          "type": "range",
          "label": "slider field",
          "unit": "",
          "min": 0.5,
          "max": 2.5,
          "step": 0.1,
          "default": "1.4"
        }
      ],
      "outputs": [
        {
          "name": "sfp-force-readout",
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        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=magnetic-levitation-meissner-lab&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "magnetic",
        "levitation",
        "meissner",
        "lab",
        "superconductor",
        "flux",
        "pinning",
        "science",
        "engineering",
        "type-ii"
      ],
      "popularity": 5383,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "magnetometer-field-log",
      "title": "🧲 Magnetic Field Log",
      "description": "If your browser exposes a magnetometer, read the phone's real magnetic field in microteslas, set a baseline, and mark changes with time. Unsupported devices stay honestly blank—no simulated readings.",
      "category": "horror-and-paranormal",
      "categoryName": "Horror & Paranormal",
      "url": "https://www.themostusefulsiteintheworld.com/tool/magnetometer-field-log.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=magnetometer-field-log&embed=1",
      "standaloneUrl": null,
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        {
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          "type": "live"
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=magnetometer-field-log&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "magnetometer",
        "field",
        "log",
        "magnetic",
        "horror",
        "paranormal",
        "browser",
        "exposes",
        "read",
        "phone"
      ],
      "popularity": 4936,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mailto-link-builder",
      "title": "✉️ Mailto Link Builder & Decoder",
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      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mailto-link-builder.html",
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      "standaloneUrl": null,
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        {
          "name": "mailto-link-builder-to",
          "type": "text",
          "label": "To (separate several addresses with commas)",
          "unit": ""
        },
        {
          "name": "mailto-link-builder-cc",
          "type": "text",
          "label": "Cc",
          "unit": ""
        },
        {
          "name": "mailto-link-builder-bcc",
          "type": "text",
          "label": "Bcc",
          "unit": ""
        },
        {
          "name": "mailto-link-builder-text",
          "type": "text",
          "label": "Link text (HTML/Markdown)",
          "unit": ""
        },
        {
          "name": "mailto-link-builder-subject",
          "type": "text",
          "label": "Subject",
          "unit": ""
        },
        {
          "name": "mailto-link-builder-body",
          "type": "textarea",
          "label": "Body — line breaks are kept",
          "unit": ""
        },
        {
          "name": "mailto-link-builder-url",
          "type": "textarea",
          "label": "mailto: URL",
          "unit": ""
        },
        {
          "name": "mailto-link-builder-html",
          "type": "textarea",
          "label": "HTML",
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        },
        {
          "name": "mailto-link-builder-md",
          "type": "textarea",
          "label": "Markdown",
          "unit": ""
        },
        {
          "name": "mailto-link-builder-decode-input",
          "type": "textarea",
          "label": "Paste a mailto: link or an <a href=\"mailto:…\"> tag",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "mailto-link-builder-status",
          "type": "live"
        },
        {
          "name": "mailto-link-builder-decode-status",
          "type": "live"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mailto-link-builder&<id>=<value>",
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      "sources": [],
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        "mailto",
        "link",
        "builder",
        "decoder",
        "algorithms",
        "computer",
        "science",
        "make",
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        "encoded"
      ],
      "popularity": 4963,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "make-change-trainer",
      "title": "💰 Make Change Trainer (UK coins)",
      "description": "Work out the change from UK coins and notes, then hand the exact coins with the fewest pieces. Learn the greedy method for 1p–£2 and practise 5 rounds. Everything runs on your device.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/make-change-trainer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=make-change-trainer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "chg-price",
          "type": "number",
          "label": "Price",
          "unit": "£",
          "min": 0.01,
          "max": 250,
          "step": 0.01,
          "default": "3.47"
        },
        {
          "name": "chg-paid",
          "type": "select-one",
          "label": "Tendered",
          "unit": "£",
          "options": [
            "5",
            "10",
            "20",
            "50"
          ],
          "default": "5"
        }
      ],
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        {
          "name": "chg-score",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=make-change-trainer&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "make",
        "change",
        "trainer",
        "coins",
        "finance",
        "money",
        "work",
        "out",
        "notes",
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      ],
      "popularity": 4239,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mandelbrot-set-explorer",
      "title": "🌀 Mandelbrot Set Explorer",
      "description": "One line — z &rarr; z² + c — repeated over and over produces infinite, self-similar complexity. Click anywhere to zoom in forever.",
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      "categoryName": "Mind-Blowing Demos",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mandelbrot-set-explorer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mandelbrot-set-explorer&embed=1",
      "standaloneUrl": null,
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        {
          "name": "mnd-iter",
          "type": "range",
          "label": "Iterations",
          "unit": "",
          "min": 40,
          "max": 600,
          "default": "150"
        }
      ],
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        {
          "name": "mnd-out",
          "type": "output"
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mandelbrot-set-explorer&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=mandelbrot-set-explorer&mnd-iter=150"
      },
      "formula": "Take any point c on the plane. Start z at 0 and keep doing z = z&sup2; +",
      "sources": [],
      "tags": [
        "mandelbrot",
        "set",
        "explorer",
        "mind-blowing",
        "demos",
        "one",
        "line",
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        "over"
      ],
      "popularity": 4391,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "manga-to-anime-chapter-converter",
      "title": "📖 Manga to Anime Finder",
      "description": "Finished an anime season and want to continue the story? Find the exact manga chapter and volume where the anime left off, along with chapter pacing and estimated reading catch-up time.",
      "category": "anime-and-otaku-culture",
      "categoryName": "Anime & Otaku Culture",
      "url": "https://www.themostusefulsiteintheworld.com/tool/manga-to-anime-chapter-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=manga-to-anime-chapter-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mb-series-select",
          "type": "select-one",
          "label": "Select Anime Season Finale",
          "unit": "",
          "options": [
            "csm_s1",
            "jjk_s2",
            "frieren_s1",
            "demon_slayer_ht",
            "vinland_s2",
            "oshi_no_ko_s1",
            "bocchi",
            "spy_family_s2",
            "solo_leveling_s1",
            "berserk"
          ],
          "default": "csm_s1"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=manga-to-anime-chapter-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=manga-to-anime-chapter-converter&mb-series-select=csm_s1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "manga",
        "anime",
        "chapter",
        "converter",
        "finder",
        "otaku",
        "culture",
        "finished",
        "season",
        "want"
      ],
      "popularity": 4890,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "map-projection-distortion-lab",
      "title": "🗺️ Map Projection Distortion Lab",
      "description": "Every flat world map lies — the only question is how. Draw nine real projections, overlay Tissot's indicatrix (circles that show exactly how the map stretches), and get the area and angle distortio...",
      "category": "interactive-art-and-living-worlds",
      "categoryName": "Interactive Art & Living Worlds",
      "url": "https://www.themostusefulsiteintheworld.com/tool/map-projection-distortion-lab.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=map-projection-distortion-lab&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mpdl-tissot",
          "type": "checkbox",
          "label": "Tissot's indicatrix",
          "unit": "",
          "default": "1"
        },
        {
          "name": "mpdl-proj",
          "type": "select-one",
          "label": "Projection",
          "unit": "",
          "options": [
            "mercator",
            "equirect",
            "gallpeters",
            "mollweide",
            "sinusoidal",
            "robinson",
            "winkel",
            "azeq",
            "ortho"
          ],
          "default": "mercator"
        },
        {
          "name": "mpdl-grid",
          "type": "select-one",
          "label": "Graticule spacing",
          "unit": "",
          "options": [
            "30",
            "15",
            "10",
            "0"
          ],
          "default": "30"
        },
        {
          "name": "mpdl-shade",
          "type": "select-one",
          "label": "Distortion shading",
          "unit": "",
          "options": [
            "area",
            "angle",
            "none"
          ],
          "default": "area"
        },
        {
          "name": "mpdl-regA",
          "type": "select-one",
          "label": "Region A",
          "unit": ""
        },
        {
          "name": "mpdl-regB",
          "type": "select-one",
          "label": "Region B",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "mpdl-readout",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=map-projection-distortion-lab&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=map-projection-distortion-lab&mpdl-tissot=1&mpdl-proj=mercator&mpdl-grid=30&mpdl-shade=area"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "map",
        "projection",
        "distortion",
        "lab",
        "interactive",
        "art",
        "living",
        "worlds",
        "every",
        "flat"
      ],
      "popularity": 4134,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "markdown-live-editor",
      "title": "📝 Markdown Live Editor",
      "description": "Write, preview, and format Markdown in real-time. Features instant HTML rendering, live word & reading time analytics, syntax quick-tags, and 1-click export to Markdown or HTML.",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/markdown-live-editor.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=markdown-live-editor&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "markdown-raw-input",
          "type": "textarea",
          "label": "markdown raw input",
          "unit": ""
        }
      ],
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      "category": "culinary-and-food-science",
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        {
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        "mean",
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        },
        {
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          "type": "number",
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      ],
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      "popularity": 5890,
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    },
    {
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      "categoryName": "Productivity & Lifestyle",
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    {
      "slug": "meat-brining-salinity-calculator",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
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      "tags": [
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      ],
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          "name": "mitg-out",
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      ],
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        {
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          "type": "textarea",
          "label": "Topics — one per line: title | minutes Check-in | 5 Project updates | 15 Decisions | 20 Next steps | 5",
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      },
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      "sources": [],
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      },
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    {
      "slug": "meeting-cost-live-ticker",
      "title": "💸 Meeting Cost Ticker",
      "description": "Track real-time company salary burn during meetings. Keep discussions focused, respect employee time, and visualize the true cost of every minute.",
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      "categoryName": "SaaS & Business Killers",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=meeting-cost-live-ticker&embed=1",
      "standaloneUrl": null,
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        {
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        {
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        {
          "name": "mct-currency",
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          "label": "currency",
          "unit": "",
          "options": [
            "$",
            "£",
            "€"
          ],
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        }
      ],
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        {
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=meeting-cost-live-ticker&<id>=<value>",
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      "sources": [],
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        "meeting",
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        "business",
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      ],
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        "meeting",
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            "15",
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            "60",
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            "UTC",
            "EST",
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            "CET",
            "IST",
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            "AEST"
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    },
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            "all",
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            "minerals",
            "common"
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        {
          "name": "mpf-sort",
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          "unit": "",
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            "1atm",
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            "high_pressure"
          ],
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        {
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        }
      ],
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    },
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        },
        {
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            "1080x1080",
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      ],
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      },
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        "productivity",
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        {
          "name": "mt-era",
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          "label": "Internet Era",
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            "gaming",
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      ],
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      "featured": false,
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    },
    {
      "slug": "memento-mori-life-ticker",
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      "standaloneUrl": null,
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          "unit": "",
          "min": 1,
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        },
        {
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          "label": "expect",
          "unit": "",
          "min": 60,
          "max": 100,
          "default": "80"
        }
      ],
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        {
          "name": "mmt-out",
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      ],
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      },
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        "memento",
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      "featured": false,
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    },
    {
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      "category": "productivity-and-lifestyle",
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      "url": "https://www.themostusefulsiteintheworld.com/tool/memorization.html",
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      "standaloneUrl": null,
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        {
          "name": "memorization-item",
          "type": "text",
          "label": "Add Item to Memorize",
          "unit": ""
        }
      ],
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        {
          "name": "mem-test-answer",
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        }
      ],
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      "sources": [],
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        "helper",
        "productivity",
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      "featured": false,
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    },
    {
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      "categoryName": "Productivity & Lifestyle",
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      "standaloneUrl": null,
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        {
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        },
        {
          "name": "mpl-item",
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          "unit": ""
        }
      ],
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        "runs": false
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        "palace",
        "loci",
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        "productivity",
        "lifestyle",
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    },
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            "1",
            "2"
          ],
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      ],
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        {
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      ],
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        },
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            "cal",
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          "default": "Next time I'm dreaming, I will remember that I'm dreaming."
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      "featured": false,
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    {
      "slug": "mime-type-lookup-table",
      "title": "📎 MIME Type Lookup",
      "description": "Convert a file extension to a MIME type, or a MIME type back to common extensions. Handy when writing Content-Type headers, nginx maps or <input accept> lists. Lookup is local.",
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      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mime-type-lookup-table.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mime-type-lookup-table&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mtlk-q",
          "type": "search",
          "label": "Extension or MIME type",
          "unit": ""
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mime-type-lookup-table&<id>=<value>",
        "runs": false
      },
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      "sources": [],
      "tags": [
        "mime",
        "type",
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      "popularity": 6507,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mind-map-studio",
      "title": "🧠 Mind Map Studio",
      "description": "A proper mind map in the browser: Tab for a child, Enter for a sibling, drag to rearrange, collapse branches you are not working on, and export as an image, a Markdown outline or a JSON file you ca...",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mind-map-studio.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mind-map-studio&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mmap-text",
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          "label": "Edit the selected node (Enter = new sibling · Ctrl+Enter = new child)",
          "unit": ""
        },
        {
          "name": "mmap-colour",
          "type": "select-one",
          "label": "Branch colour",
          "unit": ""
        }
      ],
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        {
          "name": "mmap-msg",
          "type": "live"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mind-map-studio&<id>=<value>",
        "runs": false
      },
      "formula": "Edit the selected node (Enter = new sibling · Ctrl+",
      "sources": [],
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        "mind",
        "map",
        "studio",
        "productivity",
        "lifestyle",
        "proper",
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        "tab",
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      "popularity": 5002,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "miter-bevel-angle-calculator",
      "title": "📐 Miter & Bevel Angle Calculator",
      "description": "Set the saw for a perfect corner: enter the corner angle and pick flat or crown molding, and get the miter and bevel angles to dial in.",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/miter-bevel-angle-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=miter-bevel-angle-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mtr-corner",
          "type": "number",
          "label": "Corner angle",
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        {
          "name": "mtr-type",
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          "label": "Joint type",
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          "options": [
            "flat",
            "crown"
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        {
          "name": "mtr-spring",
          "type": "select-one",
          "label": "Spring angle",
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          "options": [
            "38",
            "45",
            "52"
          ],
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        }
      ],
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        {
          "name": "mtr-out",
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        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=miter-bevel-angle-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=miter-bevel-angle-calculator&mtr-corner=90&mtr-type=flat&mtr-spring=38"
      },
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        "miter",
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        "angle",
        "home",
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        "set",
        "saw",
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        "corner",
        "enter"
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      "popularity": 4535,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mock-data-generator",
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      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mock-data-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mock-data-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mdg-count",
          "type": "number",
          "label": "Rows",
          "unit": "1–200",
          "min": 1,
          "max": 200,
          "default": "8"
        },
        {
          "name": "mdg-seed",
          "type": "number",
          "label": "Seed",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "20260907"
        },
        {
          "name": "mdg-output",
          "type": "textarea",
          "label": "Generated sample data",
          "unit": ""
        },
        {
          "name": "mdg-kind",
          "type": "select-one",
          "label": "Dataset",
          "unit": "",
          "options": [
            "customers",
            "products",
            "events"
          ],
          "default": "customers"
        },
        {
          "name": "mdg-format",
          "type": "select-one",
          "label": "Export format",
          "unit": "",
          "options": [
            "json",
            "csv",
            "sql"
          ],
          "default": "json"
        }
      ],
      "outputs": [
        {
          "name": "mdg-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mock-data-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=mock-data-generator&mdg-count=8&mdg-seed=20260907&mdg-kind=customers&mdg-format=json"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "mock",
        "data",
        "saas",
        "business",
        "killers",
        "create",
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        "customer",
        "product"
      ],
      "popularity": 5013,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "model-rocket-stability-barrowman",
      "title": "🚀 Model Rocket Stability, CP & Ballast",
      "description": "Find the centre of pressure with the Barrowman method, compare it with your centre of gravity and read the static margin in calibers — then calculate the nose ballast needed to reach a stable margin.",
      "category": "rocketry-and-propulsion",
      "categoryName": "Rocketry & Propulsion",
      "url": "https://www.themostusefulsiteintheworld.com/tool/model-rocket-stability-barrowman.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=model-rocket-stability-barrowman&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mrs-nose-len",
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          "label": "Nose length",
          "unit": "mm",
          "min": 1,
          "step": 1,
          "default": "180"
        },
        {
          "name": "mrs-body-len",
          "type": "number",
          "label": "Body tube length",
          "unit": "mm",
          "min": 1,
          "step": 1,
          "default": "420"
        },
        {
          "name": "mrs-dia",
          "type": "number",
          "label": "Body diameter",
          "unit": "mm",
          "min": 1,
          "step": 0.1,
          "default": "50"
        },
        {
          "name": "mrs-fin-root",
          "type": "number",
          "label": "Root chord",
          "unit": "mm",
          "min": 1,
          "step": 0.1,
          "default": "110"
        },
        {
          "name": "mrs-fin-tip",
          "type": "number",
          "label": "Tip chord",
          "unit": "mm",
          "min": 0,
          "step": 0.1,
          "default": "55"
        },
        {
          "name": "mrs-fin-span",
          "type": "number",
          "label": "Semi-span, body to tip",
          "unit": "mm",
          "min": 1,
          "step": 0.1,
          "default": "80"
        },
        {
          "name": "mrs-fin-sweep",
          "type": "number",
          "label": "Leading-edge sweep",
          "unit": "mm",
          "min": 0,
          "step": 0.1,
          "default": "45"
        },
        {
          "name": "mrs-mass",
          "type": "number",
          "label": "All-up mass, motor fitted",
          "unit": "g",
          "min": 1,
          "step": 1,
          "default": "620"
        },
        {
          "name": "mrs-cg",
          "type": "number",
          "label": "CG station from nose tip",
          "unit": "mm",
          "min": 0,
          "step": 1,
          "default": "410"
        },
        {
          "name": "mrs-margin",
          "type": "number",
          "label": "Target static margin",
          "unit": "calibers",
          "min": 0,
          "max": 5,
          "step": 0.1,
          "default": "1.5"
        },
        {
          "name": "mrs-ballast-station",
          "type": "number",
          "label": "Ballast station from nose tip",
          "unit": "mm",
          "min": 0,
          "step": 1,
          "default": "8"
        },
        {
          "name": "mrs-nose-shape",
          "type": "select-one",
          "label": "Nose shape",
          "unit": "",
          "options": [
            "0.666",
            "0.466",
            "0.500",
            "0.666"
          ],
          "default": "0.666"
        },
        {
          "name": "mrs-fin-count",
          "type": "select-one",
          "label": "Number of fins",
          "unit": "",
          "options": [
            "3",
            "4",
            "5",
            "6"
          ],
          "default": "3"
        }
      ],
      "outputs": [
        {
          "name": "mrs-out",
          "type": "live"
        },
        {
          "name": "mrs-cg-out",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=model-rocket-stability-barrowman&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=model-rocket-stability-barrowman&mrs-nose-len=180&mrs-body-len=420&mrs-dia=50&mrs-fin-root=110&mrs-fin-tip=55&mrs-fin-span=80"
      },
      "formula": "Each trapezoidal fin set contributes CNα(fin) = 4·N·(s/d)² / (1 + √(1 + (2·l/(a+",
      "sources": [],
      "tags": [
        "model",
        "rocket",
        "stability",
        "barrowman",
        "ballast",
        "rocketry",
        "propulsion",
        "find",
        "centre",
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      ],
      "popularity": 6254,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mohs-hardness-gallery",
      "title": "💎 The Mohs Gallery",
      "description": "Friedrich Mohs, 1812: a mineral of higher number scratches one of lower number. The steps are not equal — corundum to diamond is a canyon. Pick two specimens (or a thumbnail and a steel file) and t...",
      "category": "museum-and-collection",
      "categoryName": "Museum & Collection",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mohs-hardness-gallery.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mohs-hardness-gallery&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mohs-a",
          "type": "select-one",
          "label": "Specimen A",
          "unit": ""
        },
        {
          "name": "mohs-b",
          "type": "select-one",
          "label": "Specimen B",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "mohs-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mohs-hardness-gallery&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "mohs",
        "hardness",
        "gallery",
        "museum",
        "collection",
        "friedrich",
        "1812",
        "mineral",
        "higher",
        "number"
      ],
      "popularity": 5025,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "moire-interference-lattice",
      "title": "〰️ Moiré Optical Interference",
      "description": "Kinetic optical interference exhibit. Overlay geometric optical gratings and rotate them to observe emergent macro-scale moiré superlattices.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/moire-interference-lattice.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=moire-interference-lattice&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mil-slider-angle",
          "type": "range",
          "label": "slider angle",
          "unit": "",
          "min": 0,
          "max": 90,
          "step": 0.1,
          "default": "1.1"
        },
        {
          "name": "mil-slider-density",
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          "label": "slider density",
          "unit": "",
          "min": 16,
          "max": 90,
          "default": "48"
        },
        {
          "name": "mil-slider-scale",
          "type": "range",
          "label": "slider scale",
          "unit": "",
          "min": 0.8,
          "max": 1.2,
          "step": 0.01,
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        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=moire-interference-lattice&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=moire-interference-lattice&mil-slider-angle=1.1&mil-slider-density=48&mil-slider-scale=1.0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "moire",
        "interference",
        "lattice",
        "moir",
        "optical",
        "science",
        "engineering",
        "kinetic",
        "exhibit",
        "overlay"
      ],
      "popularity": 6666,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "moisture-capillary-simulator",
      "title": "🧪 The Moisture Lab",
      "description": "Watch water migrate through building materials via capillary action — the same force that makes a sponge soak up water and makes your walls draw moisture from the ground. See why rising damp happen...",
      "category": "museum-and-collection",
      "categoryName": "Museum & Collection",
      "url": "https://www.themostusefulsiteintheworld.com/tool/moisture-capillary-simulator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=moisture-capillary-simulator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ml-wt",
          "type": "range",
          "label": "wt",
          "unit": "",
          "min": 0,
          "max": 2,
          "step": 0.1,
          "default": "0.5"
        },
        {
          "name": "ml-hum",
          "type": "range",
          "label": "hum",
          "unit": "",
          "min": 30,
          "max": 95,
          "default": "65"
        },
        {
          "name": "ml-thick",
          "type": "range",
          "label": "thick",
          "unit": "",
          "min": 100,
          "max": 450,
          "step": 25,
          "default": "225"
        },
        {
          "name": "ml-speed",
          "type": "range",
          "label": "speed",
          "unit": "",
          "min": 1,
          "max": 10,
          "default": "1"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=moisture-capillary-simulator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=moisture-capillary-simulator&ml-wt=0.5&ml-hum=65&ml-thick=225&ml-speed=1"
      },
      "formula": "Capillary rise follows the Washburn equation : h = 2γcos(θ) /",
      "sources": [],
      "tags": [
        "moisture",
        "capillary",
        "simulator",
        "lab",
        "museum",
        "collection",
        "watch",
        "water",
        "migrate",
        "through"
      ],
      "popularity": 6661,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mojibake-text-repair",
      "title": "🔤 Mojibake Repair — Fix Garbled é ’ Text",
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      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mojibake-text-repair.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mojibake-text-repair&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mojibake-text-repair-in",
          "type": "textarea",
          "label": "Garbled text",
          "unit": ""
        },
        {
          "name": "mojibake-text-repair-out",
          "type": "textarea",
          "label": "Repaired text",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "mojibake-text-repair-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mojibake-text-repair&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "mojibake",
        "text",
        "repair",
        "fix",
        "garbled",
        "algorithms",
        "computer",
        "science",
        "turn",
        "caf"
      ],
      "popularity": 4306,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "molecule-3d-viewer",
      "title": "⚛️ Molecule 3D Viewer",
      "description": "Eleven molecules and crystals as true ball-and-stick 3D — from water to a salt lattice to a diamond unit cell. Bonds are detected automatically from atomic distances, double/triple bonds included. ...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/molecule-3d-viewer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=molecule-3d-viewer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ml3-spin",
          "type": "checkbox",
          "label": "spin",
          "unit": "",
          "default": "1"
        },
        {
          "name": "ml3-labels",
          "type": "checkbox",
          "label": "element labels",
          "unit": "",
          "default": "1"
        },
        {
          "name": "ml3-ball",
          "type": "range",
          "label": "Ball size",
          "unit": "",
          "min": 60,
          "max": 140,
          "default": "100"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=molecule-3d-viewer&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=molecule-3d-viewer&ml3-spin=1&ml3-labels=1&ml3-ball=100"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "molecule",
        "viewer",
        "science",
        "engineering",
        "eleven",
        "molecules",
        "crystals",
        "true",
        "ball-and-stick",
        "water"
      ],
      "popularity": 6289,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "monte-carlo-pi-estimator",
      "title": "🎯 Monte Carlo π Estimator",
      "description": "Watch &pi; emerge from pure chance: random points rain on a square with a circle inside, and the ratio that lands in the circle is exactly &pi;/4. No formula — just probability converging on a univ...",
      "category": "mind-blowing-demos",
      "categoryName": "Mind-Blowing Demos",
      "url": "https://www.themostusefulsiteintheworld.com/tool/monte-carlo-pi-estimator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=monte-carlo-pi-estimator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mpi-ppf",
          "type": "number",
          "label": "Points/frame",
          "unit": "",
          "min": 1,
          "max": 5000,
          "default": "300"
        }
      ],
      "outputs": [
        {
          "name": "mpi-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=monte-carlo-pi-estimator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=monte-carlo-pi-estimator&mpi-ppf=300"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "monte",
        "carlo",
        "estimator",
        "mind-blowing",
        "demos",
        "watch",
        "emerge",
        "pure",
        "chance",
        "random"
      ],
      "popularity": 5582,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "moon-phases-eclipse-geometry",
      "title": "🌘 Moon Phases & Eclipse Geometry",
      "description": "Why do phases exist, and why are eclipses so rare? Spin the Moon around Earth (its real orbital inclination is 5.14°) and rotate the line of nodes — the place where the Moon's tilted orbit crosses ...",
      "category": "astronomy-and-space",
      "categoryName": "Astronomy & Space",
      "url": "https://www.themostusefulsiteintheworld.com/tool/moon-phases-eclipse-geometry.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=moon-phases-eclipse-geometry&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mpe-slider-u",
          "type": "range",
          "label": "slider u",
          "unit": "",
          "min": 0,
          "max": 360,
          "step": 1,
          "default": "0"
        },
        {
          "name": "mpe-slider-node",
          "type": "range",
          "label": "slider node",
          "unit": "",
          "min": 0,
          "max": 360,
          "step": 1,
          "default": "0"
        },
        {
          "name": "mpe-slider-tilt",
          "type": "range",
          "label": "slider tilt",
          "unit": "",
          "min": 0,
          "max": 1,
          "step": 1,
          "default": "0"
        },
        {
          "name": "mpe-slider-cam",
          "type": "range",
          "label": "slider cam",
          "unit": "",
          "min": 0,
          "max": 88,
          "step": 1,
          "default": "20"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=moon-phases-eclipse-geometry&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=moon-phases-eclipse-geometry&mpe-slider-u=0&mpe-slider-node=0&mpe-slider-tilt=0&mpe-slider-cam=20"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "moon",
        "phases",
        "eclipse",
        "geometry",
        "astronomy",
        "space",
        "why",
        "exist",
        "eclipses",
        "rare"
      ],
      "popularity": 4783,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "morse-code-translator",
      "title": "📡 Morse Code Translator",
      "description": "Translate text to Morse code and back. Listen to the Morse code audio and learn the international standard.",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/morse-code-translator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=morse-code-translator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mc-text",
          "type": "textarea",
          "label": "Enter text...",
          "unit": ""
        },
        {
          "name": "mc-morse",
          "type": "textarea",
          "label": "Enter morse...",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=morse-code-translator&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "morse",
        "code",
        "translator",
        "writing",
        "language",
        "translate",
        "text",
        "back",
        "listen",
        "audio"
      ],
      "popularity": 5377,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mortgage-affordability-calculator",
      "title": "🏦 Mortgage Affordability — How Much Can You Borrow?",
      "description": "Lenders look at two things at once: an income multiple and an affordability stress test at a rate higher than you will actually pay. This works out which of the two bites first for your numbers, th...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mortgage-affordability-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mortgage-affordability-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "gma-inc1",
          "type": "number",
          "label": "Your annual income",
          "unit": "before tax",
          "min": 0,
          "step": 500,
          "default": "38000"
        },
        {
          "name": "gma-inc2",
          "type": "number",
          "label": "Second applicant",
          "unit": "",
          "min": 0,
          "step": 500,
          "default": "0"
        },
        {
          "name": "gma-dep",
          "type": "number",
          "label": "Deposit available",
          "unit": "£",
          "min": 0,
          "step": 500,
          "default": "25000"
        },
        {
          "name": "gma-debts",
          "type": "number",
          "label": "Monthly loan / card / finance repayments",
          "unit": "£",
          "min": 0,
          "step": 10,
          "default": "250"
        },
        {
          "name": "gma-childcare",
          "type": "number",
          "label": "Monthly childcare",
          "unit": "£",
          "min": 0,
          "step": 10,
          "default": "0"
        },
        {
          "name": "gma-term",
          "type": "number",
          "label": "Mortgage term",
          "unit": "years",
          "min": 5,
          "max": 45,
          "step": 1,
          "default": "25"
        },
        {
          "name": "gma-rate",
          "type": "number",
          "label": "Rate you expect to pay",
          "unit": "%",
          "min": 0.1,
          "max": 20,
          "step": 0.05,
          "default": "4.75"
        },
        {
          "name": "gma-mult",
          "type": "range",
          "label": "Income multiple the lender will use 4.5×",
          "unit": "",
          "min": 3,
          "max": 6,
          "step": 0.1,
          "default": "4.5"
        },
        {
          "name": "gma-stress",
          "type": "number",
          "label": "Stress-test rate",
          "unit": "%",
          "min": 1,
          "max": 20,
          "step": 0.1,
          "default": "7.75"
        },
        {
          "name": "gma-dep-mode",
          "type": "select-one",
          "label": "Deposit",
          "unit": "",
          "options": [
            "amount",
            "pct"
          ],
          "default": "amount"
        }
      ],
      "outputs": [
        {
          "name": "gma-msg",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mortgage-affordability-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=mortgage-affordability-calculator&gma-inc1=38000&gma-inc2=0&gma-dep=25000&gma-debts=250&gma-childcare=0&gma-term=25"
      },
      "formula": "Standard capital-and-interest annuity formula, P = L·r / (1 − (1 +",
      "sources": [],
      "tags": [
        "mortgage",
        "affordability",
        "how",
        "much",
        "can",
        "borrow",
        "finance",
        "money",
        "lenders",
        "look"
      ],
      "popularity": 6162,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mortgage-overpayment-calculator",
      "title": "🏦 Mortgage Overpayment Calculator",
      "description": "See how overpaying cuts your mortgage term and total interest. Add a monthly overpayment, a lump sum, or both, and compare against paying the normal schedule. Full amortisation worked out on your d...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mortgage-overpayment-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mortgage-overpayment-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mo-balance",
          "type": "number",
          "label": "Balance",
          "unit": "",
          "min": 1000,
          "default": "250000"
        },
        {
          "name": "mo-rate",
          "type": "number",
          "label": "Interest rate",
          "unit": "%",
          "min": 0,
          "step": 0.05,
          "default": "4.5"
        },
        {
          "name": "mo-term",
          "type": "number",
          "label": "Remaining term",
          "unit": "years",
          "min": 1,
          "max": 40,
          "default": "25"
        },
        {
          "name": "mo-over",
          "type": "number",
          "label": "Monthly overpayment",
          "unit": "",
          "min": 0,
          "default": "200"
        },
        {
          "name": "mo-lump",
          "type": "number",
          "label": "One-off lump sum",
          "unit": "",
          "min": 0,
          "default": "0"
        },
        {
          "name": "mo-currency",
          "type": "select-one",
          "label": "Currency",
          "unit": "",
          "options": [
            "GBP",
            "USD",
            "EUR",
            "CAD",
            "AUD"
          ],
          "default": "GBP"
        }
      ],
      "outputs": [
        {
          "name": "mo-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mortgage-overpayment-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=mortgage-overpayment-calculator&mo-balance=250000&mo-rate=4.5&mo-term=25&mo-over=200&mo-lump=0&mo-currency=GBP"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "mortgage",
        "overpayment",
        "finance",
        "money",
        "see",
        "how",
        "overpaying",
        "cuts",
        "term",
        "total"
      ],
      "popularity": 6562,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mortgage",
      "title": "🏠 Mortgage Calculator",
      "description": "Calculate detailed mortgage payments with amortization schedules, extra payments analysis, and regional comparisons. 💰 Monthly payments • Total interest • Payoff time • Amortization schedule • Reg...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mortgage.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mortgage&embed=1",
      "standaloneUrl": "https://www.themostusefulsiteintheworld.com/tools/mortgage.html",
      "inputs": [
        {
          "name": "mortgage-price",
          "type": "number",
          "label": "Property Value",
          "unit": "",
          "min": 0,
          "step": 1000,
          "default": "350000"
        },
        {
          "name": "mortgage-down",
          "type": "number",
          "label": "Down Payment",
          "unit": "",
          "min": 0,
          "step": 1000,
          "default": "35000"
        },
        {
          "name": "mortgage-rate",
          "type": "number",
          "label": "Interest Rate",
          "unit": "",
          "min": 0,
          "step": 0.01,
          "default": "4.5"
        },
        {
          "name": "mortgage-years",
          "type": "number",
          "label": "Term Length",
          "unit": "",
          "min": 1,
          "max": 50,
          "step": 1,
          "default": "25"
        },
        {
          "name": "mortgage-extra",
          "type": "number",
          "label": "Extra Monthly Payment",
          "unit": "",
          "min": 0,
          "step": 50,
          "default": "0"
        },
        {
          "name": "mc-property-tax",
          "type": "number",
          "label": "Property Tax",
          "unit": "",
          "min": 0,
          "step": 100,
          "default": "1200"
        },
        {
          "name": "mc-insurance",
          "type": "number",
          "label": "Home Insurance",
          "unit": "",
          "min": 0,
          "step": 50,
          "default": "800"
        },
        {
          "name": "mortgage-currency",
          "type": "select-one",
          "label": "mortgage currency",
          "unit": "",
          "options": [
            "GBP",
            "USD",
            "EUR",
            "CAD",
            "AUD",
            "JPY"
          ],
          "default": "GBP"
        },
        {
          "name": "mortgage-preset",
          "type": "select-one",
          "label": "Region Preset",
          "unit": "",
          "options": [
            "uk",
            "us",
            "de",
            "ca",
            "jp",
            "au",
            "fr"
          ],
          "default": "uk"
        }
      ],
      "outputs": [
        {
          "name": "mc-res-total",
          "type": "output"
        },
        {
          "name": "mc-savings-total",
          "type": "output"
        },
        {
          "name": "mc-table-summary",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mortgage&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=mortgage&mortgage-price=350000&mortgage-down=35000&mortgage-rate=4.5&mortgage-years=25&mortgage-extra=0&mc-property-tax=1200&run=1"
      },
      "formula": "M = P·r·(1+r)ⁿ ÷ ((1+r)ⁿ − 1), r=annual/12, n=years×12.",
      "sources": [],
      "tags": [
        "mortgage",
        "finance",
        "money",
        "calculate",
        "detailed",
        "payments",
        "amortization",
        "schedules",
        "extra",
        "analysis"
      ],
      "popularity": 9880,
      "featured": true,
      "updated": "2026-09-19"
    },
    {
      "slug": "mostusefulmaps",
      "title": "🗺️ MostUsefulMaps — Distance & Place Finder",
      "description": "The site's own map, right here in the card. Drop two points — a town name, a coordinate pair, a Plus Code, a UK grid reference, a UTM coordinate, a Maidenhead locator or a geohash — and get the geo...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mostusefulmaps.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mostusefulmaps&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mum-from",
          "type": "text",
          "label": "From — place, coordinates, Plus Code, grid ref, UTM, Maidenhead or geohash",
          "unit": ""
        },
        {
          "name": "mum-to",
          "type": "text",
          "label": "To — or click the map to drop the second point",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "mum-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mostusefulmaps&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "mostusefulmaps",
        "distance",
        "place",
        "finder",
        "science",
        "engineering",
        "site",
        "own",
        "map",
        "right"
      ],
      "popularity": 6360,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mot-road-tax-reminder",
      "title": "🚗 MOT, Road Tax & Insurance Deadline Reminder",
      "description": "Pop in your UK vehicle dates and see exactly how many days you have left, the earliest date you can take the MOT without losing time on your certificate, and a plain-English checklist to copy into ...",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mot-road-tax-reminder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mot-road-tax-reminder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "motr-mot",
          "type": "date",
          "label": "MOT expiry date",
          "unit": ""
        },
        {
          "name": "motr-ved",
          "type": "date",
          "label": "Road tax (VED) due",
          "unit": ""
        },
        {
          "name": "motr-ins",
          "type": "date",
          "label": "Insurance renewal",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "motr-cards",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mot-road-tax-reminder&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "mot",
        "road",
        "tax",
        "reminder",
        "insurance",
        "deadline",
        "productivity",
        "lifestyle",
        "pop",
        "vehicle"
      ],
      "popularity": 4234,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "motor-startup",
      "title": "⚡ Motor Startup Calculator",
      "description": "Calculate motor running/starting currents, cable sizing, protection devices, and voltage drop analysis for electrical installations. 🔧 Running current • Starting current • Cable sizing • Protectio...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/motor-startup.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=motor-startup&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "motor-power",
          "type": "number",
          "label": "Motor Power",
          "unit": "",
          "min": 0.1,
          "step": 0.1,
          "default": "5"
        },
        {
          "name": "motor-voltage",
          "type": "number",
          "label": "Supply Voltage",
          "unit": "",
          "min": 100,
          "step": 1,
          "default": "400"
        },
        {
          "name": "motor-pf",
          "type": "number",
          "label": "Power Factor",
          "unit": "cos φ",
          "min": 0.5,
          "max": 1,
          "step": 0.01,
          "default": "0.85"
        },
        {
          "name": "motor-eff",
          "type": "number",
          "label": "Motor Efficiency",
          "unit": "",
          "min": 50,
          "max": 98,
          "step": 0.1,
          "default": "90"
        },
        {
          "name": "ms-cable-length",
          "type": "number",
          "label": "Cable Length",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "50"
        },
        {
          "name": "ms-show-protection",
          "type": "checkbox",
          "label": "Protection Devices MCB, MCCB, Fuse sizing",
          "unit": "",
          "default": "1"
        },
        {
          "name": "ms-show-voltage-drop",
          "type": "checkbox",
          "label": "Voltage Drop Cable sizing check",
          "unit": "",
          "default": "1"
        },
        {
          "name": "ms-show-safety",
          "type": "checkbox",
          "label": "Safety Guidelines Installation warnings",
          "unit": "",
          "default": "1"
        },
        {
          "name": "motor-power-unit",
          "type": "select-one",
          "label": "power unit",
          "unit": "",
          "options": [
            "kW",
            "hp"
          ],
          "default": "kW"
        },
        {
          "name": "motor-phase",
          "type": "select-one",
          "label": "Phase Configuration",
          "unit": "",
          "options": [
            "three",
            "single"
          ],
          "default": "three"
        },
        {
          "name": "motor-method",
          "type": "select-one",
          "label": "Starting Method",
          "unit": "",
          "options": [
            "dol",
            "star-delta",
            "soft",
            "vfd",
            "auto",
            "reactor"
          ],
          "default": "dol"
        },
        {
          "name": "ms-cable-unit",
          "type": "select-one",
          "label": "cable unit",
          "unit": "",
          "options": [
            "m",
            "ft"
          ],
          "default": "m"
        },
        {
          "name": "ms-cable-material",
          "type": "select-one",
          "label": "Cable Material",
          "unit": "",
          "options": [
            "cu",
            "al"
          ],
          "default": "cu"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=motor-startup&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=motor-startup&motor-power=5&motor-voltage=400&motor-pf=0.85&motor-eff=90&ms-cable-length=50&ms-show-protection=1&run=1"
      },
      "formula": "Running Current Formula 3-phase: I = P / (√3 × V × PF × η) 1-phase: I = P / (V × PF ×",
      "sources": [],
      "tags": [
        "motor",
        "startup",
        "science",
        "engineering",
        "calculate",
        "running",
        "starting",
        "currents",
        "cable",
        "sizing"
      ],
      "popularity": 5045,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "motorsport-lap-time-stint-calculator",
      "title": "🏎️ Motorsport Lap Time & Stint Calculator",
      "description": "Turn a lap time into an average speed and a full race duration, see how much each pit stop costs, and — if you have a rival's lap time — watch the gap grow lap by lap.",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/motorsport-lap-time-stint-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=motorsport-lap-time-stint-calculator&embed=1",
      "standaloneUrl": null,
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          "name": "f1s-lm",
          "type": "number",
          "label": "Lap min",
          "unit": "",
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        },
        {
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          "type": "number",
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          "unit": "",
          "min": 0,
          "step": 0.001,
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        },
        {
          "name": "f1s-len",
          "type": "number",
          "label": "Lap length",
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          "step": 0.01,
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        },
        {
          "name": "f1s-laps",
          "type": "number",
          "label": "Race laps",
          "unit": "",
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        },
        {
          "name": "f1s-pitloss",
          "type": "number",
          "label": "Pit stop loss",
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          "min": 0,
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        },
        {
          "name": "f1s-stops",
          "type": "number",
          "label": "Pit stops",
          "unit": "",
          "min": 0,
          "default": "2"
        },
        {
          "name": "f1s-rm",
          "type": "number",
          "label": "Rival lap min",
          "unit": "",
          "min": 0,
          "default": "1"
        },
        {
          "name": "f1s-rs",
          "type": "number",
          "label": "Rival lap sec",
          "unit": "",
          "min": 0,
          "step": 0.001,
          "default": "27.9"
        }
      ],
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        {
          "name": "f1s-out",
          "type": "live"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=motorsport-lap-time-stint-calculator&<id>=<value>",
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      },
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      "sources": [],
      "tags": [
        "motorsport",
        "lap",
        "time",
        "stint",
        "sports",
        "turn",
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        "full"
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      "featured": false,
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    {
      "slug": "moving-average-forecaster",
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      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/moving-average-forecaster.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=moving-average-forecaster&embed=1",
      "standaloneUrl": null,
      "inputs": [
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        {
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          "label": "forecast steps",
          "unit": "",
          "min": 1,
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        },
        {
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          "unit": ""
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        {
          "name": "mavg-model",
          "type": "select-one",
          "label": "model",
          "unit": "",
          "options": [
            "sma",
            "ema",
            "wma"
          ],
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        }
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        {
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=moving-average-forecaster&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=moving-average-forecaster&mavg-window=3&mavg-horizon=3&mavg-model=sma"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
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      "featured": false,
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    {
      "slug": "moving-house-box-estimator",
      "title": "📦 Moving House Box & Supplies Estimator",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=moving-house-box-estimator&embed=1",
      "standaloneUrl": null,
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        {
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          "type": "select-one",
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          "options": [
            "studio",
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            "minimal",
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      "sources": [],
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        "moving",
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        "box",
        "estimator",
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      "category": "productivity-and-lifestyle",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=moving&embed=1",
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      "standaloneUrl": null,
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      "featured": false,
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    },
    {
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      "category": "mrprophecy-arcade",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mrprophecy-beat-runner&embed=1",
      "standaloneUrl": null,
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      "tags": [
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      "featured": false,
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    {
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      "category": "mrprophecy-arcade",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mrprophecy-crowd-surf&embed=1",
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      "sources": [],
      "tags": [
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mrprophecy-lyric-scramble",
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      "category": "mrprophecy-arcade",
      "categoryName": "Arcade",
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      "standaloneUrl": null,
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      ],
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        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
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        "lyric",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mrprophecy-mix-board",
      "title": "🎛️ MrProphecy: Mix Board Challenge",
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      "category": "mrprophecy-arcade",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mrprophecy-mix-board&embed=1",
      "standaloneUrl": null,
      "inputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mrprophecy-mix-board&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
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        "mix",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
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      "categoryName": "Arcade",
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      "standaloneUrl": null,
      "inputs": [],
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      ],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "mrprophecy",
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      "popularity": 4525,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mrprophecy-rhythm-tap",
      "title": "🥁 MrProphecy: Rhythm Tap",
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      "category": "mrprophecy-arcade",
      "categoryName": "Arcade",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mrprophecy-rhythm-tap.html",
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      "standaloneUrl": null,
      "inputs": [],
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      ],
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      "sources": [],
      "tags": [
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mrprophecy-studio-defender",
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      "category": "mrprophecy-arcade",
      "categoryName": "Arcade",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mrprophecy-studio-defender.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mrprophecy-studio-defender&embed=1",
      "standaloneUrl": null,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
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      "featured": false,
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    },
    {
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      "category": "mrprophecy-arcade",
      "categoryName": "Arcade",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mrprophecy-tour-manager&embed=1",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
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      "popularity": 4230,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mrprophecy-vinyl-catch",
      "title": "💿 MrProphecy: Vinyl Catch",
      "description": "Catch falling records in the crate and dodge the cracked ones. Eight misses and the set is over. Real MrProphecy tracks play from the off.",
      "category": "mrprophecy-arcade",
      "categoryName": "Arcade",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mrprophecy-vinyl-catch&embed=1",
      "standaloneUrl": null,
      "inputs": [],
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      ],
      "prefill": {
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        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
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        "dodge",
        "cracked",
        "ones"
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      "popularity": 6242,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mt4-mt5-genetic-copy-trade-lab",
      "title": "🧬 MT4 / MT5 Genetic Copy-Trade Lab",
      "description": "A local, walker-style evolutionary search for copy-signal filters, with a built-in primer on reading gold (XAU/USD) and pairs such as EUR/USD. Import a chronological trade CSV; candidate genomes co...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mt4-mt5-genetic-copy-trade-lab.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mt4-mt5-genetic-copy-trade-lab&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mt4-mt5-genetic-copy-trade-lab-csv",
          "type": "text",
          "label": "Trade CSV (time, symbol, side, pnl_points, signal_score, spread, delay, MFE, MAE)",
          "unit": ""
        },
        {
          "name": "mt4-mt5-genetic-copy-trade-lab-symbol",
          "type": "select",
          "label": "Instrument to analyse",
          "unit": ""
        },
        {
          "name": "mt4-mt5-genetic-copy-trade-lab-split",
          "type": "select",
          "label": "Train / holdout split",
          "unit": ""
        },
        {
          "name": "mt4-mt5-genetic-copy-trade-lab-point-size",
          "type": "number",
          "label": "Broker point size (price units)",
          "unit": ""
        },
        {
          "name": "mt4-mt5-genetic-copy-trade-lab-point-value",
          "type": "number",
          "label": "Cash value of one point, per 1.00 lot",
          "unit": ""
        },
        {
          "name": "mt4-mt5-genetic-copy-trade-lab-population",
          "type": "number",
          "label": "Population",
          "unit": "genomes"
        },
        {
          "name": "mt4-mt5-genetic-copy-trade-lab-generations",
          "type": "number",
          "label": "Generations",
          "unit": "generations"
        },
        {
          "name": "mt4-mt5-genetic-copy-trade-lab-seed",
          "type": "number",
          "label": "Repeatable random seed",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "mt4-mt5-genetic-copy-trade-lab-status",
          "type": "live"
        },
        {
          "name": "mt4-mt5-genetic-copy-trade-lab-results",
          "type": "live"
        },
        {
          "name": "mt4-mt5-genetic-copy-trade-lab-guess-point-value",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mt4-mt5-genetic-copy-trade-lab&<id>=<value>",
        "runs": false
      },
      "formula": "Fitness = net training points − 0.65 × maximum drawdown − 2 × longest losing streak; filters are evolved by seeded selection, crossover and mutation, then scored on a holdout the s…",
      "sources": [],
      "tags": [
        "mt4",
        "mt5",
        "genetic",
        "copy",
        "trade",
        "lab",
        "copy-trade",
        "finance",
        "money",
        "local"
      ],
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mulch-coverage-calculator",
      "title": "🍂 Mulch Coverage Calculator",
      "description": "Volume = area × depth. A 50 litre bag is 0.05 m³. Bark mulch is usually 5–8 cm; paths can be 10 cm. Order a little extra for settling — bags are sold by loose volume.",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mulch-coverage-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mulch-coverage-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mlch-l",
          "type": "number",
          "label": "Length",
          "unit": "m",
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        },
        {
          "name": "mlch-w",
          "type": "number",
          "label": "Width",
          "unit": "m",
          "min": 0,
          "default": "3"
        },
        {
          "name": "mlch-d",
          "type": "number",
          "label": "Depth",
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        },
        {
          "name": "mlch-bag",
          "type": "number",
          "label": "Bag size",
          "unit": "litres",
          "min": 1,
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        }
      ],
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        {
          "name": "mlch-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mulch-coverage-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=mulch-coverage-calculator&mlch-l=8&mlch-w=3&mlch-d=7&mlch-bag=50"
      },
      "formula": "Mulch Coverage Calculator Volume = area ×",
      "sources": [],
      "tags": [
        "mulch",
        "coverage",
        "home",
        "diy",
        "volume",
        "area",
        "depth",
        "litre",
        "bag",
        "bark"
      ],
      "popularity": 6307,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "multilingual-phrase-matrix",
      "title": "🌐 10-Language Phrasebook",
      "description": "Compare, learn, and pronounce essential survival phrases side-by-side across 10 of the world's most spoken languages with instant native audio speech synthesis.",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/multilingual-phrase-matrix.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=multilingual-phrase-matrix&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "polyglot-phrase-select",
          "type": "select-one",
          "label": "Select Essential Travel Situation",
          "unit": "",
          "options": [
            "hello",
            "thanks",
            "please",
            "help",
            "bathroom",
            "howmuch",
            "delicious",
            "goodbye"
          ],
          "default": "hello"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=multilingual-phrase-matrix&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=multilingual-phrase-matrix&polyglot-phrase-select=hello"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "multilingual",
        "phrase",
        "matrix",
        "10-language",
        "phrasebook",
        "writing",
        "language",
        "compare",
        "learn",
        "pronounce"
      ],
      "popularity": 5913,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "multisyllabic-rhyme-cadence-flow-builder",
      "title": "🎤 Multi-Syllabic Rhyme & Cadence Flow Architect",
      "description": "Master the lyrical mechanics of golden era and modern technical rap. Map your syllables across a 16-slot 4/4 measure grid to lock your flow into the pocket, identify multi-syllabic vowel rhyme sche...",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/multisyllabic-rhyme-cadence-flow-builder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=multisyllabic-rhyme-cadence-flow-builder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mrf-bpm-slider",
          "type": "range",
          "label": "Metronome BPM",
          "unit": "",
          "min": 60,
          "max": 150,
          "default": "90"
        },
        {
          "name": "mrf-lyrics-input",
          "type": "textarea",
          "label": "Enter Rap Lyrics / Bars",
          "unit": "2-4 Lines"
        },
        {
          "name": "mrf-flow-preset",
          "type": "select-one",
          "label": "Flow Cadence Preset",
          "unit": "",
          "options": [
            "custom",
            "rakim",
            "doom",
            "migos"
          ],
          "default": "custom"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=multisyllabic-rhyme-cadence-flow-builder&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=multisyllabic-rhyme-cadence-flow-builder&mrf-bpm-slider=90&mrf-flow-preset=custom"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "multisyllabic",
        "rhyme",
        "cadence",
        "flow",
        "builder",
        "multi-syllabic",
        "architect",
        "music",
        "audio",
        "master"
      ],
      "popularity": 5243,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "museum-tombstone-label",
      "title": "🏷️ The Tombstone Desk",
      "description": "The quiet rectangle beside the object. In Anglo-American practice: maker, dates, title in italics, date of work, medium, dimensions, credit line, accession number. Fill the fields; the wall card se...",
      "category": "museum-and-collection",
      "categoryName": "Museum & Collection",
      "url": "https://www.themostusefulsiteintheworld.com/tool/museum-tombstone-label.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=museum-tombstone-label&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tomb-who",
          "type": "text",
          "label": "Maker",
          "unit": "",
          "default": "J. M. W. Turner"
        },
        {
          "name": "tomb-life",
          "type": "text",
          "label": "Maker dates",
          "unit": "",
          "default": "1775–1851"
        },
        {
          "name": "tomb-nat",
          "type": "text",
          "label": "Nationality",
          "unit": "",
          "default": "British"
        },
        {
          "name": "tomb-tit",
          "type": "text",
          "label": "Title",
          "unit": "",
          "default": "Rain, Steam and Speed"
        },
        {
          "name": "tomb-date",
          "type": "text",
          "label": "Date of work",
          "unit": "",
          "default": "1844"
        },
        {
          "name": "tomb-med",
          "type": "text",
          "label": "Medium",
          "unit": "",
          "default": "Oil on canvas"
        },
        {
          "name": "tomb-dim",
          "type": "text",
          "label": "Dimensions",
          "unit": "",
          "default": "91 × 121.8 cm"
        },
        {
          "name": "tomb-cred",
          "type": "text",
          "label": "Credit line",
          "unit": "",
          "default": "Turner Bequest, 1856"
        },
        {
          "name": "tomb-acc",
          "type": "text",
          "label": "Accession no.",
          "unit": "",
          "default": "NG538"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=museum-tombstone-label&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=museum-tombstone-label&tomb-who=J.%20M.%20W.%20Turner&tomb-life=1775%E2%80%931851&tomb-nat=British&tomb-tit=Rain%2C%20Steam%20and%20Speed&tomb-date=1844&tomb-med=Oil%20on%20canvas"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "museum",
        "tombstone",
        "label",
        "desk",
        "collection",
        "quiet",
        "rectangle",
        "beside",
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        "anglo-american"
      ],
      "popularity": 4615,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "music-quiz",
      "title": "🎵 Ultimate Music Quiz",
      "description": "Interactive music knowledge challenge: Test your expertise across theory, history, instruments, and pop culture. Complete with scoring, explanations, and shareable results!",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/music-quiz.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=music-quiz&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mq-type-mc",
          "type": "checkbox",
          "label": "Multiple Choice",
          "unit": "",
          "default": "1"
        },
        {
          "name": "mq-type-tf",
          "type": "checkbox",
          "label": "True/False",
          "unit": "",
          "default": "1"
        },
        {
          "name": "mq-type-fill",
          "type": "checkbox",
          "label": "Fill-in-Blank",
          "unit": "",
          "default": "0"
        },
        {
          "name": "mq-fill-answer",
          "type": "text",
          "label": "Type your answer here...",
          "unit": ""
        },
        {
          "name": "mq-custom-question",
          "type": "text",
          "label": "Enter your music question",
          "unit": ""
        },
        {
          "name": "mq-custom-correct",
          "type": "text",
          "label": "Correct answer",
          "unit": ""
        },
        {
          "name": "mq-custom-incorrect",
          "type": "text",
          "label": "Wrong, Answers, Here",
          "unit": ""
        },
        {
          "name": "mq-search-questions",
          "type": "text",
          "label": "Search questions...",
          "unit": ""
        },
        {
          "name": "mq-category",
          "type": "select-one",
          "label": "category",
          "unit": "",
          "options": [
            "theory",
            "instruments",
            "history",
            "pop",
            "genres",
            "composition",
            "world",
            "mixed"
          ],
          "default": "mixed"
        },
        {
          "name": "mq-difficulty",
          "type": "select-one",
          "label": "difficulty",
          "unit": "",
          "options": [
            "beginner",
            "intermediate",
            "advanced",
            "expert"
          ],
          "default": "intermediate"
        },
        {
          "name": "mq-question-count",
          "type": "select-one",
          "label": "question count",
          "unit": "",
          "options": [
            "5",
            "10",
            "15",
            "20",
            "25"
          ],
          "default": "10"
        },
        {
          "name": "mq-timer",
          "type": "select-one",
          "label": "timer",
          "unit": "",
          "options": [
            "none",
            "30",
            "20",
            "15",
            "10"
          ],
          "default": "20"
        },
        {
          "name": "mq-sound",
          "type": "select-one",
          "label": "sound",
          "unit": "",
          "options": [
            "on",
            "off",
            "minimal"
          ],
          "default": "on"
        }
      ],
      "outputs": [
        {
          "name": "mq-high-score",
          "type": "output"
        },
        {
          "name": "mq-timer-display",
          "type": "output"
        },
        {
          "name": "mq-current-score",
          "type": "output"
        },
        {
          "name": "mq-final-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=music-quiz&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=music-quiz&mq-type-mc=1&mq-type-tf=1&mq-type-fill=0&mq-category=mixed&mq-difficulty=intermediate&mq-question-count=10"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "music",
        "quiz",
        "ultimate",
        "audio",
        "interactive",
        "knowledge",
        "challenge",
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        "expertise",
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      ],
      "popularity": 5035,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "music-theory",
      "title": "🎼 Circle of Fifths Explorer",
      "description": "Pick any key to see its relative minor, the closely related keys either side of it on the circle, and the seven diatonic chords built from that scale. Everything runs offline in the browser.",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/music-theory.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=music-theory&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cof-key",
          "type": "select-one",
          "label": "Key",
          "unit": ""
        },
        {
          "name": "cof-mode",
          "type": "select-one",
          "label": "Mode",
          "unit": "",
          "options": [
            "major",
            "minor"
          ],
          "default": "major"
        }
      ],
      "outputs": [
        {
          "name": "cof-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=music-theory&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=music-theory&cof-mode=major"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "music",
        "theory",
        "circle",
        "fifths",
        "explorer",
        "audio",
        "pick",
        "any",
        "key",
        "see"
      ],
      "popularity": 4725,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mutual-aid-shift-planner",
      "title": "Mutual Aid Shift Planner",
      "description": "Build a volunteer coverage proposal that respects individual limits. Match availability to community shifts, prioritise hard-to-cover slots, and reveal staffing gaps rather than silently double-boo...",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mutual-aid-shift-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mutual-aid-shift-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mutual-aid-shift-planner-volunteers",
          "type": "textarea",
          "label": "Volunteers",
          "unit": ""
        },
        {
          "name": "mutual-aid-shift-planner-shifts",
          "type": "textarea",
          "label": "Shifts",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "mutual-aid-shift-planner-status",
          "type": "live"
        },
        {
          "name": "mutual-aid-shift-planner-results",
          "type": "output"
        },
        {
          "name": "mutual-aid-shift-planner-summary",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mutual-aid-shift-planner&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "mutual",
        "aid",
        "shift",
        "planner",
        "productivity",
        "lifestyle",
        "build",
        "volunteer",
        "coverage",
        "proposal"
      ],
      "popularity": 6547,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "mutual-credit-ledger",
      "title": "🤝 Mutual Credit Ledger",
      "description": "A working money system for a street, a club or a community — with no bank in the middle. Every member starts at zero. Every exchange debits one member and credits another by exactly the same amount...",
      "category": "wellbeing-and-community",
      "categoryName": "Wellbeing & Community",
      "url": "https://www.themostusefulsiteintheworld.com/tool/mutual-credit-ledger.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mutual-credit-ledger&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "mcl-name",
          "type": "text",
          "label": "Community name",
          "unit": "",
          "default": "Our Street Exchange"
        },
        {
          "name": "mcl-limit",
          "type": "number",
          "label": "How far may anyone go into debit?",
          "unit": "",
          "min": 1,
          "max": 10000,
          "step": 1,
          "default": "12"
        },
        {
          "name": "mcl-newname",
          "type": "text",
          "label": "New member name",
          "unit": ""
        },
        {
          "name": "mcl-amount",
          "type": "number",
          "label": "How much ( h )?",
          "unit": "",
          "min": 0.25,
          "max": 10000,
          "step": 0.25,
          "default": "1"
        },
        {
          "name": "mcl-note",
          "type": "text",
          "label": "What happened?",
          "unit": ""
        },
        {
          "name": "mcl-payload",
          "type": "textarea",
          "label": "Ledger data to copy or paste",
          "unit": ""
        },
        {
          "name": "mcl-unit",
          "type": "select-one",
          "label": "Unit",
          "unit": "",
          "options": [
            "h",
            "pts",
            "£"
          ],
          "default": "h"
        },
        {
          "name": "mcl-from",
          "type": "select-one",
          "label": "Who helped?",
          "unit": ""
        },
        {
          "name": "mcl-to",
          "type": "select-one",
          "label": "Who was helped?",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "mcl-msg",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=mutual-credit-ledger&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "mutual",
        "credit",
        "ledger",
        "wellbeing",
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        "street",
        "club"
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      "featured": false,
      "updated": "2026-09-19"
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      "slug": "mycelium-slime-mold-network-solver",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=mycelium-slime-mold-network-solver&embed=1",
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            "tokyo",
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        {
          "name": "msm-mold-color",
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          "label": "Mold Bio-Luminescence",
          "unit": "",
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            "#ffd700",
            "#ffd700",
            "#ffd700"
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        "mycelium",
        "slime",
        "mold",
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        "physarum",
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      "featured": false,
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      "category": "home-and-diy",
      "categoryName": "Home & DIY",
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        "mystery",
        "noise",
        "identifier",
        "hum",
        "whine",
        "home",
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        "low",
        "night",
        "walls"
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      "featured": false,
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      "slug": "nanoid-generator",
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        {
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            "url",
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      "sources": [],
      "tags": [
        "nanoid",
        "nano",
        "algorithms",
        "computer",
        "science",
        "url-safe",
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        "crypto",
        "getrandomvalues",
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      "featured": false,
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      "slug": "nato-phonetic-alphabet-trainer",
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      "categoryName": "Writing & Language",
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      ],
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        {
          "name": "nato-score",
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      "sources": [],
      "tags": [
        "nato",
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      "popularity": 5185,
      "featured": false,
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      "slug": "nato-phonetic-speller",
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      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/nato-phonetic-speller.html",
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      "standaloneUrl": null,
      "inputs": [
        {
          "name": "nato-in",
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        {
          "name": "nato-out",
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      "sources": [],
      "tags": [
        "nato",
        "phonetic",
        "speller",
        "writing",
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        "spell",
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        "postcode",
        "booking",
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      "popularity": 5575,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "natural-electrolyte-tonic-calc",
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      "categoryName": "Natural Remedies & Herbs",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=natural-electrolyte-tonic-calc&embed=1",
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            "who"
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        {
          "name": "elec-volume",
          "type": "select-one",
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            "500",
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          "default": "1000"
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      ],
      "outputs": [],
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        "natural",
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      "featured": false,
      "updated": "2026-09-19"
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      "slug": "nature-id-trainer",
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      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/nature-id-trainer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=nature-id-trainer&embed=1",
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          "step": 1,
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        {
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          "unit": "",
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        {
          "name": "pfi-select-group",
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          "label": "select group",
          "unit": "",
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            "all",
            "tree",
            "flower",
            "fungi"
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        {
          "name": "pfi-stat-total",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=nature-id-trainer&<id>=<value>",
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "nature",
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        "plants",
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      "featured": false,
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      "slug": "nd-filter-exposure-calculator",
      "title": "🕶️ ND Filter Exposure",
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      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
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      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "number",
          "label": "Unfiltered shutter",
          "unit": "s",
          "min": 0.0001,
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        {
          "name": "ndfe-custom",
          "type": "number",
          "label": "Custom stops",
          "unit": "",
          "min": 0,
          "max": 20
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        {
          "name": "ndfe-nd",
          "type": "select-one",
          "label": "Filter",
          "unit": "",
          "options": [
            "1",
            "2",
            "3",
            "4",
            "6",
            "10",
            "15"
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          "default": "10"
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          "name": "ndfe-out",
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      ],
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      "formula": "ND Filter Exposure New shutter = old shutter ×",
      "sources": [],
      "tags": [
        "filter",
        "exposure",
        "productivity",
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        "shutter",
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      "popularity": 4138,
      "featured": false,
      "updated": "2026-09-19"
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    {
      "slug": "nda-contract-service-agreement-builder",
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      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/nda-contract-service-agreement-builder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=nda-contract-service-agreement-builder&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "default": "Apex Global Innovations LLC"
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          "name": "ls-party-b",
          "type": "text",
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          "default": "Jane Doe (Consultant)"
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        {
          "name": "ls-eff-date",
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          "default": "2026-08-29"
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        {
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          "type": "select-one",
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          "options": [
            "nda_mutual",
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            "contractor"
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        {
          "name": "ls-jurisdiction",
          "type": "select-one",
          "label": "Governing Jurisdiction",
          "unit": "",
          "options": [
            "State of Delaware, United States",
            "State of California, United States",
            "State of New York, United States",
            "England and Wales, United Kingdom",
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        {
          "name": "ls-term-years",
          "type": "select-one",
          "label": "Confidentiality Term",
          "unit": "",
          "options": [
            "2",
            "3",
            "5",
            "perpetual"
          ],
          "default": "3"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=nda-contract-service-agreement-builder&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "nda",
        "contract",
        "service",
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        "builder",
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      "featured": false,
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    {
      "slug": "negotiation-prep-studio",
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      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/negotiation-prep-studio.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=negotiation-prep-studio&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "type": "text",
          "label": "What you are negotiating",
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          "default": "salary for a new role"
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        {
          "name": "ngps-unit",
          "type": "text",
          "label": "Measured in",
          "unit": "",
          "default": "£ a year"
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        {
          "name": "ngps-target",
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          "unit": "",
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          "label": "Your walk-away (below this you leave)",
          "unit": "",
          "min": 0,
          "max": 100000000,
          "step": 1,
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        {
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          "label": "Their likely opening offer",
          "unit": "",
          "min": 0,
          "max": 100000000,
          "step": 1,
          "default": "45000"
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        {
          "name": "ngps-theirmax",
          "type": "number",
          "label": "Their likely ceiling",
          "unit": "best guess",
          "min": 0,
          "max": 100000000,
          "step": 1,
          "default": "55000"
        },
        {
          "name": "ngps-batna",
          "type": "text",
          "label": "Your BATNA — what you do if this fails",
          "unit": "",
          "default": "stay put; two other interviews in play"
        },
        {
          "name": "ngps-trade",
          "type": "text",
          "label": "A cheap thing you can give them",
          "unit": "",
          "default": "an earlier start date"
        },
        {
          "name": "ngps-first",
          "type": "select-one",
          "label": "Who names the first number?",
          "unit": "",
          "options": [
            "them",
            "me",
            "unsure"
          ],
          "default": "me"
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      ],
      "outputs": [
        {
          "name": "ngps-out",
          "type": "output"
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      "prefill": {
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
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      "popularity": 5038,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "netball-scorekeeper",
      "title": "🏐 Netball Scorekeeper",
      "description": "Four quarters, one point a goal. Tap a team to add their goals, advance the quarter, and keep a clean running score with the per-quarter breakdown.",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/netball-scorekeeper.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=netball-scorekeeper&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [
        {
          "name": "ntb-board",
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        {
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      ],
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
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      "tags": [
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        "scorekeeper",
        "sports",
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          "name": "osc-volts-per-div-value",
          "type": "output"
        },
        {
          "name": "osc-trigger-level-value",
          "type": "output"
        },
        {
          "name": "osc-freq-display",
          "type": "output"
        },
        {
          "name": "osc-dc-offset-value",
          "type": "output"
        },
        {
          "name": "osc-phase-value",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=oscilloscope&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=oscilloscope&osc-frequency=10&osc-amplitude=50&osc-timebase=5&osc-volts-per-div=10&osc-trigger-level=0&osc-dc-offset=0&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "oscilloscope",
        "visualizer",
        "science",
        "engineering",
        "visualize",
        "analyze",
        "waveforms",
        "real-time",
        "generate",
        "signals"
      ],
      "popularity": 5863,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "oven-gas-mark-temperature-converter",
      "title": "🔥 Oven Gas Mark Converter",
      "description": "Convert British gas marks to °C, °F and a typical fan/convection setting. Gas mark 4 is a moderate 180°C / 350°F oven. Fan ovens usually run about 20°C cooler than the recipe’s conventional figure.",
      "category": "culinary-and-food-science",
      "categoryName": "Culinary & Food Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/oven-gas-mark-temperature-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=oven-gas-mark-temperature-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ogmk-c",
          "type": "number",
          "label": "°C",
          "unit": "conventional",
          "min": 50,
          "max": 300,
          "default": "180"
        },
        {
          "name": "ogmk-f",
          "type": "number",
          "label": "°F",
          "unit": "",
          "min": 120,
          "max": 600,
          "default": "356"
        },
        {
          "name": "ogmk-mark",
          "type": "select-one",
          "label": "Gas mark",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "ogmk-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=oven-gas-mark-temperature-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=oven-gas-mark-temperature-converter&ogmk-c=180&ogmk-f=356"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "oven",
        "gas",
        "mark",
        "temperature",
        "converter",
        "culinary",
        "food",
        "science",
        "convert",
        "british"
      ],
      "popularity": 4096,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "overnight-shift-duration-calculator",
      "title": "🌙 Overnight Shift Duration",
      "description": "Work out how long a shift is when it crosses midnight, plus unpaid breaks and overtime after a threshold. Built for night staff, on-call rotas and timesheets — not a payroll system.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/overnight-shift-duration-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=overnight-shift-duration-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "osdc-start",
          "type": "time",
          "label": "Start",
          "unit": "",
          "default": "21:30"
        },
        {
          "name": "osdc-end",
          "type": "time",
          "label": "End",
          "unit": "",
          "default": "07:00"
        },
        {
          "name": "osdc-break",
          "type": "number",
          "label": "Unpaid break",
          "unit": "min",
          "min": 0,
          "default": "30"
        },
        {
          "name": "osdc-ot",
          "type": "number",
          "label": "Overtime after",
          "unit": "h",
          "min": 0,
          "step": 0.25,
          "default": "8"
        },
        {
          "name": "osdc-rate",
          "type": "number",
          "label": "Hourly rate",
          "unit": "",
          "min": 0,
          "step": 0.01
        }
      ],
      "outputs": [
        {
          "name": "osdc-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=overnight-shift-duration-calculator&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=overnight-shift-duration-calculator&osdc-start=21%3A30&osdc-end=07%3A00&osdc-break=30&osdc-ot=8"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "overnight",
        "shift",
        "duration",
        "productivity",
        "lifestyle",
        "work",
        "out",
        "how",
        "long",
        "when"
      ],
      "popularity": 5673,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "overthinkers-calculator",
      "title": "🧮 The Overthinker's Calculator",
      "description": "Calculate exactly how many ways a situation can go wrong. Spoiler: it's more than you think.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/overthinkers-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=overthinkers-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "overthink-anxiety",
          "type": "range",
          "label": "Current Anxiety Level",
          "unit": "",
          "min": 1,
          "max": 10,
          "default": "7"
        },
        {
          "name": "overthink-situation",
          "type": "select-one",
          "label": "What are you overthinking about?",
          "unit": "",
          "options": [
            "text",
            "email",
            "wave",
            "order",
            "present",
            "joke",
            "opinion",
            "outfit"
          ],
          "default": "text"
        }
      ],
      "outputs": [
        {
          "name": "overthink-result",
          "type": "output"
        },
        {
          "name": "overthink-total",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=overthinkers-calculator&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=overthinkers-calculator&overthink-anxiety=7&overthink-situation=text&run=1"
      },
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      "sources": [],
      "tags": [
        "overthinkers",
        "overthinker",
        "productivity",
        "lifestyle",
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      "popularity": 6561,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "overtime-pay-calculator",
      "title": "💷 Hourly Wage, Overtime & Take-Home Estimator",
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      "category": "finance-and-money",
      "categoryName": "Finance & Money",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=overtime-pay-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "number",
          "label": "Hourly rate £",
          "unit": "",
          "min": 0,
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          "default": "12.21"
        },
        {
          "name": "opwc-hrs",
          "type": "number",
          "label": "Standard hrs/week",
          "unit": "",
          "min": 0,
          "step": 0.5,
          "default": "37.5"
        },
        {
          "name": "opwc-ot1m",
          "type": "number",
          "label": "Overtime hrs @ ×",
          "unit": "",
          "min": 1,
          "step": 0.25,
          "default": "1.5"
        },
        {
          "name": "opwc-ot1",
          "type": "number",
          "label": "Overtime hrs @ ×",
          "unit": "",
          "min": 0,
          "step": 0.5,
          "default": "0"
        },
        {
          "name": "opwc-ot2m",
          "type": "number",
          "label": "Overtime hrs @ ×",
          "unit": "",
          "min": 1,
          "step": 0.25,
          "default": "2"
        },
        {
          "name": "opwc-ot2",
          "type": "number",
          "label": "Overtime hrs @ ×",
          "unit": "",
          "min": 0,
          "step": 0.5,
          "default": "0"
        },
        {
          "name": "opwc-weeks",
          "type": "number",
          "label": "Paid weeks/year",
          "unit": "",
          "min": 1,
          "max": 52,
          "step": 1,
          "default": "52"
        },
        {
          "name": "opwc-pen",
          "type": "number",
          "label": "Pension %",
          "unit": "employee",
          "min": 0,
          "step": 0.5,
          "default": "5"
        },
        {
          "name": "opwc-uk",
          "type": "checkbox",
          "label": "Estimate UK tax & NI (2025/26, England, 1257L)",
          "unit": "",
          "default": "1"
        },
        {
          "name": "opwc-sl",
          "type": "checkbox",
          "label": "Student loan Plan 2",
          "unit": "",
          "default": "0"
        },
        {
          "name": "opwc-sal",
          "type": "number",
          "label": "Annual salary £",
          "unit": "",
          "min": 0,
          "step": 100
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=overtime-pay-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=overtime-pay-calculator&opwc-rate=12.21&opwc-hrs=37.5&opwc-ot1m=1.5&opwc-ot1=0&opwc-ot2m=2&opwc-ot2=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "overtime",
        "pay",
        "hourly",
        "wage",
        "take-home",
        "estimator",
        "finance",
        "money",
        "enter",
        "rate"
      ],
      "popularity": 6213,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "ovulation-fertile-window-calculator",
      "title": "🌸 Ovulation & Fertile Window",
      "description": "Estimate ovulation and the fertile window from the first day of your last period and your typical cycle length. Sperm can survive up to five days, so the window starts before ovulation. Calendar me...",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/ovulation-fertile-window-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=ovulation-fertile-window-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ovfw-lmp",
          "type": "date",
          "label": "First day of last period",
          "unit": ""
        },
        {
          "name": "ovfw-cycle",
          "type": "number",
          "label": "Average cycle",
          "unit": "days",
          "min": 21,
          "max": 45,
          "default": "28"
        },
        {
          "name": "ovfw-luteal",
          "type": "number",
          "label": "Luteal phase",
          "unit": "days",
          "min": 10,
          "max": 16,
          "default": "14"
        },
        {
          "name": "ovfw-cycles",
          "type": "select-one",
          "label": "Show next cycles",
          "unit": "",
          "options": [
            "3",
            "6",
            "12"
          ],
          "default": "6"
        }
      ],
      "outputs": [
        {
          "name": "ovfw-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=ovulation-fertile-window-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=ovulation-fertile-window-calculator&ovfw-cycle=28&ovfw-luteal=14&ovfw-cycles=6"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "ovulation",
        "fertile",
        "window",
        "health",
        "fitness",
        "estimate",
        "first",
        "day",
        "last",
        "period"
      ],
      "popularity": 6811,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "packing",
      "title": "🧳 Smart Packing List",
      "description": "Create intelligent packing lists with categories, trip types, weather considerations, and shareable checklists. Never forget an essential item!",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/packing.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=packing&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "packing-travelers",
          "type": "number",
          "label": "Travelers",
          "unit": "",
          "min": 1,
          "max": 10,
          "step": 1,
          "default": "1"
        },
        {
          "name": "packing-item",
          "type": "text",
          "label": "Item Name",
          "unit": ""
        },
        {
          "name": "packing-essential",
          "type": "checkbox",
          "label": "Essential Item",
          "unit": "",
          "default": "0"
        },
        {
          "name": "packing-quantity",
          "type": "checkbox",
          "label": "Add Quantity",
          "unit": "",
          "default": "0"
        },
        {
          "name": "packing-quantity-value",
          "type": "number",
          "label": "Quantity",
          "unit": "",
          "min": 1,
          "max": 20,
          "step": 1,
          "default": "1"
        },
        {
          "name": "packing-trip-type",
          "type": "select-one",
          "label": "Trip Type",
          "unit": "",
          "options": [
            "business",
            "vacation",
            "beach",
            "camping",
            "ski",
            "city",
            "roadtrip",
            "weekend",
            "cruise",
            "backpacking"
          ],
          "default": "vacation"
        },
        {
          "name": "packing-duration",
          "type": "select-one",
          "label": "Trip Duration",
          "unit": "",
          "options": [
            "weekend",
            "week",
            "fortnight",
            "month",
            "extended"
          ],
          "default": "week"
        },
        {
          "name": "packing-climate",
          "type": "select-one",
          "label": "Climate",
          "unit": "",
          "options": [
            "hot",
            "warm",
            "temperate",
            "cool",
            "cold",
            "variable"
          ],
          "default": "warm"
        },
        {
          "name": "packing-category",
          "type": "select-one",
          "label": "Category",
          "unit": "",
          "options": [
            "essentials",
            "clothing",
            "toiletries",
            "electronics",
            "documents",
            "medications",
            "misc"
          ],
          "default": "essentials"
        }
      ],
      "outputs": [
        {
          "name": "packing-results",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=packing&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=packing&packing-travelers=1&packing-essential=0&packing-quantity=0&packing-quantity-value=1&packing-trip-type=vacation&packing-duration=week"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "packing",
        "smart",
        "list",
        "productivity",
        "lifestyle",
        "create",
        "intelligent",
        "lists",
        "categories",
        "trip"
      ],
      "popularity": 4551,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "page-privacy-audit",
      "title": "🕵️ Page Privacy Audit",
      "description": "See which trackers and third parties a web page talks to. Load a HAR export from your browser's DevTools, or paste page source, and get a local report. Nothing you load is uploaded.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/page-privacy-audit.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=page-privacy-audit&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "page-privacy-audit-mode-har",
          "type": "radio",
          "label": "HAR export",
          "unit": "",
          "default": "1"
        },
        {
          "name": "page-privacy-audit-mode-source",
          "type": "radio",
          "label": "Page source",
          "unit": "HTML",
          "default": "0"
        },
        {
          "name": "page-privacy-audit-mode-self",
          "type": "radio",
          "label": "This page",
          "unit": "",
          "default": "0"
        },
        {
          "name": "page-privacy-audit-source-url",
          "type": "url",
          "label": "Page address (used to tell the site's own files from third parties)",
          "unit": ""
        },
        {
          "name": "page-privacy-audit-first-party",
          "type": "text",
          "label": "The site's own domains (optional; found automatically)",
          "unit": ""
        },
        {
          "name": "page-privacy-audit-har-text",
          "type": "textarea",
          "label": "…or paste the HAR JSON",
          "unit": ""
        },
        {
          "name": "page-privacy-audit-source-text",
          "type": "textarea",
          "label": "Page source: View Source, select all, paste",
          "unit": ""
        },
        {
          "name": "page-privacy-audit-copybuf",
          "type": "textarea",
          "label": "Report text for manual copying",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "page-privacy-audit-status",
          "type": "live"
        },
        {
          "name": "page-privacy-audit-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=page-privacy-audit&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=page-privacy-audit&page-privacy-audit-mode-har=1&page-privacy-audit-mode-source=0&page-privacy-audit-mode-self=0&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "page",
        "privacy",
        "audit",
        "algorithms",
        "computer",
        "science",
        "see",
        "which",
        "trackers",
        "third"
      ],
      "popularity": 4896,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "paint-calculator",
      "title": "🎨 Paint Calculator",
      "description": "Calculate exactly how much paint you need for any room. No more buying 5 tins for a cupboard.",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/paint-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=paint-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "pntcalc-w",
          "type": "number",
          "label": "Room Width",
          "unit": "m",
          "min": 0.5,
          "step": 0.1,
          "default": "4"
        },
        {
          "name": "pntcalc-l",
          "type": "number",
          "label": "Room Length",
          "unit": "m",
          "min": 0.5,
          "step": 0.1,
          "default": "5"
        },
        {
          "name": "pntcalc-h",
          "type": "number",
          "label": "Ceiling Height",
          "unit": "m",
          "min": 1,
          "step": 0.1,
          "default": "2.4"
        },
        {
          "name": "pntcalc-door",
          "type": "checkbox",
          "label": "1 Door",
          "unit": "1.9 m²",
          "default": "1"
        },
        {
          "name": "pntcalc-win",
          "type": "checkbox",
          "label": "1 Window",
          "unit": "1.4 m²",
          "default": "0"
        },
        {
          "name": "pntcalc-coats",
          "type": "select-one",
          "label": "Number of Coats",
          "unit": "",
          "options": [
            "1",
            "2",
            "3"
          ],
          "default": "2"
        },
        {
          "name": "pntcalc-tin",
          "type": "select-one",
          "label": "Tin Size",
          "unit": "litres",
          "options": [
            "0.5",
            "1",
            "2.5",
            "5",
            "10"
          ],
          "default": "2.5"
        }
      ],
      "outputs": [
        {
          "name": "pntcalc-result",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=paint-calculator&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=paint-calculator&pntcalc-w=4&pntcalc-l=5&pntcalc-h=2.4&pntcalc-door=1&pntcalc-win=0&pntcalc-coats=2&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "paint",
        "home",
        "diy",
        "calculate",
        "exactly",
        "how",
        "much",
        "need",
        "any",
        "room"
      ],
      "popularity": 4409,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "palette-swapper",
      "title": "🎨 Advanced Palette Swapper",
      "description": "Advanced color manipulation with multiple effects, palette extraction, and real-time preview. Transform images with professional color tools!",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/palette-swapper.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=palette-swapper&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "palette-from",
          "type": "text",
          "label": "#ff0000",
          "unit": "",
          "default": "#ff0000"
        },
        {
          "name": "palette-from-color",
          "type": "color",
          "label": "palette from color",
          "unit": "",
          "default": "#ff0000"
        },
        {
          "name": "palette-to",
          "type": "text",
          "label": "#00ff00",
          "unit": "",
          "default": "#00ff00"
        },
        {
          "name": "palette-to-color",
          "type": "color",
          "label": "palette to color",
          "unit": "",
          "default": "#00ff00"
        },
        {
          "name": "palette-tolerance",
          "type": "range",
          "label": "palette tolerance",
          "unit": "",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "0"
        },
        {
          "name": "palette-effect-grayscale",
          "type": "checkbox",
          "label": "Grayscale",
          "unit": "",
          "default": "0"
        },
        {
          "name": "palette-effect-sepia",
          "type": "checkbox",
          "label": "Sepia",
          "unit": "",
          "default": "0"
        },
        {
          "name": "palette-effect-invert",
          "type": "checkbox",
          "label": "Invert",
          "unit": "",
          "default": "0"
        },
        {
          "name": "palette-effect-hue",
          "type": "checkbox",
          "label": "Hue Shift",
          "unit": "",
          "default": "0"
        },
        {
          "name": "palette-effect-brightness",
          "type": "checkbox",
          "label": "Brightness",
          "unit": "",
          "default": "0"
        },
        {
          "name": "palette-effect-contrast",
          "type": "checkbox",
          "label": "Contrast",
          "unit": "",
          "default": "0"
        },
        {
          "name": "palette-hue-shift",
          "type": "range",
          "label": "palette hue shift",
          "unit": "",
          "min": -180,
          "max": 180,
          "step": 1,
          "default": "0"
        },
        {
          "name": "palette-brightness",
          "type": "range",
          "label": "palette brightness",
          "unit": "",
          "min": -100,
          "max": 100,
          "step": 1,
          "default": "0"
        },
        {
          "name": "palette-contrast",
          "type": "range",
          "label": "palette contrast",
          "unit": "",
          "min": -100,
          "max": 100,
          "step": 1,
          "default": "0"
        },
        {
          "name": "palette-saturation",
          "type": "range",
          "label": "palette saturation",
          "unit": "",
          "min": -100,
          "max": 100,
          "step": 1,
          "default": "0"
        },
        {
          "name": "palette-resize",
          "type": "select-one",
          "label": "Resize",
          "unit": "",
          "options": [
            "original",
            "800",
            "1200",
            "1600",
            "custom"
          ],
          "default": "800"
        }
      ],
      "outputs": [
        {
          "name": "palette-results",
          "type": "live"
        },
        {
          "name": "palette-tolerance-value",
          "type": "output"
        },
        {
          "name": "palette-output",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=palette-swapper&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=palette-swapper&palette-from=%23ff0000&palette-from-color=%23ff0000&palette-to=%2300ff00&palette-to-color=%2300ff00&palette-tolerance=0&palette-effect-grayscale=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "palette",
        "swapper",
        "advanced",
        "productivity",
        "lifestyle",
        "color",
        "manipulation",
        "multiple",
        "effects",
        "extraction"
      ],
      "popularity": 4104,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pan-size-converter",
      "title": "🥘 Pan Size Converter",
      "description": "Convert between different baking pan sizes and adjust recipes. Calculates volume differences and ingredient scaling.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pan-size-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pan-size-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "pc-from-dim1",
          "type": "number",
          "label": "from dim1",
          "unit": "",
          "min": 1,
          "step": 0.1,
          "default": "9"
        },
        {
          "name": "pc-from-dim2",
          "type": "number",
          "label": "from dim2",
          "unit": "",
          "min": 1,
          "step": 0.1,
          "default": "13"
        },
        {
          "name": "pc-from-depth",
          "type": "number",
          "label": "Depth",
          "unit": "in/cm",
          "min": 0.5,
          "step": 0.1,
          "default": "2"
        },
        {
          "name": "pc-to-dim1",
          "type": "number",
          "label": "to dim1",
          "unit": "",
          "min": 1,
          "step": 0.1,
          "default": "10"
        },
        {
          "name": "pc-to-dim2",
          "type": "number",
          "label": "Auto",
          "unit": "",
          "min": 1,
          "step": 0.1
        },
        {
          "name": "pc-to-depth",
          "type": "number",
          "label": "Depth",
          "unit": "in/cm",
          "min": 0.5,
          "step": 0.1,
          "default": "3.5"
        },
        {
          "name": "pc-from-type",
          "type": "select-one",
          "label": "Pan Type",
          "unit": "",
          "options": [
            "round",
            "square",
            "rectangular",
            "loaf",
            "bundt"
          ],
          "default": "round"
        },
        {
          "name": "pc-to-type",
          "type": "select-one",
          "label": "Pan Type",
          "unit": "",
          "options": [
            "round",
            "square",
            "rectangular",
            "loaf",
            "bundt"
          ],
          "default": "bundt"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pan-size-converter&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=pan-size-converter&pc-from-dim1=9&pc-from-dim2=13&pc-from-depth=2&pc-to-dim1=10&pc-to-depth=3.5&pc-from-type=round&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "pan",
        "size",
        "converter",
        "productivity",
        "lifestyle",
        "convert",
        "between",
        "different",
        "baking",
        "sizes"
      ],
      "popularity": 5284,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pantry-freezer-stock-tracker",
      "title": "🧊 Pantry & Freezer Stock Tracker",
      "description": "Keep a quick, searchable record of what is in your pantry, fridge and freezer. Add label dates, low-stock thresholds and a shareable shopping list. Your list stays in this browser; export a backup ...",
      "category": "culinary-and-food-science",
      "categoryName": "Culinary & Food Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pantry-freezer-stock-tracker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pantry-freezer-stock-tracker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "pantry-freezer-stock-tracker-name",
          "type": "text",
          "label": "Food or household staple",
          "unit": ""
        },
        {
          "name": "pantry-freezer-stock-tracker-quantity",
          "type": "number",
          "label": "Amount on hand",
          "unit": "",
          "min": 0,
          "max": 999999,
          "step": 0.01,
          "default": "1"
        },
        {
          "name": "pantry-freezer-stock-tracker-restock",
          "type": "number",
          "label": "Flag low stock at",
          "unit": "0 disables",
          "min": 0,
          "max": 999999,
          "step": 0.01,
          "default": "0"
        },
        {
          "name": "pantry-freezer-stock-tracker-date",
          "type": "date",
          "label": "Date on label",
          "unit": ""
        },
        {
          "name": "pantry-freezer-stock-tracker-notes",
          "type": "text",
          "label": "Notes",
          "unit": ""
        },
        {
          "name": "pantry-freezer-stock-tracker-search",
          "type": "search",
          "label": "Find an item",
          "unit": ""
        },
        {
          "name": "pantry-freezer-stock-tracker-shopping-name",
          "type": "text",
          "label": "Item to buy",
          "unit": ""
        },
        {
          "name": "pantry-freezer-stock-tracker-shopping-amount",
          "type": "text",
          "label": "Amount",
          "unit": ""
        },
        {
          "name": "pantry-freezer-stock-tracker-location",
          "type": "select-one",
          "label": "Stored in",
          "unit": "",
          "options": [
            "Pantry",
            "Fridge",
            "Freezer"
          ],
          "default": "Pantry"
        },
        {
          "name": "pantry-freezer-stock-tracker-unit",
          "type": "select-one",
          "label": "Unit",
          "unit": "",
          "options": [
            "items",
            "packs",
            "tins",
            "g",
            "kg",
            "ml",
            "L",
            "portions"
          ],
          "default": "items"
        },
        {
          "name": "pantry-freezer-stock-tracker-date-kind",
          "type": "select-one",
          "label": "Label date type",
          "unit": "",
          "options": [
            "none",
            "use-by",
            "best-before"
          ],
          "default": "none"
        },
        {
          "name": "pantry-freezer-stock-tracker-filter",
          "type": "select-one",
          "label": "Show",
          "unit": "",
          "options": [
            "all",
            "date",
            "low",
            "Pantry",
            "Fridge",
            "Freezer"
          ],
          "default": "all"
        }
      ],
      "outputs": [
        {
          "name": "pantry-freezer-stock-tracker-status",
          "type": "live"
        },
        {
          "name": "pantry-freezer-stock-tracker-items",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pantry-freezer-stock-tracker&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "pantry",
        "freezer",
        "stock",
        "tracker",
        "culinary",
        "food",
        "science",
        "keep",
        "quick",
        "searchable"
      ],
      "popularity": 4376,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "paper-size-iso-us-converter",
      "title": "📄 Paper Size Converter",
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      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/paper-size-iso-us-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=paper-size-iso-us-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "papz-dpi",
          "type": "number",
          "label": "Pixels at DPI",
          "unit": "",
          "min": 72,
          "max": 1200,
          "default": "300"
        },
        {
          "name": "papz-size",
          "type": "select-one",
          "label": "Sheet",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "papz-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=paper-size-iso-us-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=paper-size-iso-us-converter&papz-dpi=300"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "paper",
        "size",
        "iso",
        "converter",
        "productivity",
        "lifestyle",
        "series",
        "letter",
        "legal",
        "tabloid"
      ],
      "popularity": 6772,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "parcel-volumetric-weight-checker",
      "title": "Parcel Volumetric Weight Checker",
      "description": "Compare actual and volumetric parcel weight, calculate length plus girth, and check against the limits on your chosen courier service.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/parcel-volumetric-weight-checker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=parcel-volumetric-weight-checker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "parcel-volumetric-weight-checker-length",
          "type": "number",
          "label": "Length",
          "unit": "cm",
          "min": 0.01,
          "max": 100000,
          "default": "40"
        },
        {
          "name": "parcel-volumetric-weight-checker-width",
          "type": "number",
          "label": "Width",
          "unit": "cm",
          "min": 0.01,
          "max": 100000,
          "default": "30"
        },
        {
          "name": "parcel-volumetric-weight-checker-height",
          "type": "number",
          "label": "Height",
          "unit": "cm",
          "min": 0.01,
          "max": 100000,
          "default": "20"
        },
        {
          "name": "parcel-volumetric-weight-checker-weight",
          "type": "number",
          "label": "Actual weight",
          "unit": "kg",
          "min": 0.01,
          "max": 100000,
          "default": "2"
        },
        {
          "name": "parcel-volumetric-weight-checker-divisor",
          "type": "number",
          "label": "Courier divisor",
          "unit": "cm³/kg",
          "min": 0.01,
          "max": 100000,
          "default": "5000"
        },
        {
          "name": "parcel-volumetric-weight-checker-limit",
          "type": "number",
          "label": "Maximum length + girth",
          "unit": "cm",
          "min": 0.01,
          "max": 100000,
          "default": "300"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=parcel-volumetric-weight-checker&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=parcel-volumetric-weight-checker&parcel-volumetric-weight-checker-length=40&parcel-volumetric-weight-checker-width=30&parcel-volumetric-weight-checker-height=20&parcel-volumetric-weight-checker-weight=2&parcel-volumetric-weight-checker-divisor=5000&parcel-volumetric-weight-checker-limit=300"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "parcel",
        "volumetric",
        "weight",
        "checker",
        "productivity",
        "lifestyle",
        "compare",
        "actual",
        "calculate",
        "length"
      ],
      "popularity": 5185,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "parts-of-speech-trainer",
      "title": "🧠 Parts of Speech Trainer",
      "description": "Name the eight parts of speech — noun, verb, adjective, adverb, pronoun, preposition, conjunction, interjection — in 10-question rounds with hints and a reference guide.",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/parts-of-speech-trainer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=parts-of-speech-trainer&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [
        {
          "name": "pos-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=parts-of-speech-trainer&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "parts",
        "speech",
        "trainer",
        "writing",
        "language",
        "name",
        "eight",
        "noun",
        "verb",
        "adjective"
      ],
      "popularity": 6741,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "party",
      "title": "Party Planner",
      "description": "Plan your party with date, location, and guest list.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/party.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=party&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "party-date",
          "type": "date",
          "label": "Date",
          "unit": ""
        },
        {
          "name": "party-location",
          "type": "text",
          "label": "Location",
          "unit": ""
        },
        {
          "name": "party-guest",
          "type": "text",
          "label": "Guest name",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "party-output",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=party&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "party",
        "planner",
        "productivity",
        "lifestyle",
        "plan",
        "date",
        "location",
        "guest",
        "list"
      ],
      "popularity": 4350,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "passive-aggressive-translator",
      "title": "📧 Passive Aggressive Email Translator",
      "description": "Type what you actually want to say. We'll make it sound professional. Ish.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/passive-aggressive-translator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=passive-aggressive-translator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "patrans-input",
          "type": "textarea",
          "label": "What you want to say",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "patrans-result",
          "type": "output"
        },
        {
          "name": "patrans-output",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=passive-aggressive-translator&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "passive",
        "aggressive",
        "translator",
        "email",
        "productivity",
        "lifestyle",
        "type",
        "what",
        "actually",
        "want"
      ],
      "popularity": 6317,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "passport-photo-size-guide",
      "title": "🛂 Passport Photo Size Guide",
      "description": "Official print sizes and pixel dimensions for UK, US, Schengen, Canada, Australia, India and China visa photos. Face-height rules are listed — a home print can still be rejected if lighting or back...",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/passport-photo-size-guide.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=passport-photo-size-guide&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ppht-dpi",
          "type": "number",
          "label": "Print DPI",
          "unit": "",
          "min": 200,
          "max": 600,
          "default": "300"
        },
        {
          "name": "ppht-where",
          "type": "select-one",
          "label": "Document",
          "unit": ""
        }
      ],
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          "name": "ppht-out",
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=passport-photo-size-guide&<id>=<value>",
        "runs": false,
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      },
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      "sources": [],
      "tags": [
        "passport",
        "photo",
        "size",
        "guide",
        "productivity",
        "lifestyle",
        "official",
        "print",
        "sizes",
        "pixel"
      ],
      "popularity": 4858,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
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      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/password-strength-checker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=password-strength-checker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "number",
          "label": "Words",
          "unit": "",
          "min": 3,
          "max": 10,
          "default": "4"
        },
        {
          "name": "psec-sep",
          "type": "text",
          "label": "Sep",
          "unit": "",
          "default": "-"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=password-strength-checker&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=password-strength-checker&psec-nw=4&psec-sep=-"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "password",
        "strength",
        "checker",
        "crack-time",
        "estimator",
        "productivity",
        "lifestyle",
        "type",
        "see",
        "entropy"
      ],
      "popularity": 6355,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "password",
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      "description": "Create strong, random passwords instantly. Customize length and character sets.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/password.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=password&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "range",
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          "min": 6,
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        },
        {
          "name": "pw-length",
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          "label": "Password Length",
          "unit": "",
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          "max": 64,
          "default": "12"
        },
        {
          "name": "pw-lowercase",
          "type": "checkbox",
          "label": "a Lowercase",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pw-uppercase",
          "type": "checkbox",
          "label": "A Uppercase",
          "unit": "",
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        {
          "name": "pw-numbers",
          "type": "checkbox",
          "label": "1 Numbers",
          "unit": "",
          "default": "1"
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        {
          "name": "pw-symbols",
          "type": "checkbox",
          "label": "# Symbols",
          "unit": "",
          "default": "1"
        }
      ],
      "outputs": [
        {
          "name": "strength-value",
          "type": "output"
        },
        {
          "name": "pw-output",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=password&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=password&pw-length-slider=12&pw-length=12&pw-lowercase=1&pw-uppercase=1&pw-numbers=1&pw-symbols=1"
      },
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      "sources": [],
      "tags": [
        "password",
        "productivity",
        "lifestyle",
        "create",
        "strong",
        "random",
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      "popularity": 6755,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pathfinding-algorithm-visualizer",
      "title": "🗺️ Pathfinding Algorithm Visualizer",
      "description": "Draw walls and watch four search algorithms hunt for the goal: DFS wanders, BFS floods evenly, Dijkstra matches BFS on a uniform grid, and A* heads straight for the target. The visited cells and th...",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pathfinding-algorithm-visualizer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pathfinding-algorithm-visualizer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "pth-algo",
          "type": "select-one",
          "label": "algo",
          "unit": "",
          "options": [
            "bfs",
            "dfs",
            "dijkstra",
            "astar"
          ],
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        }
      ],
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        {
          "name": "pth-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pathfinding-algorithm-visualizer&<id>=<value>",
        "runs": false,
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      },
      "formula": "Find path Random maze Clear walls Draw: drag = wall · click S/",
      "sources": [],
      "tags": [
        "pathfinding",
        "algorithm",
        "visualizer",
        "algorithms",
        "computer",
        "science",
        "draw",
        "walls",
        "watch",
        "four"
      ],
      "popularity": 6067,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "payday-stretch-triage",
      "title": "🛟 Payday Stretch: Make Your Last Pounds Last",
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      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/payday-stretch-triage.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=payday-stretch-triage&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "label": "Currency",
          "unit": "",
          "default": "£"
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        {
          "name": "pdst-cash",
          "type": "number",
          "label": "Cash left",
          "unit": "all accounts",
          "min": 0,
          "step": 0.5,
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        },
        {
          "name": "pdst-days",
          "type": "number",
          "label": "Days until payday",
          "unit": "",
          "min": 1,
          "max": 60,
          "step": 1,
          "default": "12"
        },
        {
          "name": "pdst-adults",
          "type": "number",
          "label": "Adults to feed",
          "unit": "",
          "min": 1,
          "max": 12,
          "step": 1,
          "default": "2"
        },
        {
          "name": "pdst-kids",
          "type": "number",
          "label": "Children to feed",
          "unit": "",
          "min": 0,
          "max": 12,
          "step": 1,
          "default": "1"
        },
        {
          "name": "pdst-region",
          "type": "select-one",
          "label": "Region (for advice wording)",
          "unit": "",
          "options": [
            "uk",
            "us",
            "other"
          ],
          "default": "uk"
        }
      ],
      "outputs": [
        {
          "name": "pdst-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=payday-stretch-triage&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "payday",
        "stretch",
        "triage",
        "make",
        "last",
        "pounds",
        "finance",
        "money",
        "broke",
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      ],
      "popularity": 4805,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pcb-trace-width",
      "title": "⚡ PCB Trace Width Calculator",
      "description": "Estimate minimum PCB trace width for a given current, copper thickness, and temperature rise.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pcb-trace-width.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pcb-trace-width&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "pcb-current",
          "type": "number",
          "label": "Current",
          "unit": "A",
          "min": 0.1,
          "max": 100,
          "step": 0.1
        },
        {
          "name": "pcb-thickness",
          "type": "number",
          "label": "Copper Thickness",
          "unit": "",
          "min": 0.5,
          "max": 4,
          "step": 0.5,
          "default": "1"
        },
        {
          "name": "pcb-temp",
          "type": "number",
          "label": "Max Temperature Rise",
          "unit": "",
          "min": 5,
          "max": 100,
          "step": 1,
          "default": "10"
        },
        {
          "name": "pcb-length",
          "type": "number",
          "label": "Trace Length",
          "unit": "",
          "min": 1,
          "max": 1000,
          "step": 1
        },
        {
          "name": "pcb-show-facts",
          "type": "checkbox",
          "label": "Show PCB Facts & Guidelines",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pcb-output",
          "type": "textarea",
          "label": "Results and calculations will appear here...",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "trace-width-value",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pcb-trace-width&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=pcb-trace-width&pcb-thickness=1&pcb-temp=10&pcb-show-facts=1&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "pcb",
        "trace",
        "width",
        "science",
        "engineering",
        "estimate",
        "minimum",
        "given",
        "current",
        "copper"
      ],
      "popularity": 5128,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pdf-copy-paste-fixer",
      "title": "📄 PDF Copy-Paste Fixer",
      "description": "Copy text out of a PDF and you get a line break every few words, “docu- ment” split in two, fi and fl ligatures that break search, and page numbers and running headers in the middle of sentences. Pas...",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pdf-copy-paste-fixer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "pdf-copy-paste-fixer-o-join",
          "type": "checkbox",
          "label": "Join broken lines into paragraphs",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pdf-copy-paste-fixer-o-hyph",
          "type": "checkbox",
          "label": "Rejoin words split by hyphens",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pdf-copy-paste-fixer-o-lig",
          "type": "checkbox",
          "label": "Expand ligatures",
          "unit": "fi fl ff",
          "default": "1"
        },
        {
          "name": "pdf-copy-paste-fixer-o-hdr",
          "type": "checkbox",
          "label": "Remove repeated headers / page numbers",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pdf-copy-paste-fixer-o-ws",
          "type": "checkbox",
          "label": "Tidy spaces",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pdf-copy-paste-fixer-o-list",
          "type": "checkbox",
          "label": "Keep bullet / numbered lists",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pdf-copy-paste-fixer-in",
          "type": "textarea",
          "label": "Pasted from PDF",
          "unit": ""
        },
        {
          "name": "pdf-copy-paste-fixer-out",
          "type": "textarea",
          "label": "Clean text",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "pdf-copy-paste-fixer-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pdf-copy-paste-fixer&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "pdf",
        "copy",
        "paste",
        "fixer",
        "copy-paste",
        "writing",
        "language",
        "text",
        "out",
        "get"
      ],
      "popularity": 4453,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pdf-toolkit-pro",
      "title": "📄 PDF Toolkit Pro — Merge, Split, Compress & Extract",
      "description": "Premium-grade PDF studio that replaces Smallpdf / Adobe Acrobat for everyday jobs — 100% offline, no uploads, no watermarks. Merge, split by pages, compress images → PDF, and extract text. Uses you...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pdf-toolkit-pro.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pdf-toolkit-pro&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "pdfpro-split-range",
          "type": "text",
          "label": "Page ranges (e.g. 1-3, 5, 7-9)",
          "unit": ""
        },
        {
          "name": "pdfpro-img-margin",
          "type": "number",
          "label": "Margin",
          "unit": "mm",
          "min": 0,
          "max": 30,
          "step": 1,
          "default": "10"
        },
        {
          "name": "pdfpro-img-numbers",
          "type": "checkbox",
          "label": "Page numbers",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pdfpro-compress-quality",
          "type": "range",
          "label": "Image JPEG quality: 0.72",
          "unit": "",
          "min": 0.3,
          "max": 0.92,
          "step": 0.02,
          "default": "0.72"
        },
        {
          "name": "pdfpro-extract-out",
          "type": "textarea",
          "label": "Extracted text will appear here … (heuristic — works best on PDFs with embedded text, not scanned images)",
          "unit": ""
        },
        {
          "name": "pdfpro-papersize",
          "type": "select-one",
          "label": "Page size",
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          "options": [
            "auto",
            "a4",
            "a4l",
            "letter",
            "letterl"
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          "default": "auto"
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        {
          "name": "pdfpro-img-quality",
          "type": "select-one",
          "label": "JPEG quality",
          "unit": "",
          "options": [
            "0.92",
            "0.82",
            "0.68",
            "0.5"
          ],
          "default": "0.82"
        }
      ],
      "outputs": [
        {
          "name": "pdfpro-split-output",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pdf-toolkit-pro&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=pdf-toolkit-pro&pdfpro-img-margin=10&pdfpro-img-numbers=1&pdfpro-compress-quality=0.72&pdfpro-papersize=auto&pdfpro-img-quality=0.82"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "pdf",
        "toolkit",
        "pro",
        "merge",
        "split",
        "compress",
        "extract",
        "saas",
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      "popularity": 5419,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "peak-normalizer-wav-export",
      "title": "Peak Normalizer & WAV Export",
      "description": "Normalize mono or stereo samples to a chosen sample-peak ceiling, with linked-channel gain and a downloadable 24-bit PCM WAV.",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/peak-normalizer-wav-export.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=peak-normalizer-wav-export&embed=1",
      "standaloneUrl": null,
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        {
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          "label": "Target sample peak",
          "unit": "dBFS",
          "min": -24,
          "max": 0,
          "default": "-1"
        }
      ],
      "outputs": [
        {
          "name": "pkne-result",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=peak-normalizer-wav-export&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=peak-normalizer-wav-export&pkne-target=-1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "peak",
        "normalizer",
        "wav",
        "export",
        "music",
        "audio",
        "normalize",
        "mono",
        "stereo",
        "samples"
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      "popularity": 4361,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pendulum-wave-harmonograph",
      "title": "🕰️ Pendulum Wave Array",
      "description": "Kinetic museum wave array. Independent pendulums with calibrated lengths execute serpentine traveling waves, choreographing standing waves and unified reconstitution.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pendulum-wave-harmonograph.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pendulum-wave-harmonograph&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "pwa-slider-speed",
          "type": "range",
          "label": "slider speed",
          "unit": "",
          "min": 0.2,
          "max": 3,
          "step": 0.1,
          "default": "1.0"
        },
        {
          "name": "pwa-slider-amp",
          "type": "range",
          "label": "slider amp",
          "unit": "",
          "min": 20,
          "max": 70,
          "default": "45"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pendulum-wave-harmonograph&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=pendulum-wave-harmonograph&pwa-slider-speed=1.0&pwa-slider-amp=45"
      },
      "formula": "Grand Cycle Phase: Traveling Serpentine Wave t = 0.0s /",
      "sources": [],
      "tags": [
        "pendulum",
        "wave",
        "harmonograph",
        "array",
        "science",
        "engineering",
        "kinetic",
        "museum",
        "independent",
        "pendulums"
      ],
      "popularity": 6123,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "penny-meals-survival-planner",
      "title": "🍲 Penny Meals: Survival Food Planner",
      "description": "Turn a tiny weekly food budget into a full 7-day meal plan for your household. Built from the cheapest nutritious staples on earth, with calories, protein and a priced shopping list worked out for ...",
      "category": "culinary-and-food-science",
      "categoryName": "Culinary & Food Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/penny-meals-survival-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=penny-meals-survival-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "pmsp-cur",
          "type": "text",
          "label": "Currency",
          "unit": "",
          "default": "£"
        },
        {
          "name": "pmsp-budget",
          "type": "number",
          "label": "Weekly budget",
          "unit": "",
          "min": 1,
          "step": 0.5,
          "default": "25"
        },
        {
          "name": "pmsp-adults",
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    {
      "slug": "phone-contract-vs-sim-only-calculator",
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        "photo",
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        "signature"
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        {
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        {
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        {
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        {
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        {
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        {
          "name": "pc-unit-from",
          "type": "select-one",
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            "mile",
            "foot"
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        {
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            "mile",
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      "slug": "picture-hanging-guide",
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        {
          "name": "pichang-wire-sag",
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            "155",
            "160"
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          "name": "pichang-result",
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=picture-hanging-guide&<id>=<value>",
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        "picture",
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    },
    {
      "slug": "pigment-cabinet-of-colour",
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      "category": "museum-and-collection",
      "categoryName": "Museum & Collection",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pigment-cabinet-of-colour.html",
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      "standaloneUrl": null,
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pigment-cabinet-of-colour&<id>=<value>",
        "runs": false
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      "sources": [],
      "tags": [
        "pigment",
        "cabinet",
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      ],
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      "featured": false,
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    },
    {
      "slug": "pipe-flow-simulator",
      "title": "💧 The Pipe Lab",
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      "category": "museum-and-collection",
      "categoryName": "Museum & Collection",
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      "standaloneUrl": null,
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      },
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        "pipe",
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      "category": "interactive-art-and-living-worlds",
      "categoryName": "Interactive Art & Living Worlds",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pixel-collaborative-infinite-mural.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pixel-collaborative-infinite-mural&embed=1",
      "standaloneUrl": null,
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          "default": "1"
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          "name": "pv-coord-display",
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pixel-collaborative-infinite-mural&<id>=<value>",
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      },
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      "featured": false,
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    },
    {
      "slug": "pizza-dough-calculator",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pizza-dough-calculator&embed=1",
      "standaloneUrl": null,
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            "roman-thin",
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        {
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          "unit": "",
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            "idy-cold",
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            "sourdough"
          ],
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      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pizza-dough-calculator&<id>=<value>",
        "runs": false,
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      },
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      "sources": [],
      "tags": [
        "pizza",
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      "featured": false,
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    },
    {
      "slug": "plagiarism-check",
      "title": "🔍 Plagiarism Checker",
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      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/plagiarism-check.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=plagiarism-check&embed=1",
      "standaloneUrl": null,
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        {
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          "default": "1"
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        {
          "name": "pc-check-academic",
          "type": "checkbox",
          "label": "Academic Terms",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pc-check-quotes",
          "type": "checkbox",
          "label": "Check Quotes",
          "unit": "",
          "default": "0"
        },
        {
          "name": "pc-show-matches",
          "type": "checkbox",
          "label": "Show Matches",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pc-input",
          "type": "textarea",
          "label": "Text to Check",
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      ],
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        {
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=plagiarism-check&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=plagiarism-check&pc-check-common=1&pc-check-academic=1&pc-check-quotes=0&pc-show-matches=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "plagiarism",
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      "featured": false,
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    },
    {
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      "category": "wellbeing-and-community",
      "categoryName": "Wellbeing & Community",
      "url": "https://www.themostusefulsiteintheworld.com/tool/plain-language-decoder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=plain-language-decoder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "pld-input",
          "type": "textarea",
          "label": "The text",
          "unit": ""
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      ],
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        {
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=plain-language-decoder&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "plain",
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        "decoder",
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        "paste",
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      "popularity": 4418,
      "featured": false,
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    },
    {
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      "category": "astronomy-and-space",
      "categoryName": "Astronomy & Space",
      "url": "https://www.themostusefulsiteintheworld.com/tool/planet-ring-designer-3d.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=planet-ring-designer-3d&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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        {
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        {
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        {
          "name": "pr3-sun",
          "type": "range",
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          "max": 90,
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        },
        {
          "name": "pr3-spin",
          "type": "checkbox",
          "label": "animate",
          "unit": "",
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        },
        {
          "name": "pr3-storm",
          "type": "checkbox",
          "label": "great storm",
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        },
        {
          "name": "pr3-cassini",
          "type": "checkbox",
          "label": "Cassini division",
          "unit": "",
          "default": "1"
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      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=planet-ring-designer-3d&<id>=<value>",
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      },
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        "planet",
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      "popularity": 4635,
      "featured": false,
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    },
    {
      "slug": "planet-surface-3d-explorer",
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      "category": "astronomy-and-space",
      "categoryName": "Astronomy & Space",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=planet-surface-3d-explorer&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "max": 2,
          "step": 0.05,
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        {
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        {
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        {
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          "label": "slider labels",
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          "step": 1,
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      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=planet-surface-3d-explorer&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=planet-surface-3d-explorer&psx-slider-spin=0.3&psx-slider-tilt=23.4&psx-slider-sun=35&psx-slider-labels=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "planet",
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        "explorer",
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        "space",
        "land",
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      "popularity": 4958,
      "featured": false,
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    },
    {
      "slug": "plant-encyclopedia",
      "title": "🌿 Plant Encyclopedia (Live)",
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      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/plant-encyclopedia.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=plant-encyclopedia&embed=1",
      "standaloneUrl": null,
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        {
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        {
          "name": "pe-source-wiki",
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          "label": "Wikipedia",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pe-source-usda",
          "type": "checkbox",
          "label": "USDA Plants",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pe-source-openfarm",
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          "label": "OpenFarm",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pe-source-trefle",
          "type": "checkbox",
          "label": "Trefle.io",
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          "default": "1"
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      ],
      "outputs": [
        {
          "name": "pe-output",
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=plant-encyclopedia&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=plant-encyclopedia&pe-source-wiki=1&pe-source-usda=1&pe-source-openfarm=1&pe-source-trefle=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "plant",
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      "featured": false,
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    },
    {
      "slug": "plastering-calculator",
      "title": "🪣 Plastering Calculator",
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      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/plastering-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=plastering-calculator&embed=1",
      "standaloneUrl": null,
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          "label": "Total Width",
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          "min": 0.5,
          "step": 0.1,
          "default": "12"
        },
        {
          "name": "plstrcalc-h",
          "type": "number",
          "label": "Height",
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        {
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        },
        {
          "name": "plstrcalc-type",
          "type": "select-one",
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            "multi",
            "board",
            "undercoat",
            "render",
            "screed",
            "lime"
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          "default": "multi"
        },
        {
          "name": "plstrcalc-coats",
          "type": "select-one",
          "label": "Number of Coats",
          "unit": "",
          "options": [
            "1",
            "2"
          ],
          "default": "1"
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      ],
      "outputs": [
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=plastering-calculator&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=plastering-calculator&plstrcalc-w=12&plstrcalc-h=2.4&plstrcalc-openings=3&plstrcalc-type=multi&plstrcalc-coats=1&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "pool",
        "spa",
        "volume",
        "home",
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        "litres",
        "gallons",
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      "popularity": 5387,
      "featured": false,
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    {
      "slug": "post-thread-splitter",
      "title": "🧵 Thread Splitter for Long Posts",
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      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/post-thread-splitter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=post-thread-splitter&embed=1",
      "standaloneUrl": null,
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          "label": "Characters per post",
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        {
          "name": "post-thread-splitter-platform",
          "type": "select-one",
          "label": "Platform",
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            "x",
            "bluesky",
            "mastodon",
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            "custom"
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        {
          "name": "post-thread-splitter-numbering",
          "type": "select-one",
          "label": "Numbering",
          "unit": "",
          "options": [
            "slash",
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          "default": "slash"
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        {
          "name": "post-thread-splitter-position",
          "type": "select-one",
          "label": "Number goes",
          "unit": "",
          "options": [
            "end",
            "start"
          ],
          "default": "end"
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          "name": "post-thread-splitter-status",
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      "sources": [],
      "tags": [
        "post",
        "thread",
        "splitter",
        "long",
        "posts",
        "writing",
        "language",
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      "featured": false,
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    },
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      "slug": "poultice-compress-remedy-lab",
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      "categoryName": "Natural Remedies & Herbs",
      "url": "https://www.themostusefulsiteintheworld.com/tool/poultice-compress-remedy-lab.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=poultice-compress-remedy-lab&embed=1",
      "standaloneUrl": null,
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            "plantain",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=poultice-compress-remedy-lab&<id>=<value>",
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      "tags": [
        "poultice",
        "compress",
        "remedy",
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        "natural",
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        "herbs",
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    },
    {
      "slug": "power-calculator",
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      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/power-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=power-calculator&embed=1",
      "standaloneUrl": null,
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        {
          "name": "powercpc-mode",
          "type": "select-one",
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          "unit": "",
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            "basic",
            "ac",
            "three-phase",
            "appliance",
            "wire-sizing",
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            "energy-cost"
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        "power",
        "science",
        "engineering",
        "calculate",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "powerlifting-dots-wilks-score",
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      "category": "sports",
      "categoryName": "Sports",
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      "standaloneUrl": null,
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        {
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          "label": "Total",
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          "min": 0,
          "step": 2.5,
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        {
          "name": "dots-sq",
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        },
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          "name": "dots-bp",
          "type": "number",
          "label": "Bench",
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          "min": 0,
          "step": 2.5,
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        },
        {
          "name": "dots-dl",
          "type": "number",
          "label": "Deadlift",
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          "step": 2.5,
          "default": "230"
        },
        {
          "name": "dots-sex",
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          "unit": "",
          "options": [
            "m",
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          ],
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      ],
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        {
          "name": "dots-out",
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      ],
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      },
      "formula": "The formulas & what a good score is Both scores = total × 500 ÷",
      "sources": [],
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        "powerlifting",
        "dots",
        "wilks",
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        "sports",
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        "lifters",
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      "featured": false,
      "updated": "2026-09-19"
    },
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      "slug": "practice-tracker",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=practice-tracker&embed=1",
      "standaloneUrl": null,
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          "type": "date",
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          "unit": "",
          "default": "${new Date().toISOString().split('T')[0]}"
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        {
          "name": "pt-duration",
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          "label": "Duration",
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          "min": 1,
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          "name": "pt-focus",
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        {
          "name": "pt-goal",
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          "label": "Target Minutes per Week",
          "unit": "",
          "min": 1,
          "step": 1
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        {
          "name": "pt-notes",
          "type": "textarea",
          "label": "Notes & Progress",
          "unit": ""
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=practice-tracker&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=practice-tracker&pt-date=%24%7Bnew%20Date().toISOString().split('T')%5B0%5D%7D"
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      "sources": [],
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        "practice",
        "tracker",
        "productivity",
        "lifestyle",
        "track",
        "analyze",
        "sessions",
        "detailed",
        "metrics",
        "progress"
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      "popularity": 6894,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pregnancy-due-date-calculator",
      "title": "🤰 Pregnancy Due Date & Week-by-Week Calculator",
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      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pregnancy-due-date-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pregnancy-due-date-calculator&embed=1",
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        {
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          "unit": ""
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        {
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          "label": "Cycle length",
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          "max": 45,
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        {
          "name": "pdwc-method",
          "type": "select-one",
          "label": "Calculate from",
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            "lmp",
            "conc",
            "ivf3",
            "ivf5",
            "due"
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          "default": "lmp"
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      ],
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        "runs": false,
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      },
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      "sources": [],
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        "pregnancy",
        "due",
        "date",
        "week-by-week",
        "health",
        "fitness",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pregnancy-weight-gain-guide",
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      "description": "IOM/NAM ranges by pre-pregnancy BMI for a singleton: underweight 12.5–18 kg, healthy 11.5–16 kg, overweight 7–11.5 kg, obese 5–9 kg. A sketch for conversations with a midwife — not a target you mus...",
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      "standaloneUrl": null,
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        },
        {
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          "label": "Pre-pregnancy weight",
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          "min": 35,
          "max": 250,
          "default": "62"
        },
        {
          "name": "pwgt-twins",
          "type": "select-one",
          "label": "Pregnancy",
          "unit": "",
          "options": [
            "one",
            "two"
          ],
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      },
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      "sources": [],
      "tags": [
        "pregnancy",
        "weight",
        "gain",
        "guide",
        "health",
        "fitness",
        "iom",
        "nam",
        "ranges",
        "pre-pregnancy"
      ],
      "popularity": 5533,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "premier-league",
      "title": "⚽ Premier League Live",
      "description": "Live Premier League data scraped from current online sources. Teams update automatically.",
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      "categoryName": "Sports",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=premier-league&embed=1",
      "standaloneUrl": null,
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            "loading"
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          "default": "loading"
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        {
          "name": "pl-type",
          "type": "select-one",
          "label": "Data Type",
          "unit": "",
          "options": [
            "standings",
            "fixtures",
            "results",
            "stats"
          ],
          "default": "standings"
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      ],
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        {
          "name": "pl-output",
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      "sources": [],
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        "premier",
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        "live",
        "sports",
        "data",
        "scraped",
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      "popularity": 5384,
      "featured": false,
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    },
    {
      "slug": "presentation-word-budget-planner",
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      "categoryName": "Writing & Language",
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        {
          "name": "presentation-word-budget-planner-questions",
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        {
          "name": "presentation-word-budget-planner-pace",
          "type": "number",
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          "min": 40,
          "max": 300,
          "default": "130"
        },
        {
          "name": "presentation-word-budget-planner-draft",
          "type": "textarea",
          "label": "Draft",
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      ],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
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        "presentation",
        "word",
        "budget",
        "planner",
        "writing",
        "language",
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      "popularity": 4666,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "price-in-work-hours",
      "title": "⏱️ Price Tag in Hours of Your Life",
      "description": "Money is frozen time. Convert any price into how many hours (and minutes) of your actual working life it costs — after tax, before snacks. That latte is cheaper once you've seen it in minutes.",
      "category": "productivity-and-lifestyle",
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      "standaloneUrl": null,
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          "step": 0.01,
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        {
          "name": "pwh-price",
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          "label": "Price of the thing",
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          "min": 0,
          "step": 0.01,
          "default": "4.50"
        }
      ],
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        {
          "name": "pwh-out",
          "type": "live"
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      ],
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "price",
        "work",
        "hours",
        "tag",
        "life",
        "productivity",
        "lifestyle",
        "money",
        "frozen",
        "time"
      ],
      "popularity": 6025,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "prime-factor-tool",
      "title": "🔍 Prime Factor Finder",
      "description": "Break a whole number into its prime factors and see whether it is prime.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/prime-factor-tool.html",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "pro",
        "doc",
        "scanner",
        "studio",
        "ocr",
        "pdf",
        "image",
        "text",
        "saas",
        "business"
      ],
      "popularity": 4890,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pro-email-visual-builder-studio",
      "title": "✉️ Pro Email Visual Builder — BeeFree & Mailchimp Killer",
      "description": "Professional email builder that replaces BeeFree $30/mo, Mailchimp builder & Stripo — 100% offline. Drag blocks, edit copy, inline CSS, dark mode, mobile/desktop preview, spam score, export HTML. N...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pro-email-visual-builder-studio.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-email-visual-builder-studio&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "pevbs-subject",
          "type": "text",
          "label": "Email subject",
          "unit": ""
        },
        {
          "name": "pevbs-preheader",
          "type": "text",
          "label": "Preheader (preview text)",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-email-visual-builder-studio&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "pro",
        "email",
        "visual",
        "builder",
        "studio",
        "beefree",
        "mailchimp",
        "killer",
        "saas",
        "business"
      ],
      "popularity": 5220,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pro-flashcard-spaced-repetition-studio",
      "title": "🧠 Pro Flashcard Studio — Spaced Repetition (Anki Killer)",
      "description": "Professional spaced repetition studio that replaces Anki $25 & Quizlet Plus $36/yr — 100% offline. Create decks, import CSV, study with SM-2 algorithm, bury/leech detection, stats, heatmap, export....",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pro-flashcard-spaced-repetition-studio.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-flashcard-spaced-repetition-studio&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "fsrs-add-tags",
          "type": "text",
          "label": "js, verbs",
          "unit": ""
        },
        {
          "name": "fsrs-browse-search",
          "type": "text",
          "label": "Search cards…",
          "unit": ""
        },
        {
          "name": "fsrs-add-front",
          "type": "textarea",
          "label": "Question / front",
          "unit": ""
        },
        {
          "name": "fsrs-add-back",
          "type": "textarea",
          "label": "Answer / back",
          "unit": ""
        },
        {
          "name": "fsrs-import-csv",
          "type": "textarea",
          "label": "front,back,tags\nWhat is closure?,Function with preserved scope,js\nBonjour?,Hello,french",
          "unit": ""
        },
        {
          "name": "fsrs-export-area",
          "type": "textarea",
          "label": "export area",
          "unit": ""
        },
        {
          "name": "fsrs-add-deck",
          "type": "select-one",
          "label": "add deck",
          "unit": ""
        },
        {
          "name": "fsrs-browse-deck",
          "type": "select-one",
          "label": "browse deck",
          "unit": ""
        },
        {
          "name": "fsrs-import-deck",
          "type": "select-one",
          "label": "import deck",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "fsrs-show-answer",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-flashcard-spaced-repetition-studio&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "pro",
        "flashcard",
        "spaced",
        "repetition",
        "studio",
        "anki",
        "killer",
        "saas",
        "business",
        "killers"
      ],
      "popularity": 5112,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pro-form-builder-studio",
      "title": "📝 Pro Form Builder Studio — Typeform & Google Forms Killer",
      "description": "Professional form builder that replaces Typeform $25/mo, Tally & Google Forms — 100% offline. Drag-drop fields, validation, logic, themes, collect responses in localStorage, export CSV/JSON, embed ...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pro-form-builder-studio.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-form-builder-studio&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "pfbs-form-title",
          "type": "text",
          "label": "Form title — e.g. Client Intake",
          "unit": ""
        },
        {
          "name": "pfbs-form-desc",
          "type": "text",
          "label": "Description",
          "unit": ""
        },
        {
          "name": "pfbs-accent",
          "type": "color",
          "label": "accent",
          "unit": "",
          "default": "#ffd700"
        },
        {
          "name": "pfbs-embed-code",
          "type": "textarea",
          "label": "embed code",
          "unit": ""
        },
        {
          "name": "pfbs-json-code",
          "type": "textarea",
          "label": "json code",
          "unit": ""
        },
        {
          "name": "pfbs-theme",
          "type": "select-one",
          "label": "theme",
          "unit": "",
          "options": [
            "dark",
            "light",
            "neon"
          ],
          "default": "dark"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-form-builder-studio&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-form-builder-studio&pfbs-accent=%23ffd700&pfbs-theme=dark"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "pro",
        "form",
        "builder",
        "studio",
        "typeform",
        "google",
        "forms",
        "killer",
        "saas",
        "business"
      ],
      "popularity": 5409,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pro-image-compressor-studio",
      "title": "🖼️ Pro Image Compressor Studio — Batch Resize, Convert & Optimize",
      "description": "Production-grade image studio that replaces TinyPNG, Squoosh & Photoshop batch — 100% offline. Batch compress, resize, convert to WebP/JPEG/PNG, strip EXIF, add watermark, and download. No uploads,...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pro-image-compressor-studio.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-image-compressor-studio&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "pics-quality",
          "type": "range",
          "label": "Quality 0.82 · lower = smaller",
          "unit": "",
          "min": 0.1,
          "max": 1,
          "step": 0.02,
          "default": "0.82"
        },
        {
          "name": "pics-maxw",
          "type": "number",
          "label": "auto",
          "unit": ""
        },
        {
          "name": "pics-maxh",
          "type": "number",
          "label": "auto",
          "unit": ""
        },
        {
          "name": "pics-keep-aspect",
          "type": "checkbox",
          "label": "Keep aspect ratio",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pics-strip-exif",
          "type": "checkbox",
          "label": "Strip EXIF / metadata",
          "unit": "privacy",
          "default": "1"
        },
        {
          "name": "pics-no-enlarge",
          "type": "checkbox",
          "label": "Never enlarge smaller images",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pics-wm-text",
          "type": "text",
          "label": "© Your Brand",
          "unit": ""
        },
        {
          "name": "pics-wm-opacity",
          "type": "range",
          "label": "wm opacity",
          "unit": "",
          "min": 0,
          "max": 0.8,
          "step": 0.05,
          "default": "0"
        },
        {
          "name": "pics-wm-color",
          "type": "color",
          "label": "wm color",
          "unit": "",
          "default": "#ffffff"
        },
        {
          "name": "pics-format",
          "type": "select-one",
          "label": "format",
          "unit": "",
          "options": [
            "original",
            "webp",
            "jpeg",
            "png"
          ],
          "default": "original"
        },
        {
          "name": "pics-wm-pos",
          "type": "select-one",
          "label": "wm pos",
          "unit": "",
          "options": [
            "br",
            "bl",
            "tr",
            "center"
          ],
          "default": "br"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-image-compressor-studio&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-image-compressor-studio&pics-quality=0.82&pics-keep-aspect=1&pics-strip-exif=1&pics-no-enlarge=1&pics-wm-opacity=0&pics-wm-color=%23ffffff"
      },
      "formula": "SmoothingQuality='high' ), then re-",
      "sources": [],
      "tags": [
        "pro",
        "image",
        "compressor",
        "studio",
        "batch",
        "resize",
        "convert",
        "optimize",
        "saas",
        "business"
      ],
      "popularity": 6668,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pro-invoice-recurring-studio",
      "title": "🧾 Pro Invoice & Recurring Studio — Estimates, Invoices, Subscriptions",
      "description": "Production invoicing studio that replaces FreshBooks, HoneyBook & Stripe Invoicing — 100% offline. Create invoices, estimates, recurring subscriptions, track paid/overdue, taxes, discounts, multi-c...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pro-invoice-recurring-studio.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-invoice-recurring-studio&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "irs-number",
          "type": "text",
          "label": "INV-2026-001",
          "unit": ""
        },
        {
          "name": "irs-date",
          "type": "date",
          "label": "Issue date",
          "unit": ""
        },
        {
          "name": "irs-due",
          "type": "date",
          "label": "Due date",
          "unit": ""
        },
        {
          "name": "irs-discount",
          "type": "number",
          "label": "Discount %",
          "unit": "",
          "min": 0,
          "max": 100,
          "default": "0"
        },
        {
          "name": "irs-shipping",
          "type": "number",
          "label": "Shipping",
          "unit": "",
          "min": 0,
          "step": 0.01,
          "default": "0"
        },
        {
          "name": "irs-c-name",
          "type": "text",
          "label": "Client / Company name",
          "unit": ""
        },
        {
          "name": "irs-c-email",
          "type": "text",
          "label": "Email",
          "unit": ""
        },
        {
          "name": "irs-c-tax",
          "type": "text",
          "label": "Tax ID / VAT",
          "unit": ""
        },
        {
          "name": "irs-search",
          "type": "text",
          "label": "Search invoices, clients…",
          "unit": ""
        },
        {
          "name": "irs-recur-next",
          "type": "date",
          "label": "Next date",
          "unit": ""
        },
        {
          "name": "irs-b-name",
          "type": "text",
          "label": "Business name",
          "unit": ""
        },
        {
          "name": "irs-b-email",
          "type": "text",
          "label": "Email",
          "unit": ""
        },
        {
          "name": "irs-b-logo",
          "type": "text",
          "label": "Logo URL (optional, https://…)",
          "unit": ""
        },
        {
          "name": "irs-b-tax",
          "type": "text",
          "label": "Tax ID / VAT ID",
          "unit": ""
        },
        {
          "name": "irs-notes",
          "type": "textarea",
          "label": "Payment due within 15 days. Wire to … Thank you!",
          "unit": ""
        },
        {
          "name": "irs-c-address",
          "type": "textarea",
          "label": "Address",
          "unit": ""
        },
        {
          "name": "irs-b-address",
          "type": "textarea",
          "label": "Address",
          "unit": ""
        },
        {
          "name": "irs-status",
          "type": "select-one",
          "label": "status",
          "unit": "",
          "options": [
            "draft",
            "sent",
            "paid",
            "overdue",
            "estimate"
          ],
          "default": "draft"
        },
        {
          "name": "irs-client",
          "type": "select-one",
          "label": "client",
          "unit": ""
        },
        {
          "name": "irs-currency",
          "type": "select-one",
          "label": "currency",
          "unit": "",
          "options": [
            "USD",
            "EUR",
            "GBP",
            "JPY",
            "INR",
            "CAD"
          ],
          "default": "USD"
        },
        {
          "name": "irs-filter-status",
          "type": "select-one",
          "label": "filter status",
          "unit": "",
          "options": [
            "draft",
            "sent",
            "paid",
            "overdue",
            "estimate"
          ],
          "default": "draft"
        },
        {
          "name": "irs-recur-invoice",
          "type": "select-one",
          "label": "recur invoice",
          "unit": ""
        },
        {
          "name": "irs-recur-freq",
          "type": "select-one",
          "label": "recur freq",
          "unit": "",
          "options": [
            "weekly",
            "monthly",
            "quarterly",
            "yearly"
          ],
          "default": "monthly"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-invoice-recurring-studio&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-invoice-recurring-studio&irs-discount=0&irs-shipping=0&irs-status=draft&irs-currency=USD&irs-filter-status=draft&irs-recur-freq=monthly"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "pro",
        "invoice",
        "recurring",
        "studio",
        "estimates",
        "invoices",
        "subscriptions",
        "saas",
        "business",
        "killers"
      ],
      "popularity": 4938,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pro-json-api-workbench",
      "title": "🧩 Pro JSON & API Workbench — Format, Query, Diff & Convert",
      "description": "Production-grade JSON studio that replaces Quicktype, JSONPath Online & Postman scratchpad — 100% offline. Format, validate, minify, query with JSONPath, diff, convert to YAML/CSV/XML/TypeScript/Py...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pro-json-api-workbench.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-json-api-workbench&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "jaws-path",
          "type": "text",
          "label": "JSONPath expression",
          "unit": "",
          "default": "$.users[*].name"
        },
        {
          "name": "jaws-mock-count",
          "type": "number",
          "label": "Count",
          "unit": "",
          "min": 1,
          "max": 100,
          "default": "5"
        },
        {
          "name": "jaws-input",
          "type": "textarea",
          "label": "JSON Input",
          "unit": ""
        },
        {
          "name": "jaws-query-out",
          "type": "textarea",
          "label": "Results appear here…",
          "unit": ""
        },
        {
          "name": "jaws-diff-a",
          "type": "textarea",
          "label": "Original JSON",
          "unit": ""
        },
        {
          "name": "jaws-diff-b",
          "type": "textarea",
          "label": "Modified JSON",
          "unit": ""
        },
        {
          "name": "jaws-convert-out",
          "type": "textarea",
          "label": "Converted code appears here…",
          "unit": ""
        },
        {
          "name": "jaws-mock-out",
          "type": "textarea",
          "label": "Mock JSON appears here…",
          "unit": ""
        },
        {
          "name": "jaws-mock-template",
          "type": "select-one",
          "label": "Template",
          "unit": "",
          "options": [
            "users",
            "products",
            "posts",
            "from-json"
          ],
          "default": "users"
        }
      ],
      "outputs": [
        {
          "name": "jaws-copy-out",
          "type": "output"
        },
        {
          "name": "jaws-diff-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-json-api-workbench&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-json-api-workbench&jaws-path=%24.users%5B*%5D.name&jaws-mock-count=5&jaws-mock-template=users&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "pro",
        "json",
        "api",
        "workbench",
        "format",
        "query",
        "diff",
        "convert",
        "saas",
        "business"
      ],
      "popularity": 6121,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pro-landing-page-builder-studio",
      "title": "🚀 Pro Landing Page Builder — Carrd & Webflow Killer",
      "description": "Professional landing page builder that replaces Carrd $19/yr, Webflow $14/mo & Framer — 100% offline. Drag sections (hero, features, pricing, FAQ, CTA), edit copy, themes, responsive preview, expor...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pro-landing-page-builder-studio.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-landing-page-builder-studio&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "plbs-site-title",
          "type": "text",
          "label": "Site title",
          "unit": ""
        },
        {
          "name": "plbs-site-desc",
          "type": "text",
          "label": "Meta description",
          "unit": ""
        },
        {
          "name": "plbs-cta-link",
          "type": "text",
          "label": "CTA link (https://…)",
          "unit": "",
          "default": "#"
        },
        {
          "name": "plbs-theme",
          "type": "select-one",
          "label": "theme",
          "unit": "",
          "options": [
            "dark",
            "light",
            "neon",
            "paper"
          ],
          "default": "dark"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-landing-page-builder-studio&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-landing-page-builder-studio&plbs-cta-link=%23&plbs-theme=dark"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "pro",
        "landing",
        "page",
        "builder",
        "studio",
        "carrd",
        "webflow",
        "killer",
        "saas",
        "business"
      ],
      "popularity": 4296,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pro-password-vault-studio",
      "title": "🔐 Pro Password Vault Studio — Generator, Encrypted Vault & TOTP",
      "description": "Military-grade password manager that replaces 1Password / Bitwarden for local use — 100% offline, zero-knowledge. Generate high-entropy passwords, check strength, store in AES-GCM vault locked by m...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/pro-password-vault-studio.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-password-vault-studio&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "pvs-len",
          "type": "range",
          "label": "len",
          "unit": "",
          "min": 8,
          "max": 64,
          "default": "20"
        },
        {
          "name": "pvs-qty",
          "type": "number",
          "label": "Quantity",
          "unit": "",
          "min": 1,
          "max": 50,
          "default": "5"
        },
        {
          "name": "pvs-upper",
          "type": "checkbox",
          "label": "A-Z",
          "unit": "",
          "default": "1"
        },
        {
          "name": "pvs-lower",
          "type": "checkbox",
          "label": "a-z",
          "unit": "",
          "default": "1"
        },
        {
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        {
          "name": "pvs-exclude-amb",
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          "name": "pvs-site",
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          "name": "pvs-user",
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          "unit": ""
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        {
          "name": "pvs-totp-secret",
          "type": "text",
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        {
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        {
          "name": "pvs-notes",
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        {
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            "random",
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          "name": "pvs-sort",
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          "label": "sort",
          "unit": "",
          "options": [
            "newest",
            "site",
            "weak"
          ],
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        {
          "name": "pvs-output",
          "type": "output"
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-password-vault-studio&<id>=<value>",
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      },
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        "pro",
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        "vault",
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      "featured": false,
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    },
    {
      "slug": "pro-rata-salary-calculator",
      "title": "💷 Pro Rata Salary Calculator",
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      "categoryName": "Finance & Money",
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          "name": "prsa-pay",
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          "type": "number",
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          "min": 0.1,
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          "name": "prsa-pt",
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          "label": "Your hours / week",
          "unit": "",
          "min": 0.1,
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        {
          "name": "prsa-weeks",
          "type": "number",
          "label": "Paid weeks / year",
          "unit": "",
          "min": 1,
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        {
          "name": "prsa-mode",
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          "options": [
            "down",
            "up"
          ],
          "default": "down"
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      ],
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        {
          "name": "prsa-out",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pro-rata-salary-calculator&<id>=<value>",
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      },
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      "sources": [],
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        "pro",
        "rata",
        "salary",
        "finance",
        "money",
        "scale",
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        "part-time",
        "hours"
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      "popularity": 5812,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "pro-regex-studio",
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      "category": "saas-and-business-killers",
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          "name": "rxs-flag-g",
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          "unit": "",
          "default": "0"
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        {
          "name": "rxs-flag-i",
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          "unit": "",
          "default": "0"
        },
        {
          "name": "rxs-flag-m",
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          "unit": "",
          "default": "0"
        },
        {
          "name": "rxs-flag-s",
          "type": "checkbox",
          "label": "s — dot matches newline",
          "unit": "",
          "default": "0"
        },
        {
          "name": "rxs-flag-u",
          "type": "checkbox",
          "label": "u — Unicode",
          "unit": "",
          "default": "0"
        },
        {
          "name": "rxs-flag-y",
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          "name": "rxs-text",
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        {
          "name": "rxs-replaced",
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          "unit": ""
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          "name": "rxs-lang",
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            "js",
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          "name": "rxs-toast",
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      "sources": [],
      "tags": [
        "pro",
        "regex",
        "studio",
        "tester",
        "explainer",
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      "featured": false,
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    },
    {
      "slug": "pro-seo-audit-toolkit",
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          "unit": ""
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        },
        {
          "name": "seoat-kw-targets",
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          "label": "Target keywords (separate with commas)",
          "unit": ""
        },
        {
          "name": "seoat-p-title",
          "type": "text",
          "label": "Page title",
          "unit": ""
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        {
          "name": "seoat-p-url",
          "type": "url",
          "label": "Page address",
          "unit": ""
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        {
          "name": "seoat-p-image",
          "type": "url",
          "label": "Share image address (1200×630 works everywhere)",
          "unit": ""
        },
        {
          "name": "seoat-p-site",
          "type": "text",
          "label": "Site name",
          "unit": ""
        },
        {
          "name": "seoat-p-handle",
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          "label": "X (Twitter) handle",
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        },
        {
          "name": "seoat-p-lang",
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          "label": "Language",
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        },
        {
          "name": "seoat-c-topic",
          "type": "text",
          "label": "Topic or main keyword",
          "unit": ""
        },
        {
          "name": "seoat-c-audience",
          "type": "text",
          "label": "Audience",
          "unit": ""
        },
        {
          "name": "seoat-html",
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        {
          "name": "seoat-kw-text",
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          "label": "Text to analyse (leave empty to use the audited page)",
          "unit": ""
        },
        {
          "name": "seoat-p-desc",
          "type": "textarea",
          "label": "Meta description",
          "unit": ""
        },
        {
          "name": "seoat-kw-type",
          "type": "select-one",
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          "unit": "",
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            "product",
            "landing",
            "news",
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            "video"
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          "default": "blog"
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        {
          "name": "seoat-p-type",
          "type": "select-one",
          "label": "Page type",
          "unit": "",
          "options": [
            "website",
            "article",
            "product",
            "profile",
            "video.other"
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          "default": "website"
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        {
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          "label": "Search engines may…",
          "unit": "",
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            "noindex, nofollow"
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          "default": "index, follow"
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        {
          "name": "seoat-c-platform",
          "type": "select-one",
          "label": "Platform",
          "unit": "",
          "options": [
            "youtube",
            "shorts",
            "tiktok",
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            "twitch",
            "linkedin",
            "podcast",
            "blog"
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          "default": "youtube"
        },
        {
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          "unit": "",
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            "helpful",
            "bold",
            "story"
          ],
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        }
      ],
      "outputs": [
        {
          "name": "seoat-fetch-status",
          "type": "live"
        },
        {
          "name": "seoat-summary",
          "type": "live"
        },
        {
          "name": "seoat-kw-results",
          "type": "live"
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        {
          "name": "seoat-toast",
          "type": "live"
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        {
          "name": "seoat-results",
          "type": "output"
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        {
          "name": "seoat-score",
          "type": "output"
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          "type": "output"
        }
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        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [
        "https://www.nhs.uk/live-well/eat-well/"
      ],
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        "pro",
        "seo",
        "audit",
        "toolkit",
        "studio",
        "page",
        "keywords",
        "readability",
        "search",
        "social"
      ],
      "popularity": 6548,
      "featured": false,
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    },
    {
      "slug": "pro-video-toolkit",
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      "description": "Professional browser video studio that replaces HandBrake, Kap, EZGIF & Adobe Media Encoder — 100% offline. Trim, compress preview, extract frames, generate thumbnails, GIF preview, mute, rotate, m...",
      "category": "saas-and-business-killers",
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          "label": "Start",
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          "min": 0,
          "step": 0.1,
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        {
          "name": "pvt-end",
          "type": "number",
          "label": "End",
          "unit": "s",
          "min": 0,
          "step": 0.1,
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        {
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          "min": 0,
          "max": 100,
          "default": "0"
        },
        {
          "name": "pvt-mute",
          "type": "checkbox",
          "label": "Mute audio on export",
          "unit": "",
          "default": "0"
        },
        {
          "name": "pvt-rotate",
          "type": "checkbox",
          "label": "Rotate 90° on export",
          "unit": "",
          "default": "0"
        },
        {
          "name": "pvt-quality",
          "type": "select-one",
          "label": "Quality preset",
          "unit": "",
          "options": [
            "original",
            "high",
            "medium",
            "low",
            "gif"
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          "default": "original"
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      ],
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      },
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        "pro",
        "video",
        "toolkit",
        "trim",
        "compress",
        "gif",
        "thumbnail",
        "metadata",
        "saas",
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      "featured": false,
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    },
    {
      "slug": "pro-whiteboard-studio",
      "title": "🧩 Pro Whiteboard Studio — Infinite Canvas, Sticky Notes & Drawing",
      "description": "Professional infinite whiteboard that replaces Miro $10/mo, FigJam & Mural — 100% offline. Pan, zoom, sticky notes, freehand drawing, shapes, connectors, text, image upload, layers, export PNG/SVG/...",
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          "name": "pwb-zoom",
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          "label": "zoom",
          "unit": "",
          "min": 10,
          "max": 300,
          "default": "100"
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      ],
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      "sources": [],
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        "pro",
        "whiteboard",
        "studio",
        "infinite",
        "canvas",
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        "drawing",
        "saas",
        "business"
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      "featured": false,
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    },
    {
      "slug": "probability-paradox-lab",
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      "category": "mathematics",
      "categoryName": "Mathematics",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=probability-paradox-lab&embed=1",
      "standaloneUrl": null,
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        {
          "name": "ppl-n",
          "type": "range",
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          "unit": "",
          "min": 2,
          "max": 100,
          "default": "23"
        }
      ],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
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        "probability",
        "paradox",
        "lab",
        "mathematics",
        "gut",
        "feeling",
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      "popularity": 5027,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "probability-tree-builder",
      "title": "🌳 Probability Tree Builder — Branches, Marginals and the Bayes Flip",
      "description": "Name the two first-branch events and their conditionals, and the whole tree draws itself: every path probability, the marginal for each second-stage outcome, and the famous flip — P(A | B) computed...",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/probability-tree-builder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=probability-tree-builder&embed=1",
      "standaloneUrl": null,
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        {
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          "type": "text",
          "label": "stage 1 · left branch label",
          "unit": "",
          "default": "has the disease"
        },
        {
          "name": "ptb-a",
          "type": "number",
          "label": "P",
          "unit": "left branch",
          "min": 0,
          "max": 1,
          "step": 0.001,
          "default": "0.01"
        },
        {
          "name": "ptb-ba",
          "type": "number",
          "label": "P(second stage · left | first · left) = positive test",
          "unit": "",
          "min": 0,
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          "label": "Check Intensity",
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            "basic",
            "standard",
            "advanced",
            "academic",
            "creative"
          ],
          "default": "standard"
        }
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        {
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=proofreading&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "proofreading",
        "style",
        "checker",
        "writing",
        "language",
        "advanced",
        "text",
        "analysis",
        "grammar",
        "readability"
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      "popularity": 5856,
      "featured": false,
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    },
    {
      "slug": "protein-daily-intake-calculator",
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      "category": "health-and-fitness",
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      "standaloneUrl": null,
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        {
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          "unit": "",
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          "max": 400,
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        },
        {
          "name": "prtn-u",
          "type": "select-one",
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          "options": [
            "kg",
            "lb"
          ],
          "default": "kg"
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        {
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          "type": "select-one",
          "label": "Activity",
          "unit": "",
          "options": [
            "0.8",
            "1.2",
            "1.6",
            "2.0",
            "2.2"
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          "default": "1.6"
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          "name": "prtn-out",
          "type": "output"
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      },
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      "sources": [],
      "tags": [
        "protein",
        "daily",
        "intake",
        "health",
        "fitness",
        "estimate",
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      "popularity": 4013,
      "featured": false,
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      "category": "writing-and-language",
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      "standaloneUrl": null,
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        {
          "name": "psc-check-vocabulary",
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        {
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        },
        {
          "name": "psc-check-engagement",
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        },
        {
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        {
          "name": "psc-speech",
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        {
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          "label": "Primary Focus",
          "unit": "",
          "options": [
            "clarity",
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            "delivery",
            "confidence",
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        {
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          "options": [
            "slow",
            "moderate",
            "fast",
            "presentation"
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          "default": "moderate"
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        {
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          "options": [
            "read",
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        {
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          "name": "psc-timer-display",
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      },
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      "sources": [],
      "tags": [
        "public",
        "speaking",
        "coach",
        "writing",
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      "featured": false,
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=pumpkin-puree-pie-planner&embed=1",
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        },
        {
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          "min": 100,
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        {
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        {
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        },
        {
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          "min": 0,
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        },
        {
          "name": "ppp-sugar",
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          "label": "Sugar per pie",
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          "step": 5,
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        },
        {
          "name": "ppp-spice",
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        {
          "name": "ppp-dish",
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          "label": "Dish size",
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          "options": [
            "8",
            "9",
            "10"
          ],
          "default": "9"
        }
      ],
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        {
          "name": "ppp-out",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=pumpkin-puree-pie-planner&<id>=<value>",
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      },
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        "pumpkin",
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      "featured": false,
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    },
    {
      "slug": "punctuation-guide",
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      "category": "writing-and-language",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=punctuation-guide&embed=1",
      "standaloneUrl": null,
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        {
          "name": "pg-search",
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          "label": "Search Punctuation",
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        },
        {
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          "label": "Enter a sentence to check",
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        },
        {
          "name": "pg-category",
          "type": "select-one",
          "label": "Category",
          "unit": "",
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            "all",
            "terminal",
            "separating",
            "enclosing",
            "omission"
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          "default": "all"
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          "name": "pg-correction-result",
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      ],
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=punctuation-guide&pg-category=all"
      },
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      "sources": [],
      "tags": [
        "punctuation",
        "guide",
        "mastery",
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        "language",
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      "featured": false,
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    },
    {
      "slug": "puppy-adult-weight-predictor",
      "title": "🐾 Puppy Adult Weight Forecaster",
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      "categoryName": "Dogs & Canine Care",
      "url": "https://www.themostusefulsiteintheworld.com/tool/puppy-adult-weight-predictor.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=puppy-adult-weight-predictor&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "max": 40,
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        {
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          "type": "number",
          "label": "Age in Weeks",
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          "max": 52,
          "step": 1,
          "default": "16"
        },
        {
          "name": "pup-frame",
          "type": "select-one",
          "label": "Breed Frame",
          "unit": "",
          "options": [
            "toy",
            "medium",
            "large",
            "giant"
          ],
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        {
          "name": "pup-growth-summary",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "puppy",
        "adult",
        "weight",
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        "dogs",
        "canine",
        "care",
        "gompertz",
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      "popularity": 5371,
      "featured": false,
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    },
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      "slug": "px-rem-em-unit-converter",
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      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/px-rem-em-unit-converter.html",
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        {
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        {
          "name": "prem-rem",
          "type": "number",
          "label": "rem",
          "unit": "",
          "min": 0,
          "default": "1"
        },
        {
          "name": "prem-em",
          "type": "number",
          "label": "em",
          "unit": "",
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          "default": "1"
        },
        {
          "name": "prem-root",
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          "label": "Root font-size",
          "unit": "px",
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        },
        {
          "name": "prem-parent",
          "type": "number",
          "label": "Parent font-size",
          "unit": "px",
          "min": 1,
          "default": "16"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=px-rem-em-unit-converter&<id>=<value>",
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      },
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      "sources": [],
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        "rem",
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        "algorithms",
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      "featured": false,
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        {
          "name": "pyt-b",
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        {
          "name": "pyt-c",
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          "min": 0
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        {
          "name": "pyt-results",
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          "name": "pyt-out",
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      ],
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      "formula": "Pythagoras' theorem: a² + b² = c² . Only works for right-",
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      "tags": [
        "pythagoras",
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    {
      "slug": "qr-code-generator",
      "title": "📱 QR Code Generator",
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      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/qr-code-generator.html",
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      "standaloneUrl": null,
      "inputs": [
        {
          "name": "qrUrl",
          "type": "url",
          "label": "https://example.com",
          "unit": ""
        },
        {
          "name": "qrWifiSsid",
          "type": "text",
          "label": "Network Name (SSID)",
          "unit": ""
        },
        {
          "name": "qrEmailTo",
          "type": "email",
          "label": "recipient@example.com",
          "unit": ""
        },
        {
          "name": "qrEmailSubject",
          "type": "text",
          "label": "Subject",
          "unit": ""
        },
        {
          "name": "qrPhone",
          "type": "tel",
          "label": "+1234567890",
          "unit": ""
        },
        {
          "name": "qrFg",
          "type": "color",
          "label": "qrFg",
          "unit": "",
          "default": "#000000"
        },
        {
          "name": "qrBg",
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          "label": "qrBg",
          "unit": "",
          "default": "#ffffff"
        },
        {
          "name": "qrText",
          "type": "textarea",
          "label": "Enter any text...",
          "unit": ""
        },
        {
          "name": "qrEmailBody",
          "type": "textarea",
          "label": "Message body",
          "unit": ""
        },
        {
          "name": "qrWifiEnc",
          "type": "select-one",
          "label": "qrWifiEnc",
          "unit": "",
          "options": [
            "WPA",
            "WEP"
          ],
          "default": "WPA"
        },
        {
          "name": "qrSize",
          "type": "select-one",
          "label": "qrSize",
          "unit": "",
          "options": [
            "200",
            "300",
            "400",
            "500"
          ],
          "default": "300"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=qr-code-generator&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=qr-code-generator&qrFg=%23000000&qrBg=%23ffffff&qrWifiEnc=WPA&qrSize=300"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "code",
        "productivity",
        "lifestyle",
        "generate",
        "codes",
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        "browser"
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      "popularity": 6303,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "qr-code-reader-scanner",
      "title": "📷 Instant QR & Image Reader",
      "description": "Decode QR codes instantly from uploaded screenshots, images, or your live camera feed. 100% private in-browser decoding — photos never leave your device.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/qr-code-reader-scanner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=qr-code-reader-scanner&embed=1",
      "standaloneUrl": null,
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        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "code",
        "reader",
        "scanner",
        "instant",
        "image",
        "productivity",
        "lifestyle",
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      ],
      "popularity": 5168,
      "featured": false,
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    },
    {
      "slug": "qr",
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      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/qr.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=qr&embed=1",
      "standaloneUrl": null,
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        }
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        "barcode",
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        "digit",
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      "slug": "qrtool",
      "title": "🔳 Advanced QR Generator",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=qrtool&embed=1",
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        {
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          "unit": ""
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        {
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        },
        {
          "name": "qrtoolwifi-encryption",
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          "label": "Error Correction",
          "unit": "",
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            "L",
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        {
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        {
          "name": "qr-size-display",
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        {
          "name": "qr-ecc-display",
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        {
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        }
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        "qtc",
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      "category": "science-and-engineering",
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      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
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      "standaloneUrl": null,
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      "featured": false,
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    {
      "slug": "quilt-tapestry-geometric-mosaic",
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            "3"
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    },
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      "slug": "quiz",
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        {
          "name": "rsol-preset",
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        "art",
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        "everyone"
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      "featured": false,
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    },
    {
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        },
        {
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        {
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        }
      ],
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        {
          "name": "rndp-numout",
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        },
        {
          "name": "rndp-diceout",
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      },
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        "random",
        "number",
        "dice",
        "name",
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        "productivity",
        "lifestyle",
        "cryptographically",
        "numbers",
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    },
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      "slug": "random-team-generator",
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        {
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        {
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        {
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        {
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          "type": "select-one",
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          "unit": "",
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            "numbers",
            "colours",
            "animals",
            "letters"
          ],
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      ],
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        {
          "name": "teamg-status",
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        {
          "name": "teamg-out",
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        }
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        },
        {
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      },
      "formula": "Ratio & Proportion Solve a/b = c/d for the blank, simplify a ratio, and scale a recipe-",
      "sources": [],
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      "category": "virtual-worlds-and-gaming",
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      "popularity": 6199,
      "featured": false,
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    },
    {
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      "categoryName": "Science & Engineering",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=rc-time-constant-calculator&embed=1",
      "standaloneUrl": null,
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        },
        {
          "name": "rctc-c",
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          "unit": "",
          "min": 0,
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        }
      ],
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        {
          "name": "rctc-out",
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      },
      "formula": "RC Time Constant τ = R × C. A capacitor charges to ~63% in one τ and ~99% in 5τ. Cut-off of a first-",
      "sources": [],
      "tags": [
        "time",
        "constant",
        "science",
        "engineering",
        "capacitor",
        "charges",
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        "first-order",
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      "featured": false,
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      "slug": "reaction-diffusion-turing-patterns",
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      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/reaction-diffusion-turing-patterns.html",
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      "standaloneUrl": null,
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      ],
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      "sources": [],
      "tags": [
        "reaction",
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        "science",
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      "popularity": 5133,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "reaction-time-click-speed-test",
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      "description": "Three quick reflex benchmarks in one place: how fast you react to a colour change (in milliseconds), how many clicks per second you can manage, and how accurately you hit moving targets. Personal b...",
      "category": "sports",
      "categoryName": "Sports",
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            "3",
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        {
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            "5",
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            "60"
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        {
          "name": "rxn-aimsize",
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          "unit": "",
          "options": [
            "60",
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            "26"
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        }
      ],
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        {
          "name": "rxn-arena",
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          "name": "rxn-result",
          "type": "output"
        }
      ],
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      "sources": [],
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        "reaction",
        "time",
        "click",
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        "sports",
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      "popularity": 6137,
      "featured": false,
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    },
    {
      "slug": "readability-score",
      "title": "📊 Readability Analyzer",
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      "category": "writing-and-language",
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          "default": "1"
        },
        {
          "name": "rs-text",
          "type": "textarea",
          "label": "Text to Analyze",
          "unit": ""
        },
        {
          "name": "rs-audience",
          "type": "select-one",
          "label": "audience",
          "unit": "",
          "options": [
            "general",
            "children",
            "teens",
            "adults",
            "academic",
            "technical"
          ],
          "default": "general"
        },
        {
          "name": "rs-content-type",
          "type": "select-one",
          "label": "content type",
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          "options": [
            "general",
            "web",
            "academic",
            "business",
            "creative",
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        "readability",
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      "featured": false,
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    },
    {
      "slug": "reading-timer",
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      "categoryName": "Productivity & Lifestyle",
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        },
        {
          "name": "rt-seconds",
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          "label": "Reading Time",
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          "min": 1,
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=reading-timer&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=reading-timer&rt-wordcount=500&rt-seconds=0"
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      "sources": [],
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        "reading",
        "timer",
        "pace",
        "productivity",
        "lifestyle",
        "time",
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        "passage",
        "measure",
        "words-per-minute"
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      "popularity": 4444,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "readingtime",
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      "category": "writing-and-language",
      "categoryName": "Writing & Language",
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        {
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        {
          "name": "rte-speed-custom",
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        {
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            "hours",
            "decimal"
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          "default": "minutes"
        }
      ],
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        {
          "name": "rte-speed-value",
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      "featured": false,
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    },
    {
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          "label": "Enhanced / ex-gratia offer on top",
          "unit": "£",
          "min": 0,
          "step": 500,
          "default": "0"
        },
        {
          "name": "rnc-holiday",
          "type": "number",
          "label": "Untaken holiday days owed",
          "unit": "",
          "min": 0,
          "max": 60,
          "step": 0.5,
          "default": "6"
        },
        {
          "name": "rnc-year",
          "type": "select-one",
          "label": "Tax year of redundancy",
          "unit": "",
          "options": [
            "751",
            "719",
            "700"
          ],
          "default": "751"
        }
      ],
      "outputs": [
        {
          "name": "rnc-res-total",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=redundancy-notice-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=redundancy-notice-calculator&rnc-age=47&rnc-years=12&rnc-weekly=800&rnc-extra=0&rnc-holiday=6&rnc-year=751"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "redundancy",
        "notice",
        "entitlement",
        "finance",
        "money",
        "work",
        "out",
        "statutory",
        "pay",
        "period"
      ],
      "popularity": 5529,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "reentry-heating-ballistic-calculator",
      "title": "🔥 Re-entry Heating & Ballistic Coefficient Calculator",
      "description": "Estimate ballistic coefficient, stagnation-point heat flux, peak heating, peak deceleration and total heat load along a constant-angle entry — the numbers that set a heat shield's size and shape.",
      "category": "rocketry-and-propulsion",
      "categoryName": "Rocketry & Propulsion",
      "url": "https://www.themostusefulsiteintheworld.com/tool/reentry-heating-ballistic-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=reentry-heating-ballistic-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rhb-mass",
          "type": "number",
          "label": "Entry mass",
          "unit": "kg",
          "min": 1,
          "step": 10,
          "default": "5000"
        },
        {
          "name": "rhb-dia",
          "type": "number",
          "label": "Vehicle diameter",
          "unit": "m",
          "min": 0.1,
          "step": 0.1,
          "default": "3.7"
        },
        {
          "name": "rhb-cd",
          "type": "number",
          "label": "Drag coefficient, Cd",
          "unit": "",
          "min": 0.1,
          "step": 0.05,
          "default": "1.2"
        },
        {
          "name": "rhb-rn",
          "type": "number",
          "label": "Nose radius",
          "unit": "m",
          "min": 0.01,
          "step": 0.01,
          "default": "0.3"
        },
        {
          "name": "rhb-vel",
          "type": "number",
          "label": "Entry velocity",
          "unit": "km/s",
          "min": 0.1,
          "step": 0.1,
          "default": "7.8"
        },
        {
          "name": "rhb-angle",
          "type": "number",
          "label": "Flight-path angle below horizon",
          "unit": "°",
          "min": 0.1,
          "max": 60,
          "step": 0.1,
          "default": "5"
        },
        {
          "name": "rhb-alt",
          "type": "number",
          "label": "Entry interface altitude",
          "unit": "km",
          "min": 20,
          "max": 200,
          "step": 5,
          "default": "120"
        },
        {
          "name": "rhb-emis",
          "type": "number",
          "label": "Surface emissivity",
          "unit": "",
          "min": 0.05,
          "max": 1,
          "step": 0.05,
          "default": "0.85"
        }
      ],
      "outputs": [
        {
          "name": "rhb-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=reentry-heating-ballistic-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=reentry-heating-ballistic-calculator&rhb-mass=5000&rhb-dia=3.7&rhb-cd=1.2&rhb-rn=0.3&rhb-vel=7.8&rhb-angle=5"
      },
      "formula": "Sutton–Graves correlation q̇ = 1.7415×10⁻⁴ √(ρ/R n ) V³ in SI units, with ρ in kg/",
      "sources": [],
      "tags": [
        "reentry",
        "heating",
        "ballistic",
        "re-entry",
        "coefficient",
        "rocketry",
        "propulsion",
        "estimate",
        "stagnation-point",
        "heat"
      ],
      "popularity": 4659,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "reminder",
      "title": "⏰ Reminder Tool",
      "description": "Create reminders that stay saved in your browser. Works offline — data saved locally.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/reminder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=reminder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rt-text",
          "type": "text",
          "label": "Reminder Text",
          "unit": ""
        },
        {
          "name": "rt-time",
          "type": "time",
          "label": "Time",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=reminder&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "reminder",
        "productivity",
        "lifestyle",
        "create",
        "reminders",
        "stay",
        "saved",
        "browser",
        "works",
        "offline"
      ],
      "popularity": 5638,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "rent-vs-buy-calculator",
      "title": "🏠 Rent vs Buy Calculator",
      "description": "Compare the 5-year cost of renting vs buying the same home. Includes mortgage interest, deposit opportunity cost, buying costs, and equity built. Estimates only — not financial advice.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/rent-vs-buy-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=rent-vs-buy-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rvb-price",
          "type": "number",
          "label": "Property price",
          "unit": "£",
          "min": 0,
          "step": 5000,
          "default": "300000"
        },
        {
          "name": "rvb-deposit",
          "type": "number",
          "label": "Deposit",
          "unit": "£",
          "min": 0,
          "step": 1000,
          "default": "30000"
        },
        {
          "name": "rvb-rate",
          "type": "number",
          "label": "Mortgage rate",
          "unit": "%",
          "min": 0,
          "max": 20,
          "step": 0.1,
          "default": "4.5"
        },
        {
          "name": "rvb-term",
          "type": "number",
          "label": "Mortgage term",
          "unit": "years",
          "min": 5,
          "max": 40,
          "step": 1,
          "default": "25"
        },
        {
          "name": "rvb-rent",
          "type": "number",
          "label": "Monthly rent",
          "unit": "£",
          "min": 0,
          "step": 50,
          "default": "1200"
        },
        {
          "name": "rvb-rent-growth",
          "type": "number",
          "label": "Annual rent rise",
          "unit": "%",
          "min": 0,
          "max": 15,
          "step": 0.5,
          "default": "3"
        },
        {
          "name": "rvb-house-growth",
          "type": "number",
          "label": "House price growth",
          "unit": "%/yr",
          "min": -5,
          "max": 15,
          "step": 0.5,
          "default": "2"
        },
        {
          "name": "rvb-buy-costs",
          "type": "number",
          "label": "Buying costs",
          "unit": "£, fees etc",
          "min": 0,
          "step": 500,
          "default": "3000"
        },
        {
          "name": "rvb-maint",
          "type": "number",
          "label": "Maintenance",
          "unit": "£/yr",
          "min": 0,
          "step": 100,
          "default": "1500"
        },
        {
          "name": "rvb-years",
          "type": "select-one",
          "label": "Compare over",
          "unit": "years",
          "options": [
            "3",
            "5",
            "7",
            "10"
          ],
          "default": "5"
        }
      ],
      "outputs": [
        {
          "name": "rvb-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=rent-vs-buy-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=rent-vs-buy-calculator&rvb-price=300000&rvb-deposit=30000&rvb-rate=4.5&rvb-term=25&rvb-rent=1200&rvb-rent-growth=3"
      },
      "formula": "Buying cost = mortgage interest + buying costs (solicitor, survey, etc.) +",
      "sources": [],
      "tags": [
        "rent",
        "buy",
        "finance",
        "money",
        "compare",
        "5-year",
        "cost",
        "renting",
        "buying",
        "same"
      ],
      "popularity": 4477,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "rent",
      "title": "🏠 Rent Calculator",
      "description": "Split rent among roommates, calculate per-person costs, and account for room size differences. Supports multiple currencies and custom splits.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/rent.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=rent&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rc-total",
          "type": "number",
          "label": "Total Monthly Rent",
          "unit": "",
          "min": 0,
          "step": 0.01,
          "default": "1200"
        },
        {
          "name": "rc-roommates",
          "type": "number",
          "label": "Number of People",
          "unit": "",
          "min": 1,
          "max": 20,
          "default": "3"
        },
        {
          "name": "rc-utilities",
          "type": "number",
          "label": "Monthly Utilities",
          "unit": "£",
          "min": 0,
          "step": 0.01,
          "default": "0"
        },
        {
          "name": "rc-security",
          "type": "number",
          "label": "Security Deposit",
          "unit": "£",
          "min": 0,
          "step": 0.01,
          "default": "0"
        },
        {
          "name": "rc-auto-ratios",
          "type": "checkbox",
          "label": "Auto-generate ratios based on inputs",
          "unit": "",
          "default": "1"
        },
        {
          "name": "rentrc-currency",
          "type": "select-one",
          "label": "currency",
          "unit": "",
          "options": [
            "£",
            "$",
            "€",
            "¥",
            "₹"
          ],
          "default": "£"
        }
      ],
      "outputs": [
        {
          "name": "rentrc-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=rent&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=rent&rc-total=1200&rc-roommates=3&rc-utilities=0&rc-security=0&rc-auto-ratios=1&rentrc-currency=%C2%A3&run=1"
      },
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      "sources": [],
      "tags": [
        "rent",
        "finance",
        "money",
        "split",
        "among",
        "roommates",
        "calculate",
        "per-person",
        "costs",
        "account"
      ],
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "rental-move-in-condition-report",
      "title": "🏠 Rental Move-in Condition Report",
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      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/rental-move-in-condition-report.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=rental-move-in-condition-report&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rental-move-in-condition-report-date",
          "type": "date",
          "label": "Inspection date",
          "unit": ""
        },
        {
          "name": "rental-move-in-condition-report-people",
          "type": "text",
          "label": "People present",
          "unit": ""
        },
        {
          "name": "rental-move-in-condition-report-move-date",
          "type": "date",
          "label": "Tenancy / move-in date",
          "unit": ""
        },
        {
          "name": "rental-move-in-condition-report-electric",
          "type": "text",
          "label": "Electric meter reading",
          "unit": ""
        },
        {
          "name": "rental-move-in-condition-report-gas",
          "type": "text",
          "label": "Gas meter reading",
          "unit": ""
        },
        {
          "name": "rental-move-in-condition-report-water",
          "type": "text",
          "label": "Water meter reading",
          "unit": ""
        },
        {
          "name": "rental-move-in-condition-report-keys",
          "type": "text",
          "label": "Keys, fobs and access items",
          "unit": ""
        },
        {
          "name": "rental-move-in-condition-report-area",
          "type": "text",
          "label": "Room / area",
          "unit": ""
        },
        {
          "name": "rental-move-in-condition-report-item",
          "type": "text",
          "label": "Item / surface",
          "unit": ""
        },
        {
          "name": "rental-move-in-condition-report-photo",
          "type": "text",
          "label": "Photo / video reference",
          "unit": ""
        },
        {
          "name": "rental-move-in-condition-report-address",
          "type": "textarea",
          "label": "Property address",
          "unit": ""
        },
        {
          "name": "rental-move-in-condition-report-general",
          "type": "textarea",
          "label": "Other check-in notes",
          "unit": ""
        },
        {
          "name": "rental-move-in-condition-report-observation",
          "type": "textarea",
          "label": "Details",
          "unit": ""
        },
        {
          "name": "rental-move-in-condition-report-output",
          "type": "textarea",
          "label": "Generated report",
          "unit": ""
        },
        {
          "name": "rental-move-in-condition-report-condition",
          "type": "select-one",
          "label": "Observed state",
          "unit": "",
          "options": [
            "Not checked",
            "No visible issue noted",
            "Wear noted",
            "Damage noted",
            "Not present / not applicable"
          ],
          "default": "Not checked"
        }
      ],
      "outputs": [
        {
          "name": "rental-move-in-condition-report-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=rental-move-in-condition-report&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=rental-move-in-condition-report&rental-move-in-condition-report-condition=Not%20checked"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "rental",
        "move",
        "condition",
        "report",
        "move-in",
        "home",
        "diy",
        "make",
        "room-by-room",
        "check-in"
      ],
      "popularity": 6933,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "rental-yield-calculator",
      "title": "🏠 Rental Yield Deal Analyser",
      "description": "Compare gross yield, net yield and monthly cash flow for a prospective rental property. All calculations stay in your browser.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/rental-yield-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=rental-yield-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rental-yield-deal-analyser-price",
          "type": "number",
          "label": "Purchase price",
          "unit": "£",
          "default": "220000"
        },
        {
          "name": "rental-yield-deal-analyser-rent",
          "type": "number",
          "label": "Monthly rent",
          "unit": "£",
          "default": "1250"
        },
        {
          "name": "rental-yield-deal-analyser-annual",
          "type": "number",
          "label": "Annual running costs",
          "unit": "£",
          "default": "2600"
        },
        {
          "name": "rental-yield-deal-analyser-mortgage",
          "type": "number",
          "label": "Monthly mortgage cost",
          "unit": "£",
          "default": "650"
        }
      ],
      "outputs": [
        {
          "name": "rental-yield-deal-analyser-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=rental-yield-calculator&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=rental-yield-calculator&rental-yield-deal-analyser-price=220000&rental-yield-deal-analyser-rent=1250&rental-yield-deal-analyser-annual=2600&rental-yield-deal-analyser-mortgage=650&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "rental",
        "yield",
        "deal",
        "analyser",
        "finance",
        "money",
        "compare",
        "gross",
        "net",
        "monthly"
      ],
      "popularity": 4765,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "repair-cafe-capacity-planner",
      "title": "Repair Café Coordinator",
      "description": "Plan a repair event around the skills and hours people actually offer. Match repair requests to volunteers, show the waiting list, and calculate the proposed workload without promising a repair wil...",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/repair-cafe-capacity-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=repair-cafe-capacity-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "repair-cafe-capacity-planner-volunteers",
          "type": "textarea",
          "label": "Repair volunteers",
          "unit": ""
        },
        {
          "name": "repair-cafe-capacity-planner-jobs",
          "type": "textarea",
          "label": "Repair requests",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "repair-cafe-capacity-planner-status",
          "type": "live"
        },
        {
          "name": "repair-cafe-capacity-planner-results",
          "type": "output"
        },
        {
          "name": "repair-cafe-capacity-planner-summary",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=repair-cafe-capacity-planner&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "repair",
        "cafe",
        "capacity",
        "planner",
        "caf",
        "coordinator",
        "home",
        "diy",
        "plan",
        "event"
      ],
      "popularity": 6417,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "repair-or-replace",
      "title": "🔧 Repair or Replace?",
      "description": "The throwaway economy wants you to bin it and buy another. This decider weighs the three things that actually matter — cost per useful year, embodied carbon and remaining life — and tells you hones...",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/repair-or-replace.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=repair-or-replace&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rr-age",
          "type": "number",
          "label": "Age",
          "unit": "years",
          "min": 0,
          "max": 60,
          "step": 0.5,
          "default": "6"
        },
        {
          "name": "rr-repaircost",
          "type": "number",
          "label": "Quote to repair",
          "unit": "£",
          "min": 0,
          "max": 20000,
          "step": 1,
          "default": "120"
        },
        {
          "name": "rr-extralife",
          "type": "number",
          "label": "Repair buys",
          "unit": "years more",
          "min": 0.5,
          "max": 20,
          "step": 0.5,
          "default": "4"
        },
        {
          "name": "rr-newprice",
          "type": "number",
          "label": "Replacement price",
          "unit": "£",
          "min": 1,
          "max": 50000,
          "step": 1,
          "default": "400"
        },
        {
          "name": "rr-newlife",
          "type": "number",
          "label": "Replacement lasts",
          "unit": "years",
          "min": 1,
          "max": 30,
          "step": 0.5,
          "default": "11"
        },
        {
          "name": "rr-kwhold",
          "type": "number",
          "label": "Old unit energy",
          "unit": "kWh/yr",
          "min": 0,
          "max": 50000,
          "step": 1,
          "default": "215"
        },
        {
          "name": "rr-kwhnew",
          "type": "number",
          "label": "New unit energy",
          "unit": "kWh/yr",
          "min": 0,
          "max": 50000,
          "step": 1,
          "default": "155"
        },
        {
          "name": "rr-price",
          "type": "number",
          "label": "Your energy price",
          "unit": "£/kWh",
          "min": 0.01,
          "max": 2,
          "step": 0.01,
          "default": "0.25"
        },
        {
          "name": "rr-embodied",
          "type": "number",
          "label": "Making a new one emits",
          "unit": "kg CO₂e",
          "min": 0,
          "max": 100000,
          "step": 5,
          "default": "390"
        },
        {
          "name": "rr-grid",
          "type": "number",
          "label": "Grid carbon",
          "unit": "kg CO₂/kWh",
          "min": 0,
          "max": 1.5,
          "step": 0.01,
          "default": "0.20"
        },
        {
          "name": "rr-item",
          "type": "select-one",
          "label": "What is it?",
          "unit": "",
          "options": [
            "custom",
            "wash",
            "dish",
            "fridge",
            "oven",
            "tv",
            "laptop",
            "phone",
            "tablet",
            "vac",
            "printer",
            "micro",
            "boiler"
          ],
          "default": "custom"
        }
      ],
      "outputs": [
        {
          "name": "rr-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=repair-or-replace&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=repair-or-replace&rr-age=6&rr-repaircost=120&rr-extralife=4&rr-newprice=400&rr-newlife=11&rr-kwhold=215"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "repair",
        "replace",
        "home",
        "diy",
        "throwaway",
        "economy",
        "wants",
        "bin",
        "buy",
        "another"
      ],
      "popularity": 4694,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "required-fire-flow-calculator",
      "title": "🚒 Required Fire Flow Calculator",
      "description": "Needed fire flow by the National Fire Academy, Iowa State and ISO methods side by side, with exposure charges and a hoseline plan for the answer.",
      "category": "fire-and-rescue-service",
      "categoryName": "Fire & Rescue Service",
      "url": "https://www.themostusefulsiteintheworld.com/tool/required-fire-flow-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=required-fire-flow-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rff-len",
          "type": "number",
          "label": "Length",
          "unit": "ft",
          "min": 0,
          "default": "60"
        },
        {
          "name": "rff-wid",
          "type": "number",
          "label": "Width",
          "unit": "ft",
          "min": 0,
          "default": "40"
        },
        {
          "name": "rff-hgt",
          "type": "number",
          "label": "Ceiling height (ft) — Iowa",
          "unit": "",
          "min": 0,
          "default": "10"
        },
        {
          "name": "rff-floors",
          "type": "number",
          "label": "Floors involved",
          "unit": "",
          "min": 1,
          "max": 20,
          "step": 1,
          "default": "1"
        },
        {
          "name": "rff-exp",
          "type": "number",
          "label": "Exposed sides",
          "unit": "25% each",
          "min": 0,
          "max": 4,
          "step": 1,
          "default": "0"
        },
        {
          "name": "rff-xp",
          "type": "number",
          "label": "X + P — ISO",
          "unit": "max 1.75",
          "min": 0,
          "max": 1.75,
          "step": 0.05,
          "default": "0"
        },
        {
          "name": "rff-inv",
          "type": "select-one",
          "label": "% involved",
          "unit": "",
          "options": [
            "100",
            "75",
            "50",
            "25",
            "15"
          ],
          "default": "50"
        },
        {
          "name": "rff-constr",
          "type": "select-one",
          "label": "Construction factor F — ISO",
          "unit": "",
          "options": [
            "1.5",
            "1.0",
            "0.8",
            "0.6"
          ],
          "default": "1.5"
        },
        {
          "name": "rff-occ",
          "type": "select-one",
          "label": "Occupancy factor O — ISO",
          "unit": "",
          "options": [
            "0.75",
            "1.00",
            "1.25",
            "1.50"
          ],
          "default": "1.00"
        },
        {
          "name": "rff-line",
          "type": "select-one",
          "label": "Attack line flow",
          "unit": "gpm",
          "options": [
            "95",
            "150",
            "185",
            "250",
            "350",
            "1000"
          ],
          "default": "250"
        }
      ],
      "outputs": [
        {
          "name": "rff-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=required-fire-flow-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=required-fire-flow-calculator&rff-len=60&rff-wid=40&rff-hgt=10&rff-floors=1&rff-exp=0&rff-xp=0"
      },
      "formula": "Construction factor F — ISO Frame (F = 1.5) Joisted masonry (F = 1.0) Non-",
      "sources": [],
      "tags": [
        "required",
        "fire",
        "flow",
        "rescue",
        "service",
        "needed",
        "national",
        "academy",
        "iowa",
        "state"
      ],
      "popularity": 5680,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "resignation-letter-generator",
      "title": "✍️ Resignation Letter Generator",
      "description": "One minute of form, one courteous letter. It works out your contractual last day, keeps the door open, and never says anything you’ll regret — fill it in and copy it out.",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/resignation-letter-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=resignation-letter-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rlg-name",
          "type": "text",
          "label": "Your name",
          "unit": "",
          "default": "Alex Smith"
        },
        {
          "name": "rlg-role",
          "type": "text",
          "label": "Your job title",
          "unit": "",
          "default": "Operations Coordinator"
        },
        {
          "name": "rlg-company",
          "type": "text",
          "label": "Company",
          "unit": "",
          "default": "Northgate Ltd"
        },
        {
          "name": "rlg-manager",
          "type": "text",
          "label": "Manager&rsquo;s name",
          "unit": "",
          "default": "Sam Jones"
        },
        {
          "name": "rlg-notice",
          "type": "number",
          "label": "Contractual notice",
          "unit": "weeks",
          "min": 1,
          "max": 26,
          "step": 1,
          "default": "4"
        },
        {
          "name": "rlg-date",
          "type": "date",
          "label": "Letter date",
          "unit": ""
        },
        {
          "name": "rlg-handover",
          "type": "checkbox",
          "label": "Offer to help with the handover",
          "unit": "",
          "default": "1"
        },
        {
          "name": "rlg-ref",
          "type": "checkbox",
          "label": "Ask for a reference / LinkedIn recommendation",
          "unit": "",
          "default": "0"
        },
        {
          "name": "rlg-tone",
          "type": "select-one",
          "label": "Tone",
          "unit": "",
          "options": [
            "professional",
            "warm",
            "firm"
          ],
          "default": "professional"
        },
        {
          "name": "rlg-reason",
          "type": "select-one",
          "label": "Reason (kept vague on purpose)",
          "unit": "",
          "options": [
            "none",
            "newrole",
            "study",
            "careerbreak",
            "personal"
          ],
          "default": "none"
        }
      ],
      "outputs": [
        {
          "name": "rlg-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=resignation-letter-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=resignation-letter-generator&rlg-name=Alex%20Smith&rlg-role=Operations%20Coordinator&rlg-company=Northgate%20Ltd&rlg-manager=Sam%20Jones&rlg-notice=4&rlg-handover=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "resignation",
        "letter",
        "writing",
        "language",
        "one",
        "minute",
        "form",
        "courteous",
        "works",
        "out"
      ],
      "popularity": 5692,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "resistor-color-code",
      "title": "🎨 Resistor Color Code",
      "description": "Decode resistor color bands into resistance values. ⚠️ Educational only — verify with multimeter.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/resistor-color-code.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=resistor-color-code&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rcc-output",
          "type": "textarea",
          "label": "output",
          "unit": ""
        },
        {
          "name": "rcc-mode",
          "type": "select-one",
          "label": "Resistor Type",
          "unit": "",
          "options": [
            "4",
            "5",
            "6"
          ],
          "default": "4"
        }
      ],
      "outputs": [
        {
          "name": "rcc-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=resistor-color-code&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=resistor-color-code&rcc-mode=4"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "resistor",
        "color",
        "code",
        "science",
        "engineering",
        "decode",
        "bands",
        "into",
        "resistance",
        "values"
      ],
      "popularity": 6993,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "resume-ats-scanner-pro",
      "title": "🎯 Resume ATS Scanner Pro — Beat the Bots",
      "description": "Paste any resume + job description and get an instant ATS score, keyword gaps, formatting traps and a line-by-line fix list. Replaces JobScan Premium ($50/mo) — 100% offline, no upload, no AI API. ...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/resume-ats-scanner-pro.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=resume-ats-scanner-pro&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "atspro-resume",
          "type": "textarea",
          "label": "Your resume text",
          "unit": ""
        },
        {
          "name": "atspro-jd",
          "type": "textarea",
          "label": "Job description",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "atspro-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=resume-ats-scanner-pro&<id>=<value>",
        "runs": false
      },
      "formula": "ATS score = 35% keyword coverage · 20% hard-skill coverage · 15% formatting · 15% length/",
      "sources": [],
      "tags": [
        "resume",
        "ats",
        "scanner",
        "pro",
        "beat",
        "bots",
        "saas",
        "business",
        "killers",
        "paste"
      ],
      "popularity": 5423,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "retainer-capacity-planner",
      "title": "⏱️ Retainer Capacity Planner",
      "description": "Check whether monthly client retainers fit your available hours and reveal effective revenue per hour. All calculations stay in your browser.",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/retainer-capacity-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=retainer-capacity-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "retainer-capacity-planner-clients",
          "type": "number",
          "label": "Retainer clients",
          "unit": "",
          "default": "8"
        },
        {
          "name": "retainer-capacity-planner-hours",
          "type": "number",
          "label": "Hours per client",
          "unit": "",
          "default": "12"
        },
        {
          "name": "retainer-capacity-planner-fee",
          "type": "number",
          "label": "Monthly fee per client",
          "unit": "£",
          "default": "900"
        },
        {
          "name": "retainer-capacity-planner-capacity",
          "type": "number",
          "label": "Available delivery hours",
          "unit": "",
          "default": "120"
        }
      ],
      "outputs": [
        {
          "name": "retainer-capacity-planner-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=retainer-capacity-planner&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=retainer-capacity-planner&retainer-capacity-planner-clients=8&retainer-capacity-planner-hours=12&retainer-capacity-planner-fee=900&retainer-capacity-planner-capacity=120&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "retainer",
        "capacity",
        "planner",
        "saas",
        "business",
        "killers",
        "check",
        "whether",
        "monthly",
        "client"
      ],
      "popularity": 5750,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "retirement",
      "title": "💰 Retirement Calculator",
      "description": "Estimate your retirement savings growth with compound interest. ⚠️ Educational only — consult a financial advisor.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/retirement.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=retirement&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rc-current-savings",
          "type": "number",
          "label": "Current Savings",
          "unit": "",
          "min": 0,
          "step": 1000,
          "default": "10000"
        },
        {
          "name": "rc-current-age",
          "type": "number",
          "label": "Current Age",
          "unit": "",
          "min": 18,
          "max": 100,
          "default": "30"
        },
        {
          "name": "retirerc-monthly-contrib",
          "type": "number",
          "label": "Monthly Contribution",
          "unit": "",
          "min": 0,
          "step": 50,
          "default": "500"
        },
        {
          "name": "rc-annual-increase",
          "type": "number",
          "label": "Annual Increase",
          "unit": "%",
          "min": 0,
          "max": 20,
          "step": 0.5,
          "default": "3"
        },
        {
          "name": "rc-annual-return",
          "type": "number",
          "label": "Annual Return",
          "unit": "%",
          "min": 0,
          "max": 20,
          "step": 0.1,
          "default": "7"
        },
        {
          "name": "rc-retirement-age",
          "type": "number",
          "label": "Retirement Age",
          "unit": "",
          "min": 40,
          "max": 100,
          "default": "65"
        },
        {
          "name": "rc-withdrawal-rate",
          "type": "number",
          "label": "Annual Withdrawal Rate",
          "unit": "%",
          "min": 1,
          "max": 10,
          "step": 0.25,
          "default": "4"
        },
        {
          "name": "rc-retirement-length",
          "type": "number",
          "label": "Retirement Length",
          "unit": "Years",
          "min": 10,
          "max": 50,
          "step": 5,
          "default": "30"
        },
        {
          "name": "retirerc-currency",
          "type": "select-one",
          "label": "retirerc currency",
          "unit": "",
          "options": [
            "$",
            "£",
            "€",
            "¥"
          ],
          "default": "$"
        }
      ],
      "outputs": [
        {
          "name": "retirerc-results",
          "type": "output"
        },
        {
          "name": "rc-future-value",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=retirement&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=retirement&rc-current-savings=10000&rc-current-age=30&retirerc-monthly-contrib=500&rc-annual-increase=3&rc-annual-return=7&rc-retirement-age=65&run=1"
      },
      "formula": "Future Value Formula: FV = P × (1+r)^n + C × [((1+r)^n − 1) /",
      "sources": [],
      "tags": [
        "retirement",
        "finance",
        "money",
        "estimate",
        "savings",
        "growth",
        "compound",
        "interest",
        "educational",
        "only"
      ],
      "popularity": 4839,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "return-window-deadline-calculator",
      "title": "Return Window Deadline Calculator",
      "description": "Calculate a calendar-day deadline from a purchase or delivery date and the retailer’s stated return period, with an optional posting buffer.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/return-window-deadline-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=return-window-deadline-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "return-window-deadline-calculator-start",
          "type": "date",
          "label": "Purchase or delivery date",
          "unit": ""
        },
        {
          "name": "return-window-deadline-calculator-days",
          "type": "number",
          "label": "Return window (calendar days)",
          "unit": "",
          "min": 1,
          "max": 3650,
          "step": 1,
          "default": "30"
        },
        {
          "name": "return-window-deadline-calculator-buffer",
          "type": "number",
          "label": "Days to allow before deadline",
          "unit": "",
          "min": 0,
          "max": 3650,
          "step": 1,
          "default": "3"
        },
        {
          "name": "return-window-deadline-calculator-asof",
          "type": "date",
          "label": "Check status as of",
          "unit": ""
        },
        {
          "name": "return-window-deadline-calculator-count",
          "type": "select-one",
          "label": "How the policy counts days Day 1 is the next day Purchase / delivery date is day 1",
          "unit": "",
          "options": [
            "after",
            "inclusive"
          ],
          "default": "after"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=return-window-deadline-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=return-window-deadline-calculator&return-window-deadline-calculator-days=30&return-window-deadline-calculator-buffer=3&return-window-deadline-calculator-count=after"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "return",
        "window",
        "deadline",
        "productivity",
        "lifestyle",
        "calculate",
        "calendar-day",
        "purchase",
        "delivery",
        "date"
      ],
      "popularity": 6319,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "reverb-pre-delay-decay-calculator",
      "title": "🌌 Reverb Pre-Delay & RT60 Decay BPM Calculator",
      "description": "Uncalculated reverb washes out hip hop vocals and turns snappy snares into a muddy blur. Calculate tempo-synced pre-delay (giving the upfront vocal clarity before reverb begins) and precise decay t...",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/reverb-pre-delay-decay-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=reverb-pre-delay-decay-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rvp-bpm-slider",
          "type": "range",
          "label": "Beat Tempo",
          "unit": "BPM",
          "min": 60,
          "max": 180,
          "default": "140"
        },
        {
          "name": "rvp-preset-select",
          "type": "select-one",
          "label": "Hip Hop Reverb Space",
          "unit": "",
          "options": [
            "tight-vocal",
            "snare-plate",
            "trap-space",
            "adlib-delay"
          ],
          "default": "tight-vocal"
        },
        {
          "name": "rvp-predelay-note",
          "type": "select-one",
          "label": "Pre-Delay Division",
          "unit": "",
          "options": [
            "64th",
            "32nd",
            "16th",
            "8th"
          ],
          "default": "16th"
        }
      ],
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        {
          "name": "rvp-out-total",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=reverb-pre-delay-decay-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=reverb-pre-delay-decay-calculator&rvp-bpm-slider=140&rvp-preset-select=tight-vocal&rvp-predelay-note=16th"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
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        "reverb",
        "pre",
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        "decay",
        "pre-delay",
        "rt60",
        "bpm",
        "music",
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      "popularity": 6140,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "reward-site-reality-check",
      "title": "💸 Reward Site Earnings Reality Check",
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      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/reward-site-reality-check.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=reward-site-reality-check&embed=1",
      "standaloneUrl": null,
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        {
          "name": "rsr-hours",
          "type": "number",
          "label": "Hours a week you can realistically spare",
          "unit": "",
          "min": 0,
          "max": 60,
          "step": 0.5,
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        },
        {
          "name": "rsr-wage",
          "type": "number",
          "label": "Hourly wage to compare against",
          "unit": "&pound;",
          "min": 0,
          "max": 200,
          "step": 0.01,
          "default": "12.71"
        },
        {
          "name": "rsr-mix-surveys",
          "type": "radio",
          "label": "Surveys only. No installs, no card details. Slowest, but nothing to undo later.",
          "unit": "",
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        },
        {
          "name": "rsr-mix-mixed",
          "type": "radio",
          "label": "Surveys plus app installs. Better rate. Some installs want a free trial with card details.",
          "unit": "",
          "default": "0"
        },
        {
          "name": "rsr-mix-games",
          "type": "radio",
          "label": "Chase the big game offers. Best hourly rate, but payouts want days or weeks of play.",
          "unit": "",
          "default": "0"
        },
        {
          "name": "rsr-mix-anything",
          "type": "radio",
          "label": "Anything, including card-detail trials. Highest rate, highest admin and risk.",
          "unit": "",
          "default": "0"
        }
      ],
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        {
          "name": "rsr-results",
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      ],
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      },
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      "sources": [],
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        "reward",
        "site",
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      "featured": false,
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    },
    {
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      "categoryName": "Science & Engineering",
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      "standaloneUrl": null,
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          "max": 500,
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        {
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          "step": 0.5,
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        {
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          "label": "RX antenna gain",
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          "step": 0.5,
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        {
          "name": "rlbf-sens",
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          "min": -160,
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        {
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          "default": "12"
        },
        {
          "name": "rlbf-h2",
          "type": "number",
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          "max": 1000,
          "step": 0.5,
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        {
          "name": "rlbf-obst",
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          "label": "Obstacle height above the path ends",
          "unit": "m",
          "min": 0,
          "max": 3000,
          "step": 1,
          "default": "0"
        },
        {
          "name": "rlbf-obstd",
          "type": "number",
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          "unit": "km",
          "min": 0,
          "max": 500,
          "step": 0.1,
          "default": "6"
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        {
          "name": "rlbf-preset",
          "type": "select-one",
          "label": "Start from a known kind of link",
          "unit": ""
        },
        {
          "name": "rlbf-k",
          "type": "select-one",
          "label": "Refraction k-factor",
          "unit": "",
          "options": [
            "1",
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            "0.66",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=rf-link-budget-fresnel-planner&<id>=<value>",
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      },
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        "link",
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      "featured": false,
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=rhyme-finder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rym-word",
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      ],
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        {
          "name": "rym-out",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=rhyme-finder&<id>=<value>",
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      "sources": [],
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        "rhyme",
        "finder",
        "writing",
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        "find",
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      ],
      "popularity": 5136,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "rhythm-generator",
      "title": "🥁 Rhythm Generator",
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      "category": "music-and-audio",
      "categoryName": "Music & Audio",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=rhythm-generator&embed=1",
      "standaloneUrl": null,
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        {
          "name": "rg-bars",
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          "label": "Pattern Length",
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        {
          "name": "rg-tempo",
          "type": "number",
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          "max": 240,
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            "4/4",
            "3/4",
            "2/4",
            "6/8",
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            "7/8"
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          "default": "4/4"
        },
        {
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          "type": "select-one",
          "label": "Style/Groove",
          "unit": "",
          "options": [
            "basic",
            "rock",
            "funk",
            "jazz",
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            "electronic",
            "syncopated",
            "polyrhythm"
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          "default": "basic"
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          "name": "rg-instrument",
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            "drumkit",
            "percussion",
            "piano",
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      ],
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        {
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          "name": "rg-results",
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=rhythm-generator&<id>=<value>",
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      },
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        "rhythm",
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      "featured": false,
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        {
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        {
          "name": "ricw-people",
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        {
          "name": "ricw-type",
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            "1.5",
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      ],
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        {
          "name": "ricw-out",
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=rice-water-ratio-calculator&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=rice-water-ratio-calculator&ricw-cups=1.5&ricw-type=1.75"
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      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
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        "rice",
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      "popularity": 6474,
      "featured": false,
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      "slug": "riemann-sum-lab",
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      "category": "mathematics",
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      "inputs": [
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        {
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          "max": 200,
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      "sources": [],
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        "riemann",
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      "featured": false,
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    {
      "slug": "riley-goblin-smasher",
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      "category": "mind-blowing-demos",
      "categoryName": "Mind-Blowing Demos",
      "url": "https://www.themostusefulsiteintheworld.com/tool/riley-goblin-smasher.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=riley-goblin-smasher&embed=1",
      "standaloneUrl": null,
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=riley-goblin-smasher&<id>=<value>",
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      "sources": [],
      "tags": [
        "riley",
        "goblin",
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        "arena",
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        "raw",
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      "popularity": 6103,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "ring-size-converter",
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      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/ring-size-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=ring-size-converter&embed=1",
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          "max": 16,
          "step": 0.25,
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        },
        {
          "name": "rngs-circ",
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          "label": "Inside circ.",
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          "max": 80,
          "default": "54.4"
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        {
          "name": "rngs-dia",
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          "min": 10,
          "max": 25,
          "default": "17.3"
        },
        {
          "name": "rngs-uk",
          "type": "select-one",
          "label": "UK / Ireland / AU",
          "unit": ""
        }
      ],
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=ring-size-converter&<id>=<value>",
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "ring",
        "size",
        "converter",
        "productivity",
        "lifestyle",
        "convert",
        "letters",
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      "popularity": 6071,
      "featured": false,
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    },
    {
      "slug": "river-meander-lab",
      "title": "🏞️ River Meander Lab",
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      "category": "interactive-art-and-living-worlds",
      "categoryName": "Interactive Art & Living Worlds",
      "url": "https://www.themostusefulsiteintheworld.com/tool/river-meander-lab.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=river-meander-lab&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rvr-q",
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          "max": 500,
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          "name": "rvr-sed",
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          "min": 0.05,
          "max": 1,
          "step": 0.05,
          "default": "0.4"
        },
        {
          "name": "rvr-coh",
          "type": "range",
          "label": "Bank cohesion 0.55",
          "unit": "",
          "min": 0.15,
          "max": 1,
          "step": 0.05,
          "default": "0.55"
        },
        {
          "name": "rvr-spd",
          "type": "range",
          "label": "Years / frame 2",
          "unit": "",
          "min": 1,
          "max": 8,
          "default": "2"
        }
      ],
      "outputs": [
        {
          "name": "rvr-out",
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      ],
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        "river",
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      "popularity": 6587,
      "featured": false,
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    {
      "slug": "robots-sitemap-generator",
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      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=robots-sitemap-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "label": "Canonical site URL",
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          "default": "https://example.com"
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        {
          "name": "rsg-lastmod",
          "type": "date",
          "label": "Last modified",
          "unit": ""
        },
        {
          "name": "rsg-crawl-delay",
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          "label": "Crawl-delay",
          "unit": "",
          "min": 0,
          "max": 120,
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        {
          "name": "rsg-allow-root",
          "type": "checkbox",
          "label": "Add Allow: /",
          "unit": "",
          "default": "1"
        },
        {
          "name": "rsg-urls",
          "type": "textarea",
          "label": "Pages — one path or full URL per line",
          "unit": ""
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        {
          "name": "rsg-disallow",
          "type": "textarea",
          "label": "Disallow paths — one per line",
          "unit": ""
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        {
          "name": "rsg-output",
          "type": "textarea",
          "label": "Generated file",
          "unit": ""
        },
        {
          "name": "rsg-frequency",
          "type": "select-one",
          "label": "Sitemap changefreq",
          "unit": "",
          "options": [
            "weekly",
            "daily",
            "monthly",
            "yearly"
          ],
          "default": "monthly"
        },
        {
          "name": "rsg-priority",
          "type": "select-one",
          "label": "Sitemap priority",
          "unit": "",
          "options": [
            "1.0",
            "0.8",
            "0.5",
            "0.3"
          ],
          "default": "0.8"
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      ],
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        {
          "name": "rsg-status",
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=robots-sitemap-generator&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=robots-sitemap-generator&rsg-site=https%3A%2F%2Fexample.com&rsg-allow-root=1&rsg-frequency=monthly&rsg-priority=0.8"
      },
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      "sources": [],
      "tags": [
        "robots",
        "sitemap",
        "txt",
        "saas",
        "business",
        "killers",
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      "popularity": 4575,
      "featured": false,
      "updated": "2026-09-19"
    },
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      "slug": "rock-cycle-mineral-id-lab",
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          "name": "rck-slider-press",
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          "label": "slider press",
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          "options": [
            "white",
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          "default": "white"
        },
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          "name": "rck-select-lustre",
          "type": "select-one",
          "label": "select lustre",
          "unit": "",
          "options": [
            "metallic",
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            "dull",
            "pearly",
            "greasy"
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          "default": "metallic"
        },
        {
          "name": "rck-select-cleavage",
          "type": "select-one",
          "label": "select cleavage",
          "unit": "",
          "options": [
            "perfect",
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            "poor",
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          "default": "perfect"
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    {
      "slug": "rocket-apogee-delay-planner",
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        {
          "name": "rap-thrust",
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          "label": "Average thrust",
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          "default": "60"
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        {
          "name": "rap-burn",
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        {
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          "name": "rap-cd",
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          "min": 0,
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        {
          "name": "rap-elev",
          "type": "number",
          "label": "Launch site elevation",
          "unit": "m",
          "min": -100,
          "step": 10,
          "default": "100"
        },
        {
          "name": "rap-temp",
          "type": "number",
          "label": "Air temperature at site",
          "unit": "°C",
          "min": -40,
          "max": 50,
          "step": 1,
          "default": "15"
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        {
          "name": "rap-delay",
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          "label": "Motor delay fitted",
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          "min": 0,
          "max": 30,
          "step": 0.5,
          "default": "10"
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      ],
      "outputs": [
        {
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=rocket-ascent-flight-simulator&embed=1",
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          "label": "Liftoff mass",
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        {
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          "label": "Propellant mass",
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          "min": 0.01,
          "step": 0.1,
          "default": "50"
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          "name": "ras-thrust",
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          "min": 0.1,
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          "name": "ras-burn",
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          "label": "Burn time",
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          "min": 0.05,
          "step": 0.1,
          "default": "16"
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        {
          "name": "ras-dia",
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          "label": "Body diameter",
          "unit": "m",
          "min": 0.005,
          "step": 0.005,
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        {
          "name": "ras-cd",
          "type": "number",
          "label": "Drag coefficient, Cd",
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          "min": 0.05,
          "step": 0.01,
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        {
          "name": "ras-elev",
          "type": "number",
          "label": "Launch site elevation",
          "unit": "m",
          "min": -100,
          "step": 10,
          "default": "100"
        },
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          "name": "ras-pitch-alt",
          "type": "number",
          "label": "Pitch-over altitude",
          "unit": "m",
          "min": 0,
          "step": 50,
          "default": "300"
        },
        {
          "name": "ras-pitch-rate",
          "type": "number",
          "label": "Pitch rate after that",
          "unit": "°/s",
          "min": 0,
          "max": 10,
          "step": 0.05,
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      ],
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      },
      "formula": "Mass falls linearly as propellant is consumed — ṁ = propellant mass ÷",
      "sources": [],
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      "featured": false,
      "updated": "2026-09-19"
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      "slug": "rocket-launch-safety-check",
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        {
          "name": "rls-rail",
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          "label": "Usable rail travel",
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          "step": 0.05,
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          "step": 0.1,
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          "step": 0.01,
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        {
          "name": "rls-wind",
          "type": "number",
          "label": "Surface wind",
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          "step": 0.5,
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        {
          "name": "rls-elev",
          "type": "number",
          "label": "Launch site elevation",
          "unit": "m",
          "min": -100,
          "step": 10,
          "default": "100"
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      "featured": false,
      "updated": "2026-09-19"
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      "slug": "rocket-multistage-delta-v-planner",
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          "label": "Target delta-v",
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          "min": 0,
          "step": 100,
          "default": "9400"
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          "min": 0.1,
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          "min": 0.1,
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          "label": "Propellant mass",
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          "min": 0.1,
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    },
    {
      "slug": "rocket-nozzle-thrust-calculator",
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      "formula": "Methods Basic ROI: ROI = ((Final - Initial) / Initial) × 100% Annualized ROI: ((1 +",
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    },
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      "categoryName": "Museum & Collection",
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      "sources": [],
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        "roman",
        "coin",
        "denominations",
        "room",
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      "popularity": 6938,
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    },
    {
      "slug": "roman-numeral-converter",
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        {
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      "popularity": 6873,
      "featured": false,
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    },
    {
      "slug": "roof-pitch-rafter-calculator",
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        {
          "name": "rfp-run",
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      ],
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      },
      "formula": "The rafter is the hypotenuse of a right triangle: rafter = run × √(1 + (pitch/12)&sup2;). The same √ factor is the roof-",
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      "featured": false,
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    {
      "slug": "room-acoustics-simulator",
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        {
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      "sources": [],
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        "room",
        "acoustics",
        "simulator",
        "echo",
        "chamber",
        "museum",
        "collection",
        "watch",
        "sound",
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      "featured": false,
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    },
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      "slug": "room-btu-hvac-calculator",
      "title": "🌡️ Room BTU & HVAC Sizing Calculator",
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      "url": "https://www.themostusefulsiteintheworld.com/tool/room-btu-hvac-calculator.html",
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      "standaloneUrl": null,
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        },
        {
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        },
        {
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        {
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            "1.2",
            "1",
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          ],
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        }
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      },
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      "sources": [],
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        "room",
        "btu",
        "hvac",
        "sizing",
        "home",
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        "heating",
        "cooling",
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      ],
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      "featured": false,
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    },
    {
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      "categoryName": "Home & DIY",
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      "standaloneUrl": null,
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        },
        {
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          "step": 0.1,
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        }
      ],
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        "room",
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        "drag",
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      "featured": false,
      "updated": "2026-09-19"
    },
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      "slug": "room-sweep-grid-mapper",
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      "categoryName": "Field Investigation & Evidence",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=room-sweep-grid-mapper&embed=1",
      "standaloneUrl": null,
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        {
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            "Measurement point",
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            "Observer position",
            "Control point",
            "Reported observation",
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            "Exit route"
          ],
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        }
      ],
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        {
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        }
      ],
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        "room",
        "sweep",
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      "featured": false,
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    },
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      "slug": "root-finder-lab",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=root-finder-lab&embed=1",
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        },
        {
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          "label": "bracket a",
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        },
        {
          "name": "nrf-b",
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        },
        {
          "name": "nrf-x0",
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          "label": "Newton/Secant start x₀",
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        {
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        }
      ],
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        {
          "name": "nrf-summary",
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=root-finder-lab&<id>=<value>",
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      },
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      "sources": [],
      "tags": [
        "root",
        "finder",
        "lab",
        "root-finder",
        "newton",
        "bisection",
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        "mathematics",
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      "popularity": 4065,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "round-robin-fixture-generator",
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      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/round-robin-fixture-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=round-robin-fixture-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rrb-count",
          "type": "number",
          "label": "Number of teams",
          "unit": "",
          "min": 2,
          "max": 30,
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        },
        {
          "name": "rrb-names",
          "type": "textarea",
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          "unit": ""
        },
        {
          "name": "rrb-mode",
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          "unit": "",
          "options": [
            "single",
            "double"
          ],
          "default": "single"
        }
      ],
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        {
          "name": "rrb-out",
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        }
      ],
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      "sources": [],
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        "round",
        "robin",
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        "sports",
        "generate",
        "full",
        "league",
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        "where"
      ],
      "popularity": 4069,
      "featured": false,
      "updated": "2026-09-19"
    },
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      "slug": "rounding-estimation-trainer",
      "title": "🔄 Rounding & Estimation Trainer",
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      "categoryName": "Mathematics",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=rounding-estimation-trainer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "label": "Number",
          "unit": "",
          "default": "3847.265"
        },
        {
          "name": "ret-ans",
          "type": "number",
          "label": "your estimate",
          "unit": ""
        },
        {
          "name": "ret-place",
          "type": "select-one",
          "label": "Round to",
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          "options": [
            "t",
            "h",
            "th",
            "1",
            "2",
            "w"
          ],
          "default": "t"
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      ],
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        {
          "name": "ret-out",
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        {
          "name": "ret-score",
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        }
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        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=rounding-estimation-trainer&ret-num=3847.265&ret-place=t"
      },
      "formula": "Estimate first: 187 × 42 ≈ 200 × 40 = 8,000. Exact: 7,854 — close enough to check your work. • Money: £3.72 +",
      "sources": [],
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        "rounding",
        "estimation",
        "trainer",
        "mathematics",
        "master",
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      ],
      "popularity": 4956,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "rowing-erg-pace-calculator",
      "title": "🚣 Rowing Erg Pace Calculator",
      "description": "The rowing machine's watts and your 500 m split are two ways of saying the same thing. Enter either and this works out the other, plus your speed and predicted times for the standard test distances.",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/rowing-erg-pace-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=rowing-erg-pace-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "erg-mm",
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          "label": "Split min",
          "unit": "",
          "min": 0,
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        },
        {
          "name": "erg-ss",
          "type": "number",
          "label": "Split sec",
          "unit": "",
          "min": 0,
          "step": 0.1,
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        },
        {
          "name": "erg-watts",
          "type": "number",
          "label": "Watts",
          "unit": "",
          "min": 0,
          "default": "203"
        }
      ],
      "outputs": [
        {
          "name": "erg-out",
          "type": "live"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=rowing-erg-pace-calculator&<id>=<value>",
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      },
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      "sources": [],
      "tags": [
        "rowing",
        "erg",
        "pace",
        "sports",
        "machine",
        "watts",
        "500",
        "split",
        "two",
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      ],
      "popularity": 5420,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "rugby-points-score-builder",
      "title": "🏉 Rugby Points Score Builder",
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      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/rugby-points-score-builder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=rugby-points-score-builder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rug-tries",
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          "label": "Tries",
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        },
        {
          "name": "rug-conv",
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        },
        {
          "name": "rug-pen",
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          "label": "Penalties",
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        },
        {
          "name": "rug-drop",
          "type": "number",
          "label": "Drop goals",
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          "min": 0,
          "default": "0"
        },
        {
          "name": "rug-target",
          "type": "number",
          "label": "Or &mdash; points gap to close (for the &ldquo;what do we need?&rdquo; list)",
          "unit": "",
          "min": 1,
          "default": "12"
        }
      ],
      "outputs": [
        {
          "name": "rug-out",
          "type": "live"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=rugby-points-score-builder&<id>=<value>",
        "runs": true,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "rugby",
        "points",
        "score",
        "builder",
        "sports",
        "try",
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        "penalty",
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      ],
      "popularity": 6736,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "rule-of-72-doubling-calculator",
      "title": "⏳ Rule of 72 Doubling Time",
      "description": "Years to double ≈ 72 ÷ annual %. At 6% that’s about 12 years; at 9% about 8. The exact figure is ln(2)/ln(1+r). A back-of-envelope for interest, inflation and population — not a guarantee.",
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      "categoryName": "Finance & Money",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=rule-of-72-doubling-calculator&embed=1",
      "standaloneUrl": null,
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        {
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          "unit": "",
          "default": "7"
        },
        {
          "name": "r72x-start",
          "type": "number",
          "label": "Starting amount",
          "unit": "",
          "min": 0,
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        }
      ],
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        {
          "name": "r72x-out",
          "type": "output"
        }
      ],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "rule",
        "doubling",
        "time",
        "finance",
        "money",
        "years",
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        "annual",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "rules-of-thumb",
      "title": "📏 Rules of Thumb — 80 Shortcuts That Actually Work",
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      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/rules-of-thumb.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=rules-of-thumb&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rot-search",
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          "label": "Search",
          "unit": ""
        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=rules-of-thumb&<id>=<value>",
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      },
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      "sources": [],
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        "rules",
        "thumb",
        "shortcuts",
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      "popularity": 6202,
      "featured": false,
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    },
    {
      "slug": "running-cadence-stride-calculator",
      "title": "🏃 Running Cadence & Stride Length",
      "description": "Cadence, pace and stride length are locked together — fix any two and the third is forced. Fill in the two you know and this computes the rest, plus your steps per kilometre and total steps for a d...",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/running-cadence-stride-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=running-cadence-stride-calculator&embed=1",
      "standaloneUrl": null,
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        },
        {
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          "min": 0,
          "max": 59,
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        },
        {
          "name": "cad-cadence",
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          "label": "Cadence",
          "unit": "steps/min",
          "min": 60,
          "max": 260,
          "default": "170"
        },
        {
          "name": "cad-stride",
          "type": "number",
          "label": "Stride length",
          "unit": "m",
          "min": 0.3,
          "step": 0.01,
          "default": "1.08"
        },
        {
          "name": "cad-dist",
          "type": "number",
          "label": "Distance",
          "unit": "km",
          "min": 0.1,
          "step": 0.1,
          "default": "5"
        }
      ],
      "outputs": [
        {
          "name": "cad-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=running-cadence-stride-calculator&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=running-cadence-stride-calculator&cad-pm=6&cad-ps=0&cad-cadence=170&cad-stride=1.08&cad-dist=5&run=1"
      },
      "formula": "The relationship & what to aim for Speed = cadence ×",
      "sources": [],
      "tags": [
        "running",
        "cadence",
        "stride",
        "length",
        "sports",
        "pace",
        "locked",
        "together",
        "fix",
        "any"
      ],
      "popularity": 5148,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "running-split-pace-calculator",
      "title": "🏃 Running Split Pace Calculator",
      "description": "Target time for a race distance → pace per km and per mile, plus even kilometre splits. Negative splits are a planning aid, not a training plan.",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/running-split-pace-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=running-split-pace-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "rspl-custom",
          "type": "number",
          "label": "Custom km",
          "unit": "",
          "min": 0.1,
          "default": "8"
        },
        {
          "name": "rspl-h",
          "type": "number",
          "label": "Hours",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "1"
        },
        {
          "name": "rspl-m",
          "type": "number",
          "label": "Minutes",
          "unit": "",
          "min": 0,
          "max": 59,
          "step": 1,
          "default": "45"
        },
        {
          "name": "rspl-s",
          "type": "number",
          "label": "Seconds",
          "unit": "",
          "min": 0,
          "max": 59,
          "step": 1,
          "default": "0"
        },
        {
          "name": "rspl-dist",
          "type": "select-one",
          "label": "Distance",
          "unit": "",
          "options": [
            "5",
            "10",
            "21.0975",
            "42.195",
            "custom"
          ],
          "default": "21.0975"
        }
      ],
      "outputs": [
        {
          "name": "rspl-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=running-split-pace-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=running-split-pace-calculator&rspl-custom=8&rspl-h=1&rspl-m=45&rspl-s=0&rspl-dist=21.0975"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "running",
        "split",
        "pace",
        "sports",
        "target",
        "time",
        "race",
        "distance",
        "per",
        "mile"
      ],
      "popularity": 4989,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "saas-churn-revenue-impact",
      "title": "📉 SaaS Churn Revenue Impact",
      "description": "Model recurring revenue lost to churn and the customers needed to maintain or grow monthly revenue. All calculations stay in your browser.",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/saas-churn-revenue-impact.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=saas-churn-revenue-impact&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "saas-churn-revenue-impact-customers",
          "type": "number",
          "label": "Current customers",
          "unit": "",
          "default": "500"
        },
        {
          "name": "saas-churn-revenue-impact-arpu",
          "type": "number",
          "label": "Monthly revenue per customer",
          "unit": "£",
          "default": "49"
        },
        {
          "name": "saas-churn-revenue-impact-churn",
          "type": "number",
          "label": "Monthly customer churn",
          "unit": "%",
          "default": "4"
        },
        {
          "name": "saas-churn-revenue-impact-newcust",
          "type": "number",
          "label": "New customers per month",
          "unit": "",
          "default": "30"
        }
      ],
      "outputs": [
        {
          "name": "saas-churn-revenue-impact-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=saas-churn-revenue-impact&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=saas-churn-revenue-impact&saas-churn-revenue-impact-customers=500&saas-churn-revenue-impact-arpu=49&saas-churn-revenue-impact-churn=4&saas-churn-revenue-impact-newcust=30&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "saas",
        "churn",
        "revenue",
        "impact",
        "business",
        "killers",
        "model",
        "recurring",
        "lost",
        "customers"
      ],
      "popularity": 4771,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "saas-metrics-ltv-cac-calculator",
      "title": "📈 SaaS LTV & CAC Calculator",
      "description": "Calculate core SaaS unit economics, Customer Lifetime Value (LTV), Customer Acquisition Cost (CAC), payback period, and cash burn runway. Replaces expensive subscription analytics dashboards.",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/saas-metrics-ltv-cac-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=saas-metrics-ltv-cac-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sm-arpu",
          "type": "number",
          "label": "Average Revenue/User",
          "unit": "ARPU $/mo",
          "min": 1,
          "max": 10000,
          "step": 5,
          "default": "85"
        },
        {
          "name": "sm-customers",
          "type": "number",
          "label": "Paying Customers",
          "unit": "",
          "min": 1,
          "max": 1000000,
          "step": 10,
          "default": "450"
        },
        {
          "name": "sm-churn",
          "type": "number",
          "label": "Monthly Churn Rate",
          "unit": "%",
          "min": 0.1,
          "max": 50,
          "step": 0.1,
          "default": "3.5"
        },
        {
          "name": "sm-margin",
          "type": "number",
          "label": "Gross Margin",
          "unit": "%",
          "min": 10,
          "max": 100,
          "step": 5,
          "default": "80"
        },
        {
          "name": "sm-cac",
          "type": "number",
          "label": "Customer Acq Cost",
          "unit": "CAC $",
          "min": 1,
          "max": 50000,
          "step": 10,
          "default": "480"
        },
        {
          "name": "sm-cash-bank",
          "type": "number",
          "label": "Cash in Bank",
          "unit": "$",
          "min": 0,
          "max": 100000000,
          "step": 10000,
          "default": "350000"
        },
        {
          "name": "sm-monthly-burn",
          "type": "number",
          "label": "Net Monthly Burn",
          "unit": "$",
          "min": 0,
          "max": 5000000,
          "step": 1000,
          "default": "22000"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=saas-metrics-ltv-cac-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=saas-metrics-ltv-cac-calculator&sm-arpu=85&sm-customers=450&sm-churn=3.5&sm-margin=80&sm-cac=480&sm-cash-bank=350000"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "saas",
        "metrics",
        "ltv",
        "cac",
        "business",
        "killers",
        "calculate",
        "core",
        "unit",
        "economics"
      ],
      "popularity": 4360,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "safe-night-shoot-planner",
      "title": "🧭 Permissioned Night-Shoot Planner",
      "description": "A hard-stop preflight for spooky video shoots. It is designed for a controlled set, booked attraction or explicitly permitted property—not abandoned, closed or restricted buildings. No address or l...",
      "category": "horror-and-paranormal",
      "categoryName": "Horror & Paranormal",
      "url": "https://www.themostusefulsiteintheworld.com/tool/safe-night-shoot-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=safe-night-shoot-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "snsp-permission",
          "type": "checkbox",
          "label": "Owner, manager or venue has explicitly authorized this exact area and time.",
          "unit": "",
          "default": "0"
        },
        {
          "name": "snsp-inspected",
          "type": "checkbox",
          "label": "Daylight walk-through completed; floors, stairs and access are stable and known. Unknown hazards mean no entry.",
          "unit": "",
          "default": "0"
        },
        {
          "name": "snsp-exits",
          "type": "checkbox",
          "label": "Exit routes are unlocked, usable and kept clear; nobody will climb, crawl or go alone into a dark area.",
          "unit": "",
          "default": "0"
        },
        {
          "name": "snsp-buddy",
          "type": "checkbox",
          "label": "A buddy stays with the crew; someone outside the shot knows the plan and check-in time.",
          "unit": "",
          "default": "0"
        },
        {
          "name": "snsp-kit",
          "type": "checkbox",
          "label": "Working flashlight, charged phone, spare power and basic first aid are on hand.",
          "unit": "",
          "default": "0"
        },
        {
          "name": "snsp-travel",
          "type": "checkbox",
          "label": "Weather and the trip home are checked; the driver is rested and sober.",
          "unit": "",
          "default": "0"
        },
        {
          "name": "snsp-consent",
          "type": "checkbox",
          "label": "Everyone on camera has opted into the planned horror effects and can stop the take at any time.",
          "unit": "",
          "default": "0"
        },
        {
          "name": "snsp-effects",
          "type": "checkbox",
          "label": "No open flames, weapons, smoke, surprise blasts, or effects that could make someone run or fall.",
          "unit": "",
          "default": "0"
        },
        {
          "name": "snsp-site",
          "type": "select-one",
          "label": "What kind of authorized set is this?",
          "unit": "",
          "options": [
            "pending",
            "studio",
            "venue",
            "property"
          ],
          "default": "pending"
        }
      ],
      "outputs": [
        {
          "name": "snsp-output",
          "type": "live"
        },
        {
          "name": "snsp-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=safe-night-shoot-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=safe-night-shoot-planner&snsp-permission=0&snsp-inspected=0&snsp-exits=0&snsp-buddy=0&snsp-kit=0&snsp-travel=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "safe",
        "night",
        "shoot",
        "planner",
        "permissioned",
        "night-shoot",
        "horror",
        "paranormal",
        "hard-stop",
        "preflight"
      ],
      "popularity": 6615,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "salary",
      "title": "💰 Salary Calculator",
      "description": "Calculate net salary after taxes, deductions, and contributions. ⚠️ Estimates only — consult a tax professional.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/salary.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=salary&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sc-hours",
          "type": "number",
          "label": "Hours/Week",
          "unit": "",
          "min": 1,
          "max": 168,
          "default": "40"
        },
        {
          "name": "sc-gross",
          "type": "number",
          "label": "Gross Income",
          "unit": "",
          "min": 0,
          "step": 1000,
          "default": "40000"
        },
        {
          "name": "sc-ni",
          "type": "number",
          "label": "National Insurance",
          "unit": "%",
          "min": 0,
          "max": 20,
          "step": 0.1,
          "default": "12"
        },
        {
          "name": "sc-pension",
          "type": "number",
          "label": "Pension Contribution",
          "unit": "%",
          "min": 0,
          "max": 20,
          "step": 0.5,
          "default": "5"
        },
        {
          "name": "sc-student-loan",
          "type": "number",
          "label": "Student Loan",
          "unit": "%",
          "min": 0,
          "max": 15,
          "step": 0.1,
          "default": "9"
        },
        {
          "name": "sc-other-deductions",
          "type": "number",
          "label": "Other Deductions",
          "unit": "Flat",
          "min": 0,
          "step": 100,
          "default": "0"
        },
        {
          "name": "sc-country",
          "type": "select-one",
          "label": "Country",
          "unit": "",
          "options": [
            "uk",
            "us",
            "ca"
          ],
          "default": "uk"
        },
        {
          "name": "sc-currency",
          "type": "select-one",
          "label": "Currency",
          "unit": "",
          "options": [
            "£",
            "$",
            "€",
            "CA$",
            "AU$"
          ],
          "default": "£"
        },
        {
          "name": "sc-pay-period",
          "type": "select-one",
          "label": "Pay Period",
          "unit": "",
          "options": [
            "annual",
            "monthly",
            "biweekly",
            "weekly",
            "daily",
            "hourly"
          ],
          "default": "annual"
        },
        {
          "name": "sc-loan-plan",
          "type": "select-one",
          "label": "Student Loan Plan",
          "unit": "UK",
          "options": [
            "none",
            "plan1",
            "plan2",
            "plan4",
            "plan5",
            "pg"
          ],
          "default": "none"
        }
      ],
      "outputs": [
        {
          "name": "sc-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=salary&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=salary&sc-hours=40&sc-gross=40000&sc-ni=12&sc-pension=5&sc-student-loan=9&sc-other-deductions=0&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "salary",
        "finance",
        "money",
        "calculate",
        "net",
        "after",
        "taxes",
        "deductions",
        "contributions",
        "estimates"
      ],
      "popularity": 6094,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sales-commission-calculator",
      "title": "💼 Sales Commission Calculator",
      "description": "Commission from a sale amount and rate, with an optional second-tier rate above a threshold (common in sales plans). Gross figures — tax is not deducted.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sales-commission-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sales-commission-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cmss-sale",
          "type": "number",
          "label": "Sale amount",
          "unit": "",
          "min": 0,
          "default": "12500"
        },
        {
          "name": "cmss-rate",
          "type": "number",
          "label": "Rate %",
          "unit": "",
          "min": 0,
          "default": "8"
        },
        {
          "name": "cmss-base",
          "type": "number",
          "label": "Salary / draw",
          "unit": "",
          "min": 0,
          "default": "0"
        },
        {
          "name": "cmss-thr",
          "type": "number",
          "label": "Tier 2 above",
          "unit": "",
          "min": 0,
          "default": "10000"
        },
        {
          "name": "cmss-rate2",
          "type": "number",
          "label": "Tier 2 rate %",
          "unit": "",
          "min": 0,
          "default": "12"
        },
        {
          "name": "cmss-tier",
          "type": "checkbox",
          "label": "Use two-tier rates",
          "unit": "",
          "default": "0"
        }
      ],
      "outputs": [
        {
          "name": "cmss-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sales-commission-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sales-commission-calculator&cmss-sale=12500&cmss-rate=8&cmss-base=0&cmss-thr=10000&cmss-rate2=12&cmss-tier=0"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "sales",
        "commission",
        "finance",
        "money",
        "sale",
        "amount",
        "rate",
        "optional",
        "second-tier",
        "above"
      ],
      "popularity": 4331,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sample-chop-cue-point-calculator",
      "title": "✂️ Sample Chop Slice & Bar Marker Calculator",
      "description": "Calculates exact mathematical slice cue points and sample frame offsets for 16-pad hardware samplers (MPC, SP-404, Maschine) and DAWs. Slice 1-bar, 2-bar, or 4-bar sample loops into clean musical c...",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sample-chop-cue-point-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sample-chop-cue-point-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "scc-sample-bpm",
          "type": "number",
          "label": "Sample Loop BPM",
          "unit": "",
          "min": 40,
          "max": 220,
          "step": 0.1,
          "default": "85.0"
        },
        {
          "name": "scc-bar-count",
          "type": "select-one",
          "label": "Loop Length",
          "unit": "Bars",
          "options": [
            "1",
            "2",
            "4",
            "8"
          ],
          "default": "4"
        },
        {
          "name": "scc-pad-count",
          "type": "select-one",
          "label": "Target Slices / Pads",
          "unit": "",
          "options": [
            "16",
            "8",
            "4"
          ],
          "default": "16"
        },
        {
          "name": "scc-sample-rate",
          "type": "select-one",
          "label": "Audio Sample Rate",
          "unit": "",
          "options": [
            "44100",
            "48000",
            "96000"
          ],
          "default": "44100"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sample-chop-cue-point-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sample-chop-cue-point-calculator&scc-sample-bpm=85.0&scc-bar-count=4&scc-pad-count=16&scc-sample-rate=44100"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "sample",
        "chop",
        "cue",
        "point",
        "slice",
        "bar",
        "marker",
        "music",
        "audio",
        "calculates"
      ],
      "popularity": 6693,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sample-delay-alignment-calculator",
      "title": "Sample-Delay Alignment Calculator",
      "description": "Translate a measured timing offset into DAW sample nudges, acoustic path difference, and predicted comb-filter notches.",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sample-delay-alignment-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sample-delay-alignment-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sdac-delay",
          "type": "number",
          "label": "Measured offset",
          "unit": "ms",
          "min": 0,
          "max": 1000,
          "default": "1"
        },
        {
          "name": "sdac-rate",
          "type": "number",
          "label": "Session sample rate",
          "unit": "Hz",
          "min": 8000,
          "max": 384000,
          "step": 1,
          "default": "48000"
        },
        {
          "name": "sdac-temp",
          "type": "number",
          "label": "Air temperature",
          "unit": "°C",
          "min": -20,
          "max": 50,
          "default": "20"
        }
      ],
      "outputs": [
        {
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      "sources": [],
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        "sample",
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        "sample-delay",
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        "translate",
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        {
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        {
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        {
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      },
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      "slug": "screen-ruler",
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        {
          "name": "srpm-cpx",
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        {
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      ],
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            "softwood",
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      "slug": "seasonal-produce-calendar",
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      "category": "culinary-and-food-science",
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      "inputs": [
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          "name": "spc-cat",
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      "popularity": 6126,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "seasons-tilt-explainer-3d",
      "title": "🌗 Seasons & Earth's Tilt — 3D Explainer",
      "description": "Drag to orbit a 3D Sun–Earth model and discover why seasons happen. It is not distance — it is the 23.4° tilt of Earth's axis, which changes the Sun's noon altitude and the length of the day.",
      "category": "astronomy-and-space",
      "categoryName": "Astronomy & Space",
      "url": "https://www.themostusefulsiteintheworld.com/tool/seasons-tilt-explainer-3d.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=seasons-tilt-explainer-3d&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "stx-date",
          "type": "range",
          "label": "Day of year 21 Jun",
          "unit": "",
          "min": 0,
          "max": 364,
          "step": 1,
          "default": "172"
        },
        {
          "name": "stx-lat",
          "type": "range",
          "label": "Your latitude 40°N",
          "unit": "",
          "min": -70,
          "max": 70,
          "step": 1,
          "default": "40"
        },
        {
          "name": "stx-tilt",
          "type": "checkbox",
          "label": "keep the 23.4° tilt",
          "unit": "",
          "default": "1"
        },
        {
          "name": "stx-spin",
          "type": "checkbox",
          "label": "spin the Earth",
          "unit": "",
          "default": "1"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=seasons-tilt-explainer-3d&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=seasons-tilt-explainer-3d&stx-date=172&stx-lat=40&stx-tilt=1&stx-spin=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "seasons",
        "tilt",
        "explainer",
        "earth",
        "astronomy",
        "space",
        "drag",
        "orbit",
        "sun",
        "model"
      ],
      "popularity": 4251,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "seawater-salinity-density-teos",
      "title": "🌊 Seawater Salinity & Density",
      "description": "Investigate ocean physics and the thermodynamic equation of seawater (TEOS-10). Calculate in-situ density ($\\rho$), freezing point depression ($-1.91^\\circ\\text{C}$), sound speed ($c$), and thermoh...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/seawater-salinity-density-teos.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=seawater-salinity-density-teos&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "os-salinity",
          "type": "number",
          "label": "Salinity",
          "unit": "$S$",
          "min": 0,
          "max": 300,
          "step": 0.5,
          "default": "35.0"
        },
        {
          "name": "os-temp",
          "type": "number",
          "label": "Water Temp",
          "unit": "$T$",
          "min": -5,
          "max": 40,
          "step": 0.5,
          "default": "15.0"
        },
        {
          "name": "os-depth",
          "type": "number",
          "label": "Depth",
          "unit": "$D$",
          "min": 0,
          "max": 11000,
          "step": 50,
          "default": "0"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=seawater-salinity-density-teos&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=seawater-salinity-density-teos&os-salinity=35.0&os-temp=15.0&os-depth=0"
      },
      "formula": "Situ Density ($\\rho$) 1,025.9 kg/m³ σₜ = 25.9 kg/m³ anomaly Freezing Point ($T_f$) -",
      "sources": [],
      "tags": [
        "seawater",
        "salinity",
        "density",
        "teos",
        "science",
        "engineering",
        "investigate",
        "ocean",
        "physics",
        "thermodynamic"
      ],
      "popularity": 4511,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "second-life-surnames-guide",
      "title": "📚 Second Life Surnames Encyclopedia",
      "description": "Explore the rich tapestry of Second Life surnames. Discover origins, cultural associations, and roleplay inspiration. A living encyclopedia with search, filters, and favorite tracking.",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/second-life-surnames-guide.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=second-life-surnames-guide&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "slsg-search",
          "type": "text",
          "label": "Search Surnames",
          "unit": ""
        },
        {
          "name": "slsg-culture-filter",
          "type": "select-one",
          "label": "Culture Filter",
          "unit": "",
          "options": [
            "all",
            "english",
            "scottish",
            "irish",
            "welsh",
            "spanish",
            "french",
            "german",
            "italian",
            "chinese",
            "japanese",
            "korean",
            "indian",
            "scandinavian",
            "eastern-european"
          ],
          "default": "all"
        },
        {
          "name": "slsg-type-filter",
          "type": "select-one",
          "label": "Type Filter",
          "unit": "",
          "options": [
            "all",
            "occupational",
            "patronymic",
            "geographic",
            "descriptive",
            "nature",
            "nobility",
            "modern"
          ],
          "default": "all"
        },
        {
          "name": "slsg-sort-by",
          "type": "select-one",
          "label": "Sort By",
          "unit": "",
          "options": [
            "name-asc",
            "name-desc",
            "culture",
            "type",
            "popularity",
            "favorites"
          ],
          "default": "name-asc"
        },
        {
          "name": "slsg-view-mode",
          "type": "select-one",
          "label": "View Mode",
          "unit": "",
          "options": [
            "list",
            "grid",
            "compact"
          ],
          "default": "list"
        }
      ],
      "outputs": [
        {
          "name": "slsg-no-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=second-life-surnames-guide&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=second-life-surnames-guide&slsg-culture-filter=all&slsg-type-filter=all&slsg-sort-by=name-asc&slsg-view-mode=list"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "second",
        "life",
        "surnames",
        "guide",
        "encyclopedia",
        "virtual",
        "worlds",
        "gaming",
        "explore",
        "rich"
      ],
      "popularity": 4359,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "second-life-visit-supadupaman",
      "title": "🌐 Visit Supadupaman Sapphire in Second Life",
      "description": "Generate a SLURL to meet Supadupaman Sapphire and configure the Arena visitor bot. Works with SupaViewer public map (no login) or a real bot account.",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/second-life-visit-supadupaman.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=second-life-visit-supadupaman&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "slvs-region",
          "type": "text",
          "label": "Region Name",
          "unit": "",
          "default": "Natoma"
        },
        {
          "name": "slvs-name",
          "type": "text",
          "label": "Your Avatar",
          "unit": "target",
          "default": "Supadupaman Sapphire"
        },
        {
          "name": "slvs-x",
          "type": "number",
          "label": "X",
          "unit": "",
          "min": 0,
          "max": 256,
          "default": "128"
        },
        {
          "name": "slvs-y",
          "type": "number",
          "label": "Y",
          "unit": "",
          "min": 0,
          "max": 256,
          "default": "128"
        },
        {
          "name": "slvs-z",
          "type": "number",
          "label": "Z",
          "unit": "",
          "min": 0,
          "max": 4096,
          "default": "22"
        },
        {
          "name": "slvs-slurl",
          "type": "text",
          "label": "slurl",
          "unit": ""
        },
        {
          "name": "slvs-map",
          "type": "text",
          "label": "map",
          "unit": ""
        },
        {
          "name": "slvs-greet",
          "type": "text",
          "label": "greet",
          "unit": "",
          "default": "Hi Supadupaman Sapphire! I'm the Arena bot from themostusefulsiteintheworld.com - you asked me to come visit you. o/"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=second-life-visit-supadupaman&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=second-life-visit-supadupaman&slvs-region=Natoma&slvs-name=Supadupaman%20Sapphire&slvs-x=128&slvs-y=128&slvs-z=22&slvs-greet=Hi%20Supadupaman%20Sapphire!%20I'm%20the%20Arena%20bot%20from%20themostusefulsiteintheworld.com%20-%20you%20asked%20me%20to%20come%20visit%20you.%20o%2F"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "second",
        "life",
        "visit",
        "supadupaman",
        "sapphire",
        "virtual",
        "worlds",
        "gaming",
        "generate",
        "slurl"
      ],
      "popularity": 5883,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "secret-santa",
      "title": "🎁 Secret Santa Generator",
      "description": "Organize a perfect Secret Santa gift exchange with automatic matching, restrictions, and wish lists! ✅ Supports: Family restrictions, wish lists, budget tracking, email notifications",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/secret-santa.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=secret-santa&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ss-name",
          "type": "text",
          "label": "Participant Name",
          "unit": ""
        },
        {
          "name": "ss-email",
          "type": "email",
          "label": "Email",
          "unit": ""
        },
        {
          "name": "ss-budget",
          "type": "number",
          "label": "Gift Budget",
          "unit": "$",
          "min": 5,
          "max": 500,
          "default": "25"
        },
        {
          "name": "ss-date",
          "type": "date",
          "label": "Gift Exchange Date",
          "unit": ""
        },
        {
          "name": "ss-no-self",
          "type": "checkbox",
          "label": "Prevent self-matching",
          "unit": "",
          "default": "1"
        },
        {
          "name": "ss-no-family",
          "type": "checkbox",
          "label": "Prevent family matching",
          "unit": "",
          "default": "1"
        },
        {
          "name": "ss-allow-rematch",
          "type": "checkbox",
          "label": "Allow re-matching from last year",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ss-show-all",
          "type": "checkbox",
          "label": "Show all matches to organizer",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ss-send-emails",
          "type": "checkbox",
          "label": "Email matches to participants",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ss-reminder",
          "type": "checkbox",
          "label": "Send reminder before event",
          "unit": "",
          "default": "1"
        },
        {
          "name": "ss-wishlist",
          "type": "textarea",
          "label": "Wish List",
          "unit": ""
        },
        {
          "name": "ss-group",
          "type": "select-one",
          "label": "Family/Group",
          "unit": "",
          "options": [
            "none",
            "family1",
            "family2",
            "family3",
            "family4"
          ],
          "default": "none"
        }
      ],
      "outputs": [
        {
          "name": "ss-individual-result",
          "type": "output"
        },
        {
          "name": "ss-all-results",
          "type": "output"
        },
        {
          "name": "ss-no-results",
          "type": "output"
        },
        {
          "name": "ss-budget-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=secret-santa&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=secret-santa&ss-budget=25&ss-no-self=1&ss-no-family=1&ss-allow-rematch=0&ss-show-all=0&ss-send-emails=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "secret",
        "santa",
        "productivity",
        "lifestyle",
        "organize",
        "perfect",
        "gift",
        "exchange",
        "automatic",
        "matching"
      ],
      "popularity": 5984,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "secure-file-vault-encryptor",
      "title": "🔒 Secure Vault — Text & File Encryption",
      "description": "Encrypt a message or a file with AES-256-GCM using a passphrase only you know, then hand over something that is meaningless without it. Password managers charge a subscription to hold notes like th...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/secure-file-vault-encryptor.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=secure-file-vault-encryptor&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sfve-plain",
          "type": "textarea",
          "label": "Message to encrypt",
          "unit": ""
        },
        {
          "name": "sfve-blob",
          "type": "textarea",
          "label": "Ciphertext (safe to paste anywhere — useless without the passphrase)",
          "unit": ""
        },
        {
          "name": "sfve-in-blob",
          "type": "textarea",
          "label": "Ciphertext to decrypt",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "sfve-result",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=secure-file-vault-encryptor&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "secure",
        "file",
        "vault",
        "encryptor",
        "text",
        "encryption",
        "saas",
        "business",
        "killers",
        "encrypt"
      ],
      "popularity": 4554,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "seed-germination-calculator",
      "title": "🌱 Seed Germination Calculator",
      "description": "Predict germination time based on seed type, temperature, and environmental factors using USDA, UC Davis, and university research data. This tool is supported by user contributions .",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/seed-germination-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=seed-germination-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tt-seed-variety",
          "type": "text",
          "label": "Variety",
          "unit": ""
        },
        {
          "name": "tt-soil-temp",
          "type": "range",
          "label": "soil temp",
          "unit": "",
          "min": 0,
          "max": 40,
          "step": 0.5,
          "default": "20"
        },
        {
          "name": "tt-air-temp",
          "type": "range",
          "label": "air temp",
          "unit": "",
          "min": 0,
          "max": 40,
          "step": 0.5,
          "default": "22"
        },
        {
          "name": "tt-seed-age",
          "type": "range",
          "label": "Seed Age",
          "unit": "",
          "min": 0,
          "max": 60,
          "default": "0"
        },
        {
          "name": "tt-seed-type",
          "type": "select-one",
          "label": "Seed Type",
          "unit": "",
          "options": [
            "tomato",
            "lettuce",
            "bean",
            "carrot",
            "pepper",
            "cucumber",
            "spinach",
            "basil",
            "zucchini",
            "radish",
            "pea",
            "corn"
          ],
          "default": "tomato"
        },
        {
          "name": "tt-soil-moisture",
          "type": "select-one",
          "label": "Soil Moisture",
          "unit": "",
          "options": [
            "optimal",
            "dry",
            "wet",
            "variable"
          ],
          "default": "optimal"
        },
        {
          "name": "tt-light-exposure",
          "type": "select-one",
          "label": "Light Exposure",
          "unit": "",
          "options": [
            "full",
            "partial",
            "shade",
            "indirect"
          ],
          "default": "full"
        }
      ],
      "outputs": [
        {
          "name": "tt-soil-temp-value",
          "type": "output"
        },
        {
          "name": "tt-air-temp-value",
          "type": "output"
        },
        {
          "name": "tt-seed-age-value",
          "type": "output"
        },
        {
          "name": "tt-output",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=seed-germination-calculator&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=seed-germination-calculator&tt-soil-temp=20&tt-air-temp=22&tt-seed-age=0&tt-seed-type=tomato&tt-soil-moisture=optimal&tt-light-exposure=full&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "seed",
        "germination",
        "science",
        "engineering",
        "predict",
        "time",
        "based",
        "type",
        "temperature",
        "environmental"
      ],
      "popularity": 5132,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "semver-compare-bump-calculator",
      "title": "📦 SemVer Compare & Bump",
      "description": "Compare two Semantic Versioning 2.0.0 strings, then bump major, minor, patch or a pre-release. Precedence follows the spec: major.minor.patch, then pre-release identifiers, build metadata ignored.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/semver-compare-bump-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=semver-compare-bump-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "smvr-a",
          "type": "text",
          "label": "Version A",
          "unit": "",
          "default": "1.4.2"
        },
        {
          "name": "smvr-b",
          "type": "text",
          "label": "Version B",
          "unit": "",
          "default": "1.5.0-rc.1"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=semver-compare-bump-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=semver-compare-bump-calculator&smvr-a=1.4.2&smvr-b=1.5.0-rc.1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "semver",
        "compare",
        "bump",
        "algorithms",
        "computer",
        "science",
        "two",
        "semantic",
        "versioning",
        "strings"
      ],
      "popularity": 5660,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sensitive-data-redactor",
      "title": "🔐 Sensitive Data Redactor",
      "description": "Mask common identifiers before sharing a message, support log, or document. Detects likely email addresses, phone numbers, IPv4 addresses and Luhn-valid payment-card numbers; add exact phrases of y...",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sensitive-data-redactor.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sensitive-data-redactor&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sensitive-data-redactor-email",
          "type": "checkbox",
          "label": "Email addresses",
          "unit": "",
          "default": "1"
        },
        {
          "name": "sensitive-data-redactor-phone",
          "type": "checkbox",
          "label": "Phone-like numbers",
          "unit": "",
          "default": "1"
        },
        {
          "name": "sensitive-data-redactor-ip",
          "type": "checkbox",
          "label": "IPv4 addresses",
          "unit": "",
          "default": "1"
        },
        {
          "name": "sensitive-data-redactor-card",
          "type": "checkbox",
          "label": "Payment-card patterns",
          "unit": "Luhn checked",
          "default": "1"
        },
        {
          "name": "sensitive-data-redactor-input",
          "type": "textarea",
          "label": "Text to inspect",
          "unit": ""
        },
        {
          "name": "sensitive-data-redactor-custom",
          "type": "textarea",
          "label": "Extra exact phrases to mask",
          "unit": "one per line"
        },
        {
          "name": "sensitive-data-redactor-output",
          "type": "textarea",
          "label": "Redacted preview",
          "unit": ""
        },
        {
          "name": "sensitive-data-redactor-token",
          "type": "select-one",
          "label": "Replace each match with",
          "unit": "",
          "options": [
            "[REDACTED]",
            "[PRIVATE]",
            "••••••"
          ],
          "default": "[REDACTED]"
        }
      ],
      "outputs": [
        {
          "name": "sensitive-data-redactor-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sensitive-data-redactor&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sensitive-data-redactor&sensitive-data-redactor-email=1&sensitive-data-redactor-phone=1&sensitive-data-redactor-ip=1&sensitive-data-redactor-card=1&sensitive-data-redactor-token=%5BREDACTED%5D"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "sensitive",
        "data",
        "redactor",
        "productivity",
        "lifestyle",
        "mask",
        "common",
        "identifiers",
        "before",
        "sharing"
      ],
      "popularity": 5616,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sequences-series",
      "title": "🔢 Sequences & Series Calculator",
      "description": "Find any term and the running sum of arithmetic or geometric sequences, test a geometric series for convergence, and see the working for the formula you used.",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sequences-series.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sequences-series&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ssq-first",
          "type": "number",
          "label": "First term a\\u2081",
          "unit": "",
          "default": "3"
        },
        {
          "name": "ssq-step",
          "type": "number",
          "label": "Common difference d",
          "unit": "",
          "default": "4"
        },
        {
          "name": "ssq-n",
          "type": "number",
          "label": "Term number n",
          "unit": "",
          "min": 1,
          "max": 100000,
          "step": 1,
          "default": "10"
        },
        {
          "name": "ssq-type",
          "type": "select-one",
          "label": "Sequence type",
          "unit": "",
          "options": [
            "arith",
            "geo"
          ],
          "default": "arith"
        }
      ],
      "outputs": [
        {
          "name": "ssq-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sequences-series&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sequences-series&ssq-first=3&ssq-step=4&ssq-n=10&ssq-type=arith&run=1"
      },
      "formula": "Formulae used Arithmetic: a\\u2099 = a\\u2081 + (n\\u22121)d and S\\u2099 = n/2 \\u00d7 (2a\\u2081 +",
      "sources": [],
      "tags": [
        "sequences",
        "series",
        "mathematics",
        "find",
        "any",
        "term",
        "running",
        "sum",
        "arithmetic",
        "geometric"
      ],
      "popularity": 4530,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "serotonin-secret-kindness-generator",
      "title": "💌 Secret Kindness Mission & Joy Ripple Engine",
      "description": "Neuroscience proves that performing unexpected micro-acts of kindness activates dopamine pathways in the giver just as powerfully as the receiver. Draw a stealth mission, craft tailored heartfelt m...",
      "category": "wellbeing-and-community",
      "categoryName": "Wellbeing & Community",
      "url": "https://www.themostusefulsiteintheworld.com/tool/serotonin-secret-kindness-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=serotonin-secret-kindness-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "skq-lantern-input",
          "type": "text",
          "label": "Wish or note",
          "unit": ""
        },
        {
          "name": "skq-ca-output",
          "type": "textarea",
          "label": "Crafted Appreciation Note",
          "unit": "editable"
        },
        {
          "name": "skq-context",
          "type": "select-one",
          "label": "Target Context",
          "unit": "",
          "options": [
            "any",
            "digital",
            "work",
            "stranger",
            "loved"
          ],
          "default": "any"
        },
        {
          "name": "skq-difficulty",
          "type": "select-one",
          "label": "Time & Effort",
          "unit": "",
          "options": [
            "all",
            "instant",
            "micro"
          ],
          "default": "all"
        },
        {
          "name": "skq-ca-target",
          "type": "select-one",
          "label": "Who is this for?",
          "unit": "",
          "options": [
            "friend",
            "colleague",
            "family",
            "mentor",
            "acquaintance"
          ],
          "default": "friend"
        },
        {
          "name": "skq-ca-trait",
          "type": "select-one",
          "label": "What do you admire?",
          "unit": "",
          "options": [
            "calm",
            "creativity",
            "humor",
            "reliability",
            "resilience",
            "listening"
          ],
          "default": "calm"
        },
        {
          "name": "skq-ca-tone",
          "type": "select-one",
          "label": "Message Tone",
          "unit": "",
          "options": [
            "heartfelt",
            "warm",
            "witty",
            "professional"
          ],
          "default": "heartfelt"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=serotonin-secret-kindness-generator&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "serotonin",
        "secret",
        "kindness",
        "mission",
        "joy",
        "ripple",
        "engine",
        "wellbeing",
        "community",
        "neuroscience"
      ],
      "popularity": 6566,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "service-disruption-readiness-map",
      "title": "When Everyday Services Go Down: A Readiness Map",
      "description": "Power, water, phone service, payments and transport can fail separately—or at the same time. Choose a few to rehearse and get a short household action list. The cause does not need to be known: thi...",
      "category": "survival-and-emergency-readiness",
      "categoryName": "Survival & Emergency Readiness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/service-disruption-readiness-map.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=service-disruption-readiness-map&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "service-disruption-readiness-map-copy-text",
          "type": "textarea",
          "label": "Private copyable checklist — review selected needs before sharing",
          "unit": ""
        },
        {
          "name": "service-disruption-readiness-map-horizon",
          "type": "select-one",
          "label": "Planning horizon for this rehearsal",
          "unit": "",
          "options": [
            "hours",
            "overnight",
            "extended"
          ],
          "default": "hours"
        }
      ],
      "outputs": [
        {
          "name": "service-disruption-readiness-map-progress",
          "type": "live"
        },
        {
          "name": "service-disruption-readiness-map-status",
          "type": "live"
        },
        {
          "name": "service-disruption-readiness-map-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=service-disruption-readiness-map&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=service-disruption-readiness-map&service-disruption-readiness-map-horizon=hours"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [
        "https://prepare.campaign.gov.uk/be-informed-about-hazards/power-cuts/",
        "https://prepare.campaign.gov.uk/get-prepared-for-emergencies/advice-for-disabled-persons-and-carers/"
      ],
      "tags": [
        "service",
        "disruption",
        "readiness",
        "map",
        "when",
        "everyday",
        "services",
        "down",
        "survival",
        "emergency"
      ],
      "popularity": 6481,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "seven-wonders-hall",
      "title": "🏺 The Seven Wonders",
      "description": "A Hellenistic tourist list, not a league table. Antipater of Sidon and others named seven sights a traveller from the Mediterranean might still catch. Only the Great Pyramid is still standing. The ...",
      "category": "museum-and-collection",
      "categoryName": "Museum & Collection",
      "url": "https://www.themostusefulsiteintheworld.com/tool/seven-wonders-hall.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=seven-wonders-hall&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [
        {
          "name": "wndr-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=seven-wonders-hall&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "seven",
        "wonders",
        "hall",
        "museum",
        "collection",
        "hellenistic",
        "tourist",
        "list",
        "not",
        "league"
      ],
      "popularity": 5218,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "shape-volume-surface-area-3d",
      "title": "🧊 3D Shape Volume & Surface Area Calculator",
      "description": "Pick a solid, type its dimensions and watch it rebuild in 3D. Get the volume, total and lateral surface area, capacity in litres and gallons, diagonals and slant heights — with the formula and work...",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/shape-volume-surface-area-3d.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=shape-volume-surface-area-3d&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "svs-unit",
          "type": "select-one",
          "label": "Unit",
          "unit": "",
          "options": [
            "0.001",
            "0.01",
            "1",
            "0.0254",
            "0.3048",
            "0.9144"
          ],
          "default": "0.01"
        },
        {
          "name": "svs-dp",
          "type": "select-one",
          "label": "Decimals",
          "unit": "",
          "options": [
            "2",
            "3",
            "4",
            "6"
          ]
        }
      ],
      "outputs": [
        {
          "name": "svs-hud",
          "type": "live"
        },
        {
          "name": "svs-steps",
          "type": "live"
        },
        {
          "name": "svs-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=shape-volume-surface-area-3d&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=shape-volume-surface-area-3d&svs-unit=0.01"
      },
      "formula": "Prisms and cylinders all share V = base area × height . Pyramids and cones are exactly a third of that: V = ⅓ ×",
      "sources": [],
      "tags": [
        "shape",
        "volume",
        "surface",
        "area",
        "mathematics",
        "pick",
        "solid",
        "type",
        "dimensions",
        "watch"
      ],
      "popularity": 4986,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sheet-music",
      "title": "🎼 Sheet Music Reference Generator",
      "description": "Generate detailed sheet music references with proper notation guidance. ⚠️ Educational only — always verify with a teacher or professional resource.",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sheet-music.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sheet-music&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sheet-show-advanced",
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          "label": "Show Advanced Options",
          "unit": "",
          "default": "0"
        },
        {
          "name": "sheet-key",
          "type": "select-one",
          "label": "Key Signature",
          "unit": "",
          "options": [
            "C",
            "G",
            "D",
            "F",
            "Bb",
            "Am",
            "Em",
            "Dm"
          ],
          "default": "C"
        },
        {
          "name": "sheet-type",
          "type": "select-one",
          "label": "Notation Type",
          "unit": "",
          "options": [
            "scale",
            "scale-3oct",
            "arpeggio",
            "exercise",
            "melody",
            "chord-progression",
            "sight-reading"
          ],
          "default": "scale"
        },
        {
          "name": "sheet-clef",
          "type": "select-one",
          "label": "Clef",
          "unit": "",
          "options": [
            "treble",
            "bass",
            "alto",
            "both"
          ],
          "default": "treble"
        },
        {
          "name": "sheet-tempo",
          "type": "select-one",
          "label": "Tempo Marking",
          "unit": "",
          "options": [
            "largo",
            "adagio",
            "andante",
            "moderato",
            "allegro",
            "presto"
          ],
          "default": "largo"
        },
        {
          "name": "sheet-time",
          "type": "select-one",
          "label": "Time Signature",
          "unit": "",
          "options": [
            "4/4",
            "3/4",
            "2/4",
            "6/8",
            "cut"
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          "default": "4/4"
        },
        {
          "name": "sheet-level",
          "type": "select-one",
          "label": "Difficulty Level",
          "unit": "",
          "options": [
            "beginner",
            "intermediate",
            "advanced"
          ],
          "default": "beginner"
        },
        {
          "name": "sheet-dynamics",
          "type": "select-one",
          "label": "Dynamics",
          "unit": "",
          "options": [
            "basic",
            "full",
            "crescendo"
          ],
          "default": "basic"
        },
        {
          "name": "sheet-articulation",
          "type": "select-one",
          "label": "Articulation",
          "unit": "",
          "options": [
            "legato",
            "staccato",
            "mixed"
          ],
          "default": "legato"
        },
        {
          "name": "sheet-show-facts",
          "type": "select-one",
          "label": "Educational Notes",
          "unit": "",
          "options": [
            "yes",
            "no"
          ],
          "default": "yes"
        }
      ],
      "outputs": [
        {
          "name": "sheet-output",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sheet-music&<id>=<value>",
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      },
      "formula": "Notes below middle C • ♩ Quarter note = 1 beat in 4/",
      "sources": [],
      "tags": [
        "sheet",
        "music",
        "reference",
        "audio",
        "generate",
        "detailed",
        "references",
        "proper",
        "notation",
        "guidance"
      ],
      "popularity": 4857,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "shelf-bracket-calculator",
      "title": "📏 Shelf Bracket Calculator",
      "description": "Calculate the right bracket size, spacing, and load capacity for your shelf project.",
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      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/shelf-bracket-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=shelf-bracket-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "shelfbrk-len",
          "type": "number",
          "label": "Shelf Length",
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          "min": 20,
          "default": "80"
        },
        {
          "name": "shelfbrk-depth",
          "type": "number",
          "label": "Shelf Depth",
          "unit": "cm",
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          "default": "25"
        },
        {
          "name": "shelfbrk-load",
          "type": "select-one",
          "label": "Expected Load",
          "unit": "",
          "options": [
            "light",
            "medium",
            "heavy"
          ],
          "default": "medium"
        },
        {
          "name": "shelfbrk-material",
          "type": "select-one",
          "label": "Shelf Material",
          "unit": "",
          "options": [
            "mdf",
            "pine",
            "hardwood",
            "plywood"
          ],
          "default": "pine"
        }
      ],
      "outputs": [
        {
          "name": "shelfbrk-result",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=shelf-bracket-calculator&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=shelf-bracket-calculator&shelfbrk-len=80&shelfbrk-depth=25&shelfbrk-load=medium&shelfbrk-material=pine&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "shelf",
        "bracket",
        "home",
        "diy",
        "calculate",
        "right",
        "size",
        "spacing",
        "load",
        "capacity"
      ],
      "popularity": 5090,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "shift-labour-cost-planner",
      "title": "🗓️ Shift Labour Cost Planner",
      "description": "Price a staffed shift including breaks, employer on-costs and overtime before publishing the rota. All calculations stay in your browser.",
      "category": "interactive-art-and-living-worlds",
      "categoryName": "Interactive Art & Living Worlds",
      "url": "https://www.themostusefulsiteintheworld.com/tool/shift-labour-cost-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=shift-labour-cost-planner&embed=1",
      "standaloneUrl": null,
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        {
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          "unit": "",
          "default": "6"
        },
        {
          "name": "shift-labour-cost-planner-hours",
          "type": "number",
          "label": "Paid hours each",
          "unit": "",
          "default": "8"
        },
        {
          "name": "shift-labour-cost-planner-rate",
          "type": "number",
          "label": "Hourly rate",
          "unit": "£",
          "default": "13.5"
        },
        {
          "name": "shift-labour-cost-planner-oncost",
          "type": "number",
          "label": "Employer on-costs",
          "unit": "%",
          "default": "18"
        }
      ],
      "outputs": [
        {
          "name": "shift-labour-cost-planner-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=shift-labour-cost-planner&<id>=<value>",
        "runs": true,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "shift",
        "labour",
        "cost",
        "planner",
        "interactive",
        "art",
        "living",
        "worlds",
        "price",
        "staffed"
      ],
      "popularity": 6973,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "shoe-size-converter",
      "title": "👟 Shoe Size Converter",
      "description": "Convert adult shoe sizes between US, UK, EU and Mondopoint (mm). Based on standard last-length charts — brands still vary by a half size, so treat this as a starting point, not a fitting.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/shoe-size-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=shoe-size-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "shoe-val",
          "type": "number",
          "label": "Size",
          "unit": "",
          "step": 0.5,
          "default": "8"
        },
        {
          "name": "shoe-who",
          "type": "select-one",
          "label": "Last",
          "unit": "",
          "options": [
            "m",
            "w"
          ],
          "default": "m"
        },
        {
          "name": "shoe-sys",
          "type": "select-one",
          "label": "I know",
          "unit": "",
          "options": [
            "uk",
            "us",
            "eu",
            "mm"
          ],
          "default": "uk"
        }
      ],
      "outputs": [
        {
          "name": "shoe-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=shoe-size-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=shoe-size-converter&shoe-val=8&shoe-who=m&shoe-sys=uk"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "shoe",
        "size",
        "converter",
        "productivity",
        "lifestyle",
        "convert",
        "adult",
        "sizes",
        "between",
        "mondopoint"
      ],
      "popularity": 4834,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "shoppinglist",
      "title": "🛒 Smart Shopping List",
      "description": "Add items, organize by category, track quantities, and manage your shopping efficiently. ✅ Features: Categories, quantity tracking, budget calculator, shareable lists",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/shoppinglist.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=shoppinglist&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "shoppinglist-item",
          "type": "text",
          "label": "Item Name",
          "unit": ""
        },
        {
          "name": "shoppinglist-quantity",
          "type": "text",
          "label": "Quantity",
          "unit": "",
          "default": "1"
        },
        {
          "name": "shoppinglist-price",
          "type": "number",
          "label": "Estimated Price",
          "unit": "$",
          "min": 0,
          "step": 0.01
        },
        {
          "name": "shoppinglist-category",
          "type": "select-one",
          "label": "Category",
          "unit": "",
          "options": [
            "groceries",
            "household",
            "personal",
            "electronics",
            "other"
          ],
          "default": "groceries"
        },
        {
          "name": "shoppinglist-priority",
          "type": "select-one",
          "label": "Priority",
          "unit": "",
          "options": [
            "low",
            "medium",
            "high",
            "urgent"
          ],
          "default": "medium"
        }
      ],
      "outputs": [
        {
          "name": "shoppinglist-total",
          "type": "output"
        },
        {
          "name": "stats-total",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=shoppinglist&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "shoppinglist",
        "smart",
        "shopping",
        "list",
        "productivity",
        "lifestyle",
        "add",
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        "organize",
        "category"
      ],
      "popularity": 6146,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "showjumping-faults-calculator",
      "title": "🐎 Showjumping Faults Calculator",
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      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/showjumping-faults-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=showjumping-faults-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sjf-kd",
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          "label": "Rails down",
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          "min": 0,
          "default": "1"
        },
        {
          "name": "sjf-ref",
          "type": "number",
          "label": "Refusals",
          "unit": "",
          "min": 0,
          "default": "0"
        },
        {
          "name": "sjf-time",
          "type": "number",
          "label": "Seconds over time",
          "unit": "",
          "min": 0,
          "default": "2"
        },
        {
          "name": "sjf-fall",
          "type": "checkbox",
          "label": "Rider fell",
          "unit": "",
          "default": "0"
        },
        {
          "name": "sjf-rf",
          "type": "number",
          "label": "Rival faults",
          "unit": "",
          "min": 0,
          "default": "0"
        },
        {
          "name": "sjf-rt",
          "type": "number",
          "label": "Rival time",
          "unit": "s",
          "min": 0,
          "step": 0.01,
          "default": "45.2"
        },
        {
          "name": "sjf-myt",
          "type": "number",
          "label": "Your jump-off time",
          "unit": "s",
          "min": 0,
          "step": 0.01,
          "default": "44.8"
        }
      ],
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        {
          "name": "sjf-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=showjumping-faults-calculator&<id>=<value>",
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "showjumping",
        "faults",
        "sports",
        "add",
        "fast",
        "knockdown",
        "refusal",
        "every",
        "second",
        "over"
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "signature-pad",
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      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/signature-pad.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=signature-pad&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sgnp-width",
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          "label": "Nib: 3 px",
          "unit": "",
          "min": 1,
          "max": 9,
          "step": 0.5,
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        },
        {
          "name": "sgnp-name",
          "type": "text",
          "label": "Type your name",
          "unit": ""
        },
        {
          "name": "sgnp-slant",
          "type": "range",
          "label": "Slant: 0 °",
          "unit": "",
          "min": -14,
          "max": 14,
          "step": 1,
          "default": "0"
        },
        {
          "name": "sgnp-guide",
          "type": "checkbox",
          "label": "Show the signing line and date",
          "unit": "",
          "default": "1"
        },
        {
          "name": "sgnp-colour",
          "type": "select-one",
          "label": "Ink",
          "unit": "",
          "options": [
            "#0b1a24",
            "#000000",
            "#1d4ed8",
            "#b91c1c",
            "#065f46"
          ],
          "default": "#0b1a24"
        },
        {
          "name": "sgnp-font",
          "type": "select-one",
          "label": "Script style",
          "unit": "",
          "options": [
            "'Segoe Script','Brush Script MT','Snell Roundhand',cursive",
            "'Brush Script MT','Segoe Script',cursive",
            "'Snell Roundhand','Segoe Script',cursive",
            "Georgia,'Times New Roman',serif",
            "system-ui,-apple-system,'Segoe UI',sans-serif"
          ],
          "default": "'Segoe Script','Brush Script MT','Snell Roundhand',cursive"
        }
      ],
      "outputs": [
        {
          "name": "sgnp-msg",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=signature-pad&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=signature-pad&sgnp-width=3&sgnp-slant=0&sgnp-guide=1&sgnp-colour=%230b1a24&sgnp-font='Segoe%20Script'%2C'Brush%20Script%20MT'%2C'Snell%20Roundhand'%2Ccursive"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "signature",
        "pad",
        "draw",
        "type",
        "save",
        "png",
        "svg",
        "saas",
        "business",
        "killers"
      ],
      "popularity": 4470,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "simple-todo-list",
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      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/simple-todo-list.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=simple-todo-list&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "todo-input",
          "type": "text",
          "label": "New task",
          "unit": ""
        },
        {
          "name": "todo-due",
          "type": "date",
          "label": "Due date",
          "unit": ""
        },
        {
          "name": "todo-search",
          "type": "search",
          "label": "Search tasks",
          "unit": ""
        },
        {
          "name": "todo-prio",
          "type": "select-one",
          "label": "Priority",
          "unit": "",
          "options": [
            "2",
            "3",
            "1"
          ],
          "default": "2"
        },
        {
          "name": "todo-sort",
          "type": "select-one",
          "label": "Sort",
          "unit": "",
          "options": [
            "manual",
            "due",
            "prio",
            "alpha"
          ],
          "default": "manual"
        }
      ],
      "outputs": [
        {
          "name": "todo-summary",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=simple-todo-list&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=simple-todo-list&todo-prio=2&todo-sort=manual"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "simple",
        "todo",
        "list",
        "to-do",
        "offline",
        "remembers",
        "itself",
        "productivity",
        "lifestyle",
        "type"
      ],
      "popularity": 4362,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "simultaneous-equations-solver",
      "title": "⚖️ Simultaneous Equations Solver — Every Line of Working",
      "description": "Feed it two or three linear equations and watch elimination, substitution or Cramer's rule unwind line by line in exact fractions — never rounded decimals. Parallel and identical lines get diagnose...",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/simultaneous-equations-solver.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=simultaneous-equations-solver&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "label": "x coefficient, equation 1",
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          "default": "2"
        },
        {
          "name": "sime-b1",
          "type": "number",
          "label": "y coefficient, equation 1",
          "unit": "",
          "default": "3"
        },
        {
          "name": "sime-d1",
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          "label": "z coefficient, equation 1",
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          "default": "0"
        },
        {
          "name": "sime-c1",
          "type": "number",
          "label": "constant, equation 1",
          "unit": "",
          "default": "13"
        },
        {
          "name": "sime-a2",
          "type": "number",
          "label": "x coefficient, equation 2",
          "unit": "",
          "default": "5"
        },
        {
          "name": "sime-b2",
          "type": "number",
          "label": "y coefficient, equation 2",
          "unit": "",
          "default": "-4"
        },
        {
          "name": "sime-d2",
          "type": "number",
          "label": "z coefficient, equation 2",
          "unit": "",
          "default": "0"
        },
        {
          "name": "sime-c2",
          "type": "number",
          "label": "constant, equation 2",
          "unit": "",
          "default": "-2"
        },
        {
          "name": "sime-a3",
          "type": "number",
          "label": "x coefficient, equation 3",
          "unit": "",
          "default": "1"
        },
        {
          "name": "sime-b3",
          "type": "number",
          "label": "y coefficient, equation 3",
          "unit": "",
          "default": "2"
        },
        {
          "name": "sime-d3",
          "type": "number",
          "label": "z coefficient, equation 3",
          "unit": "",
          "default": "3"
        },
        {
          "name": "sime-c3",
          "type": "number",
          "label": "constant, equation 3",
          "unit": "",
          "default": "16"
        },
        {
          "name": "sime-subr",
          "type": "radio",
          "label": "substitution",
          "unit": "",
          "default": "0"
        },
        {
          "name": "sime-kind",
          "type": "select-one",
          "label": "unknowns",
          "unit": "",
          "options": [
            "2",
            "3"
          ],
          "default": "2"
        }
      ],
      "outputs": [
        {
          "name": "sime-status",
          "type": "live"
        },
        {
          "name": "sime-answer",
          "type": "output"
        }
      ],
      "prefill": {
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        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=simultaneous-equations-solver&sime-a1=2&sime-b1=3&sime-d1=0&sime-c1=13&sime-a2=5&sime-b2=-4&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "simultaneous",
        "equations",
        "solver",
        "every",
        "line",
        "working",
        "mathematics",
        "feed",
        "two",
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      ],
      "popularity": 4061,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "skip-hire-volume-calculator",
      "title": "🗑️ Skip Hire Volume Calculator",
      "description": "Rough cubic yards from room waste, rubble or bags. UK skips are sold in yards: 4, 6, 8, 12, 16. Loose waste settles; rubble is heavy — many yards cap weight before the skip looks full. Not a quote.",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/skip-hire-volume-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=skip-hire-volume-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "skhv-l",
          "type": "number",
          "label": "Length m",
          "unit": "",
          "min": 0,
          "default": "3"
        },
        {
          "name": "skhv-w",
          "type": "number",
          "label": "Width m",
          "unit": "",
          "min": 0,
          "default": "2"
        },
        {
          "name": "skhv-h",
          "type": "number",
          "label": "Height m / bags / rooms",
          "unit": "",
          "min": 0,
          "default": "0.6"
        },
        {
          "name": "skhv-kind",
          "type": "select-one",
          "label": "I am filling from",
          "unit": "",
          "options": [
            "pile",
            "bags",
            "rooms"
          ],
          "default": "pile"
        }
      ],
      "outputs": [
        {
          "name": "skhv-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=skip-hire-volume-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=skip-hire-volume-calculator&skhv-l=3&skhv-w=2&skhv-h=0.6&skhv-kind=pile"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "skip",
        "hire",
        "volume",
        "home",
        "diy",
        "rough",
        "cubic",
        "yards",
        "room",
        "waste"
      ],
      "popularity": 4818,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-avatar-height-calculator",
      "title": "📏 SL Avatar Height & Proportion Calculator",
      "description": "Calculate your avatar's true height, body proportions, and get recommendations for realistic or stylized looks",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-avatar-height-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-avatar-height-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sl-av-ht",
          "type": "range",
          "label": "av ht",
          "unit": "",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "50"
        },
        {
          "name": "sl-av-thick",
          "type": "range",
          "label": "av thick",
          "unit": "",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "50"
        },
        {
          "name": "sl-av-fit",
          "type": "range",
          "label": "av fit",
          "unit": "",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "50"
        },
        {
          "name": "sl-av-head",
          "type": "range",
          "label": "av head",
          "unit": "",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "50"
        },
        {
          "name": "sl-av-leg",
          "type": "range",
          "label": "av leg",
          "unit": "",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "50"
        },
        {
          "name": "sl-av-arm",
          "type": "range",
          "label": "av arm",
          "unit": "",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "50"
        }
      ],
      "outputs": [
        {
          "name": "sl-av-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-avatar-height-calculator&<id>=<value>",
        "runs": false,
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      },
      "formula": "Common SL Issues • Slider 100 = abnormally tall • Tiny head = uncanny valley • Too-",
      "sources": [],
      "tags": [
        "avatar",
        "height",
        "proportion",
        "virtual",
        "worlds",
        "gaming",
        "calculate",
        "true",
        "body",
        "proportions"
      ],
      "popularity": 6056,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-buildmate",
      "title": "🏗️ Second Life Builder's Mate",
      "description": "Professional toolkit for Second Life builders: prim allowance, object sizing, weight calculation, grid alignment, and LOD optimization. ✅ Features: Prim/LI calculation, mesh optimization, physics a...",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-buildmate.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-buildmate&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "label": "Parcel Size",
          "unit": "m²",
          "min": 1,
          "max": 65536
        },
        {
          "name": "sl-bm-primcount",
          "type": "number",
          "label": "Existing Prims/LI",
          "unit": "",
          "min": 0
        },
        {
          "name": "sl-bm-groupbonus",
          "type": "number",
          "label": "Group Bonus",
          "unit": "%",
          "min": 0,
          "max": 100,
          "default": "10"
        },
        {
          "name": "sl-bm-length",
          "type": "number",
          "label": "Length",
          "unit": "m",
          "min": 0.01,
          "max": 64,
          "step": 0.01
        },
        {
          "name": "sl-bm-width",
          "type": "number",
          "label": "Width",
          "unit": "m",
          "min": 0.01,
          "max": 64,
          "step": 0.01
        },
        {
          "name": "sl-bm-height",
          "type": "number",
          "label": "Height",
          "unit": "m",
          "min": 0.01,
          "max": 64,
          "step": 0.01
        },
        {
          "name": "sl-bm-textures",
          "type": "number",
          "label": "Texture Count",
          "unit": "",
          "min": 0,
          "max": 100,
          "default": "1"
        },
        {
          "name": "sl-bm-x",
          "type": "number",
          "label": "X Position",
          "unit": "m",
          "step": 0.01
        },
        {
          "name": "sl-bm-y",
          "type": "number",
          "label": "Y Position",
          "unit": "m",
          "step": 0.01
        },
        {
          "name": "sl-bm-z",
          "type": "number",
          "label": "Z Position",
          "unit": "m",
          "step": 0.01
        },
        {
          "name": "sl-bm-show-advanced",
          "type": "checkbox",
          "label": "Show Advanced Options",
          "unit": "",
          "default": "0"
        },
        {
          "name": "sl-bm-triangles",
          "type": "number",
          "label": "Triangle Count",
          "unit": "",
          "min": 1,
          "max": 100000
        },
        {
          "name": "sl-bm-scriptmemory",
          "type": "number",
          "label": "Script Memory",
          "unit": "KB",
          "min": 0,
          "max": 65536
        },
        {
          "name": "sl-bm-output",
          "type": "textarea",
          "label": "Click 'Calculate All Metrics' to see detailed results…",
          "unit": ""
        },
        {
          "name": "sl-bm-landtype",
          "type": "select-one",
          "label": "Land Type",
          "unit": "",
          "options": [
            "mainland",
            "private",
            "homestead",
            "openspace"
          ],
          "default": "mainland"
        },
        {
          "name": "sl-bm-tier",
          "type": "select-one",
          "label": "Premium Tier",
          "unit": "",
          "options": [
            "0",
            "512",
            "1024",
            "2048",
            "4096"
          ],
          "default": "0"
        },
        {
          "name": "sl-bm-density",
          "type": "select-one",
          "label": "Density",
          "unit": "kg/m³",
          "options": [
            "100",
            "500",
            "1000",
            "2000",
            "7800",
            "custom"
          ],
          "default": "500"
        },
        {
          "name": "sl-bm-objecttype",
          "type": "select-one",
          "label": "Object Type",
          "unit": "",
          "options": [
            "prim",
            "mesh",
            "sculpt",
            "linkset"
          ],
          "default": "mesh"
        },
        {
          "name": "sl-bm-lod",
          "type": "select-one",
          "label": "LOD Setting",
          "unit": "",
          "options": [
            "low",
            "medium",
            "high",
            "ultra"
          ],
          "default": "medium"
        },
        {
          "name": "sl-bm-physics",
          "type": "select-one",
          "label": "Physics Type",
          "unit": "",
          "options": [
            "none",
            "prim",
            "convex",
            "mesh"
          ],
          "default": "prim"
        },
        {
          "name": "sl-bm-material",
          "type": "select-one",
          "label": "Material",
          "unit": "",
          "options": [
            "stone",
            "metal",
            "glass",
            "wood",
            "flesh",
            "plastic",
            "rubber",
            "light"
          ],
          "default": "wood"
        },
        {
          "name": "sl-bm-grid",
          "type": "select-one",
          "label": "Grid Step",
          "unit": "m",
          "options": [
            "0.125",
            "0.25",
            "0.5",
            "1",
            "custom"
          ],
          "default": "0.25"
        },
        {
          "name": "sl-bm-snap",
          "type": "select-one",
          "label": "Snap Mode",
          "unit": "",
          "options": [
            "ground",
            "surface",
            "grid",
            "none"
          ],
          "default": "surface"
        },
        {
          "name": "sl-bm-rotation",
          "type": "select-one",
          "label": "Rotation Step",
          "unit": "°",
          "options": [
            "5",
            "15",
            "30",
            "45",
            "90"
          ],
          "default": "45"
        },
        {
          "name": "sl-bm-downloadweight",
          "type": "select-one",
          "label": "Download Weight",
          "unit": "",
          "options": [
            "0.5",
            "1.0",
            "2.0",
            "4.0"
          ],
          "default": "1.0"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-buildmate&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-buildmate&sl-bm-groupbonus=10&sl-bm-textures=1&sl-bm-show-advanced=0&sl-bm-landtype=mainland&sl-bm-tier=0&sl-bm-density=500&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "buildmate",
        "second",
        "life",
        "builder",
        "mate",
        "virtual",
        "worlds",
        "gaming",
        "professional",
        "toolkit"
      ],
      "popularity": 5505,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-events",
      "title": "📅 Live Second Life Events",
      "description": "🟢 LIVE Real-time events from Second Life. Updates automatically.",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-events.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-events&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sl-events-category",
          "type": "select-one",
          "label": "Category",
          "unit": "",
          "options": [
            "all",
            "18",
            "23",
            "19",
            "24",
            "20",
            "21",
            "25",
            "26"
          ],
          "default": "18"
        },
        {
          "name": "sl-events-hours",
          "type": "select-one",
          "label": "Next Hours",
          "unit": "",
          "options": [
            "1",
            "3",
            "6",
            "12",
            "24"
          ],
          "default": "3"
        }
      ],
      "outputs": [
        {
          "name": "sl-events-output",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-events&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-events&sl-events-category=18&sl-events-hours=3"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "events",
        "live",
        "second",
        "life",
        "virtual",
        "worlds",
        "gaming",
        "real-time",
        "updates",
        "automatically"
      ],
      "popularity": 6141,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-exchange",
      "title": "💰 Linden Dollar Exchange",
      "description": "Convert Linden Dollars (Second Life virtual currency) to real-world currencies using market rates. Rates are estimates — actual exchange rates may vary.",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-exchange.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-exchange&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "lde-linden",
          "type": "number",
          "label": "Linden Dollars",
          "unit": "L$",
          "min": 0,
          "step": 1
        },
        {
          "name": "lde-exchange-rate",
          "type": "range",
          "label": "Exchange Rate",
          "unit": "L$ per USD",
          "min": 200,
          "max": 300,
          "step": 5,
          "default": "250"
        },
        {
          "name": "lde-to-currency",
          "type": "select-one",
          "label": "To Currency",
          "unit": "",
          "options": [
            "USD",
            "EUR",
            "GBP",
            "JPY",
            "CAD",
            "AUD",
            "CNY",
            "INR",
            "BRL",
            "MXN",
            "KRW",
            "RUB"
          ],
          "default": "USD"
        }
      ],
      "outputs": [
        {
          "name": "lde-rate-value",
          "type": "output"
        },
        {
          "name": "lde-results",
          "type": "output"
        },
        {
          "name": "lde-from-amount",
          "type": "output"
        },
        {
          "name": "lde-to-amount",
          "type": "output"
        },
        {
          "name": "lde-to-currency-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-exchange&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-exchange&lde-exchange-rate=250&lde-to-currency=USD&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "exchange",
        "linden",
        "dollar",
        "virtual",
        "worlds",
        "gaming",
        "convert",
        "dollars",
        "second",
        "life"
      ],
      "popularity": 6535,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-group-slot-calculator",
      "title": "👥 SL Group Slot Calculator",
      "description": "Track your group memberships — manage the 42-group limit and plan which groups to keep or drop",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-group-slot-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-group-slot-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sl-grp-name",
          "type": "text",
          "label": "Group name",
          "unit": ""
        },
        {
          "name": "sl-grp-priority",
          "type": "select-one",
          "label": "Group priority",
          "unit": "",
          "options": [
            "essential",
            "important",
            "nice",
            "optional"
          ],
          "default": "nice"
        },
        {
          "name": "sl-grp-premium",
          "type": "select-one",
          "label": "Premium bonus groups: Free account (42 max) Premium (56 max) Premium Plus",
          "unit": "70 max",
          "options": [
            "0",
            "14",
            "28"
          ],
          "default": "0"
        }
      ],
      "outputs": [
        {
          "name": "sl-grp-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-group-slot-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-group-slot-calculator&sl-grp-priority=nice&sl-grp-premium=0"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "group",
        "slot",
        "virtual",
        "worlds",
        "gaming",
        "track",
        "memberships",
        "manage",
        "42-group",
        "limit"
      ],
      "popularity": 5121,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-land-tier-calculator",
      "title": "🏠 SL Land Tier Calculator",
      "description": "Calculate monthly tier costs, prim budgets, and land area — for mainland, private regions, and homesteads",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-land-tier-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-land-tier-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sl-land-area",
          "type": "range",
          "label": "land area",
          "unit": "",
          "min": 512,
          "max": 65536,
          "step": 512,
          "default": "512"
        },
        {
          "name": "sl-land-type",
          "type": "select-one",
          "label": "land type",
          "unit": "",
          "options": [
            "mainland",
            "full",
            "homestead",
            "openspace"
          ],
          "default": "mainland"
        },
        {
          "name": "sl-land-currency",
          "type": "select-one",
          "label": "land currency",
          "unit": "",
          "options": [
            "usd",
            "gbp",
            "eur"
          ],
          "default": "usd"
        }
      ],
      "outputs": [
        {
          "name": "sl-land-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-land-tier-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-land-tier-calculator&sl-land-area=512&sl-land-type=mainland&sl-land-currency=usd"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "land",
        "tier",
        "virtual",
        "worlds",
        "gaming",
        "calculate",
        "monthly",
        "costs",
        "prim",
        "budgets"
      ],
      "popularity": 5639,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-linden-dollar-converter",
      "title": "💵 L$ Linden Dollar Converter",
      "description": "Convert between Linden Dollars (L$) and real-world currencies — USD, GBP, EUR, JPY, AUD, CAD",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-linden-dollar-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-linden-dollar-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sl-linden-amount",
          "type": "number",
          "label": "Amount in L$ (Linden Dollars)",
          "unit": "",
          "min": 0,
          "default": "1000"
        },
        {
          "name": "sl-linden-rate",
          "type": "number",
          "label": "Exchange Rate",
          "unit": "L$ per 1 USD",
          "min": 1,
          "step": 1,
          "default": "250"
        }
      ],
      "outputs": [
        {
          "name": "sl-linden-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-linden-dollar-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-linden-dollar-converter&sl-linden-amount=1000&sl-linden-rate=250"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "linden",
        "dollar",
        "converter",
        "virtual",
        "worlds",
        "gaming",
        "convert",
        "between",
        "dollars",
        "real-world"
      ],
      "popularity": 6724,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-lsl-script-generator",
      "title": "📜 LSL Script Generator",
      "description": "Generate ready-to-use Linden Scripting Language scripts — security, teleport, dance, auto-response, and more",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-lsl-script-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-lsl-script-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sl-lsl-range",
          "type": "range",
          "label": "lsl range",
          "unit": "",
          "min": 5,
          "max": 96,
          "step": 1,
          "default": "20"
        },
        {
          "name": "sl-lsl-owner",
          "type": "text",
          "label": "YourName Resident",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-lsl-script-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-lsl-script-generator&sl-lsl-range=20"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "lsl",
        "script",
        "virtual",
        "worlds",
        "gaming",
        "generate",
        "ready-to-use",
        "linden",
        "scripting",
        "language"
      ],
      "popularity": 5507,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-market",
      "title": "🛒 Second Life Marketplace Search",
      "description": "Search and browse Second Life Marketplace items. Demo data shown — in production, connect to actual Marketplace API.",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-market.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-market&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "slms-query",
          "type": "text",
          "label": "Search Marketplace",
          "unit": ""
        },
        {
          "name": "slms-min-price",
          "type": "number",
          "label": "Min",
          "unit": "",
          "min": 0,
          "max": 10000,
          "default": "0"
        },
        {
          "name": "slms-max-price",
          "type": "number",
          "label": "Max",
          "unit": "",
          "min": 0,
          "max": 10000,
          "default": "1000"
        },
        {
          "name": "slms-sort-by",
          "type": "select-one",
          "label": "Sort By",
          "unit": "",
          "options": [
            "relevance",
            "price-low",
            "price-high",
            "rating",
            "newest"
          ],
          "default": "relevance"
        },
        {
          "name": "slms-results-count",
          "type": "select-one",
          "label": "Results Count",
          "unit": "",
          "options": [
            "5",
            "10",
            "15",
            "20"
          ],
          "default": "10"
        }
      ],
      "outputs": [
        {
          "name": "slms-max-price-value",
          "type": "output"
        },
        {
          "name": "slms-results",
          "type": "output"
        },
        {
          "name": "slms-results-summary",
          "type": "output"
        },
        {
          "name": "slms-no-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-market&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-market&slms-min-price=0&slms-max-price=1000&slms-sort-by=relevance&slms-results-count=10"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "market",
        "second",
        "life",
        "marketplace",
        "search",
        "virtual",
        "worlds",
        "gaming",
        "browse",
        "items"
      ],
      "popularity": 5344,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-mesh-upload-cost",
      "title": "🔺 SL Mesh Upload Cost Calculator",
      "description": "Estimate Land Impact and upload cost for mesh objects — input triangle counts and physics shapes",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-mesh-upload-cost.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-mesh-upload-cost&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sl-mesh-hi",
          "type": "range",
          "label": "mesh hi",
          "unit": "",
          "min": 100,
          "max": 100000,
          "step": 100,
          "default": "5000"
        },
        {
          "name": "sl-mesh-med",
          "type": "range",
          "label": "mesh med",
          "unit": "",
          "min": 50,
          "max": 50000,
          "step": 50,
          "default": "2500"
        },
        {
          "name": "sl-mesh-low",
          "type": "range",
          "label": "mesh low",
          "unit": "",
          "min": 10,
          "max": 10000,
          "step": 10,
          "default": "500"
        },
        {
          "name": "sl-mesh-lowest",
          "type": "range",
          "label": "mesh lowest",
          "unit": "",
          "min": 4,
          "max": 2000,
          "step": 4,
          "default": "100"
        },
        {
          "name": "sl-mesh-mats",
          "type": "range",
          "label": "mesh mats",
          "unit": "",
          "min": 1,
          "max": 8,
          "step": 1,
          "default": "1"
        },
        {
          "name": "sl-mesh-physics",
          "type": "select-one",
          "label": "mesh physics",
          "unit": "",
          "options": [
            "prim",
            "none",
            "mesh"
          ],
          "default": "prim"
        }
      ],
      "outputs": [
        {
          "name": "sl-mesh-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-mesh-upload-cost&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-mesh-upload-cost&sl-mesh-hi=5000&sl-mesh-med=2500&sl-mesh-low=500&sl-mesh-lowest=100&sl-mesh-mats=1&sl-mesh-physics=prim"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "mesh",
        "upload",
        "cost",
        "virtual",
        "worlds",
        "gaming",
        "estimate",
        "land",
        "impact",
        "objects"
      ],
      "popularity": 4931,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-outfit-planner",
      "title": "👗 SL Outfit Planner",
      "description": "Plan and organize your Second Life outfits — track body parts, clothing layers, accessories, and color coordination",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-outfit-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-outfit-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sl-outfit-name",
          "type": "text",
          "label": "Outfit name (e.g. Cyberpunk Night)",
          "unit": ""
        },
        {
          "name": "sl-outfit-item",
          "type": "text",
          "label": "Add item...",
          "unit": ""
        },
        {
          "name": "sl-outfit-notes",
          "type": "textarea",
          "label": "Notes: store names, landmarks, SLURLs...",
          "unit": ""
        },
        {
          "name": "sl-outfit-cat",
          "type": "select-one",
          "label": "outfit cat",
          "unit": "",
          "options": [
            "body",
            "hair",
            "top",
            "bottom",
            "shoes",
            "accessory",
            "animation"
          ],
          "default": "body"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-outfit-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-outfit-planner&sl-outfit-cat=body"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "outfit",
        "planner",
        "virtual",
        "worlds",
        "gaming",
        "plan",
        "organize",
        "second",
        "life",
        "outfits"
      ],
      "popularity": 4228,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-prim-budget-planner",
      "title": "🧱 SL Prim Budget Planner",
      "description": "Plan your land's prim usage — add objects, track LI (Land Impact), and stay within your budget",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-prim-budget-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-prim-budget-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sl-prim-budget-range",
          "type": "range",
          "label": "prim budget range",
          "unit": "",
          "min": 37,
          "max": 15000,
          "step": 1,
          "default": "234"
        },
        {
          "name": "sl-prim-name",
          "type": "text",
          "label": "Object name (e.g. Sofa)",
          "unit": ""
        },
        {
          "name": "sl-prim-li",
          "type": "number",
          "label": "LI",
          "unit": "",
          "min": 1,
          "default": "5"
        }
      ],
      "outputs": [
        {
          "name": "sl-prim-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-prim-budget-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-prim-budget-planner&sl-prim-budget-range=234&sl-prim-li=5"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "prim",
        "budget",
        "planner",
        "virtual",
        "worlds",
        "gaming",
        "plan",
        "land",
        "usage",
        "add"
      ],
      "popularity": 5403,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-region-map",
      "title": "🗺️ Second Life Region Map",
      "description": "View Second Life region maps with interactive pan/zoom, coordinates, and debugging tools. Uses multiple data sources with automatic fallback.",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-region-map.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-region-map&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "slrmv-region-name",
          "type": "text",
          "label": "Region Name",
          "unit": ""
        },
        {
          "name": "slrmv-coord-x",
          "type": "number",
          "label": "X Coordinate",
          "unit": "0-255",
          "min": 0,
          "max": 255
        },
        {
          "name": "slrmv-coord-y",
          "type": "number",
          "label": "Y Coordinate",
          "unit": "0-255",
          "min": 0,
          "max": 255
        },
        {
          "name": "slrmv-direct-url",
          "type": "url",
          "label": "Direct Image URL",
          "unit": "Override"
        },
        {
          "name": "slrmv-image-source",
          "type": "select-one",
          "label": "Image Source",
          "unit": "",
          "options": [
            "auto",
            "slgrid",
            "slmap",
            "tiles"
          ],
          "default": "auto"
        },
        {
          "name": "slrmv-cors-proxy",
          "type": "select-one",
          "label": "CORS Proxy",
          "unit": "",
          "options": [
            "allorigins",
            "corsproxy",
            "corsanywhere"
          ]
        }
      ],
      "outputs": [
        {
          "name": "slrmv-coord-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-region-map&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-region-map&slrmv-image-source=auto"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "region",
        "map",
        "second",
        "life",
        "virtual",
        "worlds",
        "gaming",
        "view",
        "maps",
        "interactive"
      ],
      "popularity": 4975,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-teleport-planner",
      "title": "🌀 SL Teleport & SLURL Planner",
      "description": "Build teleport notecards, generate SLURLs, and plan region visits with coordinate calculations",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-teleport-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-teleport-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sl-tp-region",
          "type": "text",
          "label": "Region Name",
          "unit": ""
        },
        {
          "name": "sl-tp-x",
          "type": "number",
          "label": "X",
          "unit": "",
          "min": 0,
          "max": 256,
          "default": "128"
        },
        {
          "name": "sl-tp-y",
          "type": "number",
          "label": "Y",
          "unit": "",
          "min": 0,
          "max": 256,
          "default": "128"
        },
        {
          "name": "sl-tp-z",
          "type": "number",
          "label": "Z",
          "unit": "height",
          "min": 0,
          "max": 4096,
          "default": "0"
        },
        {
          "name": "sl-tp-desc",
          "type": "text",
          "label": "Description",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-teleport-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-teleport-planner&sl-tp-x=128&sl-tp-y=128&sl-tp-z=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "teleport",
        "planner",
        "slurl",
        "virtual",
        "worlds",
        "gaming",
        "build",
        "notecards",
        "generate",
        "slurls"
      ],
      "popularity": 5940,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-texture-cost-calculator",
      "title": "🖼️ SL Texture Upload Cost Calculator",
      "description": "Calculate upload costs, memory usage, and get recommendations for optimal texture sizes in Second Life",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-texture-cost-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-texture-cost-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sl-tex-count",
          "type": "number",
          "label": "Number of Textures",
          "unit": "",
          "min": 1,
          "max": 1000,
          "default": "10"
        },
        {
          "name": "sl-tex-w",
          "type": "select-one",
          "label": "Texture Width",
          "unit": "pixels",
          "options": [
            "64",
            "128",
            "256",
            "512",
            "1024",
            "2048",
            "4096"
          ],
          "default": "256"
        },
        {
          "name": "sl-tex-h",
          "type": "select-one",
          "label": "Texture Height",
          "unit": "pixels",
          "options": [
            "64",
            "128",
            "256",
            "512",
            "1024",
            "2048",
            "4096"
          ],
          "default": "256"
        },
        {
          "name": "sl-tex-format",
          "type": "select-one",
          "label": "Format",
          "unit": "",
          "options": [
            "lossy",
            "lossless"
          ],
          "default": "lossy"
        }
      ],
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        {
          "name": "sl-tex-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-texture-cost-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-texture-cost-calculator&sl-tex-count=10&sl-tex-w=256&sl-tex-h=256&sl-tex-format=lossy"
      },
      "formula": "Each texture uses VRAM = W×H×",
      "sources": [],
      "tags": [
        "texture",
        "cost",
        "upload",
        "virtual",
        "worlds",
        "gaming",
        "calculate",
        "costs",
        "memory",
        "usage"
      ],
      "popularity": 5732,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-texture",
      "title": "🖼️ Second Life Texture Tool",
      "description": "Calculate texture repeats, offsets, and rotations for Second Life prims. Perfect alignment for builders and creators. Works with any texture and prim size. This site is supported by user contributi...",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-texture.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-texture&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tt-texture-width",
          "type": "number",
          "label": "Texture Dimensions (Pixels) Standard sizes: 32, 64, 128, 256, 512, 1024, 2048",
          "unit": "",
          "min": 1,
          "max": 4096,
          "step": 1,
          "default": "512"
        },
        {
          "name": "tt-texture-height",
          "type": "number",
          "label": "Texture height in pixels",
          "unit": "",
          "min": 1,
          "max": 4096,
          "step": 1,
          "default": "512"
        },
        {
          "name": "tt-prim-width",
          "type": "number",
          "label": "Prim Face Dimensions (Meters) Common sizes: 0.5, 1.0, 2.0, 4.0, 10.0",
          "unit": "",
          "min": 0.01,
          "max": 100,
          "step": 0.01,
          "default": "1.0"
        },
        {
          "name": "tt-prim-height",
          "type": "number",
          "label": "Prim height in meters",
          "unit": "",
          "min": 0.01,
          "max": 100,
          "step": 0.01,
          "default": "1.0"
        },
        {
          "name": "tt-rotation",
          "type": "range",
          "label": "Texture Rotation",
          "unit": "",
          "min": -180,
          "max": 180,
          "step": 0.1,
          "default": "0"
        }
      ],
      "outputs": [
        {
          "name": "tt-rotation-value",
          "type": "output"
        },
        {
          "name": "sltexttt-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-texture&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-texture&tt-texture-width=512&tt-texture-height=512&tt-prim-width=1.0&tt-prim-height=1.0&tt-rotation=0&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "texture",
        "second",
        "life",
        "virtual",
        "worlds",
        "gaming",
        "calculate",
        "repeats",
        "offsets",
        "rotations"
      ],
      "popularity": 4959,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sl-time-converter",
      "title": "🕐 SL Time Converter",
      "description": "Convert between Second Life Time (SLT/PST) and your local time — never miss an event again",
      "category": "virtual-worlds-and-gaming",
      "categoryName": "Virtual Worlds & Gaming",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sl-time-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-time-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sl-time-h",
          "type": "number",
          "label": "time h",
          "unit": "",
          "min": 0,
          "max": 23,
          "default": "12"
        },
        {
          "name": "sl-time-m",
          "type": "number",
          "label": "time m",
          "unit": "",
          "min": 0,
          "max": 59,
          "default": "0"
        },
        {
          "name": "sl-tz-select",
          "type": "select-one",
          "label": "tz select",
          "unit": "",
          "options": [
            "-8",
            "-7",
            "0",
            "1",
            "2",
            "3",
            "5.5",
            "8",
            "9",
            "10",
            "12",
            "-5",
            "-6",
            "-7"
          ],
          "default": "0"
        }
      ],
      "outputs": [
        {
          "name": "sl-time-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-time-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sl-time-converter&sl-time-h=12&sl-time-m=0&sl-tz-select=0"
      },
      "formula": "SL Time = Pacific Time Second Life runs on PST (UTC-8) or PDT (UTC-",
      "sources": [],
      "tags": [
        "time",
        "converter",
        "virtual",
        "worlds",
        "gaming",
        "convert",
        "between",
        "second",
        "life",
        "slt"
      ],
      "popularity": 6004,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sleep-debt-calculator",
      "title": "😴 Sleep Debt Calculator",
      "description": "Need minus hours actually slept, summed over the week. Most adults are in the 7–9 h band; you are not. This is arithmetic, not a sleep clinic. If you stop breathing at night, talk to a GP.",
      "category": "lucid-dreaming-and-sleep",
      "categoryName": "Lucid Dreaming & Sleep",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sleep-debt-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sleep-debt-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sdeb-need",
          "type": "number",
          "label": "Need h / night",
          "unit": "",
          "min": 4,
          "max": 12,
          "step": 0.25,
          "default": "8"
        }
      ],
      "outputs": [
        {
          "name": "sdeb-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sleep-debt-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sleep-debt-calculator&sdeb-need=8"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "sleep",
        "debt",
        "lucid",
        "dreaming",
        "need",
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        "hours",
        "actually",
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      ],
      "popularity": 6994,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sleep-paralysis-hypnopompic",
      "title": "🛡️ Sleep Paralysis Navigator",
      "description": "Demystify REM motor atonia. Learn how glycine and GABA temporarily paralyze skeletal muscles, and either smoothly wake up or launch directly into a vivid lucid flight.",
      "category": "lucid-dreaming-and-sleep",
      "categoryName": "Lucid Dreaming & Sleep",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sleep-paralysis-hypnopompic.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sleep-paralysis-hypnopompic&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sleep-paralysis-hypnopompic&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "sleep",
        "paralysis",
        "hypnopompic",
        "navigator",
        "lucid",
        "dreaming",
        "demystify",
        "rem",
        "motor",
        "atonia"
      ],
      "popularity": 5703,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sleep",
      "title": "🛏️ Sleep Cycle Calculator",
      "description": "Calculate optimal wake-up times based on 90-minute sleep cycles for better rest. No affiliate links - this site is supported by user contributions .",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sleep.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sleep&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tt-bedtime",
          "type": "time",
          "label": "Planned Bedtime",
          "unit": "",
          "default": "23:00"
        },
        {
          "name": "tt-cycles-slider",
          "type": "range",
          "label": "Sleep Cycles",
          "unit": "90 min each",
          "min": 3,
          "max": 7,
          "default": "5"
        }
      ],
      "outputs": [
        {
          "name": "tt-cycles-value",
          "type": "output"
        },
        {
          "name": "sleeptt-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sleep&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sleep&tt-bedtime=23%3A00&tt-cycles-slider=5"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "sleep",
        "cycle",
        "health",
        "fitness",
        "calculate",
        "optimal",
        "wake-up",
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        "90-minute"
      ],
      "popularity": 5647,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sls-figure-composer",
      "title": "🦴 SLS-Style Figure Composer",
      "description": "Place an adjustable skeletal-tracking effect over a still photo for a clearly staged horror shot. Drag it into position with the controls, preview the framing, then export a PNG—no live camera or t...",
      "category": "horror-and-paranormal",
      "categoryName": "Horror & Paranormal",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sls-figure-composer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sls-figure-composer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "range",
          "label": "Horizontal position: 72%",
          "unit": "",
          "min": 5,
          "max": 95,
          "default": "72"
        },
        {
          "name": "sls-y",
          "type": "range",
          "label": "Vertical position: 60%",
          "unit": "",
          "min": 15,
          "max": 90,
          "default": "60"
        },
        {
          "name": "sls-size",
          "type": "range",
          "label": "Figure scale: 100%",
          "unit": "",
          "min": 50,
          "max": 160,
          "default": "100"
        },
        {
          "name": "sls-opacity",
          "type": "range",
          "label": "Glow opacity: 78%",
          "unit": "",
          "min": 15,
          "max": 100,
          "default": "78"
        },
        {
          "name": "sls-watermark",
          "type": "checkbox",
          "label": "Include a small “STAGED FX” watermark in the export",
          "unit": "",
          "default": "1"
        }
      ],
      "outputs": [
        {
          "name": "sls-status",
          "type": "live"
        },
        {
          "name": "sls-x-out",
          "type": "output"
        },
        {
          "name": "sls-y-out",
          "type": "output"
        },
        {
          "name": "sls-size-out",
          "type": "output"
        },
        {
          "name": "sls-opacity-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sls-figure-composer&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sls-figure-composer&sls-x=72&sls-y=60&sls-size=100&sls-opacity=78&sls-watermark=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "sls",
        "figure",
        "composer",
        "sls-style",
        "horror",
        "paranormal",
        "place",
        "adjustable",
        "skeletal-tracking",
        "effect"
      ],
      "popularity": 4258,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "slug-generator",
      "title": "🔗 Slug Generator",
      "description": "Convert any text into URL-friendly slugs. Perfect for blog posts, filenames, and SEO-friendly URLs.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/slug-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=slug-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sg-lower",
          "type": "checkbox",
          "label": "Lowercase",
          "unit": "",
          "default": "1"
        },
        {
          "name": "sg-numbers",
          "type": "checkbox",
          "label": "Keep numbers",
          "unit": "",
          "default": "1"
        },
        {
          "name": "sg-max",
          "type": "number",
          "label": "Max length",
          "unit": "",
          "min": 10,
          "max": 200,
          "default": "80"
        },
        {
          "name": "sg-input",
          "type": "textarea",
          "label": "Enter your title or text...",
          "unit": ""
        },
        {
          "name": "sg-sep",
          "type": "select-one",
          "label": "Separator: Hyphen (-) Underscore (_) Dot",
          "unit": ".",
          "options": [
            "-",
            "_",
            "."
          ],
          "default": "-"
        }
      ],
      "outputs": [
        {
          "name": "sg-output",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=slug-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=slug-generator&sg-lower=1&sg-numbers=1&sg-max=80&sg-sep=-"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "slug",
        "algorithms",
        "computer",
        "science",
        "convert",
        "any",
        "text",
        "into",
        "url-friendly",
        "slugs"
      ],
      "popularity": 5615,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "small-claims-lba-generator",
      "title": "📄 Small Claims Letter Before Action Builder",
      "description": "Build a proper Letter Before Action for an unpaid debt — with statutory interest calculated to the day, a claim-fee estimate and a 14-day deadline. Then copy it into your email or post. Free, local...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/small-claims-lba-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=small-claims-lba-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "lba-yours",
          "type": "text",
          "label": "Your name",
          "unit": "",
          "default": "Alex Smith"
        },
        {
          "name": "lba-theirs",
          "type": "text",
          "label": "Their name/company",
          "unit": "",
          "default": "Bright Hire Ltd"
        },
        {
          "name": "lba-amount",
          "type": "number",
          "label": "Amount owed",
          "unit": "£",
          "min": 1,
          "step": 0.01,
          "default": "1850"
        },
        {
          "name": "lba-invoice",
          "type": "text",
          "label": "Invoice/ref no.",
          "unit": "",
          "default": "INV-2041"
        },
        {
          "name": "lba-date",
          "type": "date",
          "label": "Invoice date",
          "unit": "",
          "default": "2026-05-01"
        },
        {
          "name": "lba-due",
          "type": "date",
          "label": "Payment due date",
          "unit": "",
          "default": "2026-06-01"
        },
        {
          "name": "lba-rate",
          "type": "number",
          "label": "Interest %",
          "unit": "statutory 8",
          "min": 0,
          "step": 0.1,
          "default": "8"
        },
        {
          "name": "lba-what",
          "type": "text",
          "label": "What was it for?",
          "unit": "2–3 words",
          "default": "tool hire"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=small-claims-lba-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=small-claims-lba-generator&lba-yours=Alex%20Smith&lba-theirs=Bright%20Hire%20Ltd&lba-amount=1850&lba-invoice=INV-2041&lba-date=2026-05-01&lba-due=2026-06-01"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "small",
        "claims",
        "lba",
        "letter",
        "before",
        "action",
        "builder",
        "finance",
        "money",
        "build"
      ],
      "popularity": 6847,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "smart-contract-gas-estimator",
      "title": "⛽ Web3 Gas Fee Estimator",
      "description": "Compare real-time decentralized transaction fees, DEX swap overhead, and smart contract execution costs across Solana, Base, Ethereum L1, and Polygon.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/smart-contract-gas-estimator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=smart-contract-gas-estimator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "gas-eth-gwei",
          "type": "number",
          "label": "Ethereum L1 Base Gas",
          "unit": "Gwei",
          "min": 5,
          "max": 300,
          "default": "22"
        },
        {
          "name": "gas-tx-type",
          "type": "select-one",
          "label": "Transaction Action Type",
          "unit": "",
          "options": [
            "transfer",
            "dex_swap",
            "nft_mint",
            "bridge"
          ],
          "default": "transfer"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=smart-contract-gas-estimator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=smart-contract-gas-estimator&gas-eth-gwei=22&gas-tx-type=transfer"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "smart",
        "contract",
        "gas",
        "estimator",
        "web3",
        "fee",
        "finance",
        "money",
        "compare",
        "real-time"
      ],
      "popularity": 4659,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "smoking-cost-quit-savings-planner",
      "title": "🚭 Smoking Cost & Quit Savings Planner",
      "description": "A pack a day is a used car every year. Set what you actually smoke, pick a quit date, and watch the money timeline — plus the recovery milestones your body hits along the way.",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/smoking-cost-quit-savings-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=smoking-cost-quit-savings-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "smkq-cigs",
          "type": "number",
          "label": "Cigarettes per day",
          "unit": "",
          "min": 0,
          "step": 0.5,
          "default": "10"
        },
        {
          "name": "smkq-packsize",
          "type": "number",
          "label": "Pack size",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "20"
        },
        {
          "name": "smkq-price",
          "type": "number",
          "label": "Price per pack",
          "unit": "£",
          "min": 0,
          "step": 0.1,
          "default": "14.50"
        },
        {
          "name": "smkq-years",
          "type": "number",
          "label": "Years at this rate",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "5"
        },
        {
          "name": "smkq-quit",
          "type": "date",
          "label": "Quit date",
          "unit": ""
        },
        {
          "name": "smkq-goal",
          "type": "number",
          "label": "Saving goal (£) — optional",
          "unit": "",
          "min": 0,
          "step": 50
        }
      ],
      "outputs": [
        {
          "name": "smkq-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=smoking-cost-quit-savings-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=smoking-cost-quit-savings-planner&smkq-cigs=10&smkq-packsize=20&smkq-price=14.50&smkq-years=5"
      },
      "formula": "Method. Daily spend = (cigarettes ÷ pack size) ×",
      "sources": [],
      "tags": [
        "smoking",
        "cost",
        "quit",
        "savings",
        "planner",
        "health",
        "fitness",
        "pack",
        "day",
        "used"
      ],
      "popularity": 5345,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "snooker-scorer-and-snookers",
      "title": "🎱 Snooker Snookers-Required Calculator",
      "description": "The question every frame hinges on: can the player behind still win, and how many snookers do they need? Set the balls left on the table and the score, and this works out the points remaining, the ...",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/snooker-scorer-and-snookers.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=snooker-scorer-and-snookers&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "snk-reds",
          "type": "number",
          "label": "Reds remaining",
          "unit": "",
          "min": 0,
          "max": 15,
          "default": "3"
        },
        {
          "name": "snk-lead",
          "type": "number",
          "label": "Leader's score",
          "unit": "",
          "min": 0,
          "default": "62"
        },
        {
          "name": "snk-trail",
          "type": "number",
          "label": "Trailing player's score",
          "unit": "",
          "min": 0,
          "default": "30"
        },
        {
          "name": "snk-ball",
          "type": "select-one",
          "label": "Ball on",
          "unit": "",
          "options": [
            "red",
            "yellow",
            "green",
            "brown",
            "blue",
            "pink",
            "black"
          ],
          "default": "red"
        }
      ],
      "outputs": [
        {
          "name": "snk-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=snooker-scorer-and-snookers&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=snooker-scorer-and-snookers&snk-reds=3&snk-lead=62&snk-trail=30&snk-ball=red"
      },
      "formula": "Brown 4, Blue 5, Pink 6, Black 7. Points on the table = reds ×",
      "sources": [],
      "tags": [
        "snooker",
        "scorer",
        "snookers",
        "snookers-required",
        "sports",
        "question",
        "every",
        "frame",
        "hinges",
        "can"
      ],
      "popularity": 4567,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "snowflake-crystal-lab",
      "title": "❄️ Snowflake Crystal Lab",
      "description": "Grow an ice crystal from the real Nakaya diagram: temperature and supersaturation decide its habit — plates, needles, columns, sectored plates or fern-like dendrites. Vapour is consumed by the crys...",
      "category": "interactive-art-and-living-worlds",
      "categoryName": "Interactive Art & Living Worlds",
      "url": "https://www.themostusefulsiteintheworld.com/tool/snowflake-crystal-lab.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=snowflake-crystal-lab&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "snf-slider-temp",
          "type": "range",
          "label": "slider temp",
          "unit": "",
          "min": -25,
          "max": 0,
          "step": 0.5,
          "default": "-14"
        },
        {
          "name": "snf-slider-ss",
          "type": "range",
          "label": "slider ss",
          "unit": "",
          "min": 100,
          "max": 140,
          "step": 0.5,
          "default": "120"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=snowflake-crystal-lab&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=snowflake-crystal-lab&snf-slider-temp=-14&snf-slider-ss=120"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "snowflake",
        "crystal",
        "lab",
        "interactive",
        "art",
        "living",
        "worlds",
        "grow",
        "ice",
        "real"
      ],
      "popularity": 6109,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "social-media-image-resizer-cropper",
      "title": "🎨 Social Image Resizer",
      "description": "Crop and export pixel-perfect images for every social media network directly in your browser. 100% client-side HTML5 Canvas with zero server uploads, zero watermarks, and zero monthly design subscr...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/social-media-image-resizer-cropper.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=social-media-image-resizer-cropper&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sc-zoom",
          "type": "range",
          "label": "Zoom: 1.0x",
          "unit": "",
          "min": 0.5,
          "max": 3,
          "step": 0.05,
          "default": "1.0"
        },
        {
          "name": "sc-preset",
          "type": "select-one",
          "label": "Platform Target",
          "unit": "",
          "options": [
            "1280x720",
            "1080x1080",
            "1080x1350",
            "1080x1920",
            "1200x675",
            "1500x500",
            "1584x396",
            "1200x630"
          ],
          "default": "1280x720"
        },
        {
          "name": "sc-format",
          "type": "select-one",
          "label": "Format",
          "unit": "",
          "options": [
            "image/png",
            "image/jpeg",
            "image/webp"
          ],
          "default": "image/png"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=social-media-image-resizer-cropper&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=social-media-image-resizer-cropper&sc-zoom=1.0&sc-preset=1280x720&sc-format=image%2Fpng"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "social",
        "media",
        "image",
        "resizer",
        "cropper",
        "saas",
        "business",
        "killers",
        "crop",
        "export"
      ],
      "popularity": 4957,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "social-preview",
      "title": "🖼️ Social Preview Generator",
      "description": "Create perfectly sized Open Graph and Twitter preview images with custom branding, layouts, and auto-generated HTML meta tags.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/social-preview.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=social-preview&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sp-title-input",
          "type": "text",
          "label": "Headline",
          "unit": "",
          "default": "Introducing Our New Product"
        },
        {
          "name": "sp-primary-color",
          "type": "color",
          "label": "Primary Color",
          "unit": "",
          "default": "#ffd700"
        },
        {
          "name": "sp-primary-hex",
          "type": "text",
          "label": "Primary Color Hex",
          "unit": "",
          "default": "#ffd700"
        },
        {
          "name": "sp-secondary-color",
          "type": "color",
          "label": "Secondary Color",
          "unit": "",
          "default": "#6366f1"
        },
        {
          "name": "sp-secondary-hex",
          "type": "text",
          "label": "Secondary Color Hex",
          "unit": "",
          "default": "#6366F1"
        },
        {
          "name": "sp-subtitle-input",
          "type": "textarea",
          "label": "Description",
          "unit": ""
        },
        {
          "name": "sp-meta-code",
          "type": "textarea",
          "label": "Generated HTML Meta Tags",
          "unit": ""
        },
        {
          "name": "sp-layout",
          "type": "select-one",
          "label": "Layout",
          "unit": "",
          "options": [
            "gradient",
            "solid",
            "split",
            "pattern",
            "image"
          ],
          "default": "gradient"
        },
        {
          "name": "sp-font",
          "type": "select-one",
          "label": "Font Family",
          "unit": "",
          "options": [
            "inter",
            "roboto",
            "poppins",
            "montserrat",
            "opensans"
          ],
          "default": "inter"
        }
      ],
      "outputs": [
        {
          "name": "socialsp-results",
          "type": "output"
        },
        {
          "name": "sp-size-display",
          "type": "output"
        },
        {
          "name": "sp-platform-display",
          "type": "output"
        },
        {
          "name": "sp-ratio-display",
          "type": "output"
        },
        {
          "name": "batch-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=social-preview&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=social-preview&sp-title-input=Introducing%20Our%20New%20Product&sp-primary-color=%23ffd700&sp-primary-hex=%23ffd700&sp-secondary-color=%236366f1&sp-secondary-hex=%236366F1&sp-layout=gradient"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "social",
        "preview",
        "productivity",
        "lifestyle",
        "create",
        "perfectly",
        "sized",
        "open",
        "graph",
        "twitter"
      ],
      "popularity": 6240,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "social-proof-testimonial-card-generator",
      "title": "🌟 Testimonial Card Generator",
      "description": "Turn customer reviews, tweets, and testimonials into high-converting social proof cards. Generates pure zero-dependency HTML & CSS code with zero third-party tracking scripts that hurt Google PageS...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/social-proof-testimonial-card-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=social-proof-testimonial-card-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tf-name",
          "type": "text",
          "label": "Customer / Author Name",
          "unit": "",
          "default": "Sarah Jenkins"
        },
        {
          "name": "tf-role",
          "type": "text",
          "label": "Title & Company",
          "unit": "",
          "default": "Head of Growth @ HyperScale"
        },
        {
          "name": "tf-quote",
          "type": "textarea",
          "label": "Customer Testimonial Quote",
          "unit": ""
        },
        {
          "name": "tf-rating",
          "type": "select-one",
          "label": "Star Rating",
          "unit": "",
          "options": [
            "5",
            "4",
            "3"
          ],
          "default": "5"
        },
        {
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        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=speed-reading-trainer&srd-wpm=400"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "speed",
        "reading",
        "trainer",
        "writing",
        "language",
        "measure",
        "words-per-minute",
        "then",
        "train",
        "guided"
      ],
      "popularity": 4038,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "spelling-check",
      "title": "🔍 Smart Spelling Checker",
      "description": "Advanced spelling checker using multiple open-source dictionary APIs combined for maximum accuracy. ⚠️ Requires internet connection for online dictionary checks.",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/spelling-check.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=spelling-check&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sc-ignore-case",
          "type": "checkbox",
          "label": "Ignore case differences",
          "unit": "",
          "default": "1"
        },
        {
          "name": "sc-check-grammar",
          "type": "checkbox",
          "label": "Check grammar",
          "unit": "beta",
          "default": "0"
        },
        {
          "name": "sc-suggest-synonyms",
          "type": "checkbox",
          "label": "Suggest synonyms",
          "unit": "",
          "default": "0"
        },
        {
          "name": "sc-text",
          "type": "textarea",
          "label": "Text to Check",
          "unit": ""
        },
        {
          "name": "sc-language",
          "type": "select-one",
          "label": "Language",
          "unit": "",
          "options": [
            "en_US",
            "en_GB",
            "es",
            "fr",
            "de",
            "it",
            "pt"
          ],
          "default": "en_US"
        },
        {
          "name": "sc-check-level",
          "type": "select-one",
          "label": "Check Intensity",
          "unit": "",
          "options": [
            "standard",
            "comprehensive",
            "ultra"
          ],
          "default": "standard"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=spelling-check&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=spelling-check&sc-ignore-case=1&sc-check-grammar=0&sc-suggest-synonyms=0&sc-language=en_US&sc-check-level=standard"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "spelling",
        "check",
        "smart",
        "checker",
        "writing",
        "language",
        "advanced",
        "using",
        "multiple",
        "open-source"
      ],
      "popularity": 6483,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "spf-dmarc-record-checker",
      "title": "📬 SPF & DMARC Record Builder and Checker",
      "description": "Check the syntax of an SPF or DMARC DNS record you paste, count SPF DNS lookups, or build a new record. Works offline: nothing is looked up or sent.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/spf-dmarc-record-checker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=spf-dmarc-record-checker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "spf-dmarc-record-checker-mx",
          "type": "checkbox",
          "label": "Allow this domain's MX servers",
          "unit": "mx",
          "default": "0"
        },
        {
          "name": "spf-dmarc-record-checker-a",
          "type": "checkbox",
          "label": "Allow this domain's A/AAAA address",
          "unit": "a",
          "default": "0"
        },
        {
          "name": "spf-dmarc-record-checker-pct",
          "type": "number",
          "label": "Apply policy to this % of failing mail",
          "unit": "pct",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "100"
        },
        {
          "name": "spf-dmarc-record-checker-rua",
          "type": "text",
          "label": "Aggregate report address (rua), optional",
          "unit": ""
        },
        {
          "name": "spf-dmarc-record-checker-input",
          "type": "textarea",
          "label": "Paste the TXT record value (SPF from your domain, DMARC from _dmarc.yourdomain)",
          "unit": ""
        },
        {
          "name": "spf-dmarc-record-checker-includes",
          "type": "textarea",
          "label": "Senders to include — the domain your email provider tells you to include, one per line",
          "unit": ""
        },
        {
          "name": "spf-dmarc-record-checker-ips",
          "type": "textarea",
          "label": "IP addresses or ranges that send for you (IPv4 or IPv6, optional /prefix), one per line",
          "unit": ""
        },
        {
          "name": "spf-dmarc-record-checker-output",
          "type": "textarea",
          "label": "Record value",
          "unit": ""
        },
        {
          "name": "spf-dmarc-record-checker-all",
          "type": "select-one",
          "label": "Everything else",
          "unit": "",
          "options": [
            "~all",
            "-all",
            "?all"
          ],
          "default": "~all"
        },
        {
          "name": "spf-dmarc-record-checker-p",
          "type": "select-one",
          "label": "Policy for failing mail",
          "unit": "p",
          "options": [
            "none",
            "quarantine",
            "reject"
          ],
          "default": "none"
        },
        {
          "name": "spf-dmarc-record-checker-sp",
          "type": "select-one",
          "label": "Subdomain policy",
          "unit": "sp",
          "options": [
            "none",
            "quarantine",
            "reject"
          ],
          "default": "none"
        },
        {
          "name": "spf-dmarc-record-checker-adkim",
          "type": "select-one",
          "label": "DKIM alignment",
          "unit": "adkim",
          "options": [
            "s"
          ],
          "default": "s"
        },
        {
          "name": "spf-dmarc-record-checker-aspf",
          "type": "select-one",
          "label": "SPF alignment",
          "unit": "aspf",
          "options": [
            "s"
          ],
          "default": "s"
        }
      ],
      "outputs": [
        {
          "name": "spf-dmarc-record-checker-summary",
          "type": "live"
        },
        {
          "name": "spf-dmarc-record-checker-buildnote",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=spf-dmarc-record-checker&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=spf-dmarc-record-checker&spf-dmarc-record-checker-mx=0&spf-dmarc-record-checker-a=0&spf-dmarc-record-checker-pct=100&spf-dmarc-record-checker-all=~all&spf-dmarc-record-checker-p=none&spf-dmarc-record-checker-sp=none"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "spf",
        "dmarc",
        "record",
        "checker",
        "builder",
        "algorithms",
        "computer",
        "science",
        "check",
        "syntax"
      ],
      "popularity": 5145,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sphere-cylinder-cone-volume",
      "title": "⚪ Sphere, Cylinder & Cone Volume",
      "description": "V_sphere = 4/3 π r³, A = 4 π r². Cylinder π r² h. Cone (1/3) π r² h. Enter radius and height in the same units; volume comes out in those units cubed.",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sphere-cylinder-cone-volume.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sphere-cylinder-cone-volume&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "spcc-r",
          "type": "number",
          "label": "Radius",
          "unit": "",
          "min": 0,
          "default": "3"
        },
        {
          "name": "spcc-h",
          "type": "number",
          "label": "Height",
          "unit": "cyl / cone",
          "min": 0,
          "default": "8"
        }
      ],
      "outputs": [
        {
          "name": "spcc-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sphere-cylinder-cone-volume&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=sphere-cylinder-cone-volume&spcc-r=3&spcc-h=8"
      },
      "formula": "Sphere, Cylinder & Cone Volume V_sphere = 4/3 π r³, A = 4 π r². Cylinder π r² h. Cone (1/",
      "sources": [],
      "tags": [
        "sphere",
        "cylinder",
        "cone",
        "volume",
        "mathematics",
        "v_sphere",
        "enter",
        "radius",
        "height",
        "same"
      ],
      "popularity": 5555,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "spice-blend-scaler",
      "title": "🌶️ Spice Blend Scaler — Homemade Mix Recipes",
      "description": "Supermarket blends are mostly salt and filler, and they go stale in the jar. Twelve classic blends as simple ratios here — pick one, choose how much to make, and weigh it out.",
      "category": "culinary-and-food-science",
      "categoryName": "Culinary & Food Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/spice-blend-scaler.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=spice-blend-scaler&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "spb-blend",
          "type": "select-one",
          "label": "Blend",
          "unit": "",
          "options": [
            "garam",
            "taco",
            "cajun",
            "italian",
            "fivespice",
            "curry",
            "bbq",
            "zaatar",
            "provence",
            "jerk",
            "pumpkin",
            "rasel"
          ],
          "default": "garam"
        },
        {
          "name": "spb-amount",
          "type": "select-one",
          "label": "Make how much?",
          "unit": "",
          "options": [
            "2",
            "6",
            "12",
            "24"
          ],
          "default": "6"
        }
      ],
      "outputs": [
        {
          "name": "spb-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=spice-blend-scaler&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=spice-blend-scaler&spb-blend=garam&spb-amount=6"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "spice",
        "blend",
        "scaler",
        "homemade",
        "mix",
        "recipes",
        "culinary",
        "food",
        "science",
        "supermarket"
      ],
      "popularity": 6131,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "spin-the-wheel-random-picker",
      "title": "🎡 Spin the Wheel — Random Name & Decision Picker",
      "description": "Type names, dinner options or chores one per line, spin, and let the wheel decide. Remove each winner as you go to draw a whole order. Your list is remembered on this device and nothing is sent any...",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/spin-the-wheel-random-picker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=spin-the-wheel-random-picker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wheel-autoremove",
          "type": "checkbox",
          "label": "Remove winner after each spin",
          "unit": "",
          "default": "0"
        },
        {
          "name": "wheel-sound",
          "type": "checkbox",
          "label": "Tick sound",
          "unit": "",
          "default": "1"
        },
        {
          "name": "wheel-entries",
          "type": "textarea",
          "label": "Entries — one per line",
          "unit": "0"
        },
        {
          "name": "wheel-preset",
          "type": "select-one",
          "label": "Quick lists",
          "unit": "",
          "options": [
            "yesno",
            "coin",
            "dinner",
            "chores",
            "numbers",
            "activities",
            "icebreakers"
          ],
          "default": "yesno"
        },
        {
          "name": "wheel-duration",
          "type": "select-one",
          "label": "Spin length Quick Normal Dramatic",
          "unit": "",
          "options": [
            "2500",
            "5000",
            "8000"
          ],
          "default": "5000"
        }
      ],
      "outputs": [
        {
          "name": "wheel-result",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=spin-the-wheel-random-picker&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=spin-the-wheel-random-picker&wheel-autoremove=0&wheel-sound=1&wheel-preset=yesno&wheel-duration=5000"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "spin",
        "wheel",
        "random",
        "picker",
        "name",
        "decision",
        "productivity",
        "lifestyle",
        "type",
        "names"
      ],
      "popularity": 6831,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "spirit-box-wordstream",
      "title": "📻 Spirit Box Wordstream Studio",
      "description": "A controllable, fictional word stream for horror shoots: pick a tone, set the pace, and optionally add a very soft synthesized static bed. No microphone, sensors, radio scanning, or network access.",
      "category": "horror-and-paranormal",
      "categoryName": "Horror & Paranormal",
      "url": "https://www.themostusefulsiteintheworld.com/tool/spirit-box-wordstream.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=spirit-box-wordstream&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sbw-cadence",
          "type": "range",
          "label": "Word interval: 4 s",
          "unit": "",
          "min": 2,
          "max": 9,
          "step": 1,
          "default": "4"
        },
        {
          "name": "sbw-volume",
          "type": "range",
          "label": "Soft static level: 6%",
          "unit": "",
          "min": 0,
          "max": 15,
          "step": 1,
          "default": "6"
        },
        {
          "name": "sbw-static",
          "type": "checkbox",
          "label": "Add a quiet, generated static texture (off by default). Keep the room safe and the volume comfortable.",
          "unit": "",
          "default": "0"
        },
        {
          "name": "sbw-channel",
          "type": "select-one",
          "label": "Phrase deck",
          "unit": "",
          "options": [
            "house",
            "cold",
            "slow"
          ],
          "default": "house"
        }
      ],
      "outputs": [
        {
          "name": "sbw-word",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=spirit-box-wordstream&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=spirit-box-wordstream&sbw-cadence=4&sbw-volume=6&sbw-static=0&sbw-channel=house"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "spirit",
        "box",
        "wordstream",
        "studio",
        "horror",
        "paranormal",
        "controllable",
        "fictional",
        "word",
        "stream"
      ],
      "popularity": 6864,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "spontaneous-synchronization-kuramoto",
      "title": "🔥 Firefly Kuramoto Synchronization",
      "description": "Yoshiki Kuramoto's nonlinear synchronization model. Independent bioluminescent fireflies spontaneously phase-lock into simultaneous collective pulsing.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/spontaneous-synchronization-kuramoto.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=spontaneous-synchronization-kuramoto&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "kss-slider-k",
          "type": "range",
          "label": "slider k",
          "unit": "",
          "min": 0,
          "max": 6,
          "step": 0.1,
          "default": "3.2"
        },
        {
          "name": "kss-slider-jitter",
          "type": "range",
          "label": "slider jitter",
          "unit": "",
          "min": 5,
          "max": 50,
          "default": "15"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=spontaneous-synchronization-kuramoto&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=spontaneous-synchronization-kuramoto&kss-slider-k=3.2&kss-slider-jitter=15"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "spontaneous",
        "synchronization",
        "kuramoto",
        "firefly",
        "science",
        "engineering",
        "yoshiki",
        "nonlinear",
        "model",
        "independent"
      ],
      "popularity": 5819,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "spooky-story-skeleton-generator",
      "title": "📖 Spooky Story Skeleton Generator",
      "description": "Build a campfire story from a promise, a rule, a mistake and a twist — five beats that hold together, at a scare level you choose. Every word is generated here; nothing is fetched.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/spooky-story-skeleton-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=spooky-story-skeleton-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ssg-seed",
          "type": "number",
          "label": "Seed",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "31"
        },
        {
          "name": "ssg-audience",
          "type": "select-one",
          "label": "Audience",
          "unit": "",
          "options": [
            "kids",
            "teens",
            "adults"
          ],
          "default": "kids"
        },
        {
          "name": "ssg-setting",
          "type": "select-one",
          "label": "Setting",
          "unit": "",
          "options": [
            "suburb",
            "forest",
            "house",
            "school",
            "campsite",
            "fair"
          ],
          "default": "suburb"
        },
        {
          "name": "ssg-rule",
          "type": "select-one",
          "label": "The rule",
          "unit": "",
          "options": [
            "back",
            "name",
            "door",
            "path",
            "phone"
          ],
          "default": "back"
        }
      ],
      "outputs": [
        {
          "name": "ssg-copied",
          "type": "live"
        },
        {
          "name": "ssg-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=spooky-story-skeleton-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=spooky-story-skeleton-generator&ssg-seed=31&ssg-audience=kids&ssg-setting=suburb&ssg-rule=back"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "spooky",
        "story",
        "skeleton",
        "halloween",
        "build",
        "campfire",
        "promise",
        "rule",
        "mistake",
        "twist"
      ],
      "popularity": 4227,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "sprite-cutter",
      "title": "🎮 Sprite Sheet Studio",
      "description": "Advanced sprite sheet cutter for game developers. Slice, preview, animate, and export sprite sheets with professional tools. ✨ Supports PNG, JPG, GIF, and WebP formats",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/sprite-cutter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=sprite-cutter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sprite-width",
          "type": "number",
          "label": "Frame Width",
          "unit": "px",
          "min": 1,
          "default": "64"
        },
        {
          "name": "sprite-height",
          "type": "number",
          "label": "Frame Height",
          "unit": "px",
          "min": 1,
          "default": "64"
        },
        {
          "name": "sprite-padding",
          "type": "range",
          "label": "Spacing: 0 px",
          "unit": "",
          "min": 0,
          "max": 20,
          "default": "0"
        },
        {
          "name": "sprite-fps",
          "type": "number",
          "label": "FPS",
          "unit": "",
          "min": 1,
          "max": 60,
          "default": "12"
        },
        {
          "name": "sprite-trim",
          "type": "checkbox",
          "label": "Trim transparent edges",
          "unit": "",
          "default": "0"
        },
        {
          "name": "sprite-add-padding",
          "type": "checkbox",
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        "sprite",
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        "starfield",
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        {
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        {
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          "unit": "",
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          "label": "Perception 42 px",
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    },
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        {
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          "min": 500000,
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          "step": 500000,
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        },
        {
          "name": "ct-pre-money",
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          "name": "ct-esop-pool",
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            "0.10",
            "0.12",
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      },
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    },
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      "slug": "startup-runway-burn-rate-simulator",
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        {
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        {
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        {
          "name": "rwy-raisem",
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          "min": 1,
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      ],
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          "name": "rwy-status",
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      ],
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    {
      "slug": "statistics",
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        "stud",
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        "studyplanner",
        "study",
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        {
          "name": "cidr-input-mask",
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        "subnet",
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      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/subscription.html",
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        {
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        "subscription",
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          "name": "subtitle-drift-fixer-c2",
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        "algorithms",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=sudoku-trainer&<id>=<value>",
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      "tags": [
        "sudoku",
        "trainer",
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      "featured": false,
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    {
      "slug": "summary-generator",
      "title": "AI-Style Summary Generator",
      "description": "AI-Style Summary Generator Generate intelligent summaries using advanced text analysis algorithms",
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        {
          "name": "input-text",
          "type": "textarea",
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        {
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        {
          "name": "readability-score",
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        {
          "name": "sentiment-value",
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        },
        {
          "name": "complexity-value",
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        {
          "name": "formality-value",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
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    {
      "slug": "sunday-roast-dinner-timeline",
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        {
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        {
          "name": "srdt-meat",
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            "lamb",
            "pork",
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      "tags": [
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    {
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      "category": "astronomy-and-space",
      "categoryName": "Astronomy & Space",
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          "options": [
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
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    {
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        "sunrise",
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            "simp",
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        "synonym",
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        "writing",
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        "synonyms",
        "near-synonyms",
        "100"
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      "featured": false,
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    },
    {
      "slug": "tabata-interval-timer",
      "title": "🔥 Tabata Timer",
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      "standaloneUrl": null,
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        },
        {
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        {
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          "type": "number",
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      ],
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        "tabata",
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      "featured": false,
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    {
      "slug": "table-tennis-scorekeeper",
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      "description": "Rally scoring to 11, win by two — no cap, so a deuce game can run long. Tap to score and it tracks games and the best-of-five (or seven) match for you.",
      "category": "sports",
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        "table",
        "tennis",
        "scorekeeper",
        "scorer",
        "sports",
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      "popularity": 5903,
      "featured": false,
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    },
    {
      "slug": "tanker-shuttle-calculator",
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      "categoryName": "Fire & Rescue Service",
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      "standaloneUrl": null,
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        },
        {
          "name": "tnk-dist",
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          "label": "Distance, one way",
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        },
        {
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            "1.0",
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      },
      "formula": "Vacuum or pressurised tank (k = 1.0) Gravity /",
      "sources": [],
      "tags": [
        "tanker",
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      "featured": false,
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      "slug": "tap-drill-size-chart",
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        {
          "name": "tapd-size",
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      ],
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        {
          "name": "tapd-out",
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      "sources": [],
      "tags": [
        "tap",
        "drill",
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        "chart",
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      "featured": false,
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    },
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      "url": "https://www.themostusefulsiteintheworld.com/tool/taskprioritizer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=taskprioritizer&embed=1",
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        {
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        "taskprioritizer",
        "task",
        "prioritizer",
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      "popularity": 4802,
      "featured": false,
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    },
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      "slug": "tax",
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        },
        {
          "name": "tax-pension",
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        {
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            "1257L",
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            "D0",
            "D1"
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        },
        {
          "name": "tax-region",
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          "label": "Region (income tax bands differ)",
          "unit": "",
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            "ruk",
            "scotland"
          ],
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        {
          "name": "tax-loan",
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          "label": "Student Loan Plan (England/Wales)",
          "unit": "",
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            "none",
            "1",
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            "4",
            "5",
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      ],
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        {
          "name": "tax-main-result",
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        },
        {
          "name": "tax-pension-amount",
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        "tax",
        "estimator",
        "finance",
        "money",
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            "green",
            "sencha",
            "white",
            "oolong",
            "black",
            "puerh",
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            "rooibos",
            "matcha"
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          "default": "black"
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          "name": "teab-strength",
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            "delicate",
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        {
          "name": "teab-kettle",
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            "yes",
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      "featured": false,
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        },
        {
          "name": "tpd-plate",
          "type": "select-one",
          "label": "Plate it rides on",
          "unit": ""
        }
      ],
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=tectonic-plate-drift-calculator&<id>=<value>",
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      "featured": false,
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      "slug": "telescope-collimation-check",
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      "category": "astronomy-and-space",
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          "step": 0.1,
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        {
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          "step": 1,
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        {
          "name": "cfc-type",
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            "newton",
            "sct",
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            "dob"
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          "options": [
            "visual",
            "astro",
            "planetary"
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      ],
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      "sources": [],
      "tags": [
        "telescope",
        "collimation",
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        "astronomy",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "telescope-eyepiece-calculator",
      "title": "🔭 Eyepiece & Magnification Calculator",
      "description": "Work out what an eyepiece actually gives you on a given telescope: magnification, exit pupil, true field of view and the practical limits. Covers Barlows and finds your maximum useful power.",
      "category": "astronomy-and-space",
      "categoryName": "Astronomy & Space",
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          "step": 1,
          "default": "1200"
        },
        {
          "name": "epc-aperture",
          "type": "number",
          "label": "Aperture",
          "unit": "mm",
          "min": 1,
          "step": 1,
          "default": "203"
        },
        {
          "name": "epc-ep",
          "type": "number",
          "label": "Eyepiece focal length",
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          "min": 0.5,
          "step": 0.5,
          "default": "13"
        },
        {
          "name": "epc-afov",
          "type": "number",
          "label": "Apparent field",
          "unit": "°",
          "min": 10,
          "max": 120,
          "step": 1,
          "default": "82"
        },
        {
          "name": "epc-barlow",
          "type": "number",
          "label": "Barlow factor",
          "unit": "",
          "min": 1,
          "max": 5,
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        {
          "name": "epc-pupil",
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          "label": "Your dark-adapted pupil",
          "unit": "mm",
          "min": 3,
          "max": 9,
          "step": 0.5,
          "default": "7"
        }
      ],
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          "name": "epc-out",
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=telescope-eyepiece-calculator&<id>=<value>",
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      },
      "formula": "Formulas and rules of thumb Magnification = telescope focal length ÷ (eyepiece focal length ×",
      "sources": [],
      "tags": [
        "telescope",
        "eyepiece",
        "magnification",
        "astronomy",
        "space",
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      "popularity": 6953,
      "featured": false,
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    },
    {
      "slug": "telescope-limiting-resolver",
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      "category": "astronomy-and-space",
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      "standaloneUrl": null,
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        {
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        {
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=telescope-limiting-resolver&<id>=<value>",
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      },
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    {
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=tempo-map&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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        {
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          "type": "number",
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        {
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        {
          "name": "temp-output",
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        {
          "name": "tempo-change",
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            "steady",
            "accelerando",
            "ritardando",
            "rubato",
            "subito"
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          "default": "steady"
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        {
          "name": "tempo-timesig",
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            "4/4",
            "3/4",
            "6/8",
            "2/4",
            "12/8"
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        {
          "name": "tempo-dynamic",
          "type": "select-one",
          "label": "Dynamic Marking",
          "unit": "",
          "options": [
            "mf",
            "p",
            "mp",
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            "ff",
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        {
          "name": "tempo-articulation",
          "type": "select-one",
          "label": "Articulation",
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          "options": [
            "legato",
            "staccato",
            "marcato",
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          "name": "temp-main-output",
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      },
      "formula": "Beat Duration = 60 ÷ BPM (seconds) • Section Duration = (Measures ×",
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        "tempo",
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          "name": "td-agree",
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          "label": "Tenancy end date",
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      "sources": [],
      "tags": [
        "tenancy",
        "deposit",
        "england",
        "finance",
        "money",
        "check",
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    {
      "slug": "tennis-live-scorer",
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            "3",
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        {
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=tennis-live-scorer&<id>=<value>",
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      "sources": [],
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        "tennis",
        "live",
        "scorer",
        "match",
        "sports",
        "score",
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      "popularity": 5561,
      "featured": false,
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    },
    {
      "slug": "terms-of-service-generator",
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      "category": "saas-and-business-killers",
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        {
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        {
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          "min": 0,
          "max": 21,
          "default": "16"
        },
        {
          "name": "tosg-s-accounts",
          "type": "checkbox",
          "label": "Accounts & registration",
          "unit": "",
          "default": "1"
        },
        {
          "name": "tosg-s-pay",
          "type": "checkbox",
          "label": "Payments, renewal & price changes",
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          "default": "1"
        },
        {
          "name": "tosg-s-refund",
          "type": "checkbox",
          "label": "Refunds & cancellation",
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          "default": "1"
        },
        {
          "name": "tosg-s-content",
          "type": "checkbox",
          "label": "User content & licence",
          "unit": "",
          "default": "1"
        },
        {
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          "type": "checkbox",
          "label": "Acceptable use",
          "unit": "",
          "default": "1"
        },
        {
          "name": "tosg-s-ip",
          "type": "checkbox",
          "label": "Intellectual property",
          "unit": "",
          "default": "1"
        },
        {
          "name": "tosg-s-disclaimer",
          "type": "checkbox",
          "label": "No warranty / \"as is\"",
          "unit": "",
          "default": "1"
        },
        {
          "name": "tosg-s-liability",
          "type": "checkbox",
          "label": "Limitation of liability",
          "unit": "",
          "default": "1"
        },
        {
          "name": "tosg-s-indemnity",
          "type": "checkbox",
          "label": "Indemnity",
          "unit": "",
          "default": "1"
        },
        {
          "name": "tosg-s-termination",
          "type": "checkbox",
          "label": "Suspension & termination",
          "unit": "",
          "default": "1"
        },
        {
          "name": "tosg-s-changes",
          "type": "checkbox",
          "label": "Changes to these terms",
          "unit": "",
          "default": "1"
        },
        {
          "name": "tosg-s-dmca",
          "type": "checkbox",
          "label": "Copyright complaints",
          "unit": "DMCA agent",
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        },
        {
          "name": "tosg-s-arb",
          "type": "checkbox",
          "label": "Arbitration & class-action waiver",
          "unit": "",
          "default": "0"
        },
        {
          "name": "tosg-s-force",
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          "label": "Force majeure",
          "unit": "",
          "default": "1"
        },
        {
          "name": "tosg-s-general",
          "type": "checkbox",
          "label": "General provisions",
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          "default": "1"
        },
        {
          "name": "tosg-entity",
          "type": "select-one",
          "label": "Legal entity",
          "unit": "",
          "options": [
            "company",
            "sole",
            "partnership",
            "nonprofit"
          ],
          "default": "company"
        },
        {
          "name": "tosg-law",
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          "label": "Governing law",
          "unit": "",
          "options": [
            "ew",
            "scot",
            "ca",
            "us",
            "eu",
            "ca-n",
            "au",
            "other"
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        {
          "name": "tosg-model",
          "type": "select-one",
          "label": "What you sell",
          "unit": "",
          "options": [
            "saas",
            "shop",
            "content",
            "services",
            "marketplace"
          ],
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        {
          "name": "tosg-meta",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=terms-of-service-generator&<id>=<value>",
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
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        "terms",
        "service",
        "saas",
        "business",
        "killers",
        "write",
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        "set",
        "small",
        "site"
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      "featured": false,
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    },
    {
      "slug": "text-case-converter",
      "title": "🔡 Text Case Converter",
      "description": "Paste anything and get it back in every case at once: UPPER, lower, Title Case, Sentence case, camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE, dot.case, aLtErNaTiNg, reversed and URL ...",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
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      "standaloneUrl": null,
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        {
          "name": "tcase-lines",
          "type": "checkbox",
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        },
        {
          "name": "tcase-in",
          "type": "textarea",
          "label": "Your text",
          "unit": ""
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        {
          "name": "tcase-click",
          "type": "select-one",
          "label": "Click result",
          "unit": "",
          "options": [
            "copy",
            "input"
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        {
          "name": "tcase-out",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=text-case-converter&<id>=<value>",
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      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "text",
        "case",
        "converter",
        "algorithms",
        "computer",
        "science",
        "paste",
        "anything",
        "get",
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      "popularity": 4107,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "text-diff-checker",
      "title": "🔎 Text Diff Checker",
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      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/text-diff-checker.html",
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      "standaloneUrl": null,
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        {
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          "label": "Ignore repeated whitespace",
          "unit": "",
          "default": "0"
        },
        {
          "name": "tdc-case",
          "type": "checkbox",
          "label": "Ignore case",
          "unit": "",
          "default": "0"
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        {
          "name": "tdc-left",
          "type": "textarea",
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        },
        {
          "name": "tdc-right",
          "type": "textarea",
          "label": "Changed text",
          "unit": ""
        },
        {
          "name": "tdc-mode",
          "type": "select-one",
          "label": "Compare by Lines Words",
          "unit": "",
          "options": [
            "lines",
            "words"
          ],
          "default": "lines"
        }
      ],
      "outputs": [
        {
          "name": "tdc-summary",
          "type": "live"
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        {
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=text-diff-checker&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=text-diff-checker&tdc-space=0&tdc-case=0&tdc-mode=lines"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "text",
        "diff",
        "checker",
        "saas",
        "business",
        "killers",
        "compare",
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        "see"
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      "popularity": 5387,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "text-to-handwriting",
      "title": "✍️ Text to Handwriting",
      "description": "Convert typed text into realistic handwriting. Choose styles, sizes, and colors. Download as image.",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/text-to-handwriting.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=text-to-handwriting&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "unit": "",
          "min": 12,
          "max": 32,
          "default": "18"
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          "unit": ""
        },
        {
          "name": "th-font",
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          "label": "font",
          "unit": "",
          "options": [
            "'Segoe Script','Comic Sans MS',cursive",
            "'Courier New',monospace",
            "'Georgia',serif",
            "'Brush Script MT',cursive"
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          "default": "'Segoe Script','Comic Sans MS',cursive"
        },
        {
          "name": "th-color",
          "type": "select-one",
          "label": "color",
          "unit": "",
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            "heat-transfer",
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        "thermodynamics",
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          "name": "twcp-preset",
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      "slug": "tile-flooring-estimator",
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          "name": "tileflr-price",
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            "tile-ceramic",
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        {
          "name": "tileflr-waste",
          "type": "select-one",
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          "unit": "",
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            "5",
            "10",
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            "20"
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          "name": "tileflr-result",
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        {
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      "slug": "time-duration-calculator",
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        "time",
        "duration",
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      "slug": "time-tracker-timesheet-studio",
      "title": "⏱️ Time Tracker & Timesheet Studio",
      "description": "Run a stopwatch on real work, round it the way your contracts do, and turn the week into a CSV or a printable invoice-ready timesheet. Toggl, Harvest and Hubstaff charge per seat per month and hold...",
      "category": "saas-and-business-killers",
      "categoryName": "SaaS & Business Killers",
      "url": "https://www.themostusefulsiteintheworld.com/tool/time-tracker-timesheet-studio.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=time-tracker-timesheet-studio&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ttss-project",
          "type": "text",
          "label": "Project",
          "unit": ""
        },
        {
          "name": "ttss-task",
          "type": "text",
          "label": "What you are doing",
          "unit": ""
        },
        {
          "name": "ttss-rate",
          "type": "number",
          "label": "Hourly rate",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "45"
        },
        {
          "name": "ttss-billable",
          "type": "checkbox",
          "label": "This work is billable",
          "unit": "",
          "default": "1"
        },
        {
          "name": "ttss-m-date",
          "type": "date",
          "label": "Date",
          "unit": ""
        },
        {
          "name": "ttss-m-start",
          "type": "time",
          "label": "Start",
          "unit": "",
          "step": 60,
          "default": "09:00"
        },
        {
          "name": "ttss-m-end",
          "type": "time",
          "label": "End",
          "unit": "",
          "step": 60,
          "default": "10:00"
        },
        {
          "name": "ttss-find",
          "type": "text",
          "label": "Filter by project…",
          "unit": ""
        },
        {
          "name": "ttss-cur",
          "type": "select-one",
          "label": "Currency",
          "unit": "",
          "options": [
            "£",
            "$",
            "€",
            "CA$",
            "A$"
          ],
          "default": "£"
        },
        {
          "name": "ttss-round",
          "type": "select-one",
          "label": "Round each entry to",
          "unit": "",
          "options": [
            "0",
            "6",
            "15",
            "30"
          ],
          "default": "0"
        },
        {
          "name": "ttss-filter",
          "type": "select-one",
          "label": "Show",
          "unit": "",
          "options": [
            "all",
            "week",
            "lastweek",
            "month"
          ],
          "default": "all"
        }
      ],
      "outputs": [
        {
          "name": "ttss-clock",
          "type": "live"
        },
        {
          "name": "ttss-status",
          "type": "live"
        },
        {
          "name": "ttss-s-total",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=time-tracker-timesheet-studio&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=time-tracker-timesheet-studio&ttss-rate=45&ttss-billable=1&ttss-m-start=09%3A00&ttss-m-end=10%3A00&ttss-cur=%C2%A3&ttss-round=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "time",
        "tracker",
        "timesheet",
        "studio",
        "saas",
        "business",
        "killers",
        "run",
        "stopwatch",
        "real"
      ],
      "popularity": 4402,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "timelapse-interval-calculator",
      "title": "⏱️ Timelapse Interval",
      "description": "Shots needed = clip length × frame rate. Real time covered = shots × interval. Leave the battery and a bigger card than you think. Sunset clouds often want 2–5 s; construction days want 30–60 s.",
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      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/timelapse-interval-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=timelapse-interval-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tlps-clip",
          "type": "number",
          "label": "Finished clip",
          "unit": "s",
          "min": 1,
          "default": "10"
        },
        {
          "name": "tlps-int",
          "type": "number",
          "label": "Interval",
          "unit": "s",
          "min": 0.1,
          "default": "4"
        },
        {
          "name": "tlps-mb",
          "type": "number",
          "label": "MB per still",
          "unit": "",
          "min": 0,
          "default": "8"
        },
        {
          "name": "tlps-fps",
          "type": "select-one",
          "label": "Playback fps",
          "unit": "",
          "options": [
            "24",
            "25",
            "30"
          ],
          "default": "25"
        }
      ],
      "outputs": [
        {
          "name": "tlps-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=timelapse-interval-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=timelapse-interval-calculator&tlps-clip=10&tlps-int=4&tlps-mb=8&tlps-fps=25"
      },
      "formula": "Timelapse Interval Shots needed = clip length × frame rate. Real time covered = shots ×",
      "sources": [],
      "tags": [
        "timelapse",
        "interval",
        "productivity",
        "lifestyle",
        "shots",
        "needed",
        "clip",
        "length",
        "frame",
        "rate"
      ],
      "popularity": 6653,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "timer",
      "title": "⏱️ Advanced Timer & Stopwatch",
      "description": "Advanced timer with countdown, stopwatch, intervals, lap times, and multiple alarms. Perfect for workouts, cooking, study sessions, and productivity.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/timer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=timer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "timer-hours",
          "type": "number",
          "label": "Hours",
          "unit": "",
          "min": 0,
          "max": 99,
          "step": 1,
          "default": "0"
        },
        {
          "name": "timer-minutes",
          "type": "number",
          "label": "Minutes",
          "unit": "",
          "min": 0,
          "max": 59,
          "step": 1,
          "default": "1"
        },
        {
          "name": "timer-seconds",
          "type": "number",
          "label": "Seconds",
          "unit": "",
          "min": 0,
          "max": 59,
          "step": 1,
          "default": "0"
        },
        {
          "name": "interval-work",
          "type": "number",
          "label": "Work Time",
          "unit": "seconds",
          "min": 1,
          "max": 3600,
          "step": 1,
          "default": "30"
        },
        {
          "name": "interval-rest",
          "type": "number",
          "label": "Rest Time",
          "unit": "seconds",
          "min": 0,
          "max": 3600,
          "step": 1,
          "default": "10"
        },
        {
          "name": "interval-rounds",
          "type": "number",
          "label": "Rounds",
          "unit": "",
          "min": 1,
          "max": 100,
          "step": 1,
          "default": "8"
        },
        {
          "name": "timer-presets",
          "type": "select-one",
          "label": "presets",
          "unit": "",
          "options": [
            "custom",
            "30",
            "60",
            "300",
            "600",
            "900",
            "1800",
            "3600"
          ],
          "default": "custom"
        },
        {
          "name": "timer-alarm-sound",
          "type": "select-one",
          "label": "Alarm Sound",
          "unit": "",
          "options": [
            "beep",
            "bell",
            "chime",
            "digital",
            "none"
          ],
          "default": "none"
        },
        {
          "name": "timer-alarm-repeat",
          "type": "select-one",
          "label": "Auto-repeat",
          "unit": "",
          "options": [
            "0",
            "1",
            "2",
            "5"
          ],
          "default": "0"
        }
      ],
      "outputs": [
        {
          "name": "timer-main-display",
          "type": "output"
        },
        {
          "name": "timer-mode-display",
          "type": "output"
        },
        {
          "name": "timer-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=timer&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=timer&timer-hours=0&timer-minutes=1&timer-seconds=0&interval-work=30&interval-rest=10&interval-rounds=8"
      },
      "formula": "Keyboard Shortcuts: Space = Start/Pause, R = Reset, L = Lap • Accuracy: Uses high-",
      "sources": [],
      "tags": [
        "timer",
        "advanced",
        "stopwatch",
        "productivity",
        "lifestyle",
        "countdown",
        "intervals",
        "lap",
        "times",
        "multiple"
      ],
      "popularity": 4485,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "times-tables-drill-trainer",
      "title": "🔢 Times Tables Drill Trainer",
      "description": "Drill the 1–12 times tables with instant feedback, streak tracking and a review of the facts you get wrong. Includes a full 12×12 grid and memory tricks. Everything runs in your browser — no sign-u...",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/times-tables-drill-trainer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=times-tables-drill-trainer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ttd-ans",
          "type": "number",
          "label": "ans",
          "unit": "",
          "min": 0,
          "max": 999
        },
        {
          "name": "ttd-range",
          "type": "select-one",
          "label": "Tables to drill",
          "unit": "",
          "options": [
            "5",
            "10",
            "12"
          ],
          "default": "5"
        },
        {
          "name": "ttd-len",
          "type": "select-one",
          "label": "Questions per round",
          "unit": "",
          "options": [
            "5",
            "10",
            "20"
          ],
          "default": "10"
        }
      ],
      "outputs": [
        {
          "name": "ttd-total",
          "type": "output"
        },
        {
          "name": "ttd-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=times-tables-drill-trainer&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=times-tables-drill-trainer&ttd-range=5&ttd-len=10"
      },
      "formula": "Square numbers (1, 4, 9, 16…) anchor the grid: 6 × 6 = 36, then 6 ×",
      "sources": [],
      "tags": [
        "times",
        "tables",
        "drill",
        "trainer",
        "mathematics",
        "instant",
        "feedback",
        "streak",
        "tracking",
        "review"
      ],
      "popularity": 4062,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "timezone",
      "title": "🌍 Time Zone Converter",
      "description": "Convert any date and time between time zones. Supports all major world time zones.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/timezone.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=timezone&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tz-datetime",
          "type": "datetime-local",
          "label": "Date & Time",
          "unit": ""
        },
        {
          "name": "tz-from",
          "type": "select-one",
          "label": "From Zone",
          "unit": "",
          "options": [
            "UTC",
            "America/New_York",
            "America/Los_Angeles",
            "Europe/London",
            "Europe/Paris",
            "Asia/Tokyo",
            "Australia/Sydney",
            "Asia/Dubai",
            "Asia/Shanghai",
            "Asia/Kolkata"
          ],
          "default": "America/New_York"
        },
        {
          "name": "tz-to",
          "type": "select-one",
          "label": "To Zone",
          "unit": "",
          "options": [
            "UTC",
            "America/New_York",
            "America/Los_Angeles",
            "Europe/London",
            "Europe/Paris",
            "Asia/Tokyo",
            "Australia/Sydney",
            "Asia/Dubai",
            "Asia/Shanghai",
            "Asia/Kolkata"
          ],
          "default": "Europe/London"
        }
      ],
      "outputs": [
        {
          "name": "tz-output",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=timezone&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=timezone&tz-from=America%2FNew_York&tz-to=Europe%2FLondon&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "timezone",
        "time",
        "zone",
        "converter",
        "productivity",
        "lifestyle",
        "convert",
        "any",
        "date",
        "between"
      ],
      "popularity": 6591,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "tinnitus-hearing-relief-studio",
      "title": "🔉 Tinnitus & Hearing Relief Studio",
      "description": "Nothing here cures tinnitus — no app does. What helps is not silence: a quiet, boring sound at or just below the pitch of the noise stops your brain listening for it. This makes those sounds on the...",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/tinnitus-hearing-relief-studio.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=tinnitus-hearing-relief-studio&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "thrs-vol",
          "type": "range",
          "label": "Volume — 15%",
          "unit": "",
          "min": 1,
          "max": 100,
          "step": 1,
          "default": "15"
        },
        {
          "name": "thrs-tone",
          "type": "range",
          "label": "Tone: bright",
          "unit": "",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "55"
        },
        {
          "name": "thrs-freq",
          "type": "range",
          "label": "Your pitch: 4000 Hz",
          "unit": "",
          "min": 500,
          "max": 12000,
          "step": 10,
          "default": "4000"
        },
        {
          "name": "thrs-depth",
          "type": "range",
          "label": "Notch depth: 0 dB",
          "unit": "",
          "min": 0,
          "max": 30,
          "step": 1,
          "default": "0"
        }
      ],
      "outputs": [
        {
          "name": "thrs-state",
          "type": "live"
        },
        {
          "name": "thrs-clock",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=tinnitus-hearing-relief-studio&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=tinnitus-hearing-relief-studio&thrs-vol=15&thrs-tone=55&thrs-freq=4000&thrs-depth=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "tinnitus",
        "hearing",
        "relief",
        "studio",
        "health",
        "fitness",
        "nothing",
        "here",
        "cures",
        "app"
      ],
      "popularity": 4578,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "tip-calculator",
      "title": "💸 Tip & Split Calculator",
      "description": "Calculate tips, split bills, and see exactly how much everyone owes. Supports multiple currencies!",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/tip-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=tip-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tc-bill",
          "type": "number",
          "label": "Bill Amount",
          "unit": "",
          "min": 0,
          "step": 0.01,
          "default": "50.00"
        },
        {
          "name": "tc-tip-percent",
          "type": "number",
          "label": "Tip Percentage",
          "unit": "",
          "min": 0,
          "max": 100,
          "step": 0.5,
          "default": "15"
        },
        {
          "name": "tc-people",
          "type": "number",
          "label": "Number of People",
          "unit": "",
          "min": 1,
          "max": 50,
          "step": 1,
          "default": "2"
        },
        {
          "name": "tc-round-up",
          "type": "checkbox",
          "label": "Round up to nearest whole currency unit",
          "unit": "",
          "default": "0"
        },
        {
          "name": "tc-currency",
          "type": "select-one",
          "label": "currency",
          "unit": "",
          "options": [
            "GBP",
            "USD",
            "EUR",
            "CAD",
            "AUD",
            "JPY",
            "INR"
          ],
          "default": "GBP"
        }
      ],
      "outputs": [
        {
          "name": "tc-result-total",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=tip-calculator&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=tip-calculator&tc-bill=50.00&tc-tip-percent=15&tc-people=2&tc-round-up=0&tc-currency=GBP&run=1"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "tip",
        "split",
        "finance",
        "money",
        "calculate",
        "tips",
        "bills",
        "see",
        "exactly",
        "how"
      ],
      "popularity": 4556,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "tip-split-bill-per-person",
      "title": "🍽️ Restaurant Bill Splitter with Itemised Shares",
      "description": "Split a restaurant bill fairly: add each dish and tick who shared it, set a service charge or tip, and get an exact per-person total including their proportional share of tax and tip. Handles \"I on...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/tip-split-bill-per-person.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=tip-split-bill-per-person&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tsbp-newp",
          "type": "text",
          "label": "Add a person (e.g. Sam)",
          "unit": ""
        },
        {
          "name": "tsbp-newi",
          "type": "text",
          "label": "Item (e.g. Margherita)",
          "unit": ""
        },
        {
          "name": "tsbp-newc",
          "type": "number",
          "label": "Price",
          "unit": "",
          "min": 0,
          "step": 0.01
        },
        {
          "name": "tsbp-tip",
          "type": "number",
          "label": "Tip / service %",
          "unit": "",
          "min": 0,
          "step": 0.5,
          "default": "12.5"
        },
        {
          "name": "tsbp-tax",
          "type": "number",
          "label": "Extra tax % (if not in prices)",
          "unit": "",
          "min": 0,
          "step": 0.5,
          "default": "0"
        },
        {
          "name": "tsbp-disc",
          "type": "number",
          "label": "Discount / voucher",
          "unit": "",
          "min": 0,
          "step": 0.01,
          "default": "0"
        },
        {
          "name": "tsbp-cur",
          "type": "text",
          "label": "Currency",
          "unit": "",
          "default": "£"
        },
        {
          "name": "tsbp-round",
          "type": "checkbox",
          "label": "Round each person up to the nearest whole unit (extra goes to tip)",
          "unit": "",
          "default": "0"
        }
      ],
      "outputs": [
        {
          "name": "tsbp-result",
          "type": "output"
        },
        {
          "name": "tsbp-total",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=tip-split-bill-per-person&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=tip-split-bill-per-person&tsbp-tip=12.5&tsbp-tax=0&tsbp-disc=0&tsbp-cur=%C2%A3&tsbp-round=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "tip",
        "split",
        "bill",
        "per",
        "person",
        "restaurant",
        "splitter",
        "itemised",
        "shares",
        "finance"
      ],
      "popularity": 5586,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "tire-size-comparison-calculator",
      "title": "🛞 Tyre Size Comparison",
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        "tone"
      ],
      "popularity": 6502,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "transposer",
      "title": "🎵 Music Transposer",
      "description": "Transpose chords, melodies, and entire progressions between keys. ⚠️ EDUCATIONAL TOOL — Verify with music teacher or professional resources.",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/transposer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=transposer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tp-input",
          "type": "text",
          "label": "Chords / Notes (separated by commas)",
          "unit": ""
        },
        {
          "name": "tp-semitones",
          "type": "number",
          "label": "semitones",
          "unit": "",
          "min": -12,
          "max": 12,
          "default": "2"
        },
        {
          "name": "transptp-output",
          "type": "textarea",
          "label": "transptp output",
          "unit": ""
        },
        {
          "name": "tp-original-key",
          "type": "select-one",
          "label": "Original Key",
          "unit": "",
          "options": [
            "C",
            "G",
            "D",
            "A",
            "E",
            "B",
            "F#",
            "Db",
            "Ab",
            "Eb",
            "Bb",
            "F"
          ],
          "default": "C"
        },
        {
          "name": "tp-target-key",
          "type": "select-one",
          "label": "Target Key",
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            "G",
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            "F#",
            "Db",
            "Ab",
            "Eb",
            "Bb",
            "F"
          ],
          "default": "D"
        }
      ],
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        {
          "name": "tp-visual-results",
          "type": "output"
        },
        {
          "name": "tp-original-display",
          "type": "output"
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        {
          "name": "tp-transposed-display",
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        }
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      },
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      "sources": [],
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        "transposer",
        "music",
        "audio",
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        "chords",
        "melodies",
        "entire",
        "progressions",
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      "popularity": 4639,
      "featured": false,
      "updated": "2026-09-19"
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    {
      "slug": "trap-drill-hihat-roll-pattern-generator",
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      "description": "Craft the iconic bouncing hi-hat patterns of modern Trap, Atlanta bounce, and UK/NY Drill. Program 1/32nd rolls, 1/24th triplet flurries, ascending velocity ramps, and pitch drops with live interac...",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=trap-drill-hihat-roll-pattern-generator&embed=1",
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          "label": "Tempo",
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          "min": 100,
          "max": 175,
          "default": "140"
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        {
          "name": "hrp-style-preset",
          "type": "select-one",
          "label": "Pattern Preset",
          "unit": "",
          "options": [
            "metro",
            "drill",
            "southside",
            "pierre"
          ],
          "default": "metro"
        },
        {
          "name": "hrp-tone-select",
          "type": "select-one",
          "label": "Hat Sample Tone",
          "unit": "",
          "options": [
            "metallic",
            "crisp",
            "dark"
          ],
          "default": "metallic"
        }
      ],
      "outputs": [],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "trap",
        "drill",
        "hihat",
        "roll",
        "pattern",
        "hi-hat",
        "music",
        "audio",
        "craft",
        "iconic"
      ],
      "popularity": 5899,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "travel",
      "title": "✈️ Travel Trip Planner",
      "description": "Plan your perfect trip with detailed itineraries, budget tracking, and smart recommendations. Get personalized suggestions based on your preferences!",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=travel&embed=1",
      "standaloneUrl": null,
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        {
          "name": "tp-destination",
          "type": "text",
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          "unit": ""
        },
        {
          "name": "tp-start-date",
          "type": "date",
          "label": "Start Date",
          "unit": ""
        },
        {
          "name": "tp-end-date",
          "type": "date",
          "label": "End Date",
          "unit": ""
        },
        {
          "name": "tp-adults",
          "type": "number",
          "label": "Adults",
          "unit": "",
          "min": 1,
          "max": 10,
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        },
        {
          "name": "tp-children",
          "type": "number",
          "label": "Children",
          "unit": "",
          "min": 0,
          "max": 10,
          "default": "0"
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        {
          "name": "tp-budget",
          "type": "number",
          "label": "Total Budget",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "1500"
        },
        {
          "name": "tp-trip-style",
          "type": "select-one",
          "label": "Trip Style",
          "unit": "",
          "options": [
            "budget",
            "midrange",
            "luxury",
            "backpacker",
            "family",
            "romantic"
          ],
          "default": "midrange"
        },
        {
          "name": "tp-accommodation",
          "type": "select-one",
          "label": "Accommodation",
          "unit": "",
          "options": [
            "hotel",
            "hostel",
            "airbnb",
            "resort",
            "camping"
          ],
          "default": "hotel"
        },
        {
          "name": "tp-currency",
          "type": "select-one",
          "label": "currency",
          "unit": "",
          "options": [
            "GBP",
            "USD",
            "EUR",
            "JPY"
          ],
          "default": "GBP"
        }
      ],
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        {
          "name": "tp-output",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=travel&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "travel",
        "trip",
        "planner",
        "productivity",
        "lifestyle",
        "plan",
        "perfect",
        "detailed",
        "itineraries",
        "budget"
      ],
      "popularity": 4022,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "triangle-solver",
      "title": "📐 Full Triangle Solver — Sine & Cosine Rules",
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      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/triangle-solver.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=triangle-solver&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tsol-a",
          "type": "number",
          "label": "Side a",
          "unit": "",
          "min": 0
        },
        {
          "name": "tsol-b",
          "type": "number",
          "label": "Side b",
          "unit": "",
          "min": 0
        },
        {
          "name": "tsol-c",
          "type": "number",
          "label": "Side c",
          "unit": "",
          "min": 0
        },
        {
          "name": "tsol-A",
          "type": "number",
          "label": "Angle A",
          "unit": "°",
          "min": 0,
          "max": 180
        },
        {
          "name": "tsol-B",
          "type": "number",
          "label": "Angle B",
          "unit": "°",
          "min": 0,
          "max": 180
        },
        {
          "name": "tsol-C",
          "type": "number",
          "label": "Angle C",
          "unit": "°",
          "min": 0,
          "max": 180
        },
        {
          "name": "tsol-mode",
          "type": "select-one",
          "label": "Known parts",
          "unit": "",
          "options": [
            "sss",
            "sas",
            "asa",
            "aas",
            "ssa"
          ],
          "default": "sas"
        }
      ],
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        {
          "name": "tsol-result",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=triangle-solver&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "triangle",
        "solver",
        "full",
        "sine",
        "cosine",
        "rules",
        "mathematics",
        "solve",
        "any",
        "three"
      ],
      "popularity": 6648,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "triathlon-race-planner",
      "title": "🏊‍♂️ Triathlon Race Planner",
      "description": "Build a race-day plan: pick a distance, enter your swim pace, bike speed, run pace and transitions, and this gives you the time for each leg and your finish line.",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/triathlon-race-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=triathlon-race-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tri-sm",
          "type": "number",
          "label": "Swim /100m min",
          "unit": "",
          "min": 0,
          "default": "2"
        },
        {
          "name": "tri-ss",
          "type": "number",
          "label": "Swim sec",
          "unit": "",
          "min": 0,
          "default": "0"
        },
        {
          "name": "tri-bike",
          "type": "number",
          "label": "Bike speed",
          "unit": "km/h",
          "min": 0,
          "default": "32"
        },
        {
          "name": "tri-rm",
          "type": "number",
          "label": "Run /km min",
          "unit": "",
          "min": 0,
          "default": "5"
        },
        {
          "name": "tri-rs",
          "type": "number",
          "label": "Run sec",
          "unit": "",
          "min": 0,
          "default": "30"
        },
        {
          "name": "tri-t1m",
          "type": "number",
          "label": "T1 min",
          "unit": "",
          "min": 0,
          "default": "2"
        },
        {
          "name": "tri-t1s",
          "type": "number",
          "label": "T1 sec",
          "unit": "",
          "min": 0,
          "default": "0"
        },
        {
          "name": "tri-t2m",
          "type": "number",
          "label": "T2 min",
          "unit": "",
          "min": 0,
          "default": "1"
        },
        {
          "name": "tri-t2s",
          "type": "number",
          "label": "T2 sec",
          "unit": "",
          "min": 0,
          "default": "30"
        },
        {
          "name": "tri-swimkm",
          "type": "number",
          "label": "Swim",
          "unit": "km",
          "min": 0,
          "step": 0.1,
          "default": "1.5"
        },
        {
          "name": "tri-bikekm",
          "type": "number",
          "label": "Bike",
          "unit": "km",
          "min": 0,
          "step": 0.1,
          "default": "40"
        },
        {
          "name": "tri-runkm",
          "type": "number",
          "label": "Run",
          "unit": "km",
          "min": 0,
          "step": 0.1,
          "default": "10"
        },
        {
          "name": "tri-dist",
          "type": "select-one",
          "label": "Distance",
          "unit": "",
          "options": [
            "0.75,20,5",
            "1.5,40,10",
            "1.9,90,21.1",
            "3.8,180,42.2",
            "custom"
          ],
          "default": "0.75,20,5"
        }
      ],
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        {
          "name": "tri-out",
          "type": "live"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=triathlon-race-planner&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "triathlon",
        "race",
        "planner",
        "sports",
        "build",
        "race-day",
        "plan",
        "pick",
        "distance",
        "enter"
      ],
      "popularity": 4226,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "trick-or-treat-route-planner",
      "title": "🍬 Trick-or-Treat Route Planner",
      "description": "Work out how long the rounds actually take: distance, doors, walking and doorbell time, whether you finish before dark, and how much sweets each child comes home with.",
      "category": "halloween",
      "categoryName": "Halloween",
      "url": "https://www.themostusefulsiteintheworld.com/tool/trick-or-treat-route-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=trick-or-treat-route-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tto-houses",
          "type": "number",
          "label": "Houses on the route",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "40"
        },
        {
          "name": "tto-spacing",
          "type": "number",
          "label": "Average distance between doors",
          "unit": "m",
          "min": 5,
          "step": 1,
          "default": "28"
        },
        {
          "name": "tto-speed",
          "type": "number",
          "label": "Walking speed",
          "unit": "km/h",
          "min": 0.5,
          "step": 0.1,
          "default": "2.6"
        },
        {
          "name": "tto-dwell",
          "type": "number",
          "label": "Time at each door",
          "unit": "s",
          "min": 5,
          "step": 5,
          "default": "45"
        },
        {
          "name": "tto-kids",
          "type": "number",
          "label": "Children",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "2"
        },
        {
          "name": "tto-youngest",
          "type": "number",
          "label": "Youngest child's age",
          "unit": "",
          "min": 2,
          "max": 16,
          "step": 1,
          "default": "6"
        },
        {
          "name": "tto-per-house",
          "type": "number",
          "label": "Sweets per child per house",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "2"
        },
        {
          "name": "tto-start",
          "type": "time",
          "label": "Leave time",
          "unit": "",
          "default": "16:30"
        },
        {
          "name": "tto-date",
          "type": "date",
          "label": "Date",
          "unit": "",
          "default": "2026-10-31"
        },
        {
          "name": "tto-lat",
          "type": "number",
          "label": "Latitude (°, north positive)",
          "unit": "",
          "min": -66,
          "max": 66,
          "step": 0.1,
          "default": "51.5"
        },
        {
          "name": "tto-noon",
          "type": "time",
          "label": "Solar noon on your clock",
          "unit": "",
          "default": "12:00"
        }
      ],
      "outputs": [
        {
          "name": "tto-out",
          "type": "live"
        },
        {
          "name": "tto-total",
          "type": "output"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=trick-or-treat-route-planner&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "trick",
        "treat",
        "route",
        "planner",
        "trick-or-treat",
        "halloween",
        "work",
        "out",
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        "long"
      ],
      "popularity": 4245,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "trigonometry",
      "title": "🎯 Foundation & Unit Circle",
      "description": "Sin = Opposite / Hypotenuse Cos = Adjacent / Hypotenuse Tan = Opposite / Adjacent",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/trigonometry.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=trigonometry&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "identityInput",
          "type": "text",
          "label": "Enter identity to verify",
          "unit": ""
        },
        {
          "name": "angleInput",
          "type": "select-one",
          "label": "angleInput",
          "unit": "",
          "options": [
            "Select Angle",
            "30",
            "45",
            "60",
            "90",
            "120",
            "180"
          ],
          "default": "Select Angle"
        },
        {
          "name": "problemType",
          "type": "select-one",
          "label": "problemType",
          "unit": "",
          "options": [
            "Select Problem Type",
            "Right Triangle",
            "Simplify Expression",
            "Solve Equation",
            "Graph Transformation"
          ],
          "default": "Select Problem Type"
        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=trigonometry&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=trigonometry&angleInput=Select%20Angle&problemType=Select%20Problem%20Type&run=1"
      },
      "formula": "SOH-CAH-TOA Mnemonic: S in = Opposite / Hypotenuse C os = Adjacent /",
      "sources": [],
      "tags": [
        "trigonometry",
        "foundation",
        "unit",
        "circle",
        "mathematics",
        "sin",
        "opposite",
        "hypotenuse",
        "cos",
        "adjacent"
      ],
      "popularity": 5535,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "truck-axle-weight-bridge-formula",
      "title": "⚖️ Axle Weight & Bridge Formula Checker",
      "description": "Type in the scale ticket. This checks every axle group and the federal bridge formula, then tells you which way to slide the fifth wheel or the tandems and how far — in inches and in holes — based ...",
      "category": "trucking-and-freight",
      "categoryName": "Trucking & Freight",
      "url": "https://www.themostusefulsiteintheworld.com/tool/truck-axle-weight-bridge-formula.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-axle-weight-bridge-formula&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "name": "axw-steer",
          "type": "number",
          "label": "Steer axle",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "11800"
        },
        {
          "name": "axw-drive",
          "type": "number",
          "label": "Drive group",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "34500"
        },
        {
          "name": "axw-trailer",
          "type": "number",
          "label": "Trailer group",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "32800"
        },
        {
          "name": "axw-steerlim",
          "type": "number",
          "label": "Steer limit",
          "unit": "tyre/plate",
          "min": 0,
          "step": 10,
          "default": "12000"
        },
        {
          "name": "axw-drivelim",
          "type": "number",
          "label": "Drive group limit",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "34000"
        },
        {
          "name": "axw-trailerlim",
          "type": "number",
          "label": "Trailer group limit",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "34000"
        },
        {
          "name": "axw-grosslim",
          "type": "number",
          "label": "Gross limit",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "80000"
        },
        {
          "name": "axw-btsteer",
          "type": "number",
          "label": "Bobtail steer",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "11200"
        },
        {
          "name": "axw-btdrive",
          "type": "number",
          "label": "Bobtail drive",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "15800"
        },
        {
          "name": "axw-wb",
          "type": "number",
          "label": "Wheelbase (steer &rarr; drive centre)",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "220"
        },
        {
          "name": "axw-kp",
          "type": "number",
          "label": "Centre of tandems &rarr; kingpin",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "480"
        },
        {
          "name": "axw-5w",
          "type": "number",
          "label": "Fifth wheel hole spacing",
          "unit": "",
          "min": 0.5,
          "step": 0.5,
          "default": "4"
        },
        {
          "name": "axw-th",
          "type": "number",
          "label": "Tandem hole spacing",
          "unit": "",
          "min": 0.5,
          "step": 0.5,
          "default": "6"
        }
      ],
      "outputs": [
        {
          "name": "axw-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-axle-weight-bridge-formula&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-axle-weight-bridge-formula&axw-steer=11800&axw-drive=34500&axw-trailer=32800&axw-steerlim=12000&axw-drivelim=34000&axw-trailerlim=34000"
      },
      "formula": "W = 500 × ( L×N/(N−1) + 12N +",
      "sources": [],
      "tags": [
        "truck",
        "axle",
        "weight",
        "bridge",
        "formula",
        "checker",
        "trucking",
        "freight",
        "type",
        "scale"
      ],
      "popularity": 4856,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "truck-breakdown-triage",
      "title": "🔧 Roadside Breakdown Triage",
      "description": "Something has gone wrong at the worst possible place. Pick the symptom and this walks you through what is safe to check, what each finding most likely means, whether you can carry on or stop, and e...",
      "category": "trucking-and-freight",
      "categoryName": "Trucking & Freight",
      "url": "https://www.themostusefulsiteintheworld.com/tool/truck-breakdown-triage.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-breakdown-triage&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "bdt-symptom",
          "type": "select-one",
          "label": "What is it doing?",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "bdt-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-breakdown-triage&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "truck",
        "breakdown",
        "triage",
        "roadside",
        "trucking",
        "freight",
        "something",
        "gone",
        "wrong",
        "worst"
      ],
      "popularity": 6046,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "truck-cost-per-mile",
      "title": "💵 Cost Per Mile & Break-Even Rate",
      "description": "What a mile actually costs you to run — fixed costs spread over the miles you really do, plus fuel, tyres, maintenance and driver pay — and the rate per mile that leaves a profit rather than a stor...",
      "category": "trucking-and-freight",
      "categoryName": "Trucking & Freight",
      "url": "https://www.themostusefulsiteintheworld.com/tool/truck-cost-per-mile.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-cost-per-mile&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cpm-truck",
          "type": "number",
          "label": "Truck payment",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "700"
        },
        {
          "name": "cpm-trailer",
          "type": "number",
          "label": "Trailer payment",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "150"
        },
        {
          "name": "cpm-ins",
          "type": "number",
          "label": "Insurance",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "320"
        },
        {
          "name": "cpm-permits",
          "type": "number",
          "label": "Permits, plates, IRP",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "60"
        },
        {
          "name": "cpm-eld",
          "type": "number",
          "label": "ELD, software, comms",
          "unit": "",
          "min": 0,
          "step": 5,
          "default": "35"
        },
        {
          "name": "cpm-office",
          "type": "number",
          "label": "Parking, yard, office",
          "unit": "",
          "min": 0,
          "step": 5,
          "default": "90"
        },
        {
          "name": "cpm-diesel",
          "type": "number",
          "label": "Diesel price",
          "unit": "",
          "min": 0,
          "step": 0.01,
          "default": "3.90"
        },
        {
          "name": "cpm-mpg",
          "type": "number",
          "label": "Fuel economy",
          "unit": "",
          "min": 1,
          "step": 0.1,
          "default": "6.5"
        },
        {
          "name": "cpm-maint",
          "type": "number",
          "label": "Maintenance",
          "unit": "",
          "min": 0,
          "step": 0.01,
          "default": "0.18"
        },
        {
          "name": "cpm-tyres",
          "type": "number",
          "label": "Tyres",
          "unit": "",
          "min": 0,
          "step": 0.005,
          "default": "0.045"
        },
        {
          "name": "cpm-driver",
          "type": "number",
          "label": "Driver pay",
          "unit": "",
          "min": 0,
          "step": 0.01,
          "default": "0.65"
        },
        {
          "name": "cpm-other",
          "type": "number",
          "label": "Tolls, scales, misc",
          "unit": "",
          "min": 0,
          "step": 0.01,
          "default": "0.04"
        },
        {
          "name": "cpm-miles",
          "type": "number",
          "label": "Miles / km per week",
          "unit": "",
          "min": 100,
          "step": 50,
          "default": "2500"
        },
        {
          "name": "cpm-cur",
          "type": "text",
          "label": "Currency symbol",
          "unit": "",
          "default": "$"
        },
        {
          "name": "cpm-margin",
          "type": "number",
          "label": "Target margin",
          "unit": "%",
          "min": 0,
          "max": 60,
          "step": 1,
          "default": "15"
        },
        {
          "name": "cpm-rate",
          "type": "number",
          "label": "Rate you are offered",
          "unit": "/mi or /km",
          "min": 0,
          "step": 0.01,
          "default": "2.20"
        }
      ],
      "outputs": [
        {
          "name": "cpm-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-cost-per-mile&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-cost-per-mile&cpm-truck=700&cpm-trailer=150&cpm-ins=320&cpm-permits=60&cpm-eld=35&cpm-office=90&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "truck",
        "cost",
        "per",
        "mile",
        "break-even",
        "rate",
        "trucking",
        "freight",
        "what",
        "actually"
      ],
      "popularity": 4431,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "truck-duty-clock-planner",
      "title": "🕐 Driving Hours & Duty Clock Planner",
      "description": "How much driving have you actually got left, when is your break due, and what time does your day end? Pick your rule set, drop in the numbers from your log, and this shows every limit counting down...",
      "category": "trucking-and-freight",
      "categoryName": "Trucking & Freight",
      "url": "https://www.themostusefulsiteintheworld.com/tool/truck-duty-clock-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-duty-clock-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hos-start",
          "type": "time",
          "label": "Shift / on-duty start",
          "unit": "",
          "default": "06:00"
        },
        {
          "name": "hos-drive",
          "type": "number",
          "label": "Driving used so far",
          "unit": "hours",
          "min": 0,
          "max": 24,
          "step": 0.25,
          "default": "4"
        },
        {
          "name": "hos-duty",
          "type": "number",
          "label": "Other on-duty used",
          "unit": "hours",
          "min": 0,
          "max": 24,
          "step": 0.25,
          "default": "1.5"
        },
        {
          "name": "hos-break",
          "type": "number",
          "label": "Since last qualifying break",
          "unit": "hours",
          "min": 0,
          "max": 24,
          "step": 0.25,
          "default": "3"
        },
        {
          "name": "hos-cycle",
          "type": "number",
          "label": "Cycle hours already used",
          "unit": "",
          "min": 0,
          "max": 200,
          "step": 0.5,
          "default": "38"
        },
        {
          "name": "hos-reduced",
          "type": "checkbox",
          "label": "Took a reduced daily rest (9 h) &mdash; allowed three times between weekly rests",
          "unit": "",
          "default": "0"
        },
        {
          "name": "hos-eu10",
          "type": "checkbox",
          "label": "Using the 10-hour driving day &mdash; allowed twice a week",
          "unit": "",
          "default": "0"
        },
        {
          "name": "hos-rules",
          "type": "select-one",
          "label": "Rule set",
          "unit": "",
          "options": [
            "us",
            "ca",
            "eu",
            "au"
          ],
          "default": "us"
        },
        {
          "name": "hos-cycleselect",
          "type": "select-one",
          "label": "Cycle",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "hos-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-duty-clock-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-duty-clock-planner&hos-start=06%3A00&hos-drive=4&hos-duty=1.5&hos-break=3&hos-cycle=38&hos-reduced=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "truck",
        "duty",
        "clock",
        "planner",
        "driving",
        "hours",
        "trucking",
        "freight",
        "how",
        "much"
      ],
      "popularity": 6466,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "truck-grade-descent-speed",
      "title": "🏔️ Grade, Climb & Descent Calculator",
      "description": "What a grade actually means in degrees and feet, how fast your truck can hold it, and — the part that ends careers — how much heat a descent puts into your brakes, whether your retarder can carry i...",
      "category": "trucking-and-freight",
      "categoryName": "Trucking & Freight",
      "url": "https://www.themostusefulsiteintheworld.com/tool/truck-grade-descent-speed.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-grade-descent-speed&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "grd-weight",
          "type": "number",
          "label": "Gross weight",
          "unit": "",
          "min": 1000,
          "step": 500,
          "default": "80000"
        },
        {
          "name": "grd-power",
          "type": "number",
          "label": "Engine power",
          "unit": "",
          "min": 50,
          "step": 10,
          "default": "450"
        },
        {
          "name": "grd-ret",
          "type": "number",
          "label": "Retarder + engine brake",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "400"
        },
        {
          "name": "grd-grade",
          "type": "number",
          "label": "Grade",
          "unit": "%",
          "min": -10,
          "max": 25,
          "step": 0.5,
          "default": "6"
        },
        {
          "name": "grd-speed",
          "type": "number",
          "label": "Descent speed you want to hold",
          "unit": "",
          "min": 5,
          "step": 1,
          "default": "35"
        },
        {
          "name": "grd-drive",
          "type": "number",
          "label": "Weight on the drive axles",
          "unit": "%",
          "min": 10,
          "max": 80,
          "step": 1,
          "default": "45"
        },
        {
          "name": "grd-mu",
          "type": "select-one",
          "label": "Road grip (&mu;) for traction",
          "unit": "",
          "options": [
            "0.65",
            "0.45",
            "0.25",
            "0.12"
          ],
          "default": "0.65"
        }
      ],
      "outputs": [
        {
          "name": "grd-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-grade-descent-speed&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-grade-descent-speed&grd-weight=80000&grd-power=450&grd-ret=400&grd-grade=6&grd-speed=35&grd-drive=45&run=1"
      },
      "formula": "P = v × ( m·g·C rr + m·g·sinθ +",
      "sources": [],
      "tags": [
        "truck",
        "grade",
        "descent",
        "speed",
        "climb",
        "trucking",
        "freight",
        "what",
        "actually",
        "means"
      ],
      "popularity": 4464,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "truck-load-offer-decider",
      "title": "📊 Load Offer Decider & Counter-Offer",
      "description": "Three offers on the table, one honest answer. Puts the deadhead into the rate, subtracts what the truck costs to run, turns it into money per hour, and tells you the exact number to ask for if the ...",
      "category": "trucking-and-freight",
      "categoryName": "Trucking & Freight",
      "url": "https://www.themostusefulsiteintheworld.com/tool/truck-load-offer-decider.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-load-offer-decider&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "lod-cpm",
          "type": "number",
          "label": "All-in cost per mile",
          "unit": "",
          "min": 0,
          "step": 0.05,
          "default": "2.00"
        },
        {
          "name": "lod-minp",
          "type": "number",
          "label": "Minimum profit per mile",
          "unit": "",
          "min": 0,
          "step": 0.05,
          "default": "0.30"
        },
        {
          "name": "lod-minh",
          "type": "number",
          "label": "Minimum per hour",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "45"
        },
        {
          "name": "lod-speed",
          "type": "number",
          "label": "Average speed",
          "unit": "mph/km-h",
          "min": 10,
          "step": 1,
          "default": "50"
        },
        {
          "name": "lod-dock",
          "type": "number",
          "label": "Dock time per end",
          "unit": "hours",
          "min": 0,
          "step": 0.25,
          "default": "1.5"
        },
        {
          "name": "lod-cur",
          "type": "text",
          "label": "Currency",
          "unit": "",
          "default": "$"
        }
      ],
      "outputs": [
        {
          "name": "lod-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-load-offer-decider&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-load-offer-decider&lod-cpm=2.00&lod-minp=0.30&lod-minh=45&lod-speed=50&lod-dock=1.5&lod-cur=%24"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "truck",
        "load",
        "offer",
        "decider",
        "counter-offer",
        "trucking",
        "freight",
        "three",
        "offers",
        "table"
      ],
      "popularity": 6080,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "truck-load-planner",
      "title": "📦 Trailer Load & Pallet Planner",
      "description": "How many pallets fit, which way round, where the weight ends up on the axles, and what order to load them so the first drop is at the doors. Draws the floor plan as you type, offline, for a 53’ van...",
      "category": "trucking-and-freight",
      "categoryName": "Trucking & Freight",
      "url": "https://www.themostusefulsiteintheworld.com/tool/truck-load-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=truck-load-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tlp-l1",
          "type": "number",
          "label": "Pallet dimension 1",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "48"
        },
        {
          "name": "tlp-l2",
          "type": "number",
          "label": "Pallet dimension 2",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "40"
        },
        {
          "name": "tlp-len",
          "type": "number",
          "label": "Deck length",
          "unit": "",
          "min": 10,
          "step": 1,
          "default": "636"
        },
        {
          "name": "tlp-wid",
          "type": "number",
          "label": "Deck width",
          "unit": "",
          "min": 10,
          "step": 1,
          "default": "100"
        },
        {
          "name": "tlp-ph",
          "type": "number",
          "label": "Loaded pallet height",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "55"
        },
        {
          "name": "tlp-ih",
          "type": "number",
          "label": "Interior height",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "110"
        },
        {
          "name": "tlp-stack",
          "type": "checkbox",
          "label": "Freight can be double-stacked",
          "unit": "",
          "default": "0"
        },
        {
          "name": "tlp-gross",
          "type": "number",
          "label": "Load weight",
          "unit": "",
          "min": 0,
          "step": 100,
          "default": "40000"
        },
        {
          "name": "tlp-tare",
          "type": "number",
          "label": "Trailer tare",
          "unit": "",
          "min": 0,
          "step": 100,
          "default": "14500"
        },
        {
          "name": "tlp-cg",
          "type": "range",
          "label": "Load centre: 50% back",
          "unit": "",
          "min": 10,
          "max": 90,
          "step": 1,
          "default": "50"
        },
        {
          "name": "tlp-kpset",
          "type": "number",
          "label": "Kingpin setback from nose",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "36"
        },
        {
          "name": "tlp-kp",
          "type": "number",
          "label": "Kingpin &rarr; tandem centre",
          "unit": "",
          "min": 1,
          "step": 1,
          "default": "480"
        },
        {
          "name": "tlp-btd",
          "type": "number",
          "label": "Bobtail drive weight",
          "unit": "",
          "min": 0,
          "step": 100,
          "default": "15800"
        },
        {
          "name": "tlp-drivecap",
          "type": "number",
          "label": "Drive group cap",
          "unit": "",
          "min": 0,
          "step": 100,
          "default": "34000"
        },
        {
          "name": "tlp-bogiecap",
          "type": "number",
          "label": "Trailer bogie cap",
          "unit": "",
          "min": 0,
          "step": 100,
          "default": "34000"
        },
        {
          "name": "tlp-s1",
          "type": "number",
          "label": "Stop 1 &mdash; first drop",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "8"
        },
        {
          "name": "tlp-s2",
          "type": "number",
          "label": "Stop 2",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "8"
        },
        {
          "name": "tlp-s3",
          "type": "number",
          "label": "Stop 3",
          "unit": "",
          "min": 0,
          "step": 1,
          "default": "0"
        },
        {
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          "name": "tlp-preset",
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          "label": "Pallet",
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            "gma",
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      },
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        "truck",
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      "slug": "truck-pretrip-inspection",
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        "truck",
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    },
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            "single",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=truth-table-generator&embed=1",
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      "sources": [],
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        "truth",
        "table",
        "algorithms",
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      "featured": false,
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    {
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      "category": "interactive-art-and-living-worlds",
      "categoryName": "Interactive Art & Living Worlds",
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          "unit": "",
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      },
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      "featured": false,
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    {
      "slug": "tuner",
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          "name": "tn-note",
          "type": "select-one",
          "label": "音符 Target Note",
          "unit": "",
          "options": [
            "E2",
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            "D3",
            "G3",
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            "E4",
            "C4",
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      "featured": false,
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    {
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      "title": "🦃 Turkey Thaw & Cook Time",
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      "category": "culinary-and-food-science",
      "categoryName": "Culinary & Food Science",
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      "title": "📺 TV Viewing Distance Calculator",
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      "category": "home-and-diy",
      "categoryName": "Home & DIY",
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      "standaloneUrl": null,
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          "name": "tvvd-res",
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=tv-viewing-distance-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=tv-viewing-distance-calculator&tvvd-diag=55&tvvd-unit=in&tvvd-res=1920x1080&tvvd-ar=1.7778"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "viewing",
        "distance",
        "home",
        "diy",
        "recommend",
        "sofa",
        "screen",
        "diagonal",
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      ],
      "popularity": 6913,
      "featured": false,
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    },
    {
      "slug": "twenty-twenty-twenty-eye-rest-timer",
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      "description": "Optometrists’ rule for screen strain: every 20 minutes, look at something 6 metres (20 feet) away for 20 seconds. This runs the cycle for you — start it when you sit down to work.",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/twenty-twenty-twenty-eye-rest-timer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=twenty-twenty-twenty-eye-rest-timer&embed=1",
      "standaloneUrl": null,
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        },
        {
          "name": "eye-rest",
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          "max": 300,
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        },
        {
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          "label": "Long break every 4 cycles",
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          "min": 0,
          "max": 30,
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        },
        {
          "name": "eye-sound",
          "type": "checkbox",
          "label": "Gentle chime at each switch",
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        }
      ],
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        {
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=twenty-twenty-twenty-eye-rest-timer&<id>=<value>",
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      "sources": [],
      "tags": [
        "twenty",
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        "rest",
        "timer",
        "20-20-20",
        "health",
        "fitness",
        "optometrists",
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      "popularity": 5348,
      "featured": false,
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    },
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      "slug": "typing-speed-test",
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      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/typing-speed-test.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=typing-speed-test&embed=1",
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          "type": "select-one",
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          "unit": "",
          "options": [
            "0",
            "1",
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        {
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      },
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      "sources": [],
      "tags": [
        "typing",
        "speed",
        "test",
        "writing",
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      "popularity": 6622,
      "featured": false,
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    },
    {
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      "description": "Build typing speed by retyping fascinating true mini-stories — bees, pyramids, photosynthesis. Live WPM, accuracy, tricky-key analysis and personal bests.",
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      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/typing-story-sprint.html",
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      "standaloneUrl": null,
      "inputs": [
        {
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          "label": "Typing input",
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        {
          "name": "tss-level",
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          "unit": "",
          "options": [
            "0",
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            "2"
          ],
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        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=typing-story-sprint&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=typing-story-sprint&tss-level=0"
      },
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      "sources": [],
      "tags": [
        "typing",
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        "sprint",
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        "speed",
        "retyping",
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      "popularity": 6760,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "ucas-tariff-points-calculator",
      "title": "🎓 UCAS Tariff Points",
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      "category": "finance-and-money",
      "categoryName": "Finance & Money",
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        {
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            "A",
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          ],
          "default": "A"
        },
        {
          "name": "ucas-grade",
          "type": "select-one",
          "label": "Grade",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "ucas-out",
          "type": "output"
        }
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=ucas-tariff-points-calculator&<id>=<value>",
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      },
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      "sources": [],
      "tags": [
        "ucas",
        "tariff",
        "points",
        "finance",
        "money",
        "add",
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      "popularity": 6952,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "uk-alcohol-units-calculator",
      "title": "🍺 UK Alcohol Units Calculator",
      "description": "UK units = ABV (%) × volume (ml) ÷ 1,000. The NHS low-risk guideline is 14 units a week, spread out, with several drink-free days. This is arithmetic, not medical advice.",
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      "standaloneUrl": null,
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        {
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          "unit": "",
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        },
        {
          "name": "ualc-ml",
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        {
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          "unit": "",
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        {
          "name": "ualc-out",
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        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-alcohol-units-calculator&<id>=<value>",
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      },
      "formula": "UK Alcohol Units Calculator UK units = ABV (%) × volume (ml) ÷ 1,000. The NHS low-",
      "sources": [],
      "tags": [
        "alcohol",
        "units",
        "health",
        "fitness",
        "abv",
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        "nhs",
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      ],
      "popularity": 6698,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "uk-childcare-cost-calculator",
      "title": "🧒 UK Childcare Cost Calculator",
      "description": "Funded hours, Tax-Free Childcare and Universal Credit childcare stack in ways nobody explains at the nursery door — and the difference between them is often more than a car payment. Put in what you...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
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        },
        {
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          "label": "Weeks a year you need it",
          "unit": "",
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          "step": 1,
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        },
        {
          "name": "uccc-100k",
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          "label": "Adjusted net income over £100,000",
          "unit": "",
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        },
        {
          "name": "uccc-disabled",
          "type": "checkbox",
          "label": "Disabled child (higher TFC cap)",
          "unit": "",
          "default": "0"
        },
        {
          "name": "uccc-weekly",
          "type": "number",
          "label": "Weekly bill for those hours",
          "unit": "",
          "min": 0,
          "max": 5000,
          "step": 1,
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        },
        {
          "name": "uccc-extras",
          "type": "number",
          "label": "Meals & consumables a week",
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          "min": 0,
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        },
        {
          "name": "uccc-funded-h",
          "type": "number",
          "label": "Funded hours a week",
          "unit": "",
          "min": 0,
          "max": 60,
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          "default": "15"
        },
        {
          "name": "uccc-pay",
          "type": "number",
          "label": "Your take-home pay an hour",
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          "min": 0,
          "max": 500,
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          "default": "14"
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        {
          "name": "uccc-extra-h",
          "type": "number",
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          "unit": "",
          "min": 0,
          "max": 40,
          "step": 0.5,
          "default": "4"
        },
        {
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          "label": "TFC top-up cap, per child, a year",
          "unit": "£",
          "min": 0,
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          "step": 1,
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        },
        {
          "name": "uccc-cap-uc1",
          "type": "number",
          "label": "UC cap a month, 1 child",
          "unit": "£",
          "min": 0,
          "max": 10000,
          "step": 0.01,
          "default": "1071.09"
        },
        {
          "name": "uccc-cap-uc2",
          "type": "number",
          "label": "UC cap a month, 2+ children",
          "unit": "£",
          "min": 0,
          "max": 10000,
          "step": 0.01,
          "default": "1836.16"
        },
        {
          "name": "uccc-taper",
          "type": "number",
          "label": "UC taper on extra earnings",
          "unit": "%",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "55"
        },
        {
          "name": "uccc-band",
          "type": "select-one",
          "label": "Child’s age & your situation",
          "unit": "",
          "options": [
            "30",
            "15",
            "30",
            "15",
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            "0"
          ],
          "default": "15"
        },
        {
          "name": "uccc-kids",
          "type": "select-one",
          "label": "Children in paid childcare",
          "unit": "",
          "options": [
            "1",
            "2",
            "3",
            "4"
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          "default": "1"
        },
        {
          "name": "uccc-funded-w",
          "type": "select-one",
          "label": "Weeks the funded hours cover",
          "unit": "",
          "options": [
            "38",
            "stretch"
          ],
          "default": "38"
        },
        {
          "name": "uccc-scheme",
          "type": "select-one",
          "label": "Scheme",
          "unit": "",
          "options": [
            "tfc",
            "uc",
            "none"
          ],
          "default": "tfc"
        }
      ],
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          "name": "uccc-out",
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      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-childcare-cost-calculator&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "childcare",
        "cost",
        "finance",
        "money",
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        "tax-free",
        "universal",
        "credit",
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      ],
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      "featured": false,
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    },
    {
      "slug": "uk-counties-quiz",
      "title": "🗺️ UK Counties & Regions Quiz",
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      "category": "mrprophecy-arcade",
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      "url": "https://www.themostusefulsiteintheworld.com/tool/uk-counties-quiz.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-counties-quiz&embed=1",
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      "inputs": [
        {
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          "options": [
            "england",
            "uk",
            "scotland",
            "wales",
            "ni"
          ],
          "default": "england"
        }
      ],
      "outputs": [
        {
          "name": "ukc-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-counties-quiz&<id>=<value>",
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        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-counties-quiz&ukc-scope=england"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "counties",
        "quiz",
        "regions",
        "arcade",
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      ],
      "popularity": 5651,
      "featured": false,
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    },
    {
      "slug": "uk-court-fee-calculator",
      "title": "🏛️ UK Court, Tribunal & Probate Fee Calculator",
      "description": "Work out court fees for issuing a claim, the hearing fee by track, applications, appeals, enforcement, assessment and probate — current EX50 fees, uplifted 13 July 2026.",
      "category": "legal-and-professional",
      "categoryName": "Legal & Professional",
      "url": "https://www.themostusefulsiteintheworld.com/tool/uk-court-fee-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-court-fee-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "fee-value",
          "type": "number",
          "label": "Value of the claim, including interest",
          "unit": "£",
          "min": 0,
          "step": 100,
          "default": "12500"
        },
        {
          "name": "fee-assess",
          "type": "number",
          "label": "Detailed assessment of costs of",
          "unit": "£",
          "min": 0,
          "step": 500,
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        },
        {
          "name": "fee-estate",
          "type": "number",
          "label": "Value of the estate for probate",
          "unit": "£",
          "min": 0,
          "step": 1000,
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        },
        {
          "name": "fee-copies",
          "type": "number",
          "label": "Extra sealed copies of the grant with the application",
          "unit": "",
          "min": 0,
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        },
        {
          "name": "fee-track",
          "type": "select-one",
          "label": "Track (for the hearing fee)",
          "unit": "",
          "options": [
            "none",
            "small",
            "fast",
            "intermediate",
            "multi"
          ],
          "default": "none"
        },
        {
          "name": "fee-possession",
          "type": "select-one",
          "label": "Type",
          "unit": "",
          "options": [
            "money",
            "possession",
            "nonmoney"
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          "default": "money"
        },
        {
          "name": "fee-court",
          "type": "select-one",
          "label": "Court",
          "unit": "",
          "options": [
            "cc",
            "hc"
          ],
          "default": "cc"
        },
        {
          "name": "fee-app",
          "type": "select-one",
          "label": "Add an application",
          "unit": "",
          "options": [
            "none",
            "notice",
            "consent"
          ],
          "default": "none"
        },
        {
          "name": "fee-second",
          "type": "select-one",
          "label": "Second application after a grant (power reserved)",
          "unit": "",
          "options": [
            "no",
            "yes"
          ],
          "default": "no"
        }
      ],
      "outputs": [
        {
          "name": "fee-res-total",
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        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-court-fee-calculator&<id>=<value>",
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "court",
        "fee",
        "tribunal",
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      "popularity": 6294,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "uk-employment-tribunal-award-calculator",
      "title": "⚖️ Employment Tribunal Award Calculator",
      "description": "Estimate an unfair dismissal award: the age-banded basic award against the £751 week's pay cap, the capped compensatory award, ACAS Code uplifts and the Vento bands.",
      "category": "legal-and-professional",
      "categoryName": "Legal & Professional",
      "url": "https://www.themostusefulsiteintheworld.com/tool/uk-employment-tribunal-award-calculator.html",
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      "standaloneUrl": null,
      "inputs": [
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          "type": "date",
          "label": "Date of birth",
          "unit": "",
          "default": "1979-03-14"
        },
        {
          "name": "et-edt",
          "type": "date",
          "label": "Effective date of termination",
          "unit": "EDT",
          "default": "2026-09-30"
        },
        {
          "name": "et-years",
          "type": "number",
          "label": "Complete years of service",
          "unit": "",
          "min": 0,
          "max": 50,
          "step": 1,
          "default": "11"
        },
        {
          "name": "et-weekly",
          "type": "number",
          "label": "Gross weekly pay",
          "unit": "£",
          "min": 0,
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          "default": "920"
        },
        {
          "name": "et-loss",
          "type": "number",
          "label": "Financial loss claimed for the compensatory award",
          "unit": "£",
          "min": 0,
          "step": 500,
          "default": "45000"
        },
        {
          "name": "et-vento",
          "type": "number",
          "label": "Injury to feelings — discrimination claims only",
          "unit": "£",
          "min": 0,
          "step": 250,
          "default": "0"
        },
        {
          "name": "et-polkey",
          "type": "number",
          "label": "Polkey reduction — chance of a fair dismissal anyway",
          "unit": "%",
          "min": 0,
          "max": 100,
          "step": 5,
          "default": "0"
        },
        {
          "name": "et-contrib",
          "type": "number",
          "label": "Contributory conduct",
          "unit": "%",
          "min": 0,
          "max": 100,
          "step": 5,
          "default": "0"
        },
        {
          "name": "et-acas",
          "type": "number",
          "label": "ACAS Code uplift / reduction",
          "unit": "%, up to 25",
          "min": -25,
          "max": 25,
          "step": 5,
          "default": "0"
        },
        {
          "name": "et-protected",
          "type": "checkbox",
          "label": "Protected dismissal (minimum basic award £9,157)",
          "unit": "",
          "default": "0"
        },
        {
          "name": "et-capoff",
          "type": "checkbox",
          "label": "Assume the compensatory cap is removed (dismissals on or after 1 January 2027 — ERA 2025)",
          "unit": "",
          "default": "0"
        },
        {
          "name": "et-uncapped",
          "type": "checkbox",
          "label": "Whistleblowing or health and safety dismissal (cap does not apply)",
          "unit": "",
          "default": "0"
        },
        {
          "name": "et-limits",
          "type": "select-one",
          "label": "Limits (week's pay cap, from the EDT)",
          "unit": "",
          "options": [
            "2026",
            "2025",
            "2024"
          ],
          "default": "2026"
        }
      ],
      "outputs": [
        {
          "name": "et-res-total",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-employment-tribunal-award-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-employment-tribunal-award-calculator&et-dob=1979-03-14&et-edt=2026-09-30&et-years=11&et-weekly=920&et-loss=45000&et-vento=0"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "employment",
        "tribunal",
        "award",
        "legal",
        "professional",
        "estimate",
        "unfair",
        "dismissal",
        "age-banded",
        "basic"
      ],
      "popularity": 4642,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "uk-hallmark-decoder",
      "title": "🥈 The Hallmark Bench",
      "description": "British silver and gold are punched with a standard, a town, a maker, and (historically) a date letter. The bench identifies the town mark and the millesimal fineness. Date letters cycle by assay o...",
      "category": "museum-and-collection",
      "categoryName": "Museum & Collection",
      "url": "https://www.themostusefulsiteintheworld.com/tool/uk-hallmark-decoder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-hallmark-decoder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hlmk-town",
          "type": "select-one",
          "label": "Town mark",
          "unit": "",
          "options": [
            "leopard",
            "anchor",
            "rose",
            "castle",
            "thistle",
            "harp"
          ],
          "default": "leopard"
        },
        {
          "name": "hlmk-std",
          "type": "select-one",
          "label": "Standard mark",
          "unit": "",
          "options": [
            "925",
            "958",
            "800",
            "375",
            "585",
            "750",
            "916",
            "999"
          ],
          "default": "925"
        }
      ],
      "outputs": [
        {
          "name": "hlmk-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-hallmark-decoder&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-hallmark-decoder&hlmk-town=leopard&hlmk-std=925"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "hallmark",
        "decoder",
        "bench",
        "museum",
        "collection",
        "british",
        "silver",
        "gold",
        "punched",
        "standard"
      ],
      "popularity": 5236,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "uk-holiday-entitlement-calculator",
      "title": "🌴 Holiday Entitlement & Pro-Rata Calculator",
      "description": "Work out statutory UK holiday for part-timers, mid-year starters and leavers, and irregular-hours staff — including the 12.07% accrual method. Employers get this wrong constantly. Nothing you enter...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/uk-holiday-entitlement-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-holiday-entitlement-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "hec-days",
          "type": "number",
          "label": "Days worked per week",
          "unit": "",
          "min": 0.5,
          "max": 7,
          "step": 0.5,
          "default": "3"
        },
        {
          "name": "hec-months",
          "type": "number",
          "label": "Months of the leave year worked",
          "unit": "",
          "min": 0,
          "max": 12,
          "step": 0.5,
          "default": "7"
        },
        {
          "name": "hec-hours",
          "type": "number",
          "label": "Hours worked this period",
          "unit": "",
          "min": 0,
          "step": 10,
          "default": "480"
        },
        {
          "name": "hec-taken",
          "type": "number",
          "label": "Days already taken",
          "unit": "",
          "min": 0,
          "max": 60,
          "step": 0.5,
          "default": "0"
        },
        {
          "name": "hec-rate",
          "type": "number",
          "label": "Day rate for pay-in-lieu",
          "unit": "£, optional",
          "min": 0,
          "step": 10,
          "default": "0"
        },
        {
          "name": "hec-mode",
          "type": "select-one",
          "label": "Working pattern",
          "unit": "",
          "options": [
            "fixed",
            "partyear",
            "irregular"
          ],
          "default": "fixed"
        },
        {
          "name": "hec-contract",
          "type": "select-one",
          "label": "Full-time entitlement",
          "unit": "days/yr",
          "options": [
            "28",
            "25",
            "30",
            "33"
          ],
          "default": "28"
        }
      ],
      "outputs": [
        {
          "name": "hec-res-total",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-holiday-entitlement-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-holiday-entitlement-calculator&hec-days=3&hec-months=7&hec-hours=480&hec-taken=0&hec-rate=0&hec-mode=fixed"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "holiday",
        "entitlement",
        "pro-rata",
        "finance",
        "money",
        "work",
        "out",
        "statutory",
        "part-timers",
        "mid-year"
      ],
      "popularity": 5106,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "uk-inheritance-tax-estate-calculator",
      "title": "🏡 Inheritance Tax & Probate Calculator",
      "description": "Estimate Inheritance Tax on an estate: nil-rate and residence bands with the £2m taper, spouse and charity exemptions, business and agricultural relief, failed gifts and probate fees.",
      "category": "legal-and-professional",
      "categoryName": "Legal & Professional",
      "url": "https://www.themostusefulsiteintheworld.com/tool/uk-inheritance-tax-estate-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-inheritance-tax-estate-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "iht-date",
          "type": "date",
          "label": "Date of death",
          "unit": "",
          "default": "2026-09-01"
        },
        {
          "name": "iht-home",
          "type": "number",
          "label": "Main residence",
          "unit": "£",
          "min": 0,
          "step": 5000,
          "default": "400000"
        },
        {
          "name": "iht-other",
          "type": "number",
          "label": "Other property and land",
          "unit": "£",
          "min": 0,
          "step": 5000,
          "default": "0"
        },
        {
          "name": "iht-cash",
          "type": "number",
          "label": "Cash, investments and chattels",
          "unit": "£",
          "min": 0,
          "step": 5000,
          "default": "300000"
        },
        {
          "name": "iht-business",
          "type": "number",
          "label": "Business property qualifying for 100% relief",
          "unit": "£",
          "min": 0,
          "step": 5000,
          "default": "0"
        },
        {
          "name": "iht-agri",
          "type": "number",
          "label": "Agricultural property qualifying for 100% relief",
          "unit": "£",
          "min": 0,
          "step": 5000,
          "default": "0"
        },
        {
          "name": "iht-aim",
          "type": "number",
          "label": "Unquoted / AIM shares qualifying for 50% relief",
          "unit": "£",
          "min": 0,
          "step": 5000,
          "default": "0"
        },
        {
          "name": "iht-pensionval",
          "type": "number",
          "label": "Unused pension funds",
          "unit": "£",
          "min": 0,
          "step": 5000,
          "default": "0"
        },
        {
          "name": "iht-debts",
          "type": "number",
          "label": "Liabilities, funeral and administration costs",
          "unit": "£",
          "min": 0,
          "step": 1000,
          "default": "15000"
        },
        {
          "name": "iht-spouse",
          "type": "number",
          "label": "Value passing to a spouse or civil partner — exempt",
          "unit": "£",
          "min": 0,
          "step": 5000,
          "default": "0"
        },
        {
          "name": "iht-charity",
          "type": "number",
          "label": "Charitable legacies",
          "unit": "£",
          "min": 0,
          "step": 1000,
          "default": "0"
        },
        {
          "name": "iht-g1",
          "type": "number",
          "label": "Gift 1 in the 7 years before death",
          "unit": "£",
          "min": 0,
          "step": 1000,
          "default": "0"
        },
        {
          "name": "iht-g1d",
          "type": "date",
          "label": "Gift 1 date",
          "unit": ""
        },
        {
          "name": "iht-g2",
          "type": "number",
          "label": "Gift 2 in the 7 years before death",
          "unit": "£",
          "min": 0,
          "step": 1000,
          "default": "0"
        },
        {
          "name": "iht-g2d",
          "type": "date",
          "label": "Gift 2 date",
          "unit": ""
        },
        {
          "name": "iht-g3",
          "type": "number",
          "label": "Gift 3 in the 7 years before death",
          "unit": "£",
          "min": 0,
          "step": 1000,
          "default": "0"
        },
        {
          "name": "iht-g3d",
          "type": "date",
          "label": "Gift 3 date",
          "unit": ""
        },
        {
          "name": "iht-descendant",
          "type": "checkbox",
          "label": "The residence is closely inherited by a direct descendant",
          "unit": "",
          "default": "1"
        },
        {
          "name": "iht-pension",
          "type": "checkbox",
          "label": "Include unused pension funds (deaths on or after 6 April 2027)",
          "unit": "",
          "default": "0"
        },
        {
          "name": "iht-nrbt",
          "type": "select-one",
          "label": "Unused nil-rate band transferred from a spouse",
          "unit": "%",
          "options": [
            "100",
            "0",
            "50"
          ],
          "default": "0"
        },
        {
          "name": "iht-rnrbt",
          "type": "select-one",
          "label": "Unused residence nil-rate band transferred from a spouse",
          "unit": "%",
          "options": [
            "100",
            "0",
            "50"
          ],
          "default": "0"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-inheritance-tax-estate-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-inheritance-tax-estate-calculator&iht-date=2026-09-01&iht-home=400000&iht-other=0&iht-cash=300000&iht-business=0&iht-agri=0"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "inheritance",
        "tax",
        "estate",
        "probate",
        "legal",
        "professional",
        "estimate",
        "nil-rate",
        "residence",
        "bands"
      ],
      "popularity": 6705,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "uk-limitation-period-calculator",
      "title": "⏳ Limitation & Claim Deadline Calculator (England & Wales)",
      "description": "Find the last date to bring a claim in England and Wales — contract, tort, personal injury, land, defamation, human rights and employment tribunal deadlines, with the ACAS pause.",
      "category": "legal-and-professional",
      "categoryName": "Legal & Professional",
      "url": "https://www.themostusefulsiteintheworld.com/tool/uk-limitation-period-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-limitation-period-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "lim-date",
          "type": "date",
          "label": "Date of breach, act or dismissal",
          "unit": ""
        },
        {
          "name": "lim-knowledge",
          "type": "date",
          "label": "Date of knowledge",
          "unit": "if later"
        },
        {
          "name": "lim-acas-a",
          "type": "date",
          "label": "ACAS early conciliation — Day A",
          "unit": "contact date"
        },
        {
          "name": "lim-acas-b",
          "type": "date",
          "label": "ACAS early conciliation — Day B (certificate received)",
          "unit": ""
        },
        {
          "name": "lim-type",
          "type": "select-one",
          "label": "Type of claim",
          "unit": "",
          "options": [
            "contract",
            "deed",
            "tort",
            "pi",
            "latent",
            "land",
            "judgment",
            "contribution",
            "defamation",
            "hra",
            "et-ud",
            "et-eq",
            "et-wages",
            "et-whistle",
            "et-red",
            "et-equalpay",
            "et-contract"
          ],
          "default": "contract"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-limitation-period-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-limitation-period-calculator&lim-type=contract"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "limitation",
        "period",
        "claim",
        "deadline",
        "england",
        "wales",
        "legal",
        "professional",
        "find",
        "last"
      ],
      "popularity": 6938,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "uk-parking-appeal-builder",
      "title": "🅿️ UK Parking Appeal Builder",
      "description": "A council Penalty Charge Notice and a private Parking Charge Notice look identical on the windscreen and obey completely different rules: different deadlines, different appeal bodies, different con...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/uk-parking-appeal-builder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-parking-appeal-builder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "upab-issued",
          "type": "date",
          "label": "Date on the notice",
          "unit": ""
        },
        {
          "name": "upab-amount",
          "type": "number",
          "label": "Full amount",
          "unit": "£",
          "min": 0,
          "max": 1000,
          "step": 1,
          "default": "100"
        },
        {
          "name": "upab-discount",
          "type": "number",
          "label": "Pay-early amount",
          "unit": "£",
          "min": 0,
          "max": 1000,
          "step": 1,
          "default": "60"
        },
        {
          "name": "upab-win",
          "type": "number",
          "label": "Win rate you assume",
          "unit": "%",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "40"
        },
        {
          "name": "upab-ref",
          "type": "text",
          "label": "Notice / PCN reference",
          "unit": ""
        },
        {
          "name": "upab-vrn",
          "type": "text",
          "label": "Vehicle registration",
          "unit": ""
        },
        {
          "name": "upab-where",
          "type": "text",
          "label": "Location on the notice",
          "unit": ""
        },
        {
          "name": "upab-kind",
          "type": "select-one",
          "label": "Type of notice",
          "unit": "",
          "options": [
            "council",
            "private"
          ],
          "default": "council"
        },
        {
          "name": "upab-stage",
          "type": "select-one",
          "label": "Where you are",
          "unit": "",
          "options": [
            "first",
            "nto",
            "rejected"
          ],
          "default": "first"
        }
      ],
      "outputs": [
        {
          "name": "upab-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-parking-appeal-builder&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-parking-appeal-builder&upab-amount=100&upab-discount=60&upab-win=40&upab-kind=council&upab-stage=first"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "parking",
        "appeal",
        "builder",
        "finance",
        "money",
        "council",
        "penalty",
        "charge",
        "notice",
        "private"
      ],
      "popularity": 6823,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "uk-postcode-formatter",
      "title": "📮 UK Postcode Formatter",
      "description": "Uppercase, insert the inward-code space, and check the Royal Mail pattern (e.g. LU1 2AB, EC1A 1BB, W1A 0AX). This is a format check only — it does not look up addresses.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/uk-postcode-formatter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-postcode-formatter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ukpc-in",
          "type": "text",
          "label": "Postcode",
          "unit": "",
          "default": "lu12ab"
        }
      ],
      "outputs": [
        {
          "name": "ukpc-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-postcode-formatter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-postcode-formatter&ukpc-in=lu12ab"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "postcode",
        "formatter",
        "productivity",
        "lifestyle",
        "uppercase",
        "insert",
        "inward-code",
        "space",
        "check",
        "royal"
      ],
      "popularity": 5543,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "uk-prescription-prepayment-checker",
      "title": "💊 Prescription Prepayment (PPC) Checker — England",
      "description": "More than one prescription a month? An NHS prepayment certificate caps the cost — but only past the break-even point. Enter your items and see whether paying per item, 3-month or 12-month PPC wins.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/uk-prescription-prepayment-checker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=uk-prescription-prepayment-checker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "upp-items",
          "type": "number",
          "label": "Items per month",
          "unit": "",
          "min": 0,
          "step": 0.5,
          "default": "2"
        },
        {
          "name": "upp-price",
          "type": "number",
          "label": "Charge per item",
          "unit": "£",
          "min": 0,
          "step": 0.01,
          "default": "9.90"
        },
        {
          "name": "upp-ppc3",
          "type": "number",
          "label": "3-month PPC",
          "unit": "£",
          "min": 0,
          "step": 0.01,
          "default": "32.05"
        },
        {
          "name": "upp-ppc12",
          "type": "number",
          "label": "12-month PPC",
          "unit": "£",
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    {
      "slug": "uuid-generator",
      "title": "🆔 UUID / GUID & Random ID Bulk Generator",
      "description": "Generate one or hundreds of UUID v4s, time-ordered UUID v7s, ULIDs, NanoIDs, short IDs or custom-pattern codes using the browser's cryptographic random source. Choose case, braces and separators, t...",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/uuid-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=uuid-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ugbg-count",
          "type": "number",
          "label": "How many",
          "unit": "",
          "min": 1,
          "max": 1000,
          "default": "5"
        },
        {
          "name": "ugbg-pattern",
          "type": "text",
          "label": "Pattern (X=letter, 9=digit, A=either)",
          "unit": "",
          "default": "XXXX-9999-AAAA"
        },
        {
          "name": "ugbg-upper",
          "type": "checkbox",
          "label": "UPPERCASE",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ugbg-braces",
          "type": "checkbox",
          "label": "{braces}",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ugbg-nohyphen",
          "type": "checkbox",
          "label": "No hyphens",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ugbg-quotes",
          "type": "checkbox",
          "label": "\"quoted\", comma-separated",
          "unit": "",
          "default": "0"
        },
        {
          "name": "ugbg-out",
          "type": "textarea",
          "label": "out",
          "unit": ""
        },
        {
          "name": "ugbg-type",
          "type": "select-one",
          "label": "ID type",
          "unit": "",
          "options": [
            "v4",
            "v7",
            "ulid",
            "nano",
            "short",
            "hex32",
            "hex64",
            "pattern"
          ],
          "default": "v4"
        }
      ],
      "outputs": [
        {
          "name": "ugbg-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=uuid-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=uuid-generator&ugbg-count=5&ugbg-pattern=XXXX-9999-AAAA&ugbg-upper=0&ugbg-braces=0&ugbg-nohyphen=0&ugbg-quotes=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "uuid",
        "guid",
        "random",
        "bulk",
        "algorithms",
        "computer",
        "science",
        "generate",
        "one",
        "hundreds"
      ],
      "popularity": 4479,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "van-de-graaff-electrostatic-generator",
      "title": "⚡ Van de Graaff Generator",
      "description": "Electrostatic museum exhibit. Rubber belt triboelectric charge transport accumulates up to 400 kV on the metal dome, firing high-voltage atmospheric sparks.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/van-de-graaff-electrostatic-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=van-de-graaff-electrostatic-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "vdg-slider-speed",
          "type": "range",
          "label": "slider speed",
          "unit": "",
          "min": 1,
          "max": 25,
          "default": "12"
        },
        {
          "name": "vdg-slider-humid",
          "type": "range",
          "label": "slider humid",
          "unit": "",
          "min": 10,
          "max": 90,
          "default": "25"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=van-de-graaff-electrostatic-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=van-de-graaff-electrostatic-generator&vdg-slider-speed=12&vdg-slider-humid=25"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "van",
        "graaff",
        "electrostatic",
        "science",
        "engineering",
        "museum",
        "exhibit",
        "rubber",
        "belt",
        "triboelectric"
      ],
      "popularity": 6728,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "vat-gst-sales-tax-calculator",
      "title": "💷 VAT / GST / Sales Tax Calculator",
      "description": "Add tax to a net price or extract tax from a gross (inc-VAT) figure. Presets cover UK VAT, common EU GST/VAT rates and US-style sales tax. Arithmetic only — not tax advice.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/vat-gst-sales-tax-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=vat-gst-sales-tax-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "vatx-amount",
          "type": "number",
          "label": "Amount",
          "unit": "",
          "min": 0,
          "step": 0.01,
          "default": "100"
        },
        {
          "name": "vatx-rate",
          "type": "number",
          "label": "Rate",
          "unit": "%",
          "min": 0,
          "max": 100,
          "step": 0.01,
          "default": "20"
        },
        {
          "name": "vatx-mode",
          "type": "select-one",
          "label": "The amount is",
          "unit": "",
          "options": [
            "net",
            "gross"
          ],
          "default": "net"
        },
        {
          "name": "vatx-preset",
          "type": "select-one",
          "label": "Preset",
          "unit": "",
          "options": [
            "20",
            "5",
            "0",
            "23",
            "19",
            "21",
            "20",
            "22",
            "10",
            "15",
            "5",
            "7.25",
            "8.875",
            "custom"
          ],
          "default": "20"
        }
      ],
      "outputs": [
        {
          "name": "vatx-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=vat-gst-sales-tax-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=vat-gst-sales-tax-calculator&vatx-amount=100&vatx-rate=20&vatx-mode=net&vatx-preset=20"
      },
      "formula": "Quick reference table at this rate Add: gross = net × (1 + rate). Extract: net = gross ÷ (1 +",
      "sources": [],
      "tags": [
        "vat",
        "gst",
        "sales",
        "tax",
        "finance",
        "money",
        "add",
        "net",
        "price",
        "extract"
      ],
      "popularity": 4930,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "vcard-contact-generator",
      "title": "🪪 vCard Generator",
      "description": "Build a vCard 3.0 you can save as .vcf and open on a phone. Stays in the browser — no address book is uploaded.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/vcard-contact-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=vcard-contact-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "vcrd-fn",
          "type": "text",
          "label": "Full name",
          "unit": "",
          "default": "Ada Lovelace"
        },
        {
          "name": "vcrd-org",
          "type": "text",
          "label": "Organisation",
          "unit": "",
          "default": "Analytical Engines"
        },
        {
          "name": "vcrd-tel",
          "type": "tel",
          "label": "Phone",
          "unit": "",
          "default": "+44 20 7946 0958"
        },
        {
          "name": "vcrd-em",
          "type": "email",
          "label": "Email",
          "unit": "",
          "default": "ada@example.com"
        },
        {
          "name": "vcrd-url",
          "type": "url",
          "label": "URL",
          "unit": "",
          "default": "https://example.com"
        }
      ],
      "outputs": [
        {
          "name": "vcrd-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=vcard-contact-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=vcard-contact-generator&vcrd-fn=Ada%20Lovelace&vcrd-org=Analytical%20Engines&vcrd-tel=%2B44%2020%207946%200958&vcrd-em=ada%40example.com&vcrd-url=https%3A%2F%2Fexample.com"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "vcard",
        "contact",
        "algorithms",
        "computer",
        "science",
        "build",
        "can",
        "save",
        "vcf",
        "open"
      ],
      "popularity": 6945,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "vector-3d-calculator",
      "title": "➗ 3D Vector Calculator — Dot, Cross & Triple Product Visualised",
      "description": "Enter up to three vectors and see them as glowing arrows in 3D. Instantly get the dot product, cross product, angle between them, projection, parallelogram area, scalar triple product and parallele...",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/vector-3d-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=vector-3d-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "vcc-cg",
          "type": "checkbox",
          "label": "Grid & axes",
          "unit": "",
          "default": "1"
        },
        {
          "name": "vcc-cc",
          "type": "checkbox",
          "label": "Use vector c",
          "unit": "",
          "default": "1"
        },
        {
          "name": "vcc-cd",
          "type": "checkbox",
          "label": "Drop lines to floor",
          "unit": "",
          "default": "1"
        },
        {
          "name": "vcc-show",
          "type": "select-one",
          "label": "Highlight",
          "unit": "",
          "options": [
            "cross",
            "proj",
            "triple",
            "plane",
            "sum"
          ],
          "default": "cross"
        }
      ],
      "outputs": [
        {
          "name": "vcc-hud",
          "type": "live"
        },
        {
          "name": "vcc-steps",
          "type": "live"
        },
        {
          "name": "vcc-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=vector-3d-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=vector-3d-calculator&vcc-cg=1&vcc-cc=1&vcc-cd=1&vcc-show=cross"
      },
      "formula": "Dot product a · b = aₓbₓ + a_yb_y +",
      "sources": [],
      "tags": [
        "vector",
        "dot",
        "cross",
        "triple",
        "product",
        "visualised",
        "mathematics",
        "enter",
        "three",
        "vectors"
      ],
      "popularity": 6428,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "vector-field-divergence-curl-3d",
      "title": "🌀 Vector Field, Divergence & Curl 3D",
      "description": "Type any 3D vector field F = (P, Q, R) and see it as a forest of glowing arrows with flowing particles. Calculates divergence and curl at any point, both numerically and visually, and integrates th...",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/vector-field-divergence-curl-3d.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=vector-field-divergence-curl-3d&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "vfd-P",
          "type": "text",
          "label": "P(x, y, z) — x component",
          "unit": "",
          "default": "-y"
        },
        {
          "name": "vfd-Q",
          "type": "text",
          "label": "Q(x, y, z) — y component",
          "unit": "",
          "default": "x"
        },
        {
          "name": "vfd-R",
          "type": "text",
          "label": "R(x, y, z) — z component",
          "unit": "",
          "default": "0.3*z"
        },
        {
          "name": "vfd-n",
          "type": "range",
          "label": "Arrow grid 5³",
          "unit": "",
          "min": 3,
          "max": 11,
          "step": 1,
          "default": "5"
        },
        {
          "name": "vfd-parts",
          "type": "range",
          "label": "Particles 250",
          "unit": "",
          "min": 0,
          "max": 1500,
          "step": 50,
          "default": "250"
        },
        {
          "name": "vfd-px",
          "type": "range",
          "label": "x₀ 1",
          "unit": "",
          "min": -2,
          "max": 2,
          "step": 0.05,
          "default": "1"
        },
        {
          "name": "vfd-py",
          "type": "range",
          "label": "y₀ 0",
          "unit": "",
          "min": -2,
          "max": 2,
          "step": 0.05,
          "default": "0"
        },
        {
          "name": "vfd-pz",
          "type": "range",
          "label": "z₀ 0",
          "unit": "",
          "min": -2,
          "max": 2,
          "step": 0.05,
          "default": "0"
        },
        {
          "name": "vfd-pr",
          "type": "range",
          "label": "Sphere radius 0.6",
          "unit": "",
          "min": 0.1,
          "max": 1.5,
          "step": 0.05,
          "default": "0.6"
        },
        {
          "name": "vfd-color",
          "type": "select-one",
          "label": "Colour arrows by",
          "unit": "",
          "options": [
            "mag",
            "div",
            "curl"
          ],
          "default": "mag"
        }
      ],
      "outputs": [
        {
          "name": "vfd-hud",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=vector-field-divergence-curl-3d&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=vector-field-divergence-curl-3d&vfd-P=-y&vfd-Q=x&vfd-R=0.3*z&vfd-n=5&vfd-parts=250&vfd-px=1"
      },
      "formula": "Divergence ∇·F = ∂P/∂x + ∂Q/∂y + ∂R/",
      "sources": [],
      "tags": [
        "vector",
        "field",
        "divergence",
        "curl",
        "mathematics",
        "type",
        "any",
        "see",
        "forest",
        "glowing"
      ],
      "popularity": 6566,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "venn-diagram-visualiser",
      "title": "🔵 Venn Diagram Visualiser",
      "description": "Type two lists and watch the Venn diagram draw itself — union, intersection, symmetric difference and per-zone items are listed.",
      "category": "mathematics",
      "categoryName": "Mathematics",
      "url": "https://www.themostusefulsiteintheworld.com/tool/venn-diagram-visualiser.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=venn-diagram-visualiser&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "vn-label-a",
          "type": "text",
          "label": "Label A",
          "unit": "",
          "default": "Fruit I own"
        },
        {
          "name": "vn-label-b",
          "type": "text",
          "label": "Label B",
          "unit": "",
          "default": "Fruit I like"
        },
        {
          "name": "vn-a",
          "type": "textarea",
          "label": "Set A (one item per line, or commas)",
          "unit": ""
        },
        {
          "name": "vn-b",
          "type": "textarea",
          "label": "Set B (one item per line, or commas)",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=venn-diagram-visualiser&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=venn-diagram-visualiser&vn-label-a=Fruit%20I%20own&vn-label-b=Fruit%20I%20like"
      },
      "formula": "A ∩ B (intersection) = the overlap · A − B = only in A · symmetric difference = in exactly one. Matches are case-",
      "sources": [],
      "tags": [
        "venn",
        "diagram",
        "visualiser",
        "mathematics",
        "type",
        "two",
        "lists",
        "watch",
        "draw",
        "itself"
      ],
      "popularity": 4183,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "vibration-isolation-transmissibility",
      "title": "🛡️ Vibration Isolator Designer",
      "description": "Design mechanical vibration isolators and shock mounts using force transmissibility ($T_R$). Calculate required static deflection ($\\delta_{st}$), isolation efficiency ($\\eta$), and operating frequ...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/vibration-isolation-transmissibility.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=vibration-isolation-transmissibility&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "vi-mass",
          "type": "number",
          "label": "Machine Mass",
          "unit": "$m$",
          "min": 1,
          "max": 100000,
          "step": 10,
          "default": "500"
        },
        {
          "name": "vi-rpm",
          "type": "number",
          "label": "Disturbance Speed",
          "unit": "$N$",
          "min": 60,
          "max": 60000,
          "step": 50,
          "default": "1800"
        },
        {
          "name": "vi-isolation-target",
          "type": "number",
          "label": "Target Isolation",
          "unit": "$\\eta$",
          "min": 10,
          "max": 99,
          "step": 1,
          "default": "90"
        },
        {
          "name": "vi-damping-ratio",
          "type": "select-one",
          "label": "Isolator Damping",
          "unit": "$\\zeta$",
          "options": [
            "0.01",
            "0.05",
            "0.15",
            "0.30"
          ],
          "default": "0.05"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=vibration-isolation-transmissibility&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=vibration-isolation-transmissibility&vi-mass=500&vi-rpm=1800&vi-isolation-target=90&vi-damping-ratio=0.05"
      },
      "formula": "Damping ($\\zeta$) Steel Coil Springs (ζ = 0.01) Neoprene / Rubber Pad (ζ = 0.05) High-",
      "sources": [],
      "tags": [
        "vibration",
        "isolation",
        "transmissibility",
        "isolator",
        "designer",
        "science",
        "engineering",
        "design",
        "mechanical",
        "isolators"
      ],
      "popularity": 4032,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "video-bitrate-file-size-calculator",
      "title": "🎬 Video Bitrate File Size",
      "description": "Estimate video file size from duration and video/audio bitrates, or solve for the bitrate that fits a size budget. Formula: size ≈ (video + audio) × time. Container overhead is ignored.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/video-bitrate-file-size-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=video-bitrate-file-size-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "vfsz-h",
          "type": "number",
          "label": "Hours",
          "unit": "",
          "min": 0,
          "default": "0"
        },
        {
          "name": "vfsz-m",
          "type": "number",
          "label": "Minutes",
          "unit": "",
          "min": 0,
          "default": "10"
        },
        {
          "name": "vfsz-s",
          "type": "number",
          "label": "Seconds",
          "unit": "",
          "min": 0,
          "default": "0"
        },
        {
          "name": "vfsz-vbr",
          "type": "number",
          "label": "Video bitrate",
          "unit": "Mbps",
          "min": 0,
          "default": "8"
        },
        {
          "name": "vfsz-abr",
          "type": "number",
          "label": "Audio bitrate",
          "unit": "kbps",
          "min": 0,
          "default": "192"
        },
        {
          "name": "vfsz-budget",
          "type": "number",
          "label": "Size budget",
          "unit": "MB, optional",
          "min": 0
        }
      ],
      "outputs": [
        {
          "name": "vfsz-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=video-bitrate-file-size-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=video-bitrate-file-size-calculator&vfsz-h=0&vfsz-m=10&vfsz-s=0&vfsz-vbr=8&vfsz-abr=192"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "video",
        "bitrate",
        "file",
        "size",
        "algorithms",
        "computer",
        "science",
        "estimate",
        "duration",
        "audio"
      ],
      "popularity": 6543,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "vinyl-sample-pitch-tempo-shifter",
      "title": "🎚️ Vinyl Sample Pitch & Semitone BPM Shifter",
      "description": "In golden era hip hop and modern boom-bap, pitching a vinyl sample directly changes its tempo (varispeed resampling). Calculate the exact mathematical relationship between Semitone pitch shift, cen...",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/vinyl-sample-pitch-tempo-shifter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=vinyl-sample-pitch-tempo-shifter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "type": "number",
          "label": "Original Sample BPM",
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          "max": 250,
          "step": 0.1,
          "default": "76.0"
        },
        {
          "name": "vst-semitones",
          "type": "number",
          "label": "Pitch Shift",
          "unit": "Semitones",
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          "max": 24,
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        {
          "name": "vst-target-bpm",
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          "label": "Desired Target BPM",
          "unit": "",
          "min": 40,
          "max": 250,
          "step": 0.1,
          "default": "90.0"
        },
        {
          "name": "vst-calc-mode",
          "type": "select-one",
          "label": "Calculation Mode",
          "unit": "",
          "options": [
            "pitch-to-bpm",
            "bpm-to-pitch",
            "turntable"
          ],
          "default": "pitch-to-bpm"
        },
        {
          "name": "vst-turntable-preset",
          "type": "select-one",
          "label": "Turntable / Sampler Trick",
          "unit": "",
          "options": [
            "sp1200-speedup",
            "sp1200-slowdown",
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            "technics-plus8",
            "technics-minus8"
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          "default": "sp1200-speedup"
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "vinyl",
        "sample",
        "pitch",
        "tempo",
        "shifter",
        "semitone",
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        "music",
        "audio",
        "golden"
      ],
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "vo2max",
      "title": "🏃 VO₂ Max Calculator",
      "description": "Estimate your VO₂ Max — a measure of aerobic fitness. The higher the value, the better your cardiovascular endurance.",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/vo2max.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=vo2max&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "max": 120,
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        {
          "name": "vo2max-resting",
          "type": "number",
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          "unit": "bpm",
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          "max": 200,
          "default": "60"
        }
      ],
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      },
      "formula": "How it works Formula: VO₂ Max = 15 × (HRmax ÷ HRrest). HRmax ≈ 220 − age. Categories: Elite 55+",
      "sources": [],
      "tags": [
        "vo2max",
        "max",
        "health",
        "fitness",
        "estimate",
        "measure",
        "aerobic",
        "higher",
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        "better"
      ],
      "popularity": 4221,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "vocabulary-trainer",
      "title": "Vocabulary Trainer",
      "description": "Add words with definitions and examples, practise with flashcards or quick quizzes, and track progress with simple Leitner boxes. Data is stored locally in this card.",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/vocabulary-trainer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=vocabulary-trainer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "vt-word",
          "type": "text",
          "label": "Word",
          "unit": ""
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        {
          "name": "vt-def",
          "type": "text",
          "label": "Definition",
          "unit": ""
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        {
          "name": "vt-ex",
          "type": "text",
          "label": "Example sentence",
          "unit": ""
        },
        {
          "name": "vt-tags",
          "type": "text",
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          "unit": ""
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      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=vocabulary-trainer&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "vocabulary",
        "trainer",
        "writing",
        "language",
        "add",
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        "definitions",
        "examples",
        "practise",
        "flashcards"
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      "popularity": 5498,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "vocal-compression-sidechain-calculator",
      "title": "🎙️ Hip Hop Vocal & Sidechain Compressor Calculator",
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      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/vocal-compression-sidechain-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=vocal-compression-sidechain-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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        {
          "name": "vsc-comp-target",
          "type": "select-one",
          "label": "Compression Target",
          "unit": "",
          "options": [
            "sidechain",
            "vocal-trap",
            "vocal-boombap",
            "bus-glue"
          ],
          "default": "sidechain"
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        {
          "name": "vsc-subdiv",
          "type": "select-one",
          "label": "Release Musical Note",
          "unit": "",
          "options": [
            "16th",
            "8th",
            "32nd",
            "triplet"
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      },
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      "sources": [],
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        "vocal",
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        "sidechain",
        "hip",
        "hop",
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        "music",
        "audio",
        "compressors",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "voice-clone-scam-drill",
      "title": "☎️ Could an AI Voice Clone Trick Your Family?",
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      "category": "ai-and-autonomous-agents",
      "categoryName": "AI & Autonomous Agents",
      "url": "https://www.themostusefulsiteintheworld.com/tool/voice-clone-scam-drill.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=voice-clone-scam-drill&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "voice-clone-scam-drill-share-text",
          "type": "textarea",
          "label": "Share text — includes only the practice score, not your answers or family details",
          "unit": ""
        },
        {
          "name": "voice-clone-scam-drill-plan-text",
          "type": "textarea",
          "label": "Copyable plan — contains no names, contacts or secret phrase",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "voice-clone-scam-drill-feedback",
          "type": "live"
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        {
          "name": "voice-clone-scam-drill-plan-progress",
          "type": "live"
        },
        {
          "name": "voice-clone-scam-drill-status",
          "type": "live"
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        {
          "name": "voice-clone-scam-drill-score",
          "type": "output"
        },
        {
          "name": "voice-clone-scam-drill-result",
          "type": "output"
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        {
          "name": "voice-clone-scam-drill-copy-score",
          "type": "output"
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=voice-clone-scam-drill&<id>=<value>",
        "runs": true
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "voice",
        "clone",
        "scam",
        "drill",
        "could",
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        "family",
        "autonomous",
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      "popularity": 6627,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "volcanic-eruption-simulator",
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      "category": "interactive-art-and-living-worlds",
      "categoryName": "Interactive Art & Living Worlds",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=volcanic-eruption-simulator&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "label": "slider vis",
          "unit": "",
          "min": 4,
          "max": 9.5,
          "step": 0.1,
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        },
        {
          "name": "vol-slider-gas",
          "type": "range",
          "label": "slider gas",
          "unit": "",
          "min": 0.2,
          "max": 8,
          "step": 0.1,
          "default": "1.2"
        },
        {
          "name": "vol-slider-vent",
          "type": "range",
          "label": "slider vent",
          "unit": "",
          "min": 5,
          "max": 80,
          "step": 5,
          "default": "25"
        },
        {
          "name": "vol-slider-slope",
          "type": "range",
          "label": "slider slope",
          "unit": "",
          "min": 4,
          "max": 35,
          "step": 1,
          "default": "10"
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      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=volcanic-eruption-simulator&<id>=<value>",
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      },
      "formula": "Exit velocity from chamber overpressure v = √(2ΔP/ρ). Lava flow: laminar channel speed u = ρg·sinθ·h²/",
      "sources": [],
      "tags": [
        "volcanic",
        "eruption",
        "simulator",
        "volcano",
        "interactive",
        "art",
        "living",
        "worlds",
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        "stratovolcano"
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      "popularity": 4073,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "volleyball-score-sheet",
      "title": "🏐 Volleyball Score Sheet & Rotation",
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      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/volleyball-score-sheet.html",
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      "standaloneUrl": null,
      "inputs": [
        {
          "name": "vbl-names",
          "type": "textarea",
          "label": "Players in serving order (optional, one per line &mdash; 6 total)",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "vbl-board",
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        {
          "name": "vbl-score",
          "type": "output"
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      ],
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        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "volleyball",
        "score",
        "sheet",
        "rotation",
        "sports",
        "rally",
        "scoring",
        "win",
        "two",
        "fifth"
      ],
      "popularity": 5779,
      "featured": false,
      "updated": "2026-09-19"
    },
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      "slug": "voltage-divider-calculator",
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      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/voltage-divider-calculator.html",
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          "min": 0,
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        },
        {
          "name": "vdiv-r1",
          "type": "number",
          "label": "R1 (top) Ω",
          "unit": "",
          "min": 0,
          "default": "10000"
        },
        {
          "name": "vdiv-r2",
          "type": "number",
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          "min": 0,
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        },
        {
          "name": "vdiv-vout",
          "type": "number",
          "label": "V out",
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          "min": 0
        }
      ],
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        {
          "name": "vdiv-out",
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      ],
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      },
      "formula": "Voltage Divider V out = V in × R2 / (R1 +",
      "sources": [],
      "tags": [
        "voltage",
        "divider",
        "science",
        "engineering",
        "vout",
        "vin",
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        "resistor",
        "supply",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "voltage-drop",
      "title": "⚡ Voltage Drop Calculator",
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      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/voltage-drop.html",
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          "label": "Length",
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        },
        {
          "name": "vd-size",
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          "label": "Conductor Area",
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          "step": 0.1,
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          "name": "vd-voltage",
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          "default": "230"
        },
        {
          "name": "vd-output",
          "type": "textarea",
          "label": "Results will appear here...",
          "unit": ""
        },
        {
          "name": "vd-material",
          "type": "select-one",
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          "unit": "",
          "options": [
            "copper",
            "aluminum"
          ],
          "default": "copper"
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      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=voltage-drop&<id>=<value>",
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      },
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      "sources": [],
      "tags": [
        "voltage",
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      "popularity": 5354,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "voxel-monolith-3d-time-capsule",
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      "category": "interactive-art-and-living-worlds",
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          "min": 0,
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        {
          "name": "vm-history-slider",
          "type": "range",
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          "unit": "",
          "min": 1,
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        {
          "name": "vm-material",
          "type": "select-one",
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          "options": [
            "gold",
            "cyan",
            "purple",
            "emerald",
            "obsidian",
            "white"
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          "default": "gold"
        },
        {
          "name": "vm-action-mode",
          "type": "select-one",
          "label": "Sculpting Action",
          "unit": "",
          "options": [
            "add",
            "carve"
          ],
          "default": "add"
        },
        {
          "name": "vm-preset-select",
          "type": "select-one",
          "label": "preset select",
          "unit": "",
          "options": [
            "temple",
            "tower",
            "portal"
          ],
          "default": "temple"
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      ],
      "outputs": [],
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "voxel",
        "monolith",
        "time",
        "capsule",
        "voxelmonolith",
        "interactive",
        "art",
        "living",
        "worlds",
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "waist-to-height-ratio",
      "title": "📏 Waist-to-Height Ratio",
      "description": "NICE NG246 uses waist ÷ height as a central-adiposity screen for adults with BMI under 35. Measure the waist at the midpoint between the last rib and the hip bone. Not a diagnosis.",
      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
      "url": "https://www.themostusefulsiteintheworld.com/tool/waist-to-height-ratio.html",
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          "label": "Rainfall in the period",
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          "default": "25"
        },
        {
          "name": "wpt-lpd",
          "type": "select-one",
          "label": "Litres per person/day",
          "unit": "",
          "options": [
            "3",
            "5",
            "10",
            "20"
          ],
          "default": "5"
        },
        {
          "name": "wpt-source",
          "type": "select-one",
          "label": "Emergency water source",
          "unit": "",
          "options": [
            "tap",
            "rain",
            "spring",
            "river",
            "flood",
            "none"
          ],
          "default": "tap"
        },
        {
          "name": "wpt-clarity",
          "type": "select-one",
          "label": "How clear is it?",
          "unit": "",
          "options": [
            "clear",
            "cloudy"
          ],
          "default": "clear"
        },
        {
          "name": "wpt-bleach",
          "type": "select-one",
          "label": "Bleach chlorine strength",
          "unit": "%",
          "options": [
            "2.5",
            "5",
            "8.25",
            "0"
          ],
          "default": "5"
        }
      ],
      "outputs": [
        {
          "name": "wpt-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=water-purification-treatment-calculator&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "water",
        "purification",
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        "planner",
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      "featured": false,
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    },
    {
      "slug": "water-surface-tension-capillary",
      "title": "🧪 Water Surface Tension Lab",
      "description": "Explore water's extraordinary cohesive hydrogen-bond surface tension ($\\sigma = 72.86\\text{ mN/m}$). Calculate Jurin's Law capillary rise ($h = \\frac{2\\sigma\\cos\\theta}{\\rho g r}$) and Young-Laplac...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/water-surface-tension-capillary.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=water-surface-tension-capillary&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "stc-temp",
          "type": "number",
          "label": "Water Temp",
          "unit": "$T$",
          "min": 0,
          "max": 100,
          "step": 1,
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        },
        {
          "name": "stc-radius",
          "type": "number",
          "label": "Capillary Tube Radius",
          "unit": "$r$",
          "min": 0.05,
          "max": 5,
          "step": 0.05,
          "default": "0.5"
        },
        {
          "name": "stc-contact-angle",
          "type": "number",
          "label": "Contact Angle",
          "unit": "$\\theta$",
          "min": 0,
          "max": 180,
          "step": 5,
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        },
        {
          "name": "stc-surfactant",
          "type": "select-one",
          "label": "Surfactant / Additive",
          "unit": "",
          "options": [
            "none",
            "mild_soap",
            "high_surfactant",
            "salt"
          ],
          "default": "none"
        }
      ],
      "outputs": [],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=water-surface-tension-capillary&<id>=<value>",
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      },
      "formula": "N/m}$). Calculate Jurin's Law capillary rise ($h = \\frac{2\\sigma\\cos\\theta}{\\rho g r}$) and Young-",
      "sources": [],
      "tags": [
        "water",
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        "capillary",
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      "popularity": 6264,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "wbtb-rem-sleep-calculator",
      "title": "🌙 WBTB Lucid Dream REM Planner",
      "description": "Wake-Back-To-Bed (WBTB) ultradian cycle planner based on Stanford sleep research. Targets Cycles 4 & 5 when REM duration and dream vividness peak by over 400%.",
      "category": "lucid-dreaming-and-sleep",
      "categoryName": "Lucid Dreaming & Sleep",
      "url": "https://www.themostusefulsiteintheworld.com/tool/wbtb-rem-sleep-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=wbtb-rem-sleep-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wbtb-bedtime",
          "type": "time",
          "label": "Planned Bedtime",
          "unit": "",
          "default": "23:30"
        },
        {
          "name": "wbtb-latency",
          "type": "select-one",
          "label": "Time to Fall Asleep",
          "unit": "",
          "options": [
            "10",
            "15",
            "25",
            "40"
          ],
          "default": "15"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=wbtb-rem-sleep-calculator&<id>=<value>",
        "runs": false,
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "wbtb",
        "rem",
        "sleep",
        "lucid",
        "dream",
        "planner",
        "dreaming",
        "wake-back-to-bed",
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      ],
      "popularity": 4351,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "wedding-budget-planner",
      "title": "💒 Wedding Budget Planner",
      "description": "Set the total you are actually willing to spend, choose your guest count, and get a per-category breakdown with sensible starting percentages you can push around. The cost-per-guest number keeps ev...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=wedding-budget-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wbp-total",
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          "label": "Total budget",
          "unit": "£",
          "min": 0,
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          "default": "18000"
        },
        {
          "name": "wbp-guests",
          "type": "number",
          "label": "Guests",
          "unit": "",
          "min": 0,
          "step": 1,
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        },
        {
          "name": "wbp-preset",
          "type": "select-one",
          "label": "Start from",
          "unit": "",
          "options": [
            "classic",
            "foodie",
            "minimal"
          ],
          "default": "classic"
        }
      ],
      "outputs": [
        {
          "name": "wbp-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=wedding-budget-planner&<id>=<value>",
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      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "wedding",
        "budget",
        "planner",
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      "popularity": 4147,
      "featured": false,
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    },
    {
      "slug": "weight-based-dose-calculator",
      "title": "💉 Weight-Based Dose & Volume Calculator",
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      "category": "health-and-fitness",
      "categoryName": "Health & Fitness",
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      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=weight-based-dose-calculator&embed=1",
      "standaloneUrl": null,
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        {
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        {
          "name": "wbdose-dose",
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          "min": 0,
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        },
        {
          "name": "wbdose-div",
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          "min": 1,
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        },
        {
          "name": "wbdose-conc",
          "type": "number",
          "label": "Strength",
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          "min": 0,
          "default": "50"
        },
        {
          "name": "wbdose-max",
          "type": "number",
          "label": "Max single dose (mg) — optional",
          "unit": "",
          "min": 0
        },
        {
          "name": "wbdose-max24",
          "type": "number",
          "label": "Max per 24 h (mg) — optional",
          "unit": "",
          "min": 0
        },
        {
          "name": "wbdose-dunit",
          "type": "select-one",
          "label": "Dose unit",
          "unit": "",
          "options": [
            "mg-kg",
            "mg-kg-day",
            "mcg-kg",
            "mg"
          ],
          "default": "mg-kg"
        }
      ],
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        {
          "name": "wbdose-out",
          "type": "live"
        }
      ],
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        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=weight-based-dose-calculator&<id>=<value>",
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      },
      "formula": "What it calculates. Dose in mg = mg/kg × weight. Volume in mL = dose in mg ÷ strength in mg/",
      "sources": [],
      "tags": [
        "weight",
        "based",
        "dose",
        "weight-based",
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        "health",
        "fitness",
        "milligrams",
        "millilitres",
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      "popularity": 5533,
      "featured": false,
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    },
    {
      "slug": "weightlifting-sinclair-score",
      "title": "🏋️ Weightlifting Sinclair Score",
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      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/weightlifting-sinclair-score.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=weightlifting-sinclair-score&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "label": "Bodyweight",
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          "step": 0.01,
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        },
        {
          "name": "snc-total",
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          "label": "Total",
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          "step": 0.01,
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        },
        {
          "name": "snc-sex",
          "type": "select-one",
          "label": "Sex",
          "unit": "",
          "options": [
            "M",
            "F"
          ],
          "default": "M"
        }
      ],
      "outputs": [
        {
          "name": "snc-out",
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        }
      ],
      "prefill": {
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      },
      "formula": "Sinclair Total = total ×",
      "sources": [],
      "tags": [
        "weightlifting",
        "sinclair",
        "score",
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        "lets",
        "lifters",
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      "popularity": 5396,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "what-year-are-you",
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      "description": "Discover your internet personality era based on your tastes, habits, and vibes. ← Share your result!",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/what-year-are-you.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=what-year-are-you&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "share-link",
          "type": "text",
          "label": "link",
          "unit": "",
          "default": "https://whichyear.me/results/2016-vine-era"
        }
      ],
      "outputs": [
        {
          "name": "viral-result",
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        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=what-year-are-you&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "what",
        "year",
        "which",
        "productivity",
        "lifestyle",
        "discover",
        "internet",
        "personality",
        "era",
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      "popularity": 6769,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "wheelbuilding-spoke-length-calculator",
      "title": "🛞 Wheelbuilding Spoke Length & Tension Calculator",
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      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/wheelbuilding-spoke-length-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=wheelbuilding-spoke-length-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
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          "step": 0.5,
          "default": "600"
        },
        {
          "name": "wslc-fdl",
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          "label": "Left flange diameter",
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          "min": 10,
          "max": 200,
          "step": 0.5,
          "default": "45"
        },
        {
          "name": "wslc-fdr",
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          "label": "Right flange diameter",
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          "min": 10,
          "max": 200,
          "step": 0.5,
          "default": "45"
        },
        {
          "name": "wslc-cl",
          "type": "number",
          "label": "Centre to left flange",
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          "min": 5,
          "max": 120,
          "step": 0.5,
          "default": "36"
        },
        {
          "name": "wslc-cr",
          "type": "number",
          "label": "Centre to right flange",
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          "min": 5,
          "max": 120,
          "step": 0.5,
          "default": "20"
        },
        {
          "name": "wslc-hole",
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          "label": "Hub hole diameter",
          "unit": "mm",
          "min": 1,
          "max": 6,
          "step": 0.1,
          "default": "2.6"
        },
        {
          "name": "wslc-tension",
          "type": "number",
          "label": "Target drive-side tension",
          "unit": "kgf",
          "min": 40,
          "max": 200,
          "step": 5,
          "default": "110"
        },
        {
          "name": "wslc-preset",
          "type": "select-one",
          "label": "Start from a typical build",
          "unit": ""
        },
        {
          "name": "wslc-spokes",
          "type": "select-one",
          "label": "Spoke count",
          "unit": "",
          "options": [
            "16",
            "20",
            "24",
            "28",
            "32",
            "36",
            "40",
            "48"
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        },
        {
          "name": "wslc-cross",
          "type": "select-one",
          "label": "Lacing pattern",
          "unit": "",
          "options": [
            "0",
            "1",
            "2",
            "3",
            "4"
          ],
          "default": "3"
        }
      ],
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        {
          "name": "wslc-result",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=wheelbuilding-spoke-length-calculator&<id>=<value>",
        "runs": false,
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      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "wheelbuilding",
        "spoke",
        "length",
        "tension",
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        "engineering",
        "three-dimensional",
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        "runs",
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      "featured": false,
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    },
    {
      "slug": "white-noise-sleep-sound-generator",
      "title": "🌧️ White, Pink & Brown Noise — Sleep & Focus Sound Machine",
      "description": "A sound machine that runs in the browser: white, pink and brown noise plus rain, ocean, wind and a fan, mixed to taste, with a sleep timer that fades out gently. Every sound is synthesised on your ...",
      "category": "lucid-dreaming-and-sleep",
      "categoryName": "Lucid Dreaming & Sleep",
      "url": "https://www.themostusefulsiteintheworld.com/tool/white-noise-sleep-sound-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=white-noise-sleep-sound-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "label": "Master volume 50%",
          "unit": "",
          "min": 0,
          "max": 100,
          "default": "50"
        },
        {
          "name": "noise-tone",
          "type": "range",
          "label": "Tone — muffled ↔ bright balanced",
          "unit": "",
          "min": 0,
          "max": 100,
          "default": "60"
        },
        {
          "name": "noise-timer",
          "type": "select-one",
          "label": "Sleep timer",
          "unit": "",
          "options": [
            "0",
            "15",
            "30",
            "45",
            "60",
            "90",
            "120",
            "480"
          ],
          "default": "0"
        }
      ],
      "outputs": [
        {
          "name": "noise-remaining",
          "type": "live"
        },
        {
          "name": "noise-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=white-noise-sleep-sound-generator&<id>=<value>",
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      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "white",
        "noise",
        "sleep",
        "sound",
        "pink",
        "brown",
        "focus",
        "machine",
        "lucid",
        "dreaming"
      ],
      "popularity": 4736,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "wholesale-pricing-margin-calculator",
      "title": "🏷️ Wholesale Pricing & Margin",
      "description": "Set retail and wholesale prices while seeing your margin and the retailer’s margin side by side. All calculations stay in your browser.",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/wholesale-pricing-margin-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=wholesale-pricing-margin-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wholesale-pricing-margin-calculator-cost",
          "type": "number",
          "label": "Unit cost",
          "unit": "£",
          "default": "12"
        },
        {
          "name": "wholesale-pricing-margin-calculator-wholesale",
          "type": "number",
          "label": "Wholesale price",
          "unit": "£",
          "default": "24"
        },
        {
          "name": "wholesale-pricing-margin-calculator-retail",
          "type": "number",
          "label": "Retail price",
          "unit": "£",
          "default": "48"
        },
        {
          "name": "wholesale-pricing-margin-calculator-units",
          "type": "number",
          "label": "Order quantity",
          "unit": "",
          "default": "100"
        }
      ],
      "outputs": [
        {
          "name": "wholesale-pricing-margin-calculator-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=wholesale-pricing-margin-calculator&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=wholesale-pricing-margin-calculator&wholesale-pricing-margin-calculator-cost=12&wholesale-pricing-margin-calculator-wholesale=24&wholesale-pricing-margin-calculator-retail=48&wholesale-pricing-margin-calculator-units=100&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "wholesale",
        "pricing",
        "margin",
        "finance",
        "money",
        "set",
        "retail",
        "prices",
        "while",
        "seeing"
      ],
      "popularity": 5685,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "why-sky-is-blue-lab",
      "title": "🌞 Why Is The Sky Blue? — Rayleigh Scattering Lab",
      "description": "Air molecules scatter sunlight in every direction — and short wavelengths scatter about 4× more than long ones. Slide the Sun down and watch the same physics hand the sky back as a sunset.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/why-sky-is-blue-lab.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=why-sky-is-blue-lab&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "sky-elev",
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          "label": "Sun elevation 25°",
          "unit": "",
          "min": 3,
          "max": 90,
          "default": "25"
        },
        {
          "name": "sky-clear",
          "type": "range",
          "label": "Air density (mountain ↔ sea level) 100%",
          "unit": "",
          "min": 40,
          "max": 160,
          "default": "100"
        },
        {
          "name": "sky-haze",
          "type": "range",
          "label": "Haze / pollution 0%",
          "unit": "",
          "min": 0,
          "max": 100,
          "default": "0"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=why-sky-is-blue-lab&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=why-sky-is-blue-lab&sky-elev=25&sky-clear=100&sky-haze=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "why",
        "sky",
        "blue",
        "lab",
        "rayleigh",
        "scattering",
        "science",
        "engineering",
        "air",
        "molecules"
      ],
      "popularity": 4068,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "wifi-qr-generator",
      "title": "📶 Wi-Fi QR Pass Generator",
      "description": "Generate an instant, scannable QR code for your home, studio, or office Wi-Fi network. Guests can scan with their phone camera to connect immediately without typing complicated passwords. 🔒 Genuin...",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/wifi-qr-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=wifi-qr-generator&embed=1",
      "standaloneUrl": "https://www.themostusefulsiteintheworld.com/tools/wifi-qr-generator.html",
      "inputs": [
        {
          "name": "wifi-ssid",
          "type": "text",
          "label": "Network Name",
          "unit": "SSID",
          "default": "Studio_Guest"
        },
        {
          "name": "wifi-password",
          "type": "text",
          "label": "Wi-Fi Password",
          "unit": "",
          "default": "UndergroundSound2026"
        },
        {
          "name": "wifi-hidden",
          "type": "checkbox",
          "label": "Hidden Network (SSID is not broadcast)",
          "unit": "",
          "default": "0"
        },
        {
          "name": "wifi-encryption",
          "type": "select-one",
          "label": "Security Type",
          "unit": "",
          "options": [
            "WPA",
            "WEP",
            "nopass"
          ],
          "default": "WPA"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=wifi-qr-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=wifi-qr-generator&wifi-ssid=Studio_Guest&wifi-password=UndergroundSound2026&wifi-hidden=0&wifi-encryption=WPA"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "wifi",
        "wi-fi",
        "pass",
        "productivity",
        "lifestyle",
        "generate",
        "instant",
        "scannable",
        "code",
        "home"
      ],
      "popularity": 9410,
      "featured": true,
      "updated": "2026-09-19"
    },
    {
      "slug": "wifi-speed-bandwidth-calculator",
      "title": "📶 WiFi Speed & Download Time Calculator",
      "description": "Calculate exact file download and upload durations, test bandwidth capacity for simultaneous 4K streams and video calls, and estimate mobile data cap exhaustion.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/wifi-speed-bandwidth-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=wifi-speed-bandwidth-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wsbc-size-val",
          "type": "number",
          "label": "File Size",
          "unit": "",
          "min": 0.01,
          "default": "25"
        },
        {
          "name": "wsbc-speed-val",
          "type": "number",
          "label": "Connection Speed",
          "unit": "",
          "min": 0.1,
          "default": "100"
        },
        {
          "name": "wsbc-size-unit",
          "type": "select-one",
          "label": "File size unit",
          "unit": "",
          "options": [
            "MB",
            "GB",
            "TB"
          ],
          "default": "GB"
        },
        {
          "name": "wsbc-speed-unit",
          "type": "select-one",
          "label": "Speed unit",
          "unit": "",
          "options": [
            "Kbps",
            "Mbps",
            "Gbps"
          ],
          "default": "Mbps"
        },
        {
          "name": "wsbc-overhead",
          "type": "select-one",
          "label": "Network Overhead",
          "unit": "",
          "options": [
            "0",
            "10",
            "25"
          ],
          "default": "10"
        }
      ],
      "outputs": [
        {
          "name": "wsbc-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=wifi-speed-bandwidth-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=wifi-speed-bandwidth-calculator&wsbc-size-val=25&wsbc-speed-val=100&wsbc-size-unit=GB&wsbc-speed-unit=Mbps&wsbc-overhead=10"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "wifi",
        "speed",
        "bandwidth",
        "download",
        "time",
        "algorithms",
        "computer",
        "science",
        "calculate",
        "exact"
      ],
      "popularity": 4060,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "wild-hypnagogia-tracker",
      "title": "🌀 WILD Hypnagogia Transition",
      "description": "Wake-Initiated Lucid Dreaming (WILD) mental anchor simulator. Ride the borderline hypnagogic transition directly from conscious waking state into full REM dream creation.",
      "category": "lucid-dreaming-and-sleep",
      "categoryName": "Lucid Dreaming & Sleep",
      "url": "https://www.themostusefulsiteintheworld.com/tool/wild-hypnagogia-tracker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=wild-hypnagogia-tracker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wild-anchor",
          "type": "select-one",
          "label": "Consciousness Anchor",
          "unit": "",
          "options": [
            "visual",
            "breath",
            "micro",
            "sound"
          ],
          "default": "visual"
        },
        {
          "name": "wild-stage-nav",
          "type": "select-one",
          "label": "Current Stage",
          "unit": "",
          "options": [
            "1",
            "2",
            "3",
            "4",
            "5"
          ],
          "default": "1"
        }
      ],
      "outputs": [
        {
          "name": "wild-count-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=wild-hypnagogia-tracker&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=wild-hypnagogia-tracker&wild-anchor=visual&wild-stage-nav=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "wild",
        "hypnagogia",
        "tracker",
        "transition",
        "lucid",
        "dreaming",
        "sleep",
        "wake-initiated",
        "mental",
        "anchor"
      ],
      "popularity": 4147,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "wildfire-behaviour-lab",
      "title": "🔥 Wildfire Behaviour Lab",
      "description": "A fuel-bed cellular automaton with Rothermel-style spread. Set wind, fuel moisture, fuel load and slope, then click the terrain to ignite. Watch the fire front, smoke column, ember spotting and the...",
      "category": "interactive-art-and-living-worlds",
      "categoryName": "Interactive Art & Living Worlds",
      "url": "https://www.themostusefulsiteintheworld.com/tool/wildfire-behaviour-lab.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=wildfire-behaviour-lab&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wfr-slider-wind",
          "type": "range",
          "label": "slider wind",
          "unit": "",
          "min": 0,
          "max": 20,
          "step": 0.5,
          "default": "10"
        },
        {
          "name": "wfr-slider-dir",
          "type": "range",
          "label": "slider dir",
          "unit": "",
          "min": 0,
          "max": 360,
          "step": 5,
          "default": "90"
        },
        {
          "name": "wfr-slider-moist",
          "type": "range",
          "label": "slider moist",
          "unit": "",
          "min": 3,
          "max": 30,
          "step": 0.5,
          "default": "8"
        },
        {
          "name": "wfr-slider-load",
          "type": "range",
          "label": "slider load",
          "unit": "",
          "min": 0.2,
          "max": 4,
          "step": 0.1,
          "default": "1.5"
        },
        {
          "name": "wfr-slider-slope",
          "type": "range",
          "label": "slider slope",
          "unit": "",
          "min": -15,
          "max": 45,
          "step": 1,
          "default": "10"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=wildfire-behaviour-lab&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=wildfire-behaviour-lab&wfr-slider-wind=10&wfr-slider-dir=90&wfr-slider-moist=8&wfr-slider-load=1.5&wfr-slider-slope=10"
      },
      "formula": "Spread uses a simplified Rothermel-style rate: R = R₀·exp(0.09·w)·exp(−0.09·fm)·(1+",
      "sources": [],
      "tags": [
        "wildfire",
        "behaviour",
        "lab",
        "interactive",
        "art",
        "living",
        "worlds",
        "fuel-bed",
        "cellular",
        "automaton"
      ],
      "popularity": 4408,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "will-it-fit-furniture-path",
      "title": "🛋️ Will It Fit? Sofa & Furniture Path Checker",
      "description": "Checks the whole route, not one door: a doorway, the tilt-and-pivot through it, then a 90° hallway corner — the place sofas actually get stuck. Uses the real geometry of a box turning a corner and ...",
      "category": "home-and-diy",
      "categoryName": "Home & DIY",
      "url": "https://www.themostusefulsiteintheworld.com/tool/will-it-fit-furniture-path.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=will-it-fit-furniture-path&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "will-it-fit-furniture-path-L",
          "type": "number",
          "label": "Length",
          "unit": "longest side",
          "min": 1,
          "step": 0.5,
          "default": "210"
        },
        {
          "name": "will-it-fit-furniture-path-D",
          "type": "number",
          "label": "Depth (front to back)",
          "unit": "",
          "min": 1,
          "step": 0.5,
          "default": "90"
        },
        {
          "name": "will-it-fit-furniture-path-H",
          "type": "number",
          "label": "Height (floor to top of back)",
          "unit": "",
          "min": 1,
          "step": 0.5,
          "default": "85"
        },
        {
          "name": "will-it-fit-furniture-path-A",
          "type": "number",
          "label": "Arm/back height for diagonal",
          "unit": "0 if boxy",
          "min": 0,
          "step": 0.5,
          "default": "45"
        },
        {
          "name": "will-it-fit-furniture-path-dw",
          "type": "number",
          "label": "Clear width",
          "unit": "stop to stop",
          "min": 1,
          "step": 0.5,
          "default": "76"
        },
        {
          "name": "will-it-fit-furniture-path-dh",
          "type": "number",
          "label": "Clear height",
          "unit": "",
          "min": 1,
          "step": 0.5,
          "default": "198"
        },
        {
          "name": "will-it-fit-furniture-path-h1",
          "type": "number",
          "label": "Width of corridor you arrive in",
          "unit": "",
          "min": 0,
          "step": 0.5,
          "default": "100"
        },
        {
          "name": "will-it-fit-furniture-path-h2",
          "type": "number",
          "label": "Width of corridor you turn into",
          "unit": "",
          "min": 0,
          "step": 0.5,
          "default": "95"
        },
        {
          "name": "will-it-fit-furniture-path-ch",
          "type": "number",
          "label": "Ceiling height there",
          "unit": "",
          "min": 0,
          "step": 0.5,
          "default": "240"
        },
        {
          "name": "will-it-fit-furniture-path-unit",
          "type": "select-one",
          "label": "Units centimetres inches",
          "unit": "",
          "options": [
            "cm",
            "in"
          ],
          "default": "cm"
        }
      ],
      "outputs": [
        {
          "name": "will-it-fit-furniture-path-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=will-it-fit-furniture-path&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=will-it-fit-furniture-path&will-it-fit-furniture-path-L=210&will-it-fit-furniture-path-D=90&will-it-fit-furniture-path-H=85&will-it-fit-furniture-path-A=45&will-it-fit-furniture-path-dw=76&will-it-fit-furniture-path-dh=198"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "fit",
        "furniture",
        "path",
        "sofa",
        "checker",
        "home",
        "diy",
        "checks",
        "whole",
        "route"
      ],
      "popularity": 5189,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "wind-chill-calculator",
      "title": "🌬️ Wind Chill Calculator",
      "description": "NWS/JAG/TI wind-chill (2001): valid when air is ≤ 10 °C and wind ≥ 4.8 km/h. It estimates how cold exposed skin feels — not a frostbite timer, and not for indoor fans.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/wind-chill-calculator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=wind-chill-calculator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wchl-t",
          "type": "number",
          "label": "Air temperature °C",
          "unit": "",
          "default": "-5"
        },
        {
          "name": "wchl-v",
          "type": "number",
          "label": "Wind km/h",
          "unit": "",
          "min": 0,
          "default": "30"
        }
      ],
      "outputs": [
        {
          "name": "wchl-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=wind-chill-calculator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=wind-chill-calculator&wchl-t=-5&wchl-v=30"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "wind",
        "chill",
        "science",
        "engineering",
        "nws",
        "jag",
        "wind-chill",
        "2001",
        "valid",
        "when"
      ],
      "popularity": 4088,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "wind-triangle-flight-planner",
      "title": "✈️ Wind Triangle & Flight Leg Planner",
      "description": "Air is a moving floor. Point the nose where you want to go and the wind quietly carries you somewhere else, so every navigation log starts with the same triangle. This solves it exactly — heading t...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/wind-triangle-flight-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=wind-triangle-flight-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wtfp-track",
          "type": "number",
          "label": "Desired track, true",
          "unit": "°",
          "min": 0,
          "max": 360,
          "step": 1,
          "default": "045"
        },
        {
          "name": "wtfp-dist",
          "type": "number",
          "label": "Leg distance (nautical miles)",
          "unit": "",
          "min": 1,
          "max": 5000,
          "step": 1,
          "default": "120"
        },
        {
          "name": "wtfp-tas",
          "type": "number",
          "label": "True airspeed",
          "unit": "knots",
          "min": 20,
          "max": 600,
          "step": 1,
          "default": "110"
        },
        {
          "name": "wtfp-wdir",
          "type": "number",
          "label": "Wind from, true",
          "unit": "°",
          "min": 0,
          "max": 360,
          "step": 5,
          "default": "300"
        },
        {
          "name": "wtfp-wspd",
          "type": "number",
          "label": "Wind speed",
          "unit": "knots",
          "min": 0,
          "max": 200,
          "step": 1,
          "default": "25"
        },
        {
          "name": "wtfp-var",
          "type": "number",
          "label": "Magnetic variation",
          "unit": "° W positive",
          "min": -30,
          "max": 30,
          "step": 0.5,
          "default": "1"
        },
        {
          "name": "wtfp-burn",
          "type": "number",
          "label": "Fuel burn",
          "unit": "litres/hour",
          "min": 0,
          "max": 4000,
          "step": 0.5,
          "default": "32"
        },
        {
          "name": "wtfp-fuel",
          "type": "number",
          "label": "Usable fuel on board",
          "unit": "litres",
          "min": 0,
          "max": 20000,
          "step": 1,
          "default": "130"
        },
        {
          "name": "wtfp-reserve",
          "type": "number",
          "label": "Reserve to keep",
          "unit": "minutes",
          "min": 0,
          "max": 240,
          "step": 5,
          "default": "45"
        },
        {
          "name": "wtfp-rwy",
          "type": "number",
          "label": "Landing runway (e.g. 26 for 260°)",
          "unit": "",
          "min": 1,
          "max": 36,
          "step": 1,
          "default": "26"
        },
        {
          "name": "wtfp-xwlimit",
          "type": "number",
          "label": "Your crosswind limit",
          "unit": "knots",
          "min": 1,
          "max": 60,
          "step": 1,
          "default": "15"
        }
      ],
      "outputs": [
        {
          "name": "wtfp-verdict",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=wind-triangle-flight-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=wind-triangle-flight-planner&wtfp-track=045&wtfp-dist=120&wtfp-tas=110&wtfp-wdir=300&wtfp-wspd=25&wtfp-var=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "wind",
        "triangle",
        "flight",
        "planner",
        "leg",
        "science",
        "engineering",
        "air",
        "moving",
        "floor"
      ],
      "popularity": 5941,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "wind-wave-fetch-forecaster",
      "title": "🌬️ Wind, Fetch & Wave Forecaster",
      "description": "Waves are built by three things: how hard the wind blows, how far it blows over open water, and how long it keeps blowing. This works out which of the three is holding your sea state back, using th...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/wind-wave-fetch-forecaster.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=wind-wave-fetch-forecaster&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wwff-wind",
          "type": "number",
          "label": "Wind speed",
          "unit": "",
          "min": 1,
          "max": 120,
          "step": 1,
          "default": "20"
        },
        {
          "name": "wwff-fetch",
          "type": "number",
          "label": "Fetch — open water upwind",
          "unit": "km",
          "min": 0.1,
          "max": 5000,
          "step": 1,
          "default": "20"
        },
        {
          "name": "wwff-hours",
          "type": "number",
          "label": "How long it has blown",
          "unit": "hours",
          "min": 0.1,
          "max": 120,
          "step": 0.5,
          "default": "6"
        },
        {
          "name": "wwff-depth",
          "type": "number",
          "label": "Mean water depth",
          "unit": "m",
          "min": 0.5,
          "max": 6000,
          "step": 1,
          "default": "25"
        },
        {
          "name": "wwff-preset",
          "type": "select-one",
          "label": "Load a real water",
          "unit": ""
        },
        {
          "name": "wwff-windunit",
          "type": "select-one",
          "label": "Wind speed unit",
          "unit": "",
          "options": [
            "kn",
            "ms",
            "mph",
            "kmh"
          ],
          "default": "kn"
        },
        {
          "name": "wwff-craft",
          "type": "select-one",
          "label": "What are you in?",
          "unit": "",
          "options": [
            "swim",
            "paddle",
            "kayak",
            "dinghy",
            "rib",
            "yacht",
            "ship"
          ],
          "default": "kayak"
        }
      ],
      "outputs": [
        {
          "name": "wwff-verdict",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=wind-wave-fetch-forecaster&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=wind-wave-fetch-forecaster&wwff-wind=20&wwff-fetch=20&wwff-hours=6&wwff-depth=25&wwff-windunit=kn&wwff-craft=kayak"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "wind",
        "wave",
        "fetch",
        "forecaster",
        "science",
        "engineering",
        "waves",
        "built",
        "three",
        "things"
      ],
      "popularity": 4142,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "wire-gauge",
      "title": "⚡ Wire Gauge Calculator",
      "description": "Professional wire sizing calculator for electrical installations with NEC/IEC compliance checks and safety recommendations.",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/wire-gauge.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=wire-gauge&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "current",
          "type": "number",
          "label": "Load Current",
          "unit": "",
          "min": 0.1,
          "max": 1000,
          "step": 0.1
        },
        {
          "name": "length",
          "type": "number",
          "label": "One-Way Length",
          "unit": "",
          "min": 1,
          "max": 1000,
          "step": 1
        },
        {
          "name": "custom-voltage",
          "type": "number",
          "label": "Enter voltage",
          "unit": "",
          "min": 12,
          "max": 1000
        },
        {
          "name": "max-drop",
          "type": "range",
          "label": "Max Voltage Drop",
          "unit": "",
          "min": 1,
          "max": 10,
          "step": 0.5,
          "default": "3"
        },
        {
          "name": "temperature",
          "type": "number",
          "label": "Ambient Temperature",
          "unit": "",
          "min": -20,
          "max": 50,
          "step": 1,
          "default": "30"
        },
        {
          "name": "length-unit",
          "type": "select-one",
          "label": "unit",
          "unit": "",
          "options": [
            "ft",
            "m"
          ],
          "default": "ft"
        },
        {
          "name": "voltage",
          "type": "select-one",
          "label": "System Voltage",
          "unit": "",
          "options": [
            "120",
            "230",
            "240",
            "400",
            "480",
            "custom"
          ],
          "default": "120"
        },
        {
          "name": "material",
          "type": "select-one",
          "label": "Conductor Material",
          "unit": "",
          "options": [
            "copper",
            "copper_90",
            "aluminum",
            "aluminum_90"
          ],
          "default": "copper"
        },
        {
          "name": "insulation",
          "type": "select-one",
          "label": "Insulation Type",
          "unit": "",
          "options": [
            "thhn",
            "xhhw",
            "uf",
            "mc"
          ],
          "default": "thhn"
        },
        {
          "name": "phase",
          "type": "select-one",
          "label": "Phase Configuration",
          "unit": "",
          "options": [
            "single",
            "three",
            "three_delta",
            "three_wye"
          ],
          "default": "single"
        },
        {
          "name": "conductors",
          "type": "select-one",
          "label": "Conductors in Raceway",
          "unit": "",
          "options": [
            "1-3",
            "4-6",
            "7-9",
            "10-20"
          ],
          "default": "4-6"
        },
        {
          "name": "results-format",
          "type": "select-one",
          "label": "results format",
          "unit": "",
          "options": [
            "summary",
            "detailed",
            "technical"
          ],
          "default": "summary"
        }
      ],
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        {
          "name": "drop-value",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=wire-gauge&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=wire-gauge&max-drop=3&temperature=30&length-unit=ft&voltage=120&material=copper&insulation=thhn&run=1"
      },
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      "sources": [],
      "tags": [
        "wire",
        "gauge",
        "science",
        "engineering",
        "professional",
        "sizing",
        "electrical",
        "installations",
        "nec",
        "iec"
      ],
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      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "witness-statement-worksheet",
      "title": "🗣 Neutral Witness Statement Worksheet",
      "description": "Capture a witness’s account in their own words, then record context separately. Use open prompts, interview witnesses individually, and avoid suggesting a sound, figure, or cause.",
      "category": "field-investigation-and-evidence",
      "categoryName": "Field Investigation & Evidence",
      "url": "https://www.themostusefulsiteintheworld.com/tool/witness-statement-worksheet.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=witness-statement-worksheet&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wsw-code",
          "type": "text",
          "label": "Witness code / initials only",
          "unit": ""
        },
        {
          "name": "wsw-time",
          "type": "datetime-local",
          "label": "Reported date & time",
          "unit": ""
        },
        {
          "name": "wsw-zone",
          "type": "text",
          "label": "Room / grid label only",
          "unit": ""
        },
        {
          "name": "wsw-duration",
          "type": "text",
          "label": "Estimated duration / distance",
          "unit": ""
        },
        {
          "name": "wsw-conditions",
          "type": "text",
          "label": "Light / noise / visibility",
          "unit": ""
        },
        {
          "name": "wsw-expectations",
          "type": "text",
          "label": "Prior information / expectations",
          "unit": ""
        },
        {
          "name": "wsw-narrative",
          "type": "textarea",
          "label": "1 · “Please describe what happened, from the beginning.”",
          "unit": ""
        },
        {
          "name": "wsw-senses",
          "type": "textarea",
          "label": "2 · “What did you directly see, hear, or feel?”",
          "unit": ""
        },
        {
          "name": "wsw-context",
          "type": "textarea",
          "label": "3 · “What was happening immediately before and after?”",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "wsw-status",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=witness-statement-worksheet&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "witness",
        "statement",
        "worksheet",
        "neutral",
        "field",
        "investigation",
        "evidence",
        "capture",
        "account",
        "their"
      ],
      "popularity": 6412,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "word-cloud-generator",
      "title": "☁️ Word Cloud Generator",
      "description": "Paste any text — an article, a meeting transcript, a speech, your own journal — and see what it is really about. Common filler words are stripped out, the survivors are sized by how often they appe...",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/word-cloud-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=word-cloud-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wcg-max",
          "type": "number",
          "label": "Max words",
          "unit": "",
          "min": 10,
          "max": 250,
          "step": 5,
          "default": "80"
        },
        {
          "name": "wcg-minlen",
          "type": "number",
          "label": "Min length",
          "unit": "",
          "min": 2,
          "max": 12,
          "step": 1,
          "default": "3"
        },
        {
          "name": "wcg-maxsize",
          "type": "number",
          "label": "Largest",
          "unit": "px",
          "min": 24,
          "max": 160,
          "step": 4,
          "default": "76"
        },
        {
          "name": "wcg-stop",
          "type": "checkbox",
          "label": "Remove common English filler words",
          "unit": "",
          "default": "1"
        },
        {
          "name": "wcg-numbers",
          "type": "checkbox",
          "label": "Include numbers",
          "unit": "",
          "default": "0"
        },
        {
          "name": "wcg-plural",
          "type": "checkbox",
          "label": "Group plurals (&ldquo;cat&rdquo; + &ldquo;cats&rdquo;)",
          "unit": "",
          "default": "1"
        },
        {
          "name": "wcg-text",
          "type": "textarea",
          "label": "Your text",
          "unit": ""
        },
        {
          "name": "wcg-palette",
          "type": "select-one",
          "label": "Palette",
          "unit": "",
          "options": [
            "terminal",
            "sunset",
            "ocean",
            "mono",
            "candy"
          ],
          "default": "terminal"
        },
        {
          "name": "wcg-bg",
          "type": "select-one",
          "label": "Background",
          "unit": "",
          "options": [
            "transparent",
            "#071019",
            "#ffffff",
            "#0b1a24"
          ],
          "default": "transparent"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=word-cloud-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=word-cloud-generator&wcg-max=80&wcg-minlen=3&wcg-maxsize=76&wcg-stop=1&wcg-numbers=0&wcg-plural=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "word",
        "cloud",
        "writing",
        "language",
        "paste",
        "any",
        "text",
        "article",
        "meeting",
        "transcript"
      ],
      "popularity": 4944,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "word-counter",
      "title": "📊 Text Statistics Analyzer",
      "description": "Comprehensive text analysis: word count, character count, sentence count, reading time, readability score, and more.",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/word-counter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=word-counter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "tx-input",
          "type": "textarea",
          "label": "Paste your text here for analysis...",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=word-counter&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "word",
        "counter",
        "text",
        "statistics",
        "analyzer",
        "productivity",
        "lifestyle",
        "comprehensive",
        "analysis",
        "count"
      ],
      "popularity": 9260,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "word-frequency-counter",
      "title": "📊 Keyword Density & Word Frequency",
      "description": "Paste copy and see word count, the densest terms, and an optional target keyword’s density. Counts are local and crude (no stemming). Density is a diagnostic, not a Google ranking lever — stuffing ...",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/word-frequency-counter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=word-frequency-counter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "kwds-key",
          "type": "text",
          "label": "Target keyword",
          "unit": ""
        },
        {
          "name": "kwds-text",
          "type": "textarea",
          "label": "Text",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "kwds-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=word-frequency-counter&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "word",
        "frequency",
        "counter",
        "keyword",
        "density",
        "writing",
        "language",
        "paste",
        "copy",
        "see"
      ],
      "popularity": 5520,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "workhours",
      "title": "⏱️ Work Hours & Pay Calculator",
      "description": "Calculate work hours, breaks, overtime, and pay. Track multiple shifts, different pay rates, and generate detailed timesheets. Perfect for freelancers, contractors, and employees!",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/workhours.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=workhours&embed=1",
      "standaloneUrl": null,
      "inputs": [
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          "name": "wh-start-time",
          "type": "time",
          "label": "Start Time",
          "unit": "",
          "default": "09:00"
        },
        {
          "name": "wh-end-time",
          "type": "time",
          "label": "End Time",
          "unit": "",
          "default": "17:00"
        },
        {
          "name": "wh-date",
          "type": "date",
          "label": "Date",
          "unit": ""
        },
        {
          "name": "wh-hourly-rate",
          "type": "number",
          "label": "Hourly Rate",
          "unit": "",
          "min": 0,
          "step": 0.01,
          "default": "15.00"
        },
        {
          "name": "wh-overtime-rate",
          "type": "number",
          "label": "Overtime Multiplier",
          "unit": "",
          "min": 1,
          "max": 3,
          "step": 0.1,
          "default": "1.5"
        },
        {
          "name": "wh-overtime-threshold",
          "type": "number",
          "label": "Overtime After",
          "unit": "",
          "min": 0,
          "max": 24,
          "step": 0.5,
          "default": "8"
        },
        {
          "name": "wh-break-duration",
          "type": "number",
          "label": "Total Break Time",
          "unit": "",
          "min": 0,
          "max": 480,
          "step": 5,
          "default": "60"
        },
        {
          "name": "wh-currency",
          "type": "select-one",
          "label": "currency",
          "unit": "",
          "options": [
            "GBP",
            "USD",
            "EUR",
            "CAD",
            "AUD"
          ],
          "default": "GBP"
        },
        {
          "name": "wh-break-type",
          "type": "select-one",
          "label": "Break Type",
          "unit": "",
          "options": [
            "unpaid",
            "paid",
            "none"
          ],
          "default": "unpaid"
        }
      ],
      "outputs": [
        {
          "name": "wh-time-summary",
          "type": "output"
        },
        {
          "name": "wh-pay-summary",
          "type": "output"
        },
        {
          "name": "wh-shifts-results",
          "type": "output"
        },
        {
          "name": "wh-shifts-summary",
          "type": "output"
        },
        {
          "name": "wh-currency-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=workhours&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=workhours&wh-start-time=09%3A00&wh-end-time=17%3A00&wh-hourly-rate=15.00&wh-overtime-rate=1.5&wh-overtime-threshold=8&wh-break-duration=60&run=1"
      },
      "formula": "Labor Laws Formulas: Total Hours = End Time - Start Time -",
      "sources": [],
      "tags": [
        "workhours",
        "work",
        "hours",
        "pay",
        "productivity",
        "lifestyle",
        "calculate",
        "breaks",
        "overtime",
        "track"
      ],
      "popularity": 6326,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "world-capitals-quiz",
      "title": "🌍 World Capitals Quiz",
      "description": "Learn the world's capitals with multiple choice or typed answers, region filters, streak tracking and a little history with every question. 60 countries quizzed — nothing is sent anywhere, it all r...",
      "category": "mrprophecy-arcade",
      "categoryName": "Arcade",
      "url": "https://www.themostusefulsiteintheworld.com/tool/world-capitals-quiz.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=world-capitals-quiz&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wcq-ans",
          "type": "text",
          "label": "ans",
          "unit": ""
        },
        {
          "name": "wcq-region",
          "type": "select-one",
          "label": "Region",
          "unit": "",
          "options": [
            "all",
            "Europe",
            "Asia",
            "Africa",
            "Americas",
            "Oceania"
          ],
          "default": "all"
        },
        {
          "name": "wcq-mode",
          "type": "select-one",
          "label": "Answer mode",
          "unit": "",
          "options": [
            "mc",
            "type"
          ],
          "default": "mc"
        }
      ],
      "outputs": [
        {
          "name": "wcq-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=world-capitals-quiz&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=world-capitals-quiz&wcq-region=all&wcq-mode=mc"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "world",
        "capitals",
        "quiz",
        "arcade",
        "learn",
        "multiple",
        "choice",
        "typed",
        "answers",
        "region"
      ],
      "popularity": 6308,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "world-clock-timezone-board",
      "title": "🌐 World Clock & Time Zone Board",
      "description": "A live board of any cities you care about: local time, weekday, date and real UTC offset with daylight saving already applied. Add up to twelve, drag the hour slider to see what one moment looks li...",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/world-clock-timezone-board.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=world-clock-timezone-board&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "gwc-tz-search",
          "type": "search",
          "label": "Filter the city list",
          "unit": ""
        },
        {
          "name": "gwc-hour",
          "type": "range",
          "label": "Hour of day in your time zone",
          "unit": "",
          "min": 0,
          "max": 23,
          "step": 1,
          "default": "9"
        },
        {
          "name": "gwc-city",
          "type": "select-one",
          "label": "Add a city",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "gwc-msg",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=world-clock-timezone-board&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=world-clock-timezone-board&gwc-hour=9"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "world",
        "clock",
        "timezone",
        "board",
        "time",
        "zone",
        "productivity",
        "lifestyle",
        "live",
        "any"
      ],
      "popularity": 4756,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "world-map-geography-trainer",
      "title": "🗺️ World Map Geography Trainer",
      "description": "An interactive world map with all 195 countries (UN members + observers) — every marker is a capital city. Explore flags, capitals and continents, then quiz yourself three ways: find the country on...",
      "category": "science-and-engineering",
      "categoryName": "Science & Engineering",
      "url": "https://www.themostusefulsiteintheworld.com/tool/world-map-geography-trainer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=world-map-geography-trainer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wmg-search",
          "type": "search",
          "label": "Search countries",
          "unit": ""
        },
        {
          "name": "wmg-region",
          "type": "select-one",
          "label": "Region 🌍 World Africa Americas Asia Europe Oceania",
          "unit": "",
          "options": [
            "World",
            "Africa",
            "Americas",
            "Asia",
            "Europe",
            "Oceania"
          ],
          "default": "World"
        }
      ],
      "outputs": [
        {
          "name": "wmg-info",
          "type": "live"
        },
        {
          "name": "wmg-q-fb",
          "type": "live"
        },
        {
          "name": "wmg-q-score",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=world-map-geography-trainer&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=world-map-geography-trainer&wmg-region=World"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "world",
        "map",
        "geography",
        "trainer",
        "science",
        "engineering",
        "interactive",
        "all",
        "195",
        "countries"
      ],
      "popularity": 6912,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "worry-sorter-3am",
      "title": "🌙 The 3am Worry Sorter",
      "description": "For the thoughts that queue up at 3am. Tick what's rattling around, add your own, and this will sort each one into Do Now, Schedule, or Let Go — with a kind word for each. Nothing is saved.",
      "category": "wellbeing-and-community",
      "categoryName": "Wellbeing & Community",
      "url": "https://www.themostusefulsiteintheworld.com/tool/worry-sorter-3am.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=worry-sorter-3am&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "wrs-custom",
          "type": "textarea",
          "label": "Or write your own",
          "unit": "one per line"
        }
      ],
      "outputs": [
        {
          "name": "wrs-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=worry-sorter-3am&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "worry",
        "sorter",
        "3am",
        "wellbeing",
        "community",
        "thoughts",
        "queue",
        "tick",
        "what",
        "rattling"
      ],
      "popularity": 5545,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "xmas-card-writer-assistant",
      "title": "✍️ XMAS Card Writer Assistant",
      "description": "Struggling with what to write? Get personalized Christmas card messages for everyone on your list! Save time, spread joy!",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/xmas-card-writer-assistant.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=xmas-card-writer-assistant&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "cw-recipient-name",
          "type": "text",
          "label": "Recipient's Name",
          "unit": ""
        },
        {
          "name": "cw-your-name",
          "type": "text",
          "label": "Your Name/Family",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "cw-results",
          "type": "output"
        },
        {
          "name": "cw-message-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=xmas-card-writer-assistant&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "xmas",
        "card",
        "writer",
        "assistant",
        "productivity",
        "lifestyle",
        "struggling",
        "what",
        "write",
        "get"
      ],
      "popularity": 4005,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "xmas-countdown",
      "title": "🎄 Christmas Countdown",
      "description": "Count down to Christmas with real-time tracking, festive facts, and daily suggestions! 🎅 Shows days, hours, minutes until Christmas morning",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/xmas-countdown.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=xmas-countdown&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "xmas-show-seconds",
          "type": "checkbox",
          "label": "Show seconds",
          "unit": "",
          "default": "1"
        },
        {
          "name": "xmas-show-facts",
          "type": "checkbox",
          "label": "Show daily facts",
          "unit": "",
          "default": "1"
        },
        {
          "name": "xmas-sound",
          "type": "checkbox",
          "label": "Festive sounds",
          "unit": "",
          "default": "0"
        },
        {
          "name": "xmas-message",
          "type": "text",
          "label": "Personal Christmas Message",
          "unit": ""
        },
        {
          "name": "xmas-year",
          "type": "select-one",
          "label": "Christmas Year",
          "unit": "",
          "options": [
            "2024",
            "2025",
            "2026",
            "2027",
            "2028"
          ],
          "default": "2025"
        },
        {
          "name": "xmas-timezone",
          "type": "select-one",
          "label": "Your Timezone",
          "unit": "",
          "options": [
            "-12",
            "-8",
            "-5",
            "0",
            "+1",
            "+8",
            "+10"
          ],
          "default": "0"
        }
      ],
      "outputs": [
        {
          "name": "xmas-countdown-display",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=xmas-countdown&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=xmas-countdown&xmas-show-seconds=1&xmas-show-facts=1&xmas-sound=0&xmas-year=2025&xmas-timezone=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "xmas",
        "countdown",
        "christmas",
        "productivity",
        "lifestyle",
        "count",
        "down",
        "real-time",
        "tracking",
        "festive"
      ],
      "popularity": 4747,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "xmas-gift-budget",
      "title": "💰 Christmas Gift Budget Planner",
      "description": "Plan, track, and optimize your Christmas gift spending. Avoid overspending with smart budgeting! ✅ Features: Gift ideas, price tracking, comparison shopping, receipt scanning",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/xmas-gift-budget.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=xmas-gift-budget&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "gb-total-budget",
          "type": "range",
          "label": "Total Christmas Budget",
          "unit": "$",
          "min": 100,
          "max": 5000,
          "step": 50,
          "default": "1000"
        },
        {
          "name": "gb-gift-for",
          "type": "text",
          "label": "Gift For",
          "unit": ""
        },
        {
          "name": "gb-gift-item",
          "type": "text",
          "label": "Gift Item",
          "unit": ""
        },
        {
          "name": "gb-gift-price",
          "type": "number",
          "label": "Price",
          "unit": "$",
          "min": 0,
          "step": 0.01
        },
        {
          "name": "gb-gift-status",
          "type": "select-one",
          "label": "Status",
          "unit": "",
          "options": [
            "planned",
            "purchased",
            "wrapped",
            "delivered"
          ],
          "default": "planned"
        },
        {
          "name": "gb-gift-priority",
          "type": "select-one",
          "label": "Priority",
          "unit": "",
          "options": [
            "low",
            "medium",
            "high",
            "essential"
          ],
          "default": "medium"
        }
      ],
      "outputs": [
        {
          "name": "gb-budget-display",
          "type": "output"
        },
        {
          "name": "gb-people-display",
          "type": "output"
        },
        {
          "name": "gb-stat-total",
          "type": "output"
        },
        {
          "name": "gb-spent-amount",
          "type": "output"
        },
        {
          "name": "gb-remaining-amount",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=xmas-gift-budget&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=xmas-gift-budget&gb-total-budget=1000&gb-gift-status=planned&gb-gift-priority=medium"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "xmas",
        "gift",
        "budget",
        "christmas",
        "planner",
        "finance",
        "money",
        "plan",
        "track",
        "optimize"
      ],
      "popularity": 4516,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "xmas-santa-tracker",
      "title": "🎅 Santa Tracker & Message Center",
      "description": "Track Santa's journey and send him a message! Get a personalized response from the North Pole. Perfect for kids and kids-at-heart!",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/xmas-santa-tracker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=xmas-santa-tracker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "st-name",
          "type": "text",
          "label": "Your Name",
          "unit": ""
        },
        {
          "name": "st-message",
          "type": "textarea",
          "label": "Your Message to Santa",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=xmas-santa-tracker&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "xmas",
        "santa",
        "tracker",
        "message",
        "center",
        "productivity",
        "lifestyle",
        "track",
        "journey",
        "send"
      ],
      "popularity": 6382,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "xml-formatter",
      "title": "📐 XML Formatter & Validator",
      "description": "Format, minify, validate, and explore XML. Paste messy XML, get clean indented output with syntax highlighting.",
      "category": "algorithms-and-computer-science",
      "categoryName": "Algorithms & Computer Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/xml-formatter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=xml-formatter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "xmlFmtInput",
          "type": "textarea",
          "label": "Paste XML here...",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=xml-formatter&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "xml",
        "formatter",
        "validator",
        "algorithms",
        "computer",
        "science",
        "format",
        "minify",
        "validate",
        "explore"
      ],
      "popularity": 4796,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "yeast-fresh-instant-converter",
      "title": "🍞 Yeast Converter",
      "description": "Swap fresh cake yeast, active dry and instant/fast-action using the baker’s 1 : 1.25 : 3 rule (instant : active dry : fresh by weight). Teaspoons assume 3.1 g instant per level tsp.",
      "category": "culinary-and-food-science",
      "categoryName": "Culinary & Food Science",
      "url": "https://www.themostusefulsiteintheworld.com/tool/yeast-fresh-instant-converter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=yeast-fresh-instant-converter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ystc-amt",
          "type": "number",
          "label": "Amount",
          "unit": "",
          "min": 0,
          "default": "7"
        },
        {
          "name": "ystc-kind",
          "type": "select-one",
          "label": "I have",
          "unit": "",
          "options": [
            "instant",
            "active",
            "fresh"
          ],
          "default": "instant"
        },
        {
          "name": "ystc-unit",
          "type": "select-one",
          "label": "Unit",
          "unit": "",
          "options": [
            "g",
            "tsp",
            "tbsp"
          ],
          "default": "g"
        }
      ],
      "outputs": [
        {
          "name": "ystc-out",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=yeast-fresh-instant-converter&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=yeast-fresh-instant-converter&ystc-amt=7&ystc-kind=instant&ystc-unit=g"
      },
      "formula": "Interactive — open the URL and enter your values; result is computed client-side.",
      "sources": [],
      "tags": [
        "yeast",
        "fresh",
        "instant",
        "converter",
        "culinary",
        "food",
        "science",
        "swap",
        "cake",
        "active"
      ],
      "popularity": 6706,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "younger-futhark-runes",
      "title": "ᚠ The Rune Cabinet",
      "description": "Sixteen staves, not twenty-four. After about 700 CE the north dropped Elder Futhark down to this tighter case — one rune now stands for several Latin letters. Stones from Jelling to Rök speak it. T...",
      "category": "museum-and-collection",
      "categoryName": "Museum & Collection",
      "url": "https://www.themostusefulsiteintheworld.com/tool/younger-futhark-runes.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=younger-futhark-runes&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "yfrn-q",
          "type": "text",
          "label": "Latin (Old Norse-ish)",
          "unit": "",
          "default": "kristni"
        }
      ],
      "outputs": [
        {
          "name": "yfrn-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=younger-futhark-runes&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=younger-futhark-runes&yfrn-q=kristni"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "younger",
        "futhark",
        "runes",
        "rune",
        "cabinet",
        "museum",
        "collection",
        "sixteen",
        "staves",
        "not"
      ],
      "popularity": 5851,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "youth-aesthetic-bio",
      "title": "✨ Aesthetic Bio Generator",
      "description": "Generate stylish bios for Instagram, TikTok, Discord, Twitter/X, and more — with fonts, symbols, and vibes",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/youth-aesthetic-bio.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-aesthetic-bio&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "yb-name",
          "type": "text",
          "label": "Your name / handle",
          "unit": "",
          "default": "Alex"
        },
        {
          "name": "yb-interests",
          "type": "text",
          "label": "Interests (comma separated)",
          "unit": "",
          "default": "music, gaming, art"
        },
        {
          "name": "yb-vibe",
          "type": "select-one",
          "label": "Vibe",
          "unit": "",
          "options": [
            "soft",
            "dark",
            "hype",
            "chill",
            "funny",
            "mysterious"
          ],
          "default": "soft"
        },
        {
          "name": "yb-platform",
          "type": "select-one",
          "label": "Platform",
          "unit": "",
          "options": [
            "instagram",
            "tiktok",
            "discord",
            "twitter",
            "twitch"
          ],
          "default": "instagram"
        }
      ],
      "outputs": [
        {
          "name": "yb-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-aesthetic-bio&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-aesthetic-bio&yb-name=Alex&yb-interests=music%2C%20gaming%2C%20art&yb-vibe=soft&yb-platform=instagram"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "youth",
        "aesthetic",
        "bio",
        "writing",
        "language",
        "generate",
        "stylish",
        "bios",
        "instagram",
        "tiktok"
      ],
      "popularity": 5339,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "youth-caption-generator",
      "title": "📱 Caption Generator",
      "description": "Generate Instagram, TikTok, and selfie captions — funny, aesthetic, savage, or wholesome",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/youth-caption-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-caption-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "yc-mood",
          "type": "select-one",
          "label": "mood",
          "unit": "",
          "options": [
            "aesthetic",
            "funny",
            "savage",
            "wholesome",
            "hype",
            "sad"
          ],
          "default": "aesthetic"
        },
        {
          "name": "yc-ctx",
          "type": "select-one",
          "label": "ctx",
          "unit": "",
          "options": [
            "selfie",
            "travel",
            "food",
            "friends",
            "fit",
            "pet",
            "nature",
            "random"
          ],
          "default": "selfie"
        }
      ],
      "outputs": [
        {
          "name": "yc-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-caption-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-caption-generator&yc-mood=aesthetic&yc-ctx=selfie"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "youth",
        "caption",
        "writing",
        "language",
        "generate",
        "instagram",
        "tiktok",
        "selfie",
        "captions",
        "funny"
      ],
      "popularity": 5822,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "youth-color-palette",
      "title": "🎨 Aesthetic Color Palette Generator",
      "description": "Generate beautiful color palettes for designs, social media, and vibes — click to copy hex codes",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/youth-color-palette.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-color-palette&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "yp-vibe",
          "type": "select-one",
          "label": "vibe",
          "unit": "",
          "options": [
            "pastel",
            "dark",
            "neon",
            "earth",
            "sunset",
            "ocean",
            "retro",
            "minimal"
          ],
          "default": "pastel"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-color-palette&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-color-palette&yp-vibe=pastel"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "youth",
        "color",
        "palette",
        "aesthetic",
        "productivity",
        "lifestyle",
        "generate",
        "beautiful",
        "palettes",
        "designs"
      ],
      "popularity": 5567,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "youth-money-tracker",
      "title": "💸 Money Tracker",
      "description": "Track your spending, set a budget, and see where your money goes — simple enough for your first budget",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/youth-money-tracker.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-money-tracker&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ym-budget",
          "type": "number",
          "label": "Monthly budget",
          "unit": "£",
          "default": "500"
        },
        {
          "name": "ym-item",
          "type": "text",
          "label": "What did you buy?",
          "unit": ""
        },
        {
          "name": "ym-amt",
          "type": "number",
          "label": "£",
          "unit": "",
          "min": 0,
          "step": 0.01
        },
        {
          "name": "ym-cat",
          "type": "select-one",
          "label": "Spending category",
          "unit": "",
          "options": [
            "food",
            "transport",
            "fun",
            "clothes",
            "bills",
            "other"
          ],
          "default": "food"
        }
      ],
      "outputs": [
        {
          "name": "ym-summary",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-money-tracker&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-money-tracker&ym-budget=500&ym-cat=food"
      },
      "formula": "Daily coffee/snacks (£3/day = £90/",
      "sources": [],
      "tags": [
        "youth",
        "money",
        "tracker",
        "finance",
        "track",
        "spending",
        "set",
        "budget",
        "see",
        "where"
      ],
      "popularity": 5353,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "youth-playlist-name",
      "title": "🎵 Playlist Name Generator",
      "description": "Generate creative playlist names for Spotify, Apple Music, and YouTube — match the vibe of your music",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/youth-playlist-name.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-playlist-name&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "yp-genre",
          "type": "select-one",
          "label": "genre",
          "unit": "",
          "options": [
            "pop",
            "rap",
            "indie",
            "rnb",
            "edm",
            "sad",
            "hype",
            "chill"
          ],
          "default": "pop"
        },
        {
          "name": "yp-season",
          "type": "select-one",
          "label": "season",
          "unit": "",
          "options": [
            "any",
            "summer",
            "winter",
            "night",
            "morning",
            "drive"
          ],
          "default": "any"
        }
      ],
      "outputs": [
        {
          "name": "yp-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-playlist-name&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-playlist-name&yp-genre=pop&yp-season=any"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "youth",
        "playlist",
        "name",
        "productivity",
        "lifestyle",
        "generate",
        "creative",
        "names",
        "spotify",
        "apple"
      ],
      "popularity": 6348,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "youth-resume-builder",
      "title": "📄 First Resume Builder",
      "description": "Build your first CV or resume — even with no experience. Fill in what you have, get a clean, professional resume",
      "category": "writing-and-language",
      "categoryName": "Writing & Language",
      "url": "https://www.themostusefulsiteintheworld.com/tool/youth-resume-builder.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-resume-builder&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "yr-name",
          "type": "text",
          "label": "Full Name",
          "unit": "",
          "default": "Alex Johnson"
        },
        {
          "name": "yr-email",
          "type": "text",
          "label": "Email",
          "unit": "",
          "default": "alex@email.com"
        },
        {
          "name": "yr-phone",
          "type": "text",
          "label": "Phone",
          "unit": "",
          "default": "07700 900000"
        },
        {
          "name": "yr-loc",
          "type": "text",
          "label": "Location",
          "unit": "",
          "default": "London, UK"
        },
        {
          "name": "yr-skills",
          "type": "text",
          "label": "Skills (comma separated)",
          "unit": "",
          "default": "Teamwork, Communication, Microsoft Office, Social media, Time management"
        },
        {
          "name": "yr-stmt",
          "type": "textarea",
          "label": "Personal Statement",
          "unit": ""
        },
        {
          "name": "yr-edu",
          "type": "textarea",
          "label": "Education (school, grades, dates)",
          "unit": ""
        },
        {
          "name": "yr-exp",
          "type": "textarea",
          "label": "Experience / Volunteering / Activities",
          "unit": ""
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-resume-builder&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-resume-builder&yr-name=Alex%20Johnson&yr-email=alex%40email.com&yr-phone=07700%20900000&yr-loc=London%2C%20UK&yr-skills=Teamwork%2C%20Communication%2C%20Microsoft%20Office%2C%20Social%20media%2C%20Time%20management"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "youth",
        "resume",
        "builder",
        "first",
        "writing",
        "language",
        "build",
        "even",
        "experience",
        "fill"
      ],
      "popularity": 6637,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "youth-study-timer",
      "title": "📚 Study Timer (Pomodoro)",
      "description": "Focus timer with study/break cycles, session tracking, and motivational quotes — ace your exams",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/youth-study-timer.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-study-timer&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "st-work",
          "type": "number",
          "label": "Study",
          "unit": "min",
          "min": 1,
          "max": 120,
          "default": "25"
        },
        {
          "name": "st-break",
          "type": "number",
          "label": "Break",
          "unit": "min",
          "min": 1,
          "max": 60,
          "default": "5"
        },
        {
          "name": "st-long",
          "type": "number",
          "label": "Long break",
          "unit": "",
          "min": 1,
          "max": 60,
          "default": "15"
        }
      ],
      "outputs": [],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-study-timer&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-study-timer&st-work=25&st-break=5&st-long=15"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "youth",
        "study",
        "timer",
        "pomodoro",
        "productivity",
        "lifestyle",
        "focus",
        "break",
        "cycles",
        "session"
      ],
      "popularity": 5345,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "youth-team-rotation-planner",
      "title": "👧 Youth Team Rotation Planner",
      "description": "Every child gets a fair go. Tell it how many players, how many are on the pitch at once, and how long the game lasts, and it builds a substitution plan that shares the minutes out as evenly as poss...",
      "category": "sports",
      "categoryName": "Sports",
      "url": "https://www.themostusefulsiteintheworld.com/tool/youth-team-rotation-planner.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-team-rotation-planner&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "ytr-players",
          "type": "number",
          "label": "Players in squad",
          "unit": "",
          "min": 2,
          "max": 40,
          "default": "11"
        },
        {
          "name": "ytr-onfield",
          "type": "number",
          "label": "On pitch at once",
          "unit": "",
          "min": 1,
          "max": 22,
          "default": "7"
        },
        {
          "name": "ytr-minutes",
          "type": "number",
          "label": "Match length",
          "unit": "min",
          "min": 10,
          "default": "60"
        },
        {
          "name": "ytr-rot",
          "type": "number",
          "label": "Rotate every",
          "unit": "min",
          "min": 1,
          "default": "10"
        },
        {
          "name": "ytr-names",
          "type": "textarea",
          "label": "Names (optional, one per line)",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "ytr-out",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-team-rotation-planner&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-team-rotation-planner&ytr-players=11&ytr-onfield=7&ytr-minutes=60&ytr-rot=10"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "youth",
        "team",
        "rotation",
        "planner",
        "sports",
        "every",
        "child",
        "gets",
        "fair",
        "tell"
      ],
      "popularity": 5319,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "youth-username-generator",
      "title": "🎮 Username Generator",
      "description": "Generate unique, cool usernames for gaming, social media, and streaming — check availability vibes",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/youth-username-generator.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-username-generator&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "yu-name",
          "type": "text",
          "label": "Your name / word",
          "unit": "",
          "default": "Alex"
        },
        {
          "name": "yu-key",
          "type": "text",
          "label": "Optional keyword",
          "unit": "",
          "default": "shadow"
        },
        {
          "name": "yu-style",
          "type": "select-one",
          "label": "Style",
          "unit": "",
          "options": [
            "gamer",
            "aesthetic",
            "edgy",
            "cute",
            "pro",
            "meme"
          ],
          "default": "gamer"
        }
      ],
      "outputs": [
        {
          "name": "yu-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-username-generator&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-username-generator&yu-name=Alex&yu-key=shadow&yu-style=gamer"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "youth",
        "username",
        "productivity",
        "lifestyle",
        "generate",
        "unique",
        "cool",
        "usernames",
        "gaming",
        "social"
      ],
      "popularity": 6534,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "youth-what-to-watch",
      "title": "🎬 What Should I Watch?",
      "description": "Can't decide what to watch? Answer 3 quick questions and get personalized movie/show recommendations",
      "category": "productivity-and-lifestyle",
      "categoryName": "Productivity & Lifestyle",
      "url": "https://www.themostusefulsiteintheworld.com/tool/youth-what-to-watch.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-what-to-watch&embed=1",
      "standaloneUrl": null,
      "inputs": [],
      "outputs": [
        {
          "name": "ww-results",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=youth-what-to-watch&<id>=<value>",
        "runs": false
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "youth",
        "what",
        "watch",
        "should",
        "productivity",
        "lifestyle",
        "can",
        "decide",
        "answer",
        "quick"
      ],
      "popularity": 6300,
      "featured": false,
      "updated": "2026-09-19"
    },
    {
      "slug": "youtube-dj",
      "title": "🎛️ YouTube DJ Mixer",
      "description": "Mix YouTube videos live like a professional DJ. Crossfade between tracks, apply effects, and create seamless mixes. 🎧 Live mixing • Crossfader • EQ • Effects • YouTube integration",
      "category": "music-and-audio",
      "categoryName": "Music & Audio",
      "url": "https://www.themostusefulsiteintheworld.com/tool/youtube-dj.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=youtube-dj&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "dj-deck-a-url",
          "type": "text",
          "label": "Deck A - YouTube URL",
          "unit": ""
        },
        {
          "name": "dj-deck-b-url",
          "type": "text",
          "label": "Deck B - YouTube URL",
          "unit": ""
        },
        {
          "name": "dj-deck-a-eq-low",
          "type": "range",
          "label": "Deck A, low EQ",
          "unit": "",
          "min": -12,
          "max": 12,
          "step": 0.5,
          "default": "0"
        },
        {
          "name": "dj-deck-a-eq-mid",
          "type": "range",
          "label": "Deck A, mid EQ",
          "unit": "",
          "min": -12,
          "max": 12,
          "step": 0.5,
          "default": "0"
        },
        {
          "name": "dj-deck-a-eq-high",
          "type": "range",
          "label": "Deck A, high EQ",
          "unit": "",
          "min": -12,
          "max": 12,
          "step": 0.5,
          "default": "0"
        },
        {
          "name": "dj-deck-a-volume",
          "type": "range",
          "label": "Deck A volume",
          "unit": "",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "100"
        },
        {
          "name": "dj-deck-b-eq-low",
          "type": "range",
          "label": "Deck B, low EQ",
          "unit": "",
          "min": -12,
          "max": 12,
          "step": 0.5,
          "default": "0"
        },
        {
          "name": "dj-deck-b-eq-mid",
          "type": "range",
          "label": "Deck B, mid EQ",
          "unit": "",
          "min": -12,
          "max": 12,
          "step": 0.5,
          "default": "0"
        },
        {
          "name": "dj-deck-b-eq-high",
          "type": "range",
          "label": "Deck B, high EQ",
          "unit": "",
          "min": -12,
          "max": 12,
          "step": 0.5,
          "default": "0"
        },
        {
          "name": "dj-deck-b-volume",
          "type": "range",
          "label": "Deck B volume",
          "unit": "",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "100"
        },
        {
          "name": "dj-crossfader",
          "type": "range",
          "label": "Crossfader, deck A to deck B",
          "unit": "",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "50"
        },
        {
          "name": "dj-master-volume",
          "type": "range",
          "label": "Master volume",
          "unit": "",
          "min": 0,
          "max": 100,
          "step": 1,
          "default": "100"
        },
        {
          "name": "dj-tempo",
          "type": "range",
          "label": "Tempo",
          "unit": "BPM",
          "min": 60,
          "max": 180,
          "step": 1,
          "default": "120"
        }
      ],
      "outputs": [
        {
          "name": "dj-deck-a-eq-low-value",
          "type": "output"
        },
        {
          "name": "dj-deck-a-eq-mid-value",
          "type": "output"
        },
        {
          "name": "dj-deck-a-eq-high-value",
          "type": "output"
        },
        {
          "name": "dj-deck-a-volume-value",
          "type": "output"
        },
        {
          "name": "dj-deck-b-eq-low-value",
          "type": "output"
        },
        {
          "name": "dj-deck-b-eq-mid-value",
          "type": "output"
        },
        {
          "name": "dj-deck-b-eq-high-value",
          "type": "output"
        },
        {
          "name": "dj-deck-b-volume-value",
          "type": "output"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=youtube-dj&<id>=<value>",
        "runs": false,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=youtube-dj&dj-deck-a-eq-low=0&dj-deck-a-eq-mid=0&dj-deck-a-eq-high=0&dj-deck-a-volume=100&dj-deck-b-eq-low=0&dj-deck-b-eq-mid=0"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "youtube",
        "mixer",
        "music",
        "audio",
        "mix",
        "videos",
        "live",
        "like",
        "professional",
        "crossfade"
      ],
      "popularity": 9170,
      "featured": true,
      "updated": "2026-09-19"
    },
    {
      "slug": "zero-capital-income-starter",
      "title": "💼 Zero-Capital Income Starter",
      "description": "No money to start a business? Start anyway. Tell it your skills, time and tools and it matches you with micro-businesses you can launch for almost nothing — with pricing maths, a 7-day launch plan ...",
      "category": "finance-and-money",
      "categoryName": "Finance & Money",
      "url": "https://www.themostusefulsiteintheworld.com/tool/zero-capital-income-starter.html",
      "embedUrl": "https://www.themostusefulsiteintheworld.com/tool.html?card=zero-capital-income-starter&embed=1",
      "standaloneUrl": null,
      "inputs": [
        {
          "name": "zcis-hours",
          "type": "number",
          "label": "Hours / week free",
          "unit": "",
          "min": 1,
          "max": 80,
          "step": 1,
          "default": "10"
        },
        {
          "name": "zcis-cur",
          "type": "text",
          "label": "Currency symbol",
          "unit": "",
          "default": "£"
        },
        {
          "name": "zcis-phys",
          "type": "checkbox",
          "label": "I can do physical work",
          "unit": "",
          "default": "1"
        },
        {
          "name": "zcis-net",
          "type": "checkbox",
          "label": "I have internet access",
          "unit": "",
          "default": "1"
        },
        {
          "name": "zcis-mat",
          "type": "number",
          "label": "Materials / job",
          "unit": "",
          "min": 0,
          "step": 0.5,
          "default": "3"
        },
        {
          "name": "zcis-trav",
          "type": "number",
          "label": "Travel / job",
          "unit": "",
          "min": 0,
          "step": 0.5,
          "default": "2"
        },
        {
          "name": "zcis-hrs",
          "type": "number",
          "label": "Hours / job",
          "unit": "",
          "min": 0.25,
          "step": 0.25,
          "default": "2"
        },
        {
          "name": "zcis-want",
          "type": "number",
          "label": "Want per hour",
          "unit": "",
          "min": 0,
          "step": 0.5,
          "default": "10"
        },
        {
          "name": "zcis-market",
          "type": "number",
          "label": "Others charge",
          "unit": "",
          "min": 0,
          "step": 0.5,
          "default": "0"
        },
        {
          "name": "zcis-name",
          "type": "text",
          "label": "Your name",
          "unit": ""
        },
        {
          "name": "zcis-svc",
          "type": "text",
          "label": "Service + price line",
          "unit": ""
        },
        {
          "name": "zcis-contact",
          "type": "text",
          "label": "Contact (phone / handle)",
          "unit": ""
        },
        {
          "name": "zcis-area",
          "type": "text",
          "label": "Area you cover",
          "unit": ""
        },
        {
          "name": "zcis-goal",
          "type": "number",
          "label": "Monthly goal",
          "unit": "",
          "min": 0,
          "step": 5,
          "default": "300"
        },
        {
          "name": "zcis-note",
          "type": "text",
          "label": "What you earned it from",
          "unit": ""
        },
        {
          "name": "zcis-amt",
          "type": "number",
          "label": "Amount",
          "unit": "",
          "min": 0,
          "step": 0.5
        },
        {
          "name": "zcis-where",
          "type": "select-one",
          "label": "You live in a…",
          "unit": "",
          "options": [
            "city",
            "town",
            "village"
          ],
          "default": "town"
        },
        {
          "name": "zcis-pick",
          "type": "select-one",
          "label": "Chosen idea",
          "unit": ""
        }
      ],
      "outputs": [
        {
          "name": "zcis-ideas",
          "type": "live"
        },
        {
          "name": "zcis-priceout",
          "type": "live"
        },
        {
          "name": "zcis-planout",
          "type": "live"
        },
        {
          "name": "zcis-flyerout",
          "type": "live"
        },
        {
          "name": "zcis-log",
          "type": "live"
        }
      ],
      "prefill": {
        "urlTemplate": "https://www.themostusefulsiteintheworld.com/tool.html?card=zero-capital-income-starter&<id>=<value>",
        "runs": true,
        "example": "https://www.themostusefulsiteintheworld.com/tool.html?card=zero-capital-income-starter&zcis-hours=10&zcis-cur=%C2%A3&zcis-phys=1&zcis-net=1&zcis-mat=3&zcis-trav=2&run=1"
      },
      "formula": "Interactive browser tool — no single closed-form formula (see description).",
      "sources": [],
      "tags": [
        "zero",
        "capital",
        "income",
        "starter",
        "zero-capital",
        "finance",
        "money",
        "start",
        "business",
        "anyway"
      ],
      "popularity": 4949,
      "featured": false,
      "updated": "2026-09-19"
    }
  ]
}