๐ How to embed
1. Pick a tool below.
2. Click "Copy iframe" โ the snippet is on your clipboard.
3. Paste into your site, blog, Notion page, or anywhere else that accepts HTML. You can adjust the width and height attributes.
The deal: embedding is free, forever, and the snippet keeps a small credit line linking back here โ that credit is the whole price of the free tier. Bought a licence, or want the credit gone and your own branding on? See pricing โ paste your key into the activation box and every snippet on this page switches to your licensed version automatically.
Default snippet (height 450px):
<iframe src="https://www.themostusefulsiteintheworld.com/tool.html?card=TOOL-SLUG" width="100%" height="450" style="border:none;border-radius:12px;" title="TOOL TITLE" loading="lazy"></iframe> <div data-mus-credit ...>via The Most Useful Site in the World</div>
You can also just link to a tool from your site โ each tool has a stable URL you can share.
Interactive Art & Living Worlds
๐ 3D Spirograph Nebula
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 a...
Music & Audio
๐ 808 Sub-Bass Note Tuner & Harmonics Designer
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...
Health & Fitness
๐ฉธ HbA1c โ Average Glucose
Convert HbA1c (%) to estimated average glucose with the NGSP/DCCT formula (eAG mg/dL = 28.7 ร A1c โ 46.7). Educational only โ lab methods differ (IFCC mmol/mol vs NGSP %), and this is not a diagnos...
SaaS & Business Killers
๐งช Split Test Lab
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...
Culinary & Food Science
๐ฅ ABV, Proof & Dilution
US proof is 2 ร ABV%. UK/EU labels use ABV%. Dilute with CโVโ = CโVโ (alcohol volume conserved). Mixing two bottles uses a weighted average. Not a drink-driving tool.
Wellbeing & Community
โฟ Accessible Text Prep
Paste something you need a specific person to understand โ a letter from a council, instructions for an elderly relative, a form your colleague keeps skipping. This rewrites the presentation and th...
Science & Engineering
๐ Ultrasonic Acoustic Levitation
40 kHz ultrasonic standing wave acoustic trap. Non-contact levitation of micro-beads and liquid droplets suspended in mid-air at acoustic pressure nodes.
Science & Engineering
๐พ Acres โ Hectares โ mยฒ
International acre is exactly 4,046.8564224 mยฒ; a hectare is 10,000 mยฒ (a 100 m square). UK land ads mix acres and hectares. Edit any field.
Natural Remedies & Herbs
๐ Acupressure Point Relief Map
Non-invasive somatic reflexology locator. Guides precise anatomical pressure points for rapid drug-free relief of headaches, nausea, anxiety, and cramps.
Natural Remedies & Herbs
๐ฑ Adaptogen Synergy Matcher
HPA-axis endocrine matching engine. Aligns clinical botanical adaptogens to your stress phenotype (high nighttime cortisol vs chronic adrenal exhaustion).
Productivity & Lifestyle
๐ Adulting Score Calculator
How well are you really adulting? Take this brutally honest assessment and find out.
Mathematics
๐ Exact Age Calculator (Years, Months, Days)
Work out your exact age โ or the time between any two dates โ in years, months, weeks, days, hours, minutes and seconds. Shows your next birthday countdown, the weekday you were born, your zodiac s...
AI & Autonomous Agents
๐ AI Agent ReAct Loop Studio
Launcher for the standalone AI: the ReAct loop โ thought, action, observation โ with real tool calls and a stop condition you can watch. Also runs inside the agent pipeline. In-browser.
AI & Autonomous Agents
๐ง AI Chain-of-Thought Parser
Launcher for the standalone AI: chain-of-thought reasoning as numbered steps with a visible trace, plus chain-of-verification and self-consistency on the same question. In-browser, no key.
AI & Autonomous Agents
๐ AI Context Window Budget Lab
Launcher for the standalone AI: budget a context window across system prompt, retrieved chunks, history and reserved output, with warnings and a suggested chunk count. In-browser, instant.
AI & Autonomous Agents
โก AI Few-Shot Prompt Builder
Launcher for the standalone AI: build few-shot prompts in XML, JSON, markdown or chat-message framing, with a token estimate and guidance on how many exemplars you need. In-browser.
AI & Autonomous Agents
๐ค AI Function Calling Validator
Launcher for the standalone AI: validate function/tool declarations in OpenAI, Anthropic and Gemini shapes, get errors and warnings, and copy a normalised version for each provider. In-browser.
AI & Autonomous Agents
๐ AI Hallucination & Fact Check
Launcher for the standalone AI: extract claims from an answer, check each against your indexed documents, and read coverage, verdict counts and token entropy as hallucination risk. In-browser.
AI & Autonomous Agents
๐ AI MCP Tool Protocol Inspector
Launcher for the standalone AI: a mock MCP server in the page โ initialize, ping, tools/list, tools/call, resources/list, prompts/list โ with request checks and compliance report. In-browser.
AI & Autonomous Agents
๐ฐ AI Model Cost & Speed Matrix
Launcher for the standalone AI: compare models on cost per request, per day and per period with prompt-caching discounts, tokens/sec and modelled latency. Your numbers, nothing fetched.
AI & Autonomous Agents
๐ก๏ธ AI Prompt Injection Defense
Launcher for the standalone AI: scan text against twelve injection patterns with severities and a risk score, get a sanitised copy, and read the defences that actually hold. In-browser.
Productivity & Lifestyle
๐ค AI Toolbox Generator
Build your own custom AI tools by combining different AI capabilities. Create, save, and share personalized mini-tools in minutes! โจ No coding required - drag, drop, and customize!
AI & Autonomous Agents
๐ AI Vector Similarity Matrix
Launcher for the standalone AI: compare two texts by cosine, Euclidean and dot product over 64-dim hashed embeddings, with token overlap, Jaccard and per-dimension sparklines. In-browser.
Culinary & Food Science
๐ฌ๏ธ Air Fryer โ Oven Converter
Turn a conventional-oven recipe into an air-fryer starting point: typically 20ยฐC cooler and about 20% less time. Always check food, especially poultry, with a thermometer โ baskets cook faster at t...
Astronomy & Space
๐ซ๏ธ Airmass & Extinction Calculator
How much of a star's light the atmosphere is stealing at any altitude, in which band, and how long you have before it is not worth imaging. Airmass climbs steeply below about 25ยฐ.
Writing & Language
๐ค Anagram Solver
Find every word you can make from your letters โ from two letters up to the full anagram โ with optional pattern matching.
Museum & Collection
๐ซ Ancient Egypt Quiz
Test your knowledge of ancient Egypt โ pharaohs, pyramids, gods and everyday life โ in ten-question rounds with streaks.
Anime & Otaku Culture
โฑ๏ธ Anime Binge Calculator
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.
Anime & Otaku Culture
๐ Anime Character Archetypes
Explore the psychological Dere spectrum of anime character archetypes. Inspect behavioral triggers, iconic representatives, and take the 4-question archetype diagnostic quiz.
Anime & Otaku Culture
๐ช Anime Con Budget Planner
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...
Anime & Otaku Culture
๐ก๏ธ Cosplay Prop Scaler
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.
Anime & Otaku Culture
๐ Anime Filler Guide
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.
Anime & Otaku Culture
๐ Anime Phrases & Tropes
Decode iconic anime verbal tics (*dattebayo*, *de gozaru*, *nya*), battle cries (*omae wa mou shindeiru*), and dialogue tropes with native Japanese audio pronunciation.
Anime & Otaku Culture
๐ต Anime Music BPM Analyzer
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.
Anime & Otaku Culture
๐ฎ Anime Mood Matcher
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...
Anime & Otaku Culture
๐ Anime Schedule Converter
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 ...
Science & Engineering
๐ณ๏ธ Antipode & Gravity Tunnel Explorer
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...
Wellbeing & Community
๐ค Sincere Apology Builder
Most apologies fail for one of four reasons: they contain โbutโ, they apologise for the other personโs feelings instead of your behaviour, they explain rather than own it, or they promise nothing. ...
Finance & Money
๐ฆ APR โ APY Converter
APY = (1 + APR/n)n โ 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.
Aquatics & Fishkeeping
๐ซง Aquarium COโ Calculator
Dial in high-tech planted tank COโ injection. Calculate dissolved COโ concentration (ppm) from pH/KH equilibrium, simulate 4 dKH drop checker reagent colors, and estimate cylinder gas lifespan.
Aquatics & Fishkeeping
๐ค Fish Feeding & Vacation Planner
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 ...
Aquatics & Fishkeeping
๐ก๏ธ Aquarium Heater & Chiller
Calculate precision heating wattage, evaporative surface loss, and cooling chiller ratings. Eliminates the catastrophic "stuck heater" disaster using fail-safe dual heater redundancy math.
Aquatics & Fishkeeping
๐ก Aquarium PAR Lighting
Calculate photosynthetically active radiation (PAR) penetration at substrate depth, daily light integral (DLI), and generate split photoperiod schedules to suppress nuisance algae.
Aquatics & Fishkeeping
๐ Fish Medication Dosing
Identify fish ailments by symptom and calculate precision medication dosages based on true net water volume. Includes invertebrate toxicity warnings and scaleless fish safety flags.
Aquatics & Fishkeeping
๐ Nitrogen Cycle Tracker
Master the nitrogen cycle without harming livestock. Calculate exact pure ammonia dosing, simulate bacterial colonisation curves (Nitrosomonas & Nitrospira), and validate your 24-hour clearance...
Aquatics & Fishkeeping
๐ Fish Stocking Compatibility
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.
Aquatics & Fishkeeping
๐ชจ Aquarium Substrate Estimator
Plan your planted tank and hardscape layout. Calculate exact substrate volume, sloped perspective depth, commercial bag counts (3L/9L aqua soil, 20lb/50lb sand), and stone weight for Iwagumi and Ry...
Aquatics & Fishkeeping
๐ Aquarium Volume & Weight
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.
Aquatics & Fishkeeping
๐งช Water Change & Salinity
Precision aquatic water chemistry toolkit. Calculate exact nitrate dilution percentages, RO/DI remineralization buffers for dwarf shrimp and plants, and marine saltwater salt batch mixing.
Sports
๐ฏ Archery Score Calculator
Tap the value of each arrow as you shoot and this keeps the running total, your Xs and 10s, and how far through the round you are โ the way scorers count at the line.
Museum & Collection
๐๏ธ The Orders Bench
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...
Algorithms & Computer Science
๐ค Text โ Hex โ Binary
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.
Productivity & Lifestyle
๐ค ASCII Banner Generator
Generate retro ASCII text banners and terminal art for code headers, GitHub READMEs, Discord bots, and CLI scripts.
Science & Engineering
๐ Aspect Ratio Resizer
Calculate pixel dimensions while locking exact aspect ratios (16:9 widescreen, 9:16 vertical TikTok/Shorts, 4:3 classic, 1:1 square, 21:9 cinema). Generates modern CSS `aspect-ratio` code snippets.
Astronomy & Space
๐ Astronaut Artificial Gravity Calculator
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.
Astronomy & Space
๐ซง Spacecraft Cabin Atmosphere Planner
Convert cabin pressure and gas fractions into oxygen, carbon-dioxide, water-vapour and inert-gas partial pressures. Compare oxygen availability across mixed-pressure habitat concepts.
Astronomy & Space
๐ฆ Astronaut Crew Consumables Planner
Turn crew size and mission duration into a first-pass launch mass for water, food, oxygen and daily supplies. Every per-person assumption is editable, including water recovery and contingency.
Astronomy & Space
๐ก Deep-Space Communications Planner
Turn range into one-way light time, round-trip conversation delay, file-transfer finish time and free-space path loss. Useful for planning when a crew cannot wait for real-time help from Earth.
Astronomy & Space
๐งโ๐ EVA Timeline & Consumables
Check a spacewalk timeline against oxygen, carbon-dioxide removal, battery and cooling endurance. The tightest resource sets the planning margin while overhead reveals usable task time.
Astronomy & Space
๐ช Astronaut Hohmann Transfer Planner
Estimate the two burns, coast time, departure phase angle and repeat opportunity for a coplanar Hohmann transfer between circular orbits around the same central body.
Astronomy & Space
๐ซธ Microgravity Push-Off Planner
Model a controlled push across a cabin: impulse sets speed, distance sets coast time, and the same momentum must be removed at the destination. Include cargo and recoil from a free-floating support...
Astronomy & Space
โข๏ธ Astronaut Radiation Dose Ledger
Combine prior dose, mission duration, a measured or assumed daily rate, shielding reduction and one-off events. Compare the total with a value you choose without pretending that one universal caree...
Astronomy & Space
๐ Astronaut Rocket Equation & Delta-v Budget
Apply Tsiolkovskyโs rocket equation to wet mass, dry mass and specific impulse. Check ideal delta-v capability, propellant needed for a manoeuvre, reserve allowance and remaining mass.
Astronomy & Space
๐ Spacecraft Power & Eclipse Budget
Balance solar generation, sunlit and eclipse loads, orbital timing and usable battery depth. See both the eclipse survival margin and whether each orbit finishes with an energy surplus.
Science & Engineering
Astronomy Calculators
Planets move in elliptical orbits with the Sun at one focus.
Sports
๐ฅ Athletics Decathlon & Heptathlon Points
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...
Science & Engineering
๐ Aurora Solar Wind Chamber
Kristian Birkeland's Terrella experiment. Solar wind plasma streams channeled along geomagnetic dipole field lines excite shimmering atmospheric auroral ovals.
Science & Engineering
โก Tesla Atmospheric Plasma
High-frequency Tesla coil discharge globe. Noble gas ionization streamers branch from the central electrode and focus to your touch via capacitive coupling.
Algorithms & Computer Science
๐ง Audio File Size
Uncompressed WAV/AIFF size = sample rate ร channels ร (bit depth รท 8) ร seconds. MP3/AAC size โ bitrate ร seconds รท 8. Headers are a few kilobytes โ ignored here.
Music & Audio
๐๏ธ Audio Tone Generator
Generate pure acoustic tones, test speaker frequency responses, and monitor live audio waveforms using the Web Audio API.
Productivity & Lifestyle
๐ฃ๏ธ Awkward Silence Filler
The silence is deafening. Someone needs to say something. Let us help. (Results may make it worse.)
SaaS & Business Killers
โ๏ธ B2B Cold Email Generator
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...
Health & Fitness
๐ผ Baby Formula Mixing
Most UK powders use 1 level scoop per 30 ml of water (check the tin). Water first, then powder. This is arithmetic โ NHS mixing and sterilising steps still apply, and never microwave a bottle.
Health & Fitness
๐ผ Baby Sleep & Feeding Day Planner
Babies run on wake windows โ 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...
Birdwatching & Ornithology
๐ป Backyard Bird Feeder Nutrition
Avian nutritional formulation matrix. Matches seed types to bill morphology, prevents feeder pests (squirrels/starlings), and maintains disease-free feeding stations.
Sports
๐ธ Badminton Match Scorer
Rally scoring to 21, win by two โ 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.
Finance & Money
๐
Bank Complaint Deadline Tracker
Track your complaint deadlines โ never miss a bank's response window, FOS deadline, or court limitation period
Finance & Money
๐ Credit Score Dispute Letter Generator
Challenge incorrect entries on your credit report โ generate dispute letters for credit agencies and banks
Finance & Money
โ๏ธ Bank Charge Dispute Letter Generator
Generate formal dispute letters for unauthorized charges, unfair fees, and billing errors โ ready to send to your bank
Finance & Money
๐ฐ Hidden Bank Fee Calculator
Calculate the TRUE cost of your bank account โ overdraft fees, ATM charges, FX markups, and hidden costs that banks hope you won't notice
Finance & Money
โ๏ธ Financial Ombudsman Complaint Builder
Build a complete FOS complaint โ step by step. Get your money back when the bank refuses to help
Finance & Money
๐ Overdraft & Interest Reclaim Calculator
Calculate how much you've been overcharged on overdraft interest and fees โ then generate a reclaim letter
Finance & Money
๐ Subject Access Request (SAR) Generator
Force your bank to reveal ALL data they hold on you โ internal notes, decision records, credit scoring, and communications
Finance & Money
๐ก๏ธ Section 75 Claim Calculator & Letter
Check if your credit card purchase is protected under Section 75 โ calculate your claim and generate the letter
Finance & Money
โ๏ธ Small Claims Court Guide & Cost Calculator
Calculate court costs, check eligibility, and generate your claim โ the nuclear option when banks refuse to play fair
Finance & Money
๐ Bank Switching Bonus Calculator
Compare bank switching bonuses, calculate total savings, and see how much your loyalty is costing you
Science & Engineering
โฒ๏ธ Bar โ PSI โ kPa
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 โ this is a unit convert only.
Mind-Blowing Demos
๐ฟ Barnsley Fern
Four simple rules, chosen at random, draw a perfect fern. No one programmed a leaf โ the fern is the fixed point of the chaos, and every frond is a tiny copy of the whole.
Algorithms & Computer Science
๐ Base64, Hex & Binary Text Encoder / Decoder
Encode text to Base64 (standard or URL-safe), hexadecimal, binary, HTML entities, Unicode escapes or ROT13 โ and decode back. Full UTF-8 and emoji support. Live in both directions; nothing leaves y...
Sports
โพ Baseball Stats Calculator
The slash line every hitter lives by โ batting average, on-base and slugging, plus OPS โ and the pitching numbers (ERA and WHIP). Enter a box score and get the exact formulas and a read on what the...
Sports
๐ Basketball Efficiency Calculator
Type in a box score and get the metrics the analysts use: Game Score, effective and true shooting percentage, points per shot and assist-to-turnover ratio โ all with the exact formulas and a plain-...
Science & Engineering
๐ Battery Runtime (mAh)
Hours โ (capacity mAh ร (voltage / load voltage) ร efficiency) / load mA. A 2000 mAh cell at 100 mA is about 20 hours at 100% โ real packs are less because of cut-off voltage and converter loss.
Science & Engineering
Battery Sizing Calculator
Accounts for battery aging, temperature, and discharge limits
Museum & Collection
๐ง The Bayes Workshop
Conditional probability you can feel: what a positive test really means (Bayes' theorem), a 300-game Monty Hall simulation, and the prosecutor's fallacy โ with a 10,000-person grid painted live by ...
Science & Engineering
๐๏ธ Beam Vibration Analyzer
Compute natural flexural vibration eigenfrequencies and mode shapes for structural beams ($EI \frac{\partial^4 w}{\partial x^4} + \rho A \frac{\partial^2 w}{\partial t^2} = 0$). Inspect nodal point...
Science & Engineering
๐ฌ๏ธ Beaufort Wind Scale
Convert wind speed to a Beaufort force (0โ12) using the Met Office mean-speed bands. Force is a class, not a precision instrument. Gusts can sit a force higher than the mean.
Science & Engineering
๐ Coanda & Bernoulli Air Levitation
Aerodynamic levitation exhibit. High-velocity air jet traps a floating sphere via Bernoulli low-pressure depression and Coandฤ wall adhesion even when tilted.
Sports
๐ฐ Betting Odds & Each-Way Calculator
Work out fractional odds as a decimal and a probability, and see exactly what an each-way bet returns โ whether your horse wins, only places, or finishes nowhere. The stake, odds and place terms al...
Mind-Blowing Demos
๐ฆ Bifurcation: Order to Chaos
One equation, one knob. The logistic map x → r·x·(1โx) doubles its rhythm again and again, then dissolves into chaos โ and the same pattern of period-doubling appears...
Algorithms & Computer Science
๐ Big-O Complexity Explorer
Why does an O(nยฒ) algorithm feel instant for 10 items but crawl for a million? Watch each complexity class grow, and see how long each would really take at one operation per nanosecond โ the number...
Sports
๐ด Bike Gear, Cadence & Speed Calculator
Works out what every gear on your bike actually does โ how far one pedal turn takes you, what speed you will be doing at a given cadence, and which gears are duplicates you never need. The thing mo...
Algorithms & Computer Science
๐ข Binary, Bits & Bitwise Playground
Everything on a computer is bits. Tap the cells to flip bits and see the number change, then run the bitwise operations โ AND, OR, XOR, NOT, shifts โ that power everything from colours to cryptogra...
Lucid Dreaming & Sleep
๐ง Lucid Binaural REM Stimulator
Real-time stereo binaural synthesizer with 40 Hz gamma stimulation (Voss et al., Nature Neuroscience 2014) and 6 Hz theta hypnagogic carriers. Requires stereo headphones.
Music & Audio
๐ง Binaural Neuro Tuner
Generate scientifically tuned binaural beats and isochronic frequencies using pure Web Audio synthesis. Entrain your brainwaves for laser focus, flow state, deep meditation, or rapid sleep. ๐ง Head....
Science & Engineering
โจ Bioluminescent Luciferin Chemical Cascade Lab
Bioluminescence is the miracle of "cold light"โproducing near 100% luminous efficiency with zero thermal waste. Discover how enzyme Luciferase oxidizes substrate Luciferin using cellular ATP, agita...
Interactive Art & Living Worlds
๐ฆ Bioma Petri Dish
An artificial life (ALife) Darwinian simulation. Engineer genetic cellular strains, watch natural selection optimize camouflage and hunting behaviors across thousands of generations, and introduce ...
Birdwatching & Ornithology
๐ค๏ธ Migration & Thermal Lift Calc
Predict hawk watches, songbird flyways, and coastal fallouts. Evaluates synoptic frontal boundaries, barometric rise, wind vectors, and solar thermal lift.
Birdwatching & Ornithology
๐ชถ Bird Molt Cycle & Ageing Lab
Avian Humphrey-Parkes (H-P) plumage terminology and molt-limit ageing engine. Decode annual feather replacement cycles between juvenile, alternate, and basic plumages.
Birdwatching & Ornithology
๐ชบ Bird Nest Box Dimensions Guide
Cornell Lab of Ornithology nest box builder. Exact hole diameters, interior floor dimensions, and predator exclusion clearance for native cavity nesters.
Birdwatching & Ornithology
๐ฆ
Raptor & Flight Silhouette ID
Identify raptors and aerial birds in high-overhead flight by wing aspect ratio, tail proportions, wingtip finger slots, and characteristic wingbeat cadence.
Birdwatching & Ornithology
๐ถ Bird Song Mnemonic Trainer
Acoustic field ornithology trainer. Decode avian vocalizations using phonetic mnemonics, pitch contours, and synthesized frequency playback.
Birdwatching & Ornithology
๐ Avian Anatomy & Field Marks
Standard ornithological avian topography map. Learn precise feather tracts, facial stripes, wing coverts, and bill structures to nail difficult field identifications.
Birdwatching & Ornithology
๐ญ Binocular Optics & FOV Lab
Optical performance evaluator for birdwatchers. Calculates exit pupil, twilight factor, relative brightness, and converts field of view across feet, meters, and angular degrees.
Birdwatching & Ornithology
๐ Birding Life List & Big Year
Personal field lifer ledger & annual Big Year tally. Records lifetime ticks, date of observation, habitat biome, and exports to CSV for eBird backup.
Productivity & Lifestyle
Birthday Reminder
No birthdays added yet. Add your first birthday above!
Astronomy & Space
๐ณ๏ธ Black Hole Horizon Calculator
Event horizon radius, surface gravity, Hawking temperature, evaporation time and the tidal force at the horizon for any mass. Compares stellar and supermassive black holes side by side.
Productivity & Lifestyle
๐ข Blame Deflector 3000
Something went wrong? Don't worry โ it's definitely not your fault. Let science* find someone else to blame. *Not science.
Health & Fitness
๐ฉบ Blood Pressure Category Guide
Home-monitor numbers compared with NHS adult clinic bands (and a note on AHA). One reading is not a diagnosis. Seek urgent help for chest pain, one-sided weakness, or a sudden severe headache. This...
Health & Fitness
โ๏ธ BMI Calculator
Calculate your Body Mass Index (BMI) with accurate WHO classification. BMI is a simple screening tool for weight categories that may lead to health problems.
Health & Fitness
๐ฅ BMR & TDEE Calculator
Calculate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) using scientifically validated formulas.
Home & DIY
๐ชต Board-Foot Lumber Calculator
A board foot is 1" ร 12" ร 12". Enter the dimensions of your boards and the quantity, and get the board footage, linear footage and cost.
MrProphecy Arcade
๐ฒ Backgammon
Classic backgammon: move your pieces around the board and bear them off first. Roll dice and race against the AI!
MrProphecy Arcade
๐ดโซ Checkers / Draughts
Classic checkers with mandatory jumps and king promotion. Click a piece then click where to move. Play against the AI.
MrProphecy Arcade
โ๏ธ Chess
Play chess against a simple AI. Full rules: castling, en passant, pawn promotion. Click a piece then click where to move.
MrProphecy Arcade
๐ดโซ Connect Four
Drop discs to connect four in a row โ horizontally, vertically, or diagonally. Play against a smart AI with animations.
MrProphecy Arcade
๐ฃ Dominoes
Block dominoes: match ends to play your tiles. If you can't play, draw from the boneyard. Lowest hand score wins!
MrProphecy Arcade
๐ฒ Ludo
Race your 4 tokens from start to home! Roll a 6 to enter the board. Land on opponents to send them back. 2-4 player local.
MrProphecy Arcade
๐ชจ Mancala
Ancient strategy game โ sow seeds around the board, capture your opponent's stones. Free turn if your last seed lands in your store.
MrProphecy Arcade
โฌ Nine Men's Morris
Place and slide pieces to form mills (3 in a row). A mill lets you remove an opponent's piece. Reduce them to 2 to win!
MrProphecy Arcade
โซโช Othello (Reversi)
Place discs to flip your opponent's pieces. The player with the most discs when the board is full wins. Play against a strategic AI.
MrProphecy Arcade
๐ Snakes & Ladders
Roll the dice and race to square 100! Ladders boost you up, snakes drag you down. Play against the AI on a beautiful animated board.
MrProphecy Arcade
๐ฒ Yahtzee
Roll five dice up to three times per turn. Score in 13 categories. Get the highest total!
Health & Fitness
๐ง Body Surface Area Calculator
Estimate body surface area with Mosteller, Du Bois and Haycock formulae from height and weight. Used for some drug doses and cardiac index. Educational only โ never override a prescribed dose.
Health & Fitness
๐๏ธ Body Fat Calculator
Estimate your body fat percentage using the U.S. Navy method and understand your fitness level.
Science & Engineering
Boiling Point Finder
Look up boiling points of common substances at 1 atm. Converts between Celsius, Fahrenheit, and Kelvin. Values are at standard pressure (1 atm). Actual boiling points may vary with altitude and pur...
Sports
๐ง Bouldering Score Comparison
In bouldering, tops beat everything. Enter two climbers' results and this applies the ranking order โ most tops, then fewest attempts to top, then most zones, then fewest attempts to zone โ and dec...
Sports
๐ณ Ten-Pin Bowling Score Calculator
Enter the pinfall for each roll and this scores the game for you โ strikes and spares with the bonuses, and the tenth frame's extra balls, all handled automatically.
Sports
๐ Boxing Fight Outcome Projector
Mid-fight maths for fans and cornermen. Enter the score so far and see exactly what each fighter needs in the remaining rounds โ including whether a knockout has become the only route.
Sports
โ๏ธ Boxing Judging Criteria Weigher
Score a single round against the four official criteria โ clean punching, effective aggression, ring generalship and defence โ in their correct priority order. Shows which criterion decided the rou...
Sports
๐๏ธ Boxing Knockdown & Count Rules Assistant
Work out whether an incident is a scoring knockdown or a slip, how the count runs, and what it does to the round score. Includes a live count timer at the official pace.
Sports
๐ Boxing Punch Stat Tracker
Live compubox-style punch counter. Tap as you watch to log jabs and power shots landed or thrown, and get instant connect percentages plus a work-rate comparison.
Sports
๐ Boxing Momentum & Swing Round Analyser
Paste a completed card and see the shape of the fight โ momentum swings, the longest run of rounds, who finished stronger, and which rounds were decisive enough to change the result.
Sports
๐ Boxing Round Timer & Bell
Full bout timer with authentic bell and ten-second clapper, generated live in your browser. Configure round length, rest interval and round count for sparring, training or scoring practice.
Sports
๐ Boxing Scorecard Comparator
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.
Sports
๐ฅ Boxing 10-Point Must Scorecard
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.
Sports
๐จโโ๏ธ Boxing Three-Judge Decision Simulator
Enter three official cards and get the correct verdict โ unanimous, split, majority, or draw. Handles every decision type including the frequently confused majority draw.
Sports
โ๏ธ Boxing Weight Class & Weigh-In Checker
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.
Music & Audio
BPM Tap Counter (Pro)
Instant, free online BPM Tap Counter (Pro) tool. No signup required.
Productivity & Lifestyle
๐ Bra Size Converter
Convert UK, US, EU/FR and AU band + cup. Sister sizes keep the same cup volume (one band up, one cup down). Brands still vary โ treat this as a starting letter, not a fitting.
Science & Engineering
โก Brachistochrone & Tautochrone: The Curve of Fastest Descent
In 1696, Johann Bernoulli challenged the world to find the path of fastest descent between two points under gravity. The answer is not a straight lineโit is a cycloid! Test the race in real-time an...
Writing & Language
๐ต Braille Alphabet Trainer
Learn the 26 letters of English Braille by building cells dot by dot and decoding them. Each letter is a 2ร3 grid of raised dots โ once you see the pattern, the whole alphabet unfolds. All local, n...
SaaS & Business Killers
โ๏ธ Brand Mark Forge
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...
Finance & Money
BreakโEven Calculator
Find the sales volume needed to break even and calculate required revenue. For educational and planning purposes only.
Science & Engineering
โก Breaker Sizing Calculator
Estimate breaker size for a circuit. Always verify with a qualified electrician and local electrical codes. โ ๏ธ Educational only โ not for actual electrical installations.
Home & DIY
๐งฑ Brick Calculator
Calculate how many bricks you need for any wall โ including mortar joints, waste, and pallets to order. Works for UK standard, metric, and imperial bricks.
Museum & Collection
๐ British Monarchs Quiz
Name the kings and queens of England, Scotland and the UK from 1066 to today โ ten questions per round with streaks.
Museum & Collection
๐ The Regnal Desk
English and British legal years used to be counted from the accession, not 1 January. โ3 Geo. IIIโ is the third year of George IIIโs reign. The desk covers the Hanoverians to the present, plus a Tu...
Finance & Money
๐ฐ Financial Budget Dashboard
Smart budgeting with predictive analytics, financial health scoring, and personalized optimization strategies.
Mind-Blowing Demos
๐ฒ Buffon's Needle π
In 1777 Buffon realised you can measure π by dropping needles on floorboards. Watch the probability of a needle crossing a line converge on 2/π โ π again, this time from pure g...
Science & Engineering
๐จ Virtual Builder's Workmate
Virtual measurement and leveling tools using device sensors. Requires camera and motion sensor permissions.
Productivity & Lifestyle
๐ณ Business Card Size Guide
Print sizes and pixels for UK/EU (85 ร 55 mm), US (3.5 ร 2 in), Japanese and Chinese cards. Add 3 mm bleed if a printer asks for it. Not a design studio โ just the millimetres they keep getting wro...
Finance & Money
๐
Business Days Calculator
Count weekdays between two dates, or add N working days to a start date. Weekends are skipped; paste extra holidays if you need them. All counting stays on this device.
SaaS & Business Killers
๐งฉ Business Model Canvas
The one-page strategy board that consultants charge a day rate to facilitate. Fill the nine blocks of a Business Model Canvas or a Lean Canvas, get prompted when a block is too thin to be true, and...
Writing & Language
Business Writing Assistant
Draft clear, professional business documents: memos, executive summaries, proposals, and meeting notes. Choose the document type, enter the purpose and key points, then generate a polished draft yo...
Algorithms & Computer Science
๐พ Bytes โ KB โ MB โ GB
Convert file sizes with SI (1000) or binary IEC (1024) prefixes. Hard-drive boxes use decimal GB; Windows historically used 1024 and still called them GB. Edit any field.
Productivity & Lifestyle
๐งณ Cabin Bag Size Checker
Type your suitcase in centimetres and see which common airlines it should fit, including wheels and handles as the airline measures them. Limits change โ confirm on the carrierโs site before you fl...
Productivity & Lifestyle
โ Will You Sleep Tonight? (Caffeine Check)
Caffeine has a half-life of roughly five hours, which is why the 4pm espresso is still in your system at midnight. Log what you drank and when, and find out how much will still be circulating at be...
Finance & Money
๐ CAGR โ Compound Annual Growth
CAGR = (end รท start)1/years โ 1. The smoothed yearly rate that takes a starting value to an ending value. It ignores deposits, fees and the bumpy path in between โ a sketch, not a forecast.
Mathematics
Calculus Helper
Work with derivatives and integrals. Enter a function of x, choose operation, and generate stepโbyโstep results.
Health & Fitness
๐ Calorie Deficit Timeline
Rough weeks to a goal weight from a daily calorie deficit. Uses ~7,700 kcal per kg (about 3,500 kcal per lb). Real bodies adapt โ this is a sketch, not a promise, and not medical advice.
Health & Fitness
Calorie Calculator
Estimate daily calorie needs with BMR calculation, weight goals, and macronutrient breakdown. Auto-saves profiles for quick access.
Culinary & Food Science
๐ฌ Candy & Sugar Stages Guide
Confectionery science & sugar crystallization guide. Features automatic boiling-point elevation correction, cold-water ball test simulations, and invert sugar balancing.
Science & Engineering
Capacitor Calculator
Calculate capacitor values, RC time constants, impedance, and filter characteristics. โ ๏ธ Educational only โ verify with datasheets and professional standards.
Music & Audio
๐ธ Capo Calculator
Find capo placement for key transposition, chord conversion, and song adaptation. Supports sharps/flats, multiple fret options, and tuning adjustments.
Home & DIY
๐ Car Care & MOT Due-Date Tracker
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 โ n...
Finance & Money
๐ Car Ownership Cost Calculator (UK)
Work out the true cost of running a car in the UK โ depreciation, fuel or electricity, insurance, VED road tax, servicing, MOT, tyres and repairs โ per month and per mile. Everything calculates loc...
Productivity & Lifestyle
Career Path Planner
Map out your career goals, milestones, and track progress over time. Save and manage multiple career plans.
Wellbeing & Community
๐ซ Carer's Respite Planner
Most carers never get a break, and it is rarely because nobody wants to help. It is because the carer is the only person who knows what needs doing. This turns what is in your head into a handover ...
Music & Audio
๐ต Christmas Carol Karaoke Machine
Sing along to Christmas classics with synchronized lyrics, pitch detection, and festive backgrounds! ๐ค Features: 50+ carols, pitch meter, key changer, duet mode, recording
Productivity & Lifestyle
๐บ๏ธ Cartographer's World Forge
Forge an entire fantasy world from a single seed. Tectonic uplift raises mountains, rain shadows carve deserts, rivers find the sea, and civilisations rise where the land is kind. Every kingdom, to...
Productivity & Lifestyle
Cat Photo Viewer
Browse cat photos from free public APIs. Features infinite scrolling, favorites, and breed info.
Algorithms & Computer Science
๐ฒ Cellular Automata Explorer
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...
Science & Engineering
๐ก๏ธ Celsius โ Fahrenheit โ Kelvin
ยฐF = ยฐC ร 9/5 + 32. Kelvin = ยฐC + 273.15. Absolute zero is 0 K (โ273.15 ยฐC). Edit any box โ weather, ovens and science labs all use different scales.
Productivity & Lifestyle
๐ Censorship Monitor
Monitor Wikipedia blocks and Reddit content moderation in real-time. โ ๏ธ Educational tool - uses public APIs
Science & Engineering
๐งญ Chaotic Magnetic Pendulum
Nonlinear chaos theory exhibit. A metallic pendulum swings over three magnetic attractors, demonstrating sensitive dependence on initial conditions.
Writing & Language
๐ค Platform Character Counter
Count characters against the live limits for X/Twitter, SMS, Google titles, Instagram, LinkedIn and more. Everything stays in this box โ no draft is uploaded.
Science & Engineering
๐งช Solution Dilution Lab
Precision wet-lab chemistry solver for serial dilutions ($C_1 V_1 = C_2 V_2$) and molarity-to-mass conversions ($\text{Mass} = M \times V \times \text{MW}$) with step-by-step bench pipetting protoc...
Productivity & Lifestyle
Chemistry Helper
Calculate molar mass, balance equations, analyze compounds, and reference periodic table data.
Sports
โ๏ธ Chess Elo Rating Calculator
See what a single game does to a rating. Enter both players' ratings and the result, and this gives the expected score, the exact rating change, the new rating, and the performance rating for that ...
Health & Fitness
Child Growth Tracker
Track your child's growth, compare with WHO percentiles, and monitor development milestones.
Writing & Language
๐จ๐ณ Chinese Tones & Pinyin
Conquer the 4 tonal contours of Mandarin Chinese (High Flat, Rising, Dipping, Falling) and explore foundational HSK 1 vocabulary with native Mandarin speech audio (`zh-CN`).
Culinary & Food Science
๐ซ Chocolate Tempering Curves
Cocoa butter polymorphism & Beta-V crystallization guide. Calculates 3-stage thermal curve temperatures, 80/20 seeding ratios, and diagnoses fat bloom versus clean snap.
Music & Audio
๐ต Chord Finder
Identify chords from selected notes. Perfect for songwriters and beginners!
Music & Audio
๐ผ Chord Progression Builder
Build, analyze, and explore chord progressions for songwriting. Perfect for musicians and composers!
Productivity & Lifestyle
๐ Christmas Card Maker
Design and generate beautiful, custom HTML Christmas cards in seconds. Perfect for emails, social media, or personal websites.
Productivity & Lifestyle
๐
Santa's Naughty List Quiz
Take this scientific* holiday quiz to discover if you're getting coal or presents this Christmas! *Not actually scientific
Interactive Art & Living Worlds
๐ฟ ChronoGarden Terrarium
Cultivate a communal fractal botanical garden over time. Plant mathematical trees using Aristid Lindenmayer's L-Systems, cross-breed genetic strains, watch branches sway in the dynamic breeze, and ...
Science & Engineering
๐ Circuit Calculator
Calculate circuit load, breaker size, and wire sizing. Perfect for DIY projects and planning.
Writing & Language
๐ Citation Generator
Generate perfectly formatted citations in APA, MLA, or Chicago style. Supports multiple authors, websites, and academic sources.
Algorithms & Computer Science
๐ Classical Cipher Suite
Encrypt like the Romans and the Victorians: Caesar shifts, Atbash mirrors, ROT13 and the Vigenรจre key cipher. Then watch the โcrackโ button undo a Caesar cipher in one click โ because letter freque...
Productivity & Lifestyle
๐งน Cleaning Schedule
Plan, track, and manage cleaning tasks with smart scheduling. Never forget a chore again!
SaaS & Business Killers
๐ผ ClientFlow Pro โ Quote, Invoice, Contract & E-Sign Studio
The offline PandaDoc / HoneyBook killer โ build a branded quote, invoice or proposal, add your terms, collect a legally-binding drawn e-signature, and export a print-ready PDF. Payment link, QR, au...
Science & Engineering
๐ง Climbing Anchor Force & Fall Factor Calculator
A falling climber does not load the system with their body weight โ they load it with several times that, and the top runner takes more than the climber does. This works out impact force from the f...
Productivity & Lifestyle
๐ฌ ClipโtoโShorts Repackager
Upload a gameplay clip, pick a segment, and export a perfectly framed vertical short (9:16) or other preset. Adds caption safe zone and optional watermark.
Productivity & Lifestyle
๐ Clipboard History
Save and manage text snippets. Copy, pin, search, and organize your frequently used text. Persists in browser storage.
Mathematics
๐ Clock Angle Calculator
Angle between hour and minute hands. Minute hand = 6ยฐ ร minutes. Hour hand = 0.5ยฐ ร (60รhours + minutes). The smaller angle is min(ฮธ, 360 โ ฮธ).
Mathematics
๐ฐ๏ธ Clock Reading & Telling Time Trainer
Read the hands, set the clock yourself, and work out elapsed time โ three modes, five questions each, with instant feedback. The clock is drawn locally; nothing leaves your device.
Productivity & Lifestyle
๐ Clothing Size Converter
Convert common adult clothing sizes between US, UK and EU for tops, dresses and menโs shirts. Charts are industry averages โ cut, stretch and brand vanity sizing still win. Measure twice.
Productivity & Lifestyle
๐งฅ Coat, Hoodie, or Regret?
The daily sartorial gamble, solved. Dial in the temperature, wind and rain, tell it how long you'll be out, and it will tell you what to wear โ with the correct level of weather-based sass.
Culinary & Food Science
โ Coffee Brew Ratio & TDS Lab
Specialty Coffee Association (SCA) Golden Cup extraction calculator. Computes precise dose, brew water yield, multi-stage pour intervals, grind microns, and theoretical extraction yield.
Writing & Language
๐ Cognitive Bias Detector
Interrogate any argument, news headline, debate talking point, or internal decision. TruthLens scans text against 24 universal cognitive biases and logical fallacies to sharpen your critical thinki...
Productivity & Lifestyle
๐ฎ Coincidence Finder & Synchronicity Tracker
Discover meaningful coincidences and synchronicities across multiple real-time data sources. Tracks news, numbers, dates, names, and global patterns!
Natural Remedies & Herbs
๐ฏ Cold & Flu Botanical Guide
Phase-specific botanical recovery matrix. Synchronizes natural remedies to viral replication curvesโfrom neuraminidase inhibitors at hour zero to diaphoretic fever teas and expectorants.
Survival & Emergency Readiness
๐ Cold Water, Ice & Drowning Rescue
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 โ they fell in, gasped, and i...
Productivity & Lifestyle
๐ค AI Team Hub
AI-powered team management with workload balancing, predictive analytics, and automated optimization. โก Smart suggestions โข ๐ฏ Predictive deadlines โข ๐ Real-time analytics
Algorithms & Computer Science
๐๏ธ WCAG Contrast & Vision
Test color contrast ratios against WCAG 2.2 accessibility standards (AA / AAA) and simulate color-vision deficiencies in real time.
Productivity & Lifestyle
๐จ Color Converter & Palette Harmony Studio
Convert between HEX, RGB, HSL, HSV, CMYK, and OKLCH color spaces, generate color harmonies, test WCAG 2.1 contrast ratios, and copy CSS color code.
Science & Engineering
๐จ Color Palette Extractor
Generate algorithmic color harmonies (Complementary, Triadic, Analogous, Split) and verify accessibility with real-time WCAG 2.1 AA/AAA contrast ratio verification.
Writing & Language
โ๏ธ Common English Mistakes Trainer
Fix the most common English errors โ its/it's, there/their, affect/effect and more โ one sentence at a time.
Productivity & Lifestyle
๐ Commute Calculator
Calculate commute time, cost, and environmental impact. Compare different transportation modes. โ
Tracks daily, weekly, monthly, and yearly totals
Science & Engineering
๐งญ Compass Bearings Trainer
Learn the 16-point compass rose: convert between named bearings and degrees, then practise reading them on a marked compass โ forward and back bearings, with instant feedback. Runs in your browser,...
Mathematics
๐งฎ Complex Numbers Calculator
Perform operations with complex numbers in rectangular (a+bi) and polar (rโ ฮธ) forms. Visualize results on the complex plane with step-by-step solutions. โ
Supports: + โ ร รท โ ^ log sin cos conjugat...
Finance & Money
๐ฐ Compound Interest Calculator
Calculate future value, growth projections, and compare investment scenarios. Visualize wealth accumulation over time with detailed breakdowns. โ
Features: Regular contributions, inflation adjustme...
Home & DIY
๐งฑ Concrete Mix Calculator
Calculate cement, sand, gravel, and water for any concrete project โ from fence posts to shed bases.
Science & Engineering
โก Conduit Sizing Calculator
Calculate conduit sizes based on NEC requirements, wire types, and installation conditions. โ ๏ธ Disclaimer: For educational purposes. Always consult NEC codebook and licensed electrician.
Science & Engineering
๐ก The Light Budget
Light is a loan with interest. Museums cap both instant lux and lux-hours per year. Pick a material class, the gallery level and the hours the case is lit. The plaque says whether the year is still...
Productivity & Lifestyle
๐คก Conspiracy Theory Generator
Generate absurd conspiracy theories that are somehow more believable than the real ones.
Museum & Collection
๐ The Constant Treasury
The constants that run the universe, as numbered exhibits โ provenance, exact or measured, and what each does. Includes a live pi engine (Machin's formula computed with big integers), a golden-rati...
Interactive Art & Living Worlds
โจ Constellation Weaver
Weave constellations across a shared celestial sphere. Place spectral stars, connect mythological asterisms, record astronomical lore, and preserve collective starlit storytelling over time.
SaaS & Business Killers
๐ก๏ธ Contract Sentinel Pro โ Risk Analyzer
Paste any contract, terms of service or NDA and get an instant risk map โ plain-English summary, red flags, missing protections and a clause-by-clause fix list. Replaces LegalZoom contract review (...
Mind-Blowing Demos
๐งฌ Conway's Game of Life
Three tiny rules, no designer, and yet gliders, blinkers and whole ecosystems appear. Click cells to seed life, then watch a universe build itself from nothing.
Culinary & Food Science
โฑ๏ธ Cooking Time Adjuster
PROFESSIONAL TOOL - Adjust cooking times when scaling recipes, changing pan sizes, or cooking at different temperatures. Used by chefs and home cooks worldwide.
Culinary & Food Science
๐ฅ Cooking Unit Converter
PROFESSIONAL CONVERTER - Convert cooking units with food-specific densities. Accurate conversions for flour, sugar, butter, liquids, and more.
Science & Engineering
๐งญ Coordinate Format Translator
One position, every notation: GPS decimal degrees, degrees-minutes-seconds, marine DDM, UTM, MGRS, the British Ordnance Survey grid, geohash, Plus Code and the Maidenhead locator used by radio amat...
MrProphecy Arcade
๐ Coordinates Trainer
Read points and plot your own on a โ5 to +5 grid. Learn the four quadrants, the meaning of (x, y) and how negative coordinates work โ with instant feedback and 5-question rounds. All on your device...
Science & Engineering
๐ The Coriolis Effect โ Turntable & Storms
Nothing "curves" in the air โ but on a rotating planet, straight motion looks curved. Throw a ball across a spinning disk, then watch the same physics organise hurricanes: right-deflected in the no...
Algorithms & Computer Science
๐ CORS Header Builder
Emit Access-Control-* headers for a simple or preflight response. * plus credentials is invalid. Prefer an explicit origin in production.
Science & Engineering
๐ซ๏ธ Wilson Cloud Chamber
Supersaturated alcohol vapor chamber detecting cosmic muons and subatomic radioactive decay tracks via ion-nucleated condensation.
Productivity & Lifestyle
๐ Cost-Per-Use: Should You Buy It?
The antidote to impulse buying. Feed it a price and honest usage guesses, and it tells you whether that thing is a bargain, a luxury, or a future eBay listing.
MrProphecy Arcade
๐ฉ Country Flags Quiz
Guess the country from its flag, or pick the right flag for a named country โ with three difficulty pools, ten questions per round and colour-based clues. All drawn locally, nothing sent anywhere.
Science & Engineering
๐๏ธ Coupled Oscillators Lab
Simulate multi-degree-of-freedom coupled mechanical oscillators. Observe symmetric ($\omega_1$) vs anti-symmetric ($\omega_2$) normal modes and cyclic mechanical energy sloshing ($T_{beat}$).
Writing & Language
โ๏ธ Cover Letter Builder
PROFESSIONAL TOOL - Create tailored cover letters with industry-specific templates, ATS optimization, and professional tone analysis. Used by career coaches worldwide.
Writing & Language
โ๏ธ Creative Writing Studio
Prompts, character and plot generators, story ideas, world builder, word bank and focus timer for writers.
Sports
๐ Cricket Run-Chase Calculator
Second innings, chasing a target: enter the score you are after, how far the chase has got, and see the current rate, the required rate, your projected total, and exactly how fast the run rate has ...
Sports
๐ Cricket Net Run Rate Calculator
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 โ applying the rule that a team bowled out is counted as fa...
Health & Fitness
๐ Crisis Triage Guide
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...
Algorithms & Computer Science
โฑ๏ธ Cron Schedule Builder
Construct cron expressions with interactive dials, read instant plain-English explanations, and preview the next 10 trigger times.
Productivity & Lifestyle
๐ผ๏ธ Crop Factor & 35 mm Equivalent
35 mm-equivalent focal length = actual focal length ร crop factor. Also shows equivalent f-number for depth of field (same framing). Field of view matches; light-gathering of the aperture does not ...
SaaS & Business Killers
โจ CSS Animation Generator
Preview common CSS keyframe animations, tune duration, delay and easing, then copy a small standalone animation block. The preview honours reduced-motion preferences; use motion as polish, never as...
SaaS & Business Killers
๐ CSS Border Radius Generator
Shape a card, button or image frame with four independent corner radii, preview the result and copy the compact CSS shorthand. Switch between pixels and percentages, link corners while you explore,...
SaaS & Business Killers
๐ CSS Box Shadow Generator
Tune a CSS box-shadow visually, choose a colour and opacity, test inset mode and copy production-ready CSS. The preview updates as you move the controls, so there is no design account or upload ste...
SaaS & Business Killers
๐๏ธ CSS Filter Generator
Combine brightness, contrast, saturation, hue, blur and monochrome effects with a live visual preview, then copy one filter declaration. Useful for hero images, hover states and quick image treatme...
SaaS & Business Killers
โ๏ธ CSS Flexbox Playground
Explore real flexbox controls side by side: direction, wrapping, gap and alignment update the preview immediately, then a copyable CSS block records the exact settings. Use it to build nav rows, ce...
Productivity & Lifestyle
๐จ CSS Glass & Gradients
Design modern frosted glass (glassmorphism) components and mesh gradients. Real-time visual canvas with 1-click cross-browser CSS.
SaaS & Business Killers
๐ฒ CSS Grid Layout Generator
Build a responsive CSS Grid visually: set tracks, gap, flow and item alignment, optionally make one card span multiple cells, then copy the CSS. The preview uses real grid properties and runs entir...
Algorithms & Computer Science
๐ฏ CSS Specificity Calculator
Paste a selector. Counts IDs, classes/attributes/pseudo-classes, and types/pseudo-elements as (A, B, C). :not() is ignored as a class; its argument is counted. :is() / :where() / :has() take the mo...
SaaS & Business Killers
๐ CSV Data Studio
Paste a spreadsheet, get a clean dataset. Parses CSV/TSV, detects the delimiter, profiles every column, cleans the rows, and re-exports as JSON, SQL, Markdown, XML or HTML. Nothing is uploaded โ th...
Algorithms & Computer Science
๐ CSV โ JSON โ Markdown Table Converter
Paste CSV, TSV or a JSON array and convert it to JSON, CSV, Markdown table, HTML table or SQL INSERT statements. Handles quoted fields, custom delimiters and header detection. Everything stays in y...
Algorithms & Computer Science
ใฐ๏ธ Cubic Bรฉzier Easing
CSS transition-timing-function: cubic-bezier(x1, y1, x2, y2). x is time (0โ1), y is progress (can overshoot). Copy the declaration after you like the motion. Respects reduced-motion.
SaaS & Business Killers
๐ฅ๏ธ cURL Command Builder
Assemble a safe-to-copy cURL command from a URL, method, headers and optional request body. It quotes shell values correctly and never sends the request itself, so you can prepare API calls private...
Sports
๐ฅ Curling Score Calculator
In each end, the team with the stone closest to the button scores one point for every stone nearer than the opposition's best. Enter each end and this keeps the running score to the last stone.
Finance & Money
๐ฑ Currency Converter
Convert between 20 major currencies using built-in offline reference rates. No sign-up, no network โ works fully offline. Rates are indicative (refreshed Sep 2026); check your provider for live quo...
Productivity & Lifestyle
๐ Professional CV Builder
PROFESSIONAL CV CREATOR - Build ATS-optimized CVs with multiple templates, real-time preview, and export options. Used by career coaches worldwide.
Sports
๐ด Cycling Power & Speed Calculator
How many watts to hold 40 km/h up a 4% climb? Or what speed does your FTP actually buy you? This models the three forces a rider fights โ rolling resistance, air drag and gravity โ and splits your ...
Science & Engineering
๐ 3D Cymatic Sound Sculpture
Acoustic resonance installation. Granular silica particles migrate across a vibrating resonant Chladni plate into standing wave geometric nodal lines.
Science & Engineering
๐ Chladni Cymatics Plate
Explore Ernst Chladni's 1787 acoustic nodal resonance figures. Observe sand grains scatter away from high-amplitude vibrating antinodes and crystallize into intricate geometric standing wave geomet...
Astronomy & Space
๐ญ Daily Cosmic Awe & Micro-Wonder Portal
Psychological research shows that experiencing awe instantly silences self-critical rumination and triggers spontaneous gratitude. Traverse 40 orders of magnitude through the cosmos, feed your worr...
Productivity & Lifestyle
โจ Curiosity Fact Deck
48 verified fascinating facts across space, nature, history, the body, Earth and technology โ with a fact of the day, favourites and a quiz mode that turns trivia into knowledge.
Home & DIY
๐ง Damp & Mould Diagnostic (UK homes)
Answer a few questions about the damp patches, mould and smells in your home and get the most likely cause โ condensation, penetrating damp, rising damp or a leak โ with the practical fixes and whe...
Science & Engineering
โก Damped Oscillator Simulator
Analyze classical mass-spring-damper dynamics ($m\ddot{x} + c\dot{x} + kx = F_0\cos\omega t$). Inspect damping ratios ($\zeta$), Q-factor resonance peaks, phase lag, and transient vs steady-state r...
Astronomy & Space
๐ Dark Sky Quality Planner
Turn a Sky Quality Meter reading, a Bortle class or a naked-eye limiting magnitude into the others, and see what each sky condition is worth for deep-sky work. Useful for choosing a site before you...
Sports
๐ฏ Darts 501 Average & Leg Tracker
Log each visit of three darts and watch your three-dart average climb. Handles the bust rules for you โ scoring more than you have left, or leaving yourself on 1 โ and tracks legs won across a sess...
Sports
๐ฏ Darts Checkout Calculator
Stood at the oche wondering how to finish? Type the score you have left and get the standard two- or three-dart checkout. Includes the full 2โ170 checkout chart and a practice mode that hides the a...
Finance & Money
๐
Date Calculator
Calculate date differences, add/subtract days, and discover interesting date facts instantly.
Museum & Collection
โ๏ธ The Daylight Lab
Watch sunlight enter a room and cast shadows as the sun moves across the sky. See how window orientation, room depth, and time of year affect daylight levels. The sun path diagram shows the sun's a...
Finance & Money
๐ฐ Debt Payoff Calculator
Calculate how long one balance takes to clear โ and what extra payments save in interest. Estimates only, not financial advice. If debt feels unmanageable, speak to a free debt adviser.
Productivity & Lifestyle
โ๏ธ Decision Matrix Scorer
Evaluate complex career, business, or lifestyle choices using weighted multi-criteria scoring. Removes emotional bias and highlights the winning tradeoff.
Home & DIY
๐ชต Deck Joist Span & Footing Calculator
Check how far a joist can safely span: pick the lumber size, spacing, wood type and load, and get the maximum span plus the beam and post spacing to match.
Home & DIY
๐ชต Decking Calculator
Calculate boards, joists, posts, screws, and total cost for a timber decking project. Works for softwood, hardwood, and composite decking.
Astronomy & Space
๐ธ Deep Sky Exposure Planner
How long a single subframe needs to be before the target signal clears the read and sky noise, and how many of them you need to stack. Includes the f-ratio squared penalty that makes fast scopes so...
Museum & Collection
๐๏ธ Deep Time Museum
Walk 4.6 billion years of Earth's story in one scroll โ Hadean to Holocene, an era per hall, with an Earth-in-one-day clock, jump-chips and a catalogue-numbered plaque for every exhibit...
Music & Audio
๐๏ธ Delay Time BPM Calculator
Convert tempo to delay, reverb pre-delay and LFO times. Note length in milliseconds = 240,000 รท BPM รท denominator (crotchet = 4). Dotted is ร 1.5; triplet is ร โ
.
Interactive Art & Living Worlds
๐ Bouncy Ball Box
A box full of bouncy balls โ shake, tilt, add gravity wells, and watch the chaos unfold
Interactive Art & Living Worlds
๐ซง Bubble Wrap Popper
Satisfying bubble wrap popping โ click to pop, hold to drag-pop entire rows, shake to reset
Interactive Art & Living Worlds
๐น Catapult Simulator
Build a medieval trebuchet, load projectiles, set the counterweight, and launch!
Interactive Art & Living Worlds
๐ Domino Chain Reaction
Place dominoes in a line, tap the first one, and watch the satisfying chain reaction cascade
Interactive Art & Living Worlds
๐ฆ Drinking Bird
The classic heat-engine desk toy โ a bird that perpetually dips its beak into water using thermodynamics
Interactive Art & Living Worlds
๐ Fidget Spinner
Spin a fidget spinner with realistic angular momentum โ flick to spin, hold to accelerate, watch it slow down
Interactive Art & Living Worlds
๐ซง Lava Lamp
Mesmerizing blob physics โ watch wax rise, split, merge, and fall in a heated glass vessel
Interactive Art & Living Worlds
๐ฑ Marble Run Builder
Place ramps and bumpers, then release marbles and watch them roll with real physics
Interactive Art & Living Worlds
๐ชข Rope Physics
Drag, swing, and wrap a realistic rope with verlet integration โ pin ends, cut segments, add weights
Interactive Art & Living Worlds
โณ Sand Hourglass
Granular physics โ watch thousands of sand grains flow, pile, and avalanche through a narrow neck
Interactive Art & Living Worlds
Slinky Physics
Watch a spring slinky walk downstairs with realistic coil physics โ grab it, stretch it, let it go
Interactive Art & Living Worlds
ใฐ๏ธ Wave Machine
A chain of coupled pendulums โ drag to create waves, watch interference patterns, and explore resonance
Science & Engineering
โ๏ธ Psychrometric & Dew Point
Analyze atmospheric water vapor psychrometrics using Magnus-Tetens formulas. Calculate exact Dew Point ($T_{dp}$), saturation vapor pressure ($e_s$), moisture humidity ratio ($W$), and surface cond...
Museum & Collection
๐ The Dewey Stacks
Melvil Dewey, 1876: knowledge in ten main classes, each split by tens. Museums and small libraries still live by it. Search a word or tap a hall. This is the public summary, not a licensed DDC sche...
Algorithms & Computer Science
๐ฒ Diceware Passphrase
Six words from a 256-word list, picked with crypto.getRandomValues (~48 bits). Not the official 7,776-word EFF list โ treat this as a strong memorable password, then store it in a manager. Generate...
Finance & Money
๐งฎ AI Differential Equations Solver
WORLD'S FIRST interactive DE solver with step-by-step explanations, visual graphs, and real-world applications. Used by universities worldwide!
Wellbeing & Community
๐ฌ Difficult Conversation Scripter
Builds you the words for a conversation you have been putting off. Nothing is sent anywhere โ this works offline and nothing you type leaves your device.
Science & Engineering
๐ Holographic Laser Spectrograph
Optical spectrometer bench. High-density holographic diffraction grating disperses atomic gas emission into discrete quantum spectral fingerprints.
Productivity & Lifestyle
๐ฆ Dimensional Weight Calculator
Carriers bill the higher of actual weight and volumetric (dimensional) weight. Enter the box and compare IATA /6000, DHLยทFedEx /5000 and US domestic /139. Not a postage quote.
Museum & Collection
๐ฆ The Scale Hall
Lengths and masses as the casts in the hall give them โ mid-range figures from the current literature, not movie posters. Enter your height; the gold line is you, standing at the snout.
Finance & Money
Discount Calculator
Calculate final prices after discounts and taxes. Compare multiple deals and save your calculations.
Mathematics
๐งฎ Discrete Math Toolkit
WORKING CALCULATOR for Computer Science & Mathematics. Real calculations for set theory, combinatorics, and logic. Everything works instantly!
Finance & Money
๐ Dividend Yield Calculator
Trailing yield = annual dividends per share รท price. Forward yield uses the next expected year. Cover = EPS รท DPS. This is a ratio, not investment advice, and ignores tax wrappers.
Sports
๐คธ Diving Score Calculator
Score a dive the way the judges do: enter the judges' marks and the degree of difficulty, and this drops the outliers and applies the official formula to give the dive its total.
Science & Engineering
๐งฌ DNA Helix 3D Builder
Type any DNA sequence and watch it become a spinning double helix โ with correct AโT / GโC pairing, hydrogen bonds, live GC content, mRNA transcription and protein translation. Includes a mutation ...
Dogs & Canine Care
๐ฅฉ Canine Daily Calorie Portioner
WSAVA metabolic energy calculator. Formulates exact Resting Energy Requirements (RER) and daily food cup portions to maintain ideal body condition.
Dogs & Canine Care
๐ซ Dog Chocolate Toxicity Calc
Emergency veterinary theobromine toxicity calculator. Computes methylxanthine dose (mg/kg) to determine risk of cardiac arrhythmia, vomiting, and seizures.
Dogs & Canine Care
๐ฏ Dog Clicker Trainer & Sound
Operant conditioning event marker. Features synthesized metallic clicker audio and a reaction-time latency game to calibrate your 0.8-second reward marking window.
Dogs & Canine Care
๐ Dog Crate Sizing & Den Guide
Orthopedic crate sizing & housebreaking den blueprint. Computes exact crate length, height, and maximum continuous confinement hours by age.
Dogs & Canine Care
๐ฆฎ Dog Daily Walk & Activity Calc
Canine exercise prescription engine. Formulates daily cardio walking duration, growth-plate puppy limits (5 min/month rule), and sniffari mental enrichment.
Dogs & Canine Care
๐ฉบ Dog Vital Signs & Hydration
Clinical canine triage assessment. Evaluate skin turgor snapback, gum capillary refill time (CRT), normal body temperatures, and resting respiratory rates.
Dogs & Canine Care
๐ Dog Human Years Age Clock
UCSD School of Medicine DNA methylation epigenetic calculator (Wang et al., Cell Systems). Replaces the debunked 7-year myth with cellular age biology.
Productivity & Lifestyle
๐ Dog Photo Viewer
COMPLETE DOG VIEWER - Browse thousands of dog photos with breed information, favorites, and infinite scrolling. Multiple API sources for maximum reliability.
Dogs & Canine Care
๐ฅฉ Dog Food Safety & Toxicity Key
Emergency canine food safety encyclopedia. Search common household foods to identify lethal toxicities (Xylitol, grapes, alliums) versus safe nutrient-dense superfoods.
Dogs & Canine Care
๐ฏ Dog Ultrasonic Whistle Lab
High-frequency acoustic trainer (14,000 Hz to 22,000 Hz). Capitalizes on canine ultrasonic hearing up to 45 kHz for long-distance park recalls and focus interrupts.
Science & Engineering
๐ Doppler Effect Simulator
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.
Science & Engineering
๐ Double Pendulum Chaos
Simulate non-linear Hamiltonian chaos via Lagrangian mechanics solved with 4th-Order Runge-Kutta (RK4). Track sensitive dependence on initial conditions (Butterfly Effect) with an overlaid $0.001$ ...
Science & Engineering
๐ฌ Quantum Eraser & Double Slit
Quantum optics delayed-choice experiment. Observe wave interference, wavefunction collapse via which-way detectors, and quantum erasure recovery.
Home & DIY
๐ก Downlight Spacing Calculator
A common rule is spacing โ 0.5โ0.75 ร ceiling height, with the first lamp about half that from the wall. Check beam angle and joists โ this is a layout sketch, not a lighting design.
Lucid Dreaming & Sleep
๐ Lucid Dream Sign Analyzer
Identify personal recurring anomalies across your dreams (LaBerge 4-Category taxonomy). Recognizing your frequent dream signs is the #1 trigger for spontaneous lucidity.
Survival & Emergency Readiness
๐ Driving Emergency Survival Guide
Almost every driving emergency has one instinctive response that makes it worse and one trained response that fixes it. Pick the situation. You get the correct order of actions, the specific thing ...
Home & DIY
๐งฑ Drywall (Plasterboard) Calculator
Order the right amount of board: enter the wall and ceiling area, pick a sheet size and wastage, and get the sheet count plus the joint compound, tape and screws to finish it.
Algorithms & Computer Science
๐งน Duplicate Line Remover
Paste a list: drop duplicate lines, sort AโZ or ZโA, trim spaces, ignore case. Stays in this browser โ mailing lists and log dumps never leave the device.
Astronomy & Space
๐ Earth Tide Clock
Two tidal bulges, not one. The Moon (and a weaker Sun) stretch Earth into a prolate spheroid; a port rotates through both bulges and sees two highs a day. Align Moon and Sun for spring tide; put th...
Science & Engineering
โก Earthing Conductor Calculator
Size earthing conductors for fault protection. For qualified electricians โ always verify with local regulations.
Interactive Art & Living Worlds
๐ซจ Earthquake Seismograph Lab
Trigger a fault rupture and watch P, S and surface waves race outward โ then read the synthetic seismogram: SโP time lag gives the distance, amplitude gives the magnitude, and seismic attenuation b...
Interactive Art & Living Worlds
๐ EchoPond Cymatics
A communal fluid-dynamics sanctuary. Cast water drops into a resonant pond. Wave ripples interfere via the physical wave equation, triggering soothing pentatonic water chimes when constructive wave...
Science & Engineering
๐ Eco Footprint Calculator
Move past vague carbon guilt. PlanetPositive pinpoints the exact 80/20 high-leverage lifestyle actions that slash personal emissions the fastest while saving hundreds of pounds each year.
Science & Engineering
๐ Professional Ecology Calculator
๐ฌ A comprehensive suite of ecological calculations for researchers, environmental scientists, and conservation professionals. Includes statistical analysis, biodiversity metrics, and ecosystem mod....
Science & Engineering
๐ซ Human Anatomy Explorer
Interactive body systems โ click organs and systems to learn their functions, facts, and connections
Astronomy & Space
โญ Constellation Map
Interactive star map โ explore 30 major constellations, click stars for names and facts
Science & Engineering
๐ Country Data Visualizer
Compare countries by population, area, GDP, and more โ with animated bar charts and data cards
Science & Engineering
๐งฌ DNA โ Protein Translator
Paste a DNA or mRNA sequence and watch it get transcribed and translated into amino acids โ with a visual codon table
Music & Audio
๐ต Music Theory Visualizer
Explore scales, chords, and intervals on a virtual piano โ hear how they sound and see the theory behind them
Science & Engineering
โ๏ธ Interactive Periodic Table
Explore all 118 elements โ search by name, symbol or number, then click any element for detailed properties, electron configuration, discovery history and curator notes
Science & Engineering
๐ชจ Rock & Mineral Identifier
Answer a few questions about your rock and get an identification โ with visual examples and properties
Astronomy & Space
๐ช Solar System Explorer
Animated orrery of our solar system โ watch planets orbit in real time, click for detailed facts
Science & Engineering
๐ Historical Timeline Builder
Create beautiful visual timelines โ add events, see them plotted chronologically with color-coded categories
Museum & Collection
๐ The Uniliteral Case
The twenty-four single-consonant signs every student copies first โ Gardinerโs teaching alphabet. Vowels were not written. Type a name; the case sets the glyphs and the catalogue codes. This is not...
Science & Engineering
๐ Electrical Standards Guide
Global electrical standards reference (IEC, NEC, BS): wiring, protection and installation rules. For qualified electricians and engineers.
Science & Engineering
โก Electrical Engineering Calculator
๐ฌ A comprehensive electrical engineering toolkit for professionals and students. Includes circuit analysis, power calculations, and energy conversions with real-world context.
SaaS & Business Killers
๐ง Signature Forge
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...
SaaS & Business Killers
โ๏ธ Email Subject Line Tester
Preview how a subject line and preheader may truncate on mobile or desktop, check length and punctuation, and get practical editing prompts. This is a transparent writing heuristic โ not a delivera...
Writing & Language
๐ง Email Template Generator
๐ผ Generate perfectly crafted professional emails, LinkedIn messages, and business communications. Includes tone analysis, etiquette tips, and productivity features.
Survival & Emergency Readiness
๐ก Emergency Communications & Radio Planner
In every major incident the mobile network is the first thing to fail โ not from damage, but from everybody calling at once. This works out what you can actually reach with, how far a handheld radi...
Productivity & Lifestyle
๐ค What Does That Emoji *Actually* Mean?
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 ๐ in the grou....
Finance & Money
๐ฅ Employee True Cost Calculator
Estimate the fully loaded annual and monthly cost of hiring beyond the headline salary. All calculations stay in your browser.
Finance & Money
โก Energy Tariff Comparator
Suppliers advertise the unit rate because it is the flattering number, but the standing charge is paid every single day whether you use anything or not. This compares the real annual cost โ and, mo...
Museum & Collection
โก The Watt Exchange
Energy literacy in the only currency that needs no conversion: bananas, stairs and phone charges. Decode any item, your monthly meter, and the kinetic energy of a moving car (E = ยฝmvยฒ).
Science & Engineering
โก Energy Consumption Calculator
Calculate electricity costs, carbon footprint, and savings potential for any appliance. Track your energy usage and find ways to save money!
Interactive Art & Living Worlds
๐ ๏ธ Engine Displacement
Convert litres, cubic centimetres and cubic inches (CID). 1 L = 1,000 cc; 1 inยณ = 16.387064 cmยณ. A โ5.0โ V8 is 5,000 cc โ 305 CID. Bore ร stroke ร cylinders is the geometric displacement, not power...
Science & Engineering
๐ Environmental Science Tools
Calculate environmental impacts, explore sustainability metrics, and learn fascinating facts about Earth's systems. Make informed decisions for a greener planet!
Music & Audio
๐๏ธ Hip Hop EQ Frequency Masking & Pocket Allocator
Muddy hip hop mixes happen when competing instruments fight for the same acoustic frequency space. Select any common mix conflict pair to visualize precise complementary boost & notch carving c...
Mathematics
๐ Equation Solver
Solve algebraic equations step-by-step. Supports linear, quadratic, and cubic equations. Try examples below!
Astronomy & Space
๐งญ Equatorial Coordinate Finder
Convert right ascension and declination into altitude and azimuth for your latitude and local sidereal time โ or go the other way. Tells you whether a target is up, where to point, and when it tran...
Interactive Art & Living Worlds
โฐ๏ธ Erosion & Landscape Lab
Sculpt a landscape and watch it move. Set rainfall, soil erodibility, vegetation cover and steepness โ the runoff erodes the hills, transport by flowing water sorts/deposits the sediment downstream...
Writing & Language
๐ Essay Writing Assistant
Generate structured essay outlines, starter paragraphs, and writing guidance for any topic. Perfect for students, writers, and professionals!
Writing & Language
๐งญ Argument Mapper
Structure an essay or debate case before you write it. Lay out your thesis, the premises supporting it and the strongest objections, then score how well each one actually holds up.
Natural Remedies & Herbs
๐ง Essential Oil Dilution Calc
Aromatherapy dermal safety calculator (Tisserand Institute standards). Computes precise drop counts per carrier oil volume to prevent sensitization and burns.
Mind-Blowing Demos
โก Euler's Identity: e^{iπ} = โ1
The "most beautiful equation" in one picture: eiθ is just a point rotating around a circle. Wind θ up to π and you've spun exactly half a turn โ to โ1. eiπ + 1 = 0...
Finance & Money
๐ EV Charging Cost & Time
Estimate kWh, cost and wall-clock time to charge an electric car. Uses usable battery size, start/end state of charge, charger kW and unit rate. Peak DC rates taper โ treat rapid times as optimisti...
Survival & Emergency Readiness
๐ Evacuation & Go-Bag Planner
Three different emergencies need three different bags, and most people prepare the wrong one. Build all three here, weigh them against what you can actually carry, and print a checklist. The point ...
Productivity & Lifestyle
๐
Event Reminder
Set reminders for upcoming events with notifications, priorities, and recurrence options.
Mind-Blowing Demos
๐งฌ Evolution Arena โ 3D Creature Evolution
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.
Science & Engineering
Evolution AI Walker
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 selectio...
Mathematics
๐ Exam Prep - Mathematics
COMPLETE MATH PREP - Generate practice problems with step-by-step solutions. Track your progress across 500+ questions covering all major topics.
Productivity & Lifestyle
๐ฏ Exam & Study Planner
๐ A comprehensive exam planning and study management system for students and professionals. Track exams, create study schedules, set goals, and manage revision.
Productivity & Lifestyle
๐ Professional Excuse Generator
Generate increasingly absurd excuses for any situation. From "plausible" to "they'll never believe you."
Science & Engineering
๐ฌ Science Experiment Generator
Generate creative, hands-on science experiment ideas for all ages. Perfect for students, teachers, and curious minds!
Mathematics
โก Exponents & Roots Calculator
Calculate powers, roots, and exponential functions with detailed steps and visualizations. Perfect for students learning algebra and calculus.
Productivity & Lifestyle
โ๏ธ Extruded 3D Text Studio
Design chunky 3D logos: real perspective rotation (rendered slice-by-slice in software), adjustable extrusion depth, bevel light, backdrops and one-click PNG export. No WebGL, no libraries โ just m...
Productivity & Lifestyle
๐งต Fabric Yardage Estimator
Pattern envelopes quote fabric for one specific width, and most fabric is not sold in that width. This converts for the width you actually bought, then adds the three allowances people forget: a pa...
Mathematics
๐ข Factors & Multiples Trainer
List the factors and multiples of any number, then practise finding the highest common factor, lowest common multiple and factor/multiple facts.
Science & Engineering
๐ง Faraday Fluid Waves
Simulate Michael Faraday's 1831 parametric liquid surface waves ($\omega^2 = [gk + \frac{\sigma}{\rho}k^3]\tanh kh$). Observe subharmonic resonance ($f_{wave} = f_0/2$) and pattern transitions acro...
SaaS & Business Killers
๐ช Favicon & SVG Icon Generator
Make a sharp, lightweight vector favicon from initials or one emoji, tune its colours and shape, then download a ready-to-use SVG. It also gives you the HTML link tag and a data URI โ no image uplo...
Science & Engineering
๐ Feet & Inches โ cm
Convert height between feet+inches, centimetres and metres. Uses the international inch (exactly 25.4 mm). Edit any box โ the others update.
Home & DIY
๐๏ธ Fence Calculator
Calculate posts, panels, gravel boards, concrete, and total cost for a garden fence. Works for panel fencing, closeboard, and picket styles.
Culinary & Food Science
๐ฅฌ Lacto-Fermentation Salt Calc
Microbiological lacto-fermentation salt formulation tool. Calculates total-mass salinity, microbial succession timelines (Leuconostoc to Lactobacillus), and target pH < 4.6.
Science & Engineering
๐งฒ Ferrofluid Spiking Lab
Rosensweig normal-field magnetic instability simulator. Superparamagnetic liquid self-organizes into conical spikes balancing surface tension and magnetic stress.
Science & Engineering
โจ Fiber Optic Light Guide Lab
Total internal reflection fiber optics lab. Explore critical angle guidance, acceptance cone numerical aperture (NA), and macro-bending radiation loss.
Survival & Emergency Readiness
๐ฅ Fire Escape & Smoke Safety Planner
Most fire deaths are not from flames โ 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, ...
Finance & Money
๐ฅ FIRE Retirement Planner
Estimate your Financial Independence number, years until retirement, and compound investment growth trajectory using the 4% Safe Withdrawal Rule. Illustrative projections, not financial advice.
Finance & Money
๐ Fiscal Quarter Finder
Calendar quarters, the UK tax year (6 Aprilโ5 April) and the US federal fiscal year (starts 1 October). Pick a date; see which Q you are in and when it ends.
Health & Fitness
๐โโ๏ธ Fitness Score Analyzer
Calculate your comprehensive fitness score with detailed insights and personalized recommendations. Based on scientific health metrics and activity analysis.
Interactive Art & Living Worlds
๐ง๏ธ Rainfall & Flash Flood Lab
A catchment that converts rain into a flood hydrograph. Horton infiltration soaks the soil, the rational method produces peak discharge, and a Kirpich time-of-concentration shapes the river's rise ...
Productivity & Lifestyle
๐ Smart Flashcards
Create beautiful, interactive flashcards for effective studying. Supports rich text, categories, and spaced repetition.
Productivity & Lifestyle
๐ฉ Flat-Pack Confidence Meter
Enter the flat-pack battlefield armed with the truth: how many pieces, which tools, who's helping, and how many drinks deep you are. It will forecast your evening with alarming accuracy.
Culinary & Food Science
๐ท Food & Wine Pairing Matrix
Sommelier palate chemistry engine. Evaluates flavor interactions between tannins, fats, acids, umami, and capsaicin to recommend optimal wine varietals and serving temperatures.
Finance & Money
โ๏ธ Flight Delay Compensation Checker
Delayed, cancelled or denied boarding? UK261 can entitle you to up to ยฃ520 per passenger โ and claim firms take 25โ40% of it for filling in a form. Check your entitlement and generate the airline l...
Science & Engineering
๐ฅ Flue Draft & Stove Sizing Calculator
A chimney is an engine: hot gas inside, cold air outside, and the density difference pulls the fire along. This works out how much draught your flue actually generates, how fast the gas moves, how ...
Science & Engineering
๐ Reynolds Number Simulator
Calculate the dimensionless Reynolds number ($\text{Re} = \frac{\rho v D}{\mu}$) for internal pipe flow and aerodynamics. Visualize laminar streamline transitions into chaotic turbulent vortices.
Productivity & Lifestyle
๐ Fluid Type Scale Generator
Generates a typographic scale where every size scales smoothly between two screen widths, using the CSS clamp() function โ no media queries, no jump at a breakpoint, and no text that is 14px on a p...
Science & Engineering
๐ช๏ธ Fluid Smoke Tunnel
Aerodynamic wind tunnel museum exhibit. Visualize laminar airflow, von Kรกrmรกn vortex shedding, and lift/drag forces around aerodynamic obstacles.
Productivity & Lifestyle
โฑ๏ธ Deep Focus Timer
Advanced Pomodoro timer with productivity tracking, ambient sounds, and progress visualization. Stay focused, maximize productivity!
Culinary & Food Science
๐ง Food Shelf-Life & Safety
USDA / FDA Food Safety & Inspection Service shelf-life database. Evaluates storage windows across Pantry, Refrigerator, and Freezer, plus Danger Zone temperature limits.
Interactive Art & Living Worlds
๐ธ๏ธ Food Web & Trophic Energy Lab
Build a food web and see it breathe. Pick a habitat, toggle species in or out, set sunlight/rainfall and the predation rate โ then run the simulation: producer growth, consumerโprey dynamics (logis...
Sports
โฝ Football Points-Needed Calculator
The run-in made simple. Put in where your team stands, how many games are left, and the points you are aiming for โ a title, promotion, safety mark or a rival โ and see exactly what the remaining f...
Mathematics
๐ Scientific Formula Library
Interactive scientific formula calculator with detailed explanations, 3D visualizations, and step-by-step solutions. Perfect for students and professionals in STEM fields.
Sports
๐ F1 Championship Points Calculator
Tally a driver's season under the current 2025 points system โ 25 down to 1 for the top ten, 8 down to 1 for a sprint โ and see the running total, points per round, and how it compares with a rival...
Science & Engineering
๐ Foucault Pendulum Spin
Lรฉon Foucault's 1851 Paris Panthรฉon experiment proving Earth's diurnal rotation. The swing plane stays fixed in inertial space while Earth rotates below.
Science & Engineering
โ๏ธ Four-Bar Mechanism Lab
Synthesize planar four-bar kinematic mechanisms. Classify via Grashof's Theorem ($s + l \le p + q$), trace coupler curves (Chebyshev, Watt, Hoeken), and analyze transmission angles.
Mind-Blowing Demos
๐ Fourier Series Synthesizer
Any repeating shape โ a square wave, a sawtooth, your favourite tune โ is just spinning circles added together. Watch a few sine waves stack into a crisp corner, then add more and see it sharpen.
Mathematics
๐ข Fractions Calculator & Visualizer
Master fractions with calculations, visual representations, and step-by-step explanations. Perfect for students learning fractions!
Finance & Money
๐ผ Freelance Rate Calculator
Stop undercharging. Calculate your true sustainable hourly and day rates by factoring in unbillable admin time, self-employment taxes, equipment expenses, pension, and paid time off.
Writing & Language
๐ซ๐ท French Verbs & Pronunciation
Master the most critical French irregular verbs (รชtre, avoir, aller, faire) and unlock fluent French pronunciation with our guide to silent consonants and natural liaisons.
Productivity & Lifestyle
โฝ Fuel Economy Converter: MPG โ L/100km โ km/L
Convert between UK MPG, US MPG, litres per 100 km, km per litre and miles per litre in one go โ or calculate your real-world economy from a fill-up (miles driven and litres added). Includes a cost ...
Finance & Money
โฝ Fuel Cost Calculator Pro
Calculate trip fuel costs, compare vehicles, track carbon footprint, and find optimal routes. Real-time calculations with environmental impact!
Mathematics
โฐ๏ธ Function Terrain 3D Explorer
Type any z = f(x, y) formula and watch it become a spinning 3D mountain range. Safe built-in math parser (no eval), orbit/zoom controls, height colormaps and a random-function dice for beautiful ac...
Science & Engineering
๐บ Gallons, Litres & Pints
UK pint is 568 ml; US pint is 473 ml. UK gallon is 4.54609 L; US gallon is 3.78541 L. Edit any box โ the others follow using the same liquid volume. Cooking cups are a different mess.
Mind-Blowing Demos
๐ Galton Board & the Bell Curve
Every ball bounces left or right by pure chance โ yet the pile always forms a perfect bell curve. This is the Central Limit Theorem: order emerging from randomness, and the reason so much of nature...
Home & DIY
๐ฑ Plant Spacing Calculator
How many plants fit a bed at a given spacing. Square grid is simplest; triangular (hex) packing fits about 15% more. Leave paths out of the length and width.
Productivity & Lifestyle
Smart Garden Task Planner
Plan, track, and grow your perfect garden with AI-powered suggestions and smart scheduling.
Productivity & Lifestyle
๐ฟ Garden Planning Assistant
Plan, track, and optimize your garden with planting schedules, care reminders, and plant databases. Grow your perfect garden!
Survival & Emergency Readiness
๐ซ Gas Leak & Carbon Monoxide Response
Three things people get wrong in the first two minutes, and all three can be fatal: what to touch when you smell gas, how to recognise carbon monoxide poisoning before someone collapses, and what a...
Mathematics
๐งฎ GCF, LCM & Prime Factors
Find the greatest common factor, least common multiple and prime factorisation of one or more integers. Enter a single integer to also see whether it is prime and its neighbouring primes. Euclidean...
SaaS & Business Killers
๐ก๏ธ Privacy Policy Generator
Generate legally-compliant Privacy Policies for websites, mobile apps, SaaS, and e-commerce stores. Includes GDPR, CCPA/CPRA, cookie consent, and third-party processor disclosures without paying re...
Interactive Art & Living Worlds
โจ Generative Joy Kaleidoscope & Luminous Mandala
An interactive radial symmetry mirror engine and meditative visual sanctuary. Draw luminous ribbons with your cursor, activate mesmerizing mathematical auto-drift, listen to resonant harmonic drone...
Science & Engineering
๐งฌ Genetics Laboratory
Explore genetics through interactive simulations, DNA analysis tools, and educational content. Perfect for students and enthusiasts!
Science & Engineering
๐ Geodesic Area & Parcel Calculator
Type or click out a boundary and get its true area on the curved Earth using the spherical-excess formula โ the same maths GIS packages use โ alongside the flat-map answer so you can see exactly ho...
Science & Engineering
๐ Flag & Capital Quiz
Learn 40 countries with flip flashcards, then test yourself on capitals and flags. Streaks, scoring and fun facts make world geography stick.
Science & Engineering
Geography Helper
Add countries, capitals, and notes to build your geography study list.
Science & Engineering
Geology Tools & Facts
Explore geology concepts and discover fascinating facts about Earth's structure and processes.
Mind-Blowing Demos
๐ Geometric Size Illusion Lab
Six classic length illusions โ Mรผller-Lyer, Ponzo, Ebbinghaus, Delboeuf, vertical-horizontal and Jastrow โ drawn live, with a strength slider, a measure-it overlay printing true pixel lengths and a...
Mathematics
Geometry Calculator
Calculate areas, perimeters, and volumes for common shapes. Choose a shape, enter dimensions, and get results with formulas shown.
Writing & Language
๐ฉ๐ช German Cases & Gender
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.
Productivity & Lifestyle
Gift Helper ๐
Find the perfect gift with smart suggestions, reminders, and inspiration for every occasion.
Algorithms & Computer Science
๐ .gitignore Builder
Tick the stacks you use. Output is a combined .gitignore โ copy into the repo root. Git still tracks files you already committed; git rm --cached those separately.
Productivity & Lifestyle
๐ค๏ธ Go Outsideometer
A scientifically unserious instrument that measures how long it has been since you touched grass. Answer honestly, and it will tell you exactly how urgently you need to go outside โ then give you a...
Productivity & Lifestyle
Goal Tracker ๐ฏ
Set, track, and achieve your goals with progress monitoring, milestones, and motivational reminders.
Productivity & Lifestyle
ฯ Golden Ratio Crop Calculator
Grow or crop a rectangle to ฯ โ 1.618, place a golden-section grid, and convert any length into its complementary pair. Used by photographers and layout designers. Pure geometry โ no image upload.
Sports
โณ Golf Stableford Points Calculator
Enter your course handicap and your gross score for each hole, and this works out the shots you receive, your net score, and the Stableford points per hole โ the friendly format where a blob costs ...
Sports
โณ Golf WHS Handicap Calculator
The World Handicap System in two steps. Work out a round's Score Differential (what actually feeds your handicap), then turn a Handicap Index into your Course Handicap and Playing Handicap for that...
Mathematics
๐ International GPA Calculator
Calculate GPA for universities worldwide. Supports multiple grading systems and conversions.
Mathematics
Grade Calculator ๐
Calculate weighted grades, predict final scores, and see what you need to achieve your target grade.
Mathematics
๐ Smart Graphing Calculator
Interactive math visualization: Plot functions, find roots, compute derivatives/integrals, solve equations, and create beautiful graphs. Perfect for students, teachers, and professionals.
Wellbeing & Community
๐ Gratitude Constellation & Celestial Memory Map
Map your cherished memories, loved ones, and moments of gratitude into glowing stars in an interactive 3D celestial sphere. Connect your stars into named constellations, listen to harmonic crystal ...
Home & DIY
๐ชจ Gravel & Aggregate Calculator
Calculate how much gravel, slate, chippings, or aggregate you need for driveways, paths, patios, or garden beds. Includes tonnes, bulk bags, and cost.
Science & Engineering
๐ณ๏ธ Gravitational Lensing Lab
General Relativity astrophysics exhibit. Drag a supermassive Schwarzschild black hole across cosmic starfields to observe Einstein rings and photon deflection.
Science & Engineering
๐ Galaxy Collision & Tidal Tails
Gravitational N-body astrophysical simulation. Watch two disk galaxies collide as differential tidal forces eject long parabolic stellar bridges and tails.
Science & Engineering
โ๏ธ Great-Circle Route Planner
Why does a LondonโTokyo flight arc over Siberia? Compute the true shortest path between any two points โ Vincenty distance on the real ellipsoid, initial and final bearings, waypoints along the way...
Productivity & Lifestyle
๐ฌ Great Minds Quote Explorer
40 inspiring quotes from history's greatest scientists, inventors and thinkers โ each with context about who said it and why it matters. Search, filter by theme, save favourites.
Science & Engineering
๐ก๏ธ Greenhouse Effect โ Energy Balance Lab
Sunlight arrives easily, but the infrared Earth re-radiates gets intercepted by greenhouse gases. Watch photons battle through the atmosphere and see why the surface must warm until the books balan...
MrProphecy Arcade
๐งญ Grid Reference Trainer (OS)
Learn four- and six-figure Ordnance Survey grid references on a visual grid โ remember: eastings (across) first, northings (up) second.
Wellbeing & Community
๐ฏ๏ธ Grief Companion
There is nothing to fix here, and nothing you are supposed to be over by now. What this does is help with the two things grief actually makes hard: getting through an ordinary day, and not being bl...
Finance & Money
๐ Grocery Budget Tracker
Track your grocery spending, categorize items, and stay within your budget with smart insights.
Wellbeing & Community
๐ซ Grounding & Breathing Coach
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...
Home & DIY
๐งฑ Grout & Tile Adhesive Calculator
The tiles are one thing โ 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.
Music & Audio
๐ธ Guitar Fret Position Calculator
Equal-temperament fret rule: distance from nut to fret n = L ร (1 โ 1/2^(n/12)) where L is scale length. 12th fret is the octave (halfway). Not a CNC file.
Sports
๐คธ Gymnastics Score Calculator
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.
Science & Engineering
๐งญ Gyroscopic Precession Lab
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...
Productivity & Lifestyle
๐ Habit Tracker
Build consistent habits with visual streaks and daily tracking. Save your progress automatically!
Sports
๐คพ Handball Scorekeeper
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.
Interactive Art & Living Worlds
๐ช HarmonicOrbit Loom
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...
Productivity & Lifestyle
๐ File Hash Checker
Verify file integrity and calculate cryptographic hashes. Compare hashes to verify file authenticity!
Productivity & Lifestyle
๐ Crypto & Hash Suite
Generate cryptographic hashes (SHA-256, SHA-512, MD5), HMAC signatures, and multi-format encodings (Base64, Hex, URL). Fast, client-side, and zero-knowledge.
Algorithms & Computer Science
๐ Hash Generator
Generate cryptographic hashes instantly. Supports MD5, SHA-1, SHA-256, SHA-384, SHA-512. All processing happens in your browser โ nothing is sent to any server.
Productivity & Lifestyle
๐ฉ Hat Size Converter
Convert head circumference to UK, US and cm hat sizes. US size โ circumference in inches รท ฯ. Measure just above the ears, level around the widest part. Felt hats often want a snug fit; straw can r...
Health & Fitness
โค๏ธ Heart Rate Zones Calculator
Calculate Karvonen training zones, VOโ max estimates, heart rate variability (HRV), and recovery metrics. Professional-grade analytics for athletes!
Survival & Emergency Readiness
๐ฅถ Heat & Cold Exposure Calculator
Temperature alone lies. Wind takes heat off you far faster than the number suggests, humidity stops you cooling yourself down, and wet clothing changes everything again. This works out what the air...
Science & Engineering
๐ฅต Heat Index Calculator
NWS Rothfusz heat index from shade air temperature and relative humidity. Officially for โฅ 27 ยฐC. Full sun can feel several degrees worse. Not medical advice โ heatstroke is an emergency.
Interactive Art & Living Worlds
โฐ๏ธ Heightmap 3D Sculptor
Paint mountains with your pointer on the map (left) and watch a living 3D island grow (right) โ with beaches, forests, snowcaps, animated water and erosion. Or generate procedural islands, ridges a...
Museum & Collection
๐ก๏ธ The Blazon Workshop
A teaching coat, not a grant. Choose a field, an ordinary and a charge. The plaque writes the blazon in the old word-order: metal or colour first, then the ordinary, then what stands upon it. Rule ...
Natural Remedies & Herbs
โ ๏ธ Herb & Prescription Safety
Clinical botanical pharmacodynamics checker. Cross-references herbal compounds against prescription drug classes to prevent CYP450 enzyme conflicts and adverse events.
Natural Remedies & Herbs
๐ซ Herbal Tea & Extraction Timer
Scientific phytotherapy extraction guide. Tailors thermal temperatures, liquid-to-herb ratios, and brew times between volatile floral infusions and dense root decoctions.
Natural Remedies & Herbs
๐งด Herbal Salve & Balm Crafter
Formulate medicinal balms and herbal salves. Calculates exact beeswax-to-infused-oil ratios for soft rubs, standard tins, or heat-resistant summer lip balms.
Natural Remedies & Herbs
๐ฟ Herbal Tincture Ratio Calc
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.
Mathematics
๐ข Hex & Decimal Converter
Convert between hexadecimal, decimal, binary, octal, and ASCII with bitwise operations. Essential for developers, modders, and reverse engineering!
Science & Engineering
๐ฅพ Hike & Walk Time Planner
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...
Music & Audio
๐ฅ MPC & SP Swing Groove Quantize Calculator
The secret to head-nodding hip hop bounce lies in micro-timing: Roger Linn's legendary MPC 16th-note swing formula, J Dilla's unquantized lazy pocket, and modern Drill swing offsets. Calculate exac...
Productivity & Lifestyle
๐ Advanced History Timeline Builder
Create interactive timelines, explore historical databases, and visualize events across civilizations. Perfect for students, educators, and history enthusiasts!
Finance & Money
๐ HMRC Mileage Allowance
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...
Museum & Collection
๐งฌ The Hominin Corridor
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...
Science & Engineering
๐
Horizon & Line-of-Sight Calculator
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...
Science & Engineering
๐๏ธ Horsepower, kW & Torque
Convert mechanical horsepower, metric PS and kilowatts, and compute power from torque ร RPM. 1 hp = 745.7 W; 1 PS = 735.5 W. Power (kW) = torque (Nยทm) ร RPM / 9549.
Finance & Money
๐ท Hourly โ Annual Salary
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 โ tax is not deducted.
Wellbeing & Community
๐จ Household Emergency Plan
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 โ whi...
Productivity & Lifestyle
๐ Advanced Household Chore Tracker
Manage household chores, assign tasks, set schedules, and track completion with reminders. Perfect for families and shared living!
Productivity & Lifestyle
๐ชด Houseplant Matchmaker
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.
Algorithms & Computer Science
๐ Apache & Nginx Redirect Generator
Build 301/302 redirect snippets for Apache (.htaccess) or Nginx (server { }): HTTPโHTTPS, www/apex canonical hosts and page redirects. Review before deploying โ a bad rule loops a site (test Nginx ...
Algorithms & Computer Science
๐ฆ HTML / CSS Minifier
Strip comments and collapse idle whitespace in HTML or CSS. Not a full parser โ keep <pre> and <textarea> out of the input, and do not minify JavaScript here. Local only.
Algorithms & Computer Science
๐ค HTML Entity Encoder & Decoder
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 ...
SaaS & Business Killers
๐ HTML Table Generator
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 ...
Algorithms & Computer Science
๐ HTML to Markdown Converter
A practical subset: headings, paragraphs, links, images, lists, bold/italic, code, blockquotes, hr. Scripts and styles are dropped. Not a full CommonMark round-trip.
Algorithms & Computer Science
๐ก HTTP Status Code Encyclopedia
Look up any HTTP status code, filter by class, and copy a one-line explanation. Covers the registered 1xxโ5xx codes developers hit in the wild. Entirely offline.
Algorithms & Computer Science
๐๏ธ Huffman Coding: How Compression Works
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 ...
Birdwatching & Ornithology
๐ธ Hummingbird Nectar & Spoilage
Formulate natural 20% sucrose syrup and monitor microbial fermentation rates. Calculates exact water-to-cane-sugar ratios and temperature-driven spoilage limits.
Interactive Art & Living Worlds
๐ Hurricane Engine
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...
Health & Fitness
๐ง Daily Hydration Calculator
Calculate your personalized daily water intake needs. Track your progress throughout the day!
Mind-Blowing Demos
๐ง Hypercube 4D Explorer
Spin a real tesseract โ a 4D cube โ with true four-dimensional rotation. Twist the XW, YW and ZW planes that don't exist in our world, slide 4D perspective until it turns inside-out, and meet its s...
Productivity & Lifestyle
๐ท Hyperfocal & Depth of Field
Hyperfocal distance H = fยฒ / (N ร c) + f. Focus there and everything from H/2 to infinity is acceptably sharp. Circle of confusion defaults: full frame 0.030 mm, APS-C 0.019 mm, Micro Four Thirds 0...
Algorithms & Computer Science
๐ฆ IBAN Validator & Formatter
Check an International Bank Account Number with the ISO 13616 MOD-97 algorithm, then pretty-print it in groups of four. This confirms the check digits only โ it cannot prove an account exists.
Sports
๐ Ice Hockey Goalie Stats
Turn a goalie's box score into the numbers that matter: goals-against average, save percentage, and a winโloss record โ with a read on how good they actually are.
Algorithms & Computer Science
๐
ICS Event Builder
Make a .ics file any calendar app can import. Times are written as floating local (no time-zone math). All-day events use DATE values.
Health & Fitness
โ๏ธ Ideal Weight & BMI
Get a comprehensive analysis of your ideal weight range using multiple scientific formulas and personalized factors.
Algorithms & Computer Science
๐ข IEEE-754 Converter
32-bit binary32 (float) and 64-bit binary64 (double) bit patterns via typed arrays. Paste a decimal, hex (0xโฆ) or 32/64-bit 0/1 string.
Productivity & Lifestyle
๐ผ๏ธ Image to Base64 Studio
Convert images to Base64 data URLs for inline CSS & HTML embedding, or decode Base64 strings back into downloadable images.
SaaS & Business Killers
๐๏ธ Image Optimiser Studio
Batch-shrink photos and screenshots without uploading a single byte. Drop files in, pick a target size and format, and watch the real compressed file size update as you move the quality slider. Exp...
Mind-Blowing Demos
๐ Impossible Object Viewer
A spinning Necker cube that flips inside your head, a Penrose triangle with an X-ray slider that reveals the cheat, and endless stairs with a ball that descends forever. True 3D rotation of impossi...
Science & Engineering
โก Inductance Calculator
Professional inductance calculator with real-time visualization, multiple coil types, and comprehensive electrical analysis.
Finance & Money
๐ Inflation Impact Calculator
Calculate real-world purchasing power with historical data, multiple currencies, and personalized financial scenarios.
Productivity & Lifestyle
๐งฎ Recipe Ingredient Scaler
Perfectly scale any recipe with smart parsing, automatic unit conversions, and kitchen-tested measurements.
Music & Audio
๐ถ Instrument Care Guide
Get detailed care instructions with maintenance schedules, required tools, and professional tips for your specific instrument.
Home & DIY
๐ง Insulation Savings Calculator
Estimate how much you could save by insulating your loft, walls, or floor. Based on UK energy prices.
Interactive Art & Living Worlds
๐ Solarpunk Wind Chime Sanctuary
An acoustic sanctuary of physics-driven resonant wind chimes and generative ambient soundscapes. Drag individual chimes to play them, summon warm wind gusts, or relax and let the natural breeze cre...
Health & Fitness
โณ Intermittent Fasting Window
Pick a 16:8, 18:6, 20:4 or custom fast and see todayโs eat-from / eat-until times. Educational scheduling only โ not medical advice, and not for anyone who is pregnant, under 18, or has an eating-d...
Music & Audio
๐ต Interval Ear Trainer
Essential for musicians: Learn to identify intervals by ear. Perfect for singers, composers, and anyone learning music theory!
SaaS & Business Killers
๐ฆ Inventory Reorder Point Planner
Calculate when to reorder stock using sales velocity, supplier lead time and safety stock. All calculations stay in your browser.
Science & Engineering
โก Solar Inverter Sizing
Essential for solar/off-grid setups: Calculate the right inverter size for your needs. Always consult a professional before installation!
Finance & Money
๐ Investment Growth Calculator
Watch your money multiply: Calculate how small investments today can grow into significant wealth over time through compounding. Illustrative estimates only โ not financial advice; markets can fall...
SaaS & Business Killers
๐งพ InvoiceForge Generator
Generate clean, client-ready invoices with zero watermarks. Calculates multi-currency line items, tax, discounts, and payment terms with 1-click browser print to PDF. Instant browser-based invoicin...
Finance & Money
๐งพ Invoice Late Fee Calculator
Calculate statutory or agreed late-payment interest and a clear updated invoice total. All calculations stay in your browser.
Finance & Money
โ๏ธ IR35 Inside vs Outside Comparator
Compare take-home pay as a contractor: inside IR35 through an umbrella company versus outside IR35 through your own limited company. Editable tax rates, full working shown, nothing leaves your devi...
Writing & Language
๐ Irregular Verbs Trainer
Drill the English verbs that refuse to follow the rules โ go/went/gone, swim/swam/swum โ in 8-question rounds, with a full reference table and your personal missed list. All local.
Algorithms & Computer Science
๐ ISBN-10 โ ISBN-13 Converter
Validate an ISBN-10 or ISBN-13, compute the check digit, and convert between the two. Hyphens and spaces are ignored. Check digits follow the ISBN / EAN rules โ this does not look up a book.
Productivity & Lifestyle
๐ ISO Week Number Finder
Convert a date to its ISO-8601 week (YYYY-Www-d) and the other way around. Weeks start on Monday; week 1 is the week with 4 January (the week containing the first Thursday).
Museum & Collection
๐ฏ The Nengล Desk
Japanese objects are dated in era years: Meiji 6, Shลwa 20, Reiwa 6. Year 1 of an era is the year it was proclaimed, even if that was December. The desk covers Meiji (1868) to Reiwa. Earlier nengล ...
Writing & Language
๐ JLPT Vocabulary Studio
Supercharge your Japanese vocabulary for the JLPT N5 and N4 examinations. Includes native audio pronunciation, Furigana reading toggles, English definitions, and contextual example sentences.
Writing & Language
๐ Japanese Kana Trainer
Master the foundation of Japanese. Interactive 46-character syllabaries for both Hiragana and Katakana with native audio pronunciation, dakuten/handakuten sound changes, and a speed flashcard drill...
Writing & Language
๐ Japanese Keigo Master
Navigate the 3 crucial Japanese speech registers: Casual (with friends), Teineigo (everyday polite), Sonkeigo (honorific/clients), and Kenjougo (humble/self-lowering).
Writing & Language
๐ข Japanese Counters & Numbers
Conquer Japanese counter words (ๅฉๆฐ่ฉ - Josลซshi). In Japanese, you cannot simply say "three beers" or "two cats"โobjects require specific counters with euphonic sound shifts (rendaku).
Writing & Language
๐งฉ Japanese Particles Master
Master the grammatical glue of Japanese sentences (ๅฉ่ฉ - Joshi). Practice tricky distinctions like ใฏ vs ใ (topic vs subject) and ใซ vs ใง (time/target vs location of action) with interactive fill-in-t...
Writing & Language
๐ Romaji & Kana Converter
Type in standard alphabet (Romaji) and watch it convert in real-time into Hiragana and Katakana. Also translates Kana back into Hepburn Romaji with 1-click text-to-speech audio pronunciation.
Writing & Language
โก Japanese Verb Conjugator
Instantly conjugate any Japanese verb across all core grammatical forms (Present, Negative, Past, Te-form, Potential, Volitional, and Passive) with group detection (Godan, Ichidan, Irregular).
Lucid Dreaming & Sleep
โ๏ธ Jet Lag Sleep Shift Planner
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.
Wellbeing & Community
๐ JoySpark: Micro-Victory Celebration Cannon
Big milestones are rare, but everyday micro-victories deserve roaring celebrations! Log any small win, blast physics-driven confetti cannons with uplifting audio fanfares, collect custom victory ba...
Interactive Art & Living Worlds
๐ชจ Joyful Zen Rock Garden & Ripple Raker
Experience the tactile calm of a Japanese Karesansui dry landscape garden. Rake intricate sand ripples with real-time displacement textures, arrange smooth river stones and moss mounds, listen to s...
Algorithms & Computer Science
๐งฉ JSON Flatten / Unflatten
Nested objects become dotted keys (user.address.city); arrays use items.0. Unflatten rebuilds the tree. Runs in this page โ nothing is uploaded.
SaaS & Business Killers
๐ท๏ธ Rich Result Forge
Build valid schema.org JSON-LD for the rich results Google actually shows โ products with price and availability, FAQs, breadcrumbs, events, local businesses, articles. Fields are validated as you ...
SaaS & Business Killers
๐งฌ JSON Schema Forge
Paste any JSON response and get production-ready types in six dialects at once: TypeScript interfaces, a Zod schema, Python dataclasses, Go structs, C# classes and a JSON Schema document. Nested ob...
Productivity & Lifestyle
๐ง JSON & YAML Studio
Format, validate, convert between JSON & YAML, and compare structural diffs side-by-side. 100% private in-browser processing.
Productivity & Lifestyle
๐ Julian Day Converter
Convert a calendar date to Julian Day Number (JDN) and Modified Julian Date (MJD = JD โ 2,400,000.5). Astronomers count days from noon UTC on 1 January 4713 BCE. Gregorian calendar after 15 Oct 158...
Algorithms & Computer Science
๐ JWT Token Inspector
Decode and audit JSON Web Tokens offline. Zero network calls โ your security tokens never leave your browser.
Productivity & Lifestyle
๐ Offline Kanban Sprint Board
Lightweight, private Kanban board with drag-and-drop cards, custom columns, priority tags, WIP counts, markdown export, and local storage auto-save.
Writing & Language
๐ Japanese Kanji Helper
Learn, practice, and master Japanese kanji with REAL stroke order animations, meanings, readings, and example words.
Science & Engineering
โ๏ธ Kelvin-Helmholtz Waves
Atmospheric fluid shear-flow instability. Two fluid layers with differing densities and velocities roll up into breaking ocean-billow cloud vortices.
Algorithms & Computer Science
โจ๏ธ Keyboard Tester & Event Inspector
Press any key to test it live โ handy when a laptop key died or a layout is fighting you. Shows event.key, event.code, keyCode, which, modifiers, location, and ready-to-copy event listener code. No...
Science & Engineering
๐งช Kitchen Science Lab
10 safe, spectacular experiments using stuff already in your kitchen โ each with step-by-step instructions, the real science explained, and safety notes. Perfect for curious kids and parents.
Mathematics
๐ Klein Bottle & Mรถbius Lab
Surfaces that shouldn't exist: a Mรถbius strip with adjustable twists, a Klein bottle (inside IS outside), and torus knots you design with p/q sliders. Points, wireframe or solid candy render.
Science & Engineering
โต Knots โ mph โ km/h
One knot is one nautical mile per hour. A nautical mile is exactly 1,852 m, so 1 kn = 1.852 km/h โ 1.15078 mph. Used by ships, aircraft and marine forecasts.
Science & Engineering
๐ฆ๏ธ Kรถppen Climate Classifier
Type in twelve monthly temperatures and rainfall totals and this runs the full KรถppenโGeiger decision tree on them โ the same classification used on every climate map โ showing not just the code (C...
Writing & Language
๐ฐ๐ท Korean Hangul Trainer
Learn Hangul (ํ๊ธ), the world's most scientific writing system. Explore the 14 basic consonants, 10 vowels, and combine them into complete Korean syllable blocks with native audio pronunciation (`ko...
Science & Engineering
Lab Planner
Plan lab experiments by organizing materials, steps, and timing. Enter details and generate a structured plan.
Science & Engineering
Lab Safety Tools & Facts
Review lab safety rules and generate reminders for safe scientific work.
Home & DIY
๐ชต Laminate Flooring Calculator
Work out how many packs of laminate to buy: enter the room, the plank size, planks per pack and pack price, and this adds the wastage so you don't run short mid-lay.
Writing & Language
Languages Tool
Translate words, check meanings, and practice languages. Uses open-source translation services.
Finance & Money
โฐ Late Payment Interest & Chaser Letter
Unpaid invoice? UK law lets you charge 8% above the Bank of England base rate plus fixed compensation on overdue business invoices โ automatically, even if your contract never mentioned it. Calcula...
Museum & Collection
๐ The Kalends Desk
Romans counted forward to the next named day, inclusively. The named days are the Kalends (1st), the Nones (5th, or 7th in Mar/May/Jul/Oct) and the Ides (13th, or 15th in those four months). The Id...
Wellbeing & Community
๐ The Laugh Laboratory & Mood Prescription
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...
Productivity & Lifestyle
๐งบ Laundry Care & Stain Solver
The complete โhow to actually do itโ guide: pick a fabric and get the right water, cycle and drying, get a step-by-step recipe for any stain, and decode those cryptic care-label symbols in plain En...
Productivity & Lifestyle
Laundry Tracker
Log laundry loads, track completion, and monitor laundry habits with statistics.
Health & Fitness
Lean Body Mass Calculator
Estimate your lean body mass using multiple formulas and get detailed body composition analysis.
Productivity & Lifestyle
๐ Leap Year & Weekday
Gregorian leap years are divisible by 4, except centuries unless divisible by 400. 1900 was not a leap year; 2000 was. Also shows the weekday for any date your browser can represent.
Productivity & Lifestyle
๐งญ Learning Style Self-Assessment
Answer 8 quick questions to discover your preferred learning style: Visual, Auditory, Reading/Writing, or Kinaesthetic.
Finance & Money
๐ Lease vs Buy Calculator
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.
Science & Engineering
๐ก LED Current-Limiting Resistor
R = (supply โ LED Vf) / current. Typical Vf: red ~1.8โ2.2 V, green/blue/white ~3.0โ3.4 V. Always put a resistor in series with a bare LED on a voltage source โ the LED will not self-limit.
Science & Engineering
๐ก LED Watt Equivalent Calculator
Rough incandescent, halogen and CFL wattage versus LED lumens. Packaging lumens win over โ60 W equivalentโ marketing. Efficacy defaults to typical household LEDs (~90 lm/W).
Science & Engineering
๐ก Lighting Design Calculator
Professional lighting design calculator with comprehensive room analysis, fixture selection, and energy efficiency recommendations. โ ๏ธ Educational tool โ consult certified lighting designers for ac...
Science & Engineering
โก Lightning โ Storm Anatomy in 5 Steps
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...
Mathematics
Linear Algebra Helper
Perform comprehensive linear algebra operations with step-by-step solutions, matrix visualization, and educational explanations.
Algorithms & Computer Science
๐ Bash Script Builder
Build bash scripts from common patterns โ select blocks, customize, and copy the complete script
Algorithms & Computer Science
๐ chmod Permission Calculator
Visually set file permissions โ toggle read/write/execute for owner, group, and others. Get octal, symbolic, and the full command
Algorithms & Computer Science
๐ง Linux Command Cheat Sheet
Searchable reference of 200+ Linux commands โ filter by category, copy with one click
Algorithms & Computer Science
๐พ Disk Space Analyzer & Planner
Calculate partition sizes, plan disk layouts, convert units, and get the commands to set it all up
Algorithms & Computer Science
๐ Log Analyzer & Command Generator
Paste log output to get instant analysis, or generate commands to search, filter, and monitor logs
Algorithms & Computer Science
๐ Regex Tester & Builder
Test regular expressions live โ see matches highlighted, capture groups extracted, and get the grep/sed/awk command
Algorithms & Computer Science
๐ก Linux Process & Signal Reference
Complete reference of Linux signals, process states, and process management commands with examples
Algorithms & Computer Science
๐ SSH Command Generator
Build SSH, SCP, and SSH tunnel commands โ fill in the options, copy the command
Algorithms & Computer Science
โ๏ธ Systemd Service Generator
Generate systemd .service unit files โ fill in the details, get a complete service file with install instructions
Science & Engineering
โก Lissajous Laser Projector
Dual-galvanometer laser projector simulating orthogonal harmonic oscillations, phase shifts, and phosphorescent persistence curves.
Writing & Language
๐ง AI Study Assistant
๐ Ace your exams: Transform any topic into flashcards, practice quizzes, study guides, and mnemonics. Perfect for students, lifelong learners, and professionals.
Writing & Language
๐ AI Literature Analyzer
๐ Ultimate literary toolkit: Analyze any text AND generate study materials. Perfect for students, teachers, and book lovers.
Writing & Language
๐ฌ LLM Prompt Token Counter
Estimate LLM token usage, calculate API cost per query, and compress prompt text to eliminate token waste and latency.
Science & Engineering
โก Electrical Load Calculator
๐ง Professional-grade calculations: Calculate electrical loads for homes, offices, or circuits. Includes NEC compliance tips and safety warnings.
Finance & Money
๐ Loan & Mortgage Amortization Schedule Calculator
Calculate monthly loan payments, view complete annual and monthly amortization schedules, and simulate the interest savings of extra principal payments.
Finance & Money
๐ฐ Smart Loan Calculator
๐ธ Plan your finances: Calculate mortgage, car, personal and student loan payments with amortization schedule. Compare scenarios and save thousands!
Music & Audio
๐ผ Lo-Fi Vintage SP-1200 & Tape Saturation Lab
Recreate the legendary gritty texture of golden era hip hop and chill lo-fi beats. Dial in 12-bit sampler downsampling (E-mu SP-1200, Akai S950), cassette tape wow/flutter pitch drift, and analog v...
Mathematics
๐ Logarithm Calculator
Evaluate logarithms in any base, convert between bases, and solve for an unknown exponent. Shows the change-of-base working so you can follow it on paper.
Mind-Blowing Demos
๐ต๏ธ Logic Detective Puzzle Club
8 classic logic puzzles that have stumped clever people for centuries โ with progressive hints, full solutions and detective-rank progress tracking. No maths degree required.
Science & Engineering
โก Logic Gate Simulator
Simulate fundamental boolean logic gates (AND, OR, XOR, NAND) and digital circuits with live voltage probes and dynamic truth tables.
Mathematics
โ Long Division Step-by-Step Trainer
See every step of long division โ divide, multiply, subtract, bring down โ then practise on a generated calculation with full remainder and check-back working. All local, nothing sent anywhere.
Writing & Language
๐ Lorem Ipsum & Placeholder Text
Generate filler text for mockups and layouts: classic Lorem Ipsum, plain English, or themed flavours (tech jargon, cooking, pirate, corporate, hip hop). Choose paragraphs, sentences or words, wrap ...
Mind-Blowing Demos
๐ช๏ธ Lorenz Attractor โ the Butterfly Effect
Three perfectly deterministic equations, zero randomness โ yet the path swirls forever around two wings and never repeats. This is chaos: predictability with a built-in expiry date, the seed of the...
Finance & Money
๐ฆ LTV Mortgage Calculator
Loan-to-value = mortgage รท property price. UK product tiers often sit at 60, 75, 85, 90, 95%. Deposit is price โ loan. Not a lender decision and not advice.
Lucid Dreaming & Sleep
๐ฏ Lucid Dream Quest Taskboard
Intentional task priming board. Having a clear pre-sleep mission dramatically reinforces prospective memory once lucidity strikes, eliminating disorientation.
Lucid Dreaming & Sleep
โจ Lucid Dream Stabilizer Lab
Emergency stabilization maneuvers when lucidity triggers. Overcome the premature waking reflex, dream scene fading, and false awakenings.
Lucid Dreaming & Sleep
๐๏ธ Lucid Reality Check Trainer
Condition waking critical state-testing reflexes into your subconscious. Performing 10+ intentional reality tests during the day carries directly into REM dreams.
Lucid Dreaming & Sleep
๐ Lucid Dream Supplement Clock
Pharmacokinetic timing for lucid dreaming oneirogens based on LaBerge's PLOS ONE studies. Synchronizes peak Acetylcholine plasma levels ($T_{\max}$) with late REM cycles.
Algorithms & Computer Science
๐ข Luhn Check Digit Validator
Validate or generate a Luhn (mod 10) check digit. Used by card numbers, IMEI, NPI and some barcodes. This only tests the checksum โ it cannot tell you whether a number is issued, active or real.
Science & Engineering
๐ก Lumens โ Lux
Lux = lumens รท area (mยฒ) when light is spread evenly. A 800 lm bulb over a 10 mยฒ desk is 80 lux โ offices often want 300โ500 lux. Beam angle and bounce are ignored.
Astronomy & Space
๐ Lunar Phase & Illumination
Phase, illumination fraction, age and a drawn disc for any date and time โ plus the next new and full Moons and how much moonlight is washing out the sky. Runs entirely offline.
Interactive Art & Living Worlds
๐ Lunar Tide Simulator
The equilibrium tide, live: Moon and Sun each raise two opposing bulges (H โ cosยฒฮธ), Earth rotates beneath them, and the 24h50m lunar day makes the tide arrive 50 minutes later every day. Set the l...
Health & Fitness
๐ฅ Smart Macros Calculator
๐๏ธ Achieve your goals: Calculate protein, carbs, and fats for weight loss, muscle gain, or maintenance. Get personalized meal plans and food suggestions.
SaaS & Business Killers
โจ Magic Background Eraser & Upscaler Pro
One-tap background removal, chroma key, edge feathering and 2ร/4ร upscaling โ the offline replacement for remove.bg & Let's Enhance. Flood-fill magic wand, color distance, and canvas compositin...
Finance & Money
๐งฒ Lenz's Law Eddy Current Tube
Lenz's law electromagnetic braking exhibit. Drop a strong neodymium magnet down metal tubes; circulating eddy currents oppose motion, creating levitation-like terminal float.
Science & Engineering
๐งฒ Superconductor Flux Pinning
Type-II high-temperature superconductor cryogenic lab. Explore Meissner effect magnetic field expulsion and quantum flux pinning levitation.
Finance & Money
๐ฐ Make Change Trainer (UK coins)
Work out the change from UK coins and notes, then hand the exact coins with the fewest pieces. Learn the greedy method for 1pโยฃ2 and practise 5 rounds. Everything runs on your device.
Mind-Blowing Demos
๐ Mandelbrot Set Explorer
One line โ z → zยฒ + c โ repeated over and over produces infinite, self-similar complexity. Click anywhere to zoom in forever.
Anime & Otaku Culture
๐ Manga to Anime Finder
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.
Interactive Art & Living Worlds
๐บ๏ธ Map Projection Distortion Lab
Every flat world map lies โ 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...
Writing & Language
๐ Markdown Live Editor
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.
SaaS & Business Killers
๐๏ธ Deck Forge
Write a presentation as plain text and present it from the browser. Split slides with ---, get a live thumbnail rail, speaker notes, a run timer and full-screen mode, then export a single self-cont...
Algorithms & Computer Science
๐ Markdown & ASCII Table Generator
Interactive spreadsheet grid editor to create, format, and convert tables to GitHub-flavored Markdown, ASCII box art, Unicode borders, HTML, and CSV.
Writing & Language
๐ Markdown Document Forge
Transform raw Markdown into publication-ready corporate memos, academic whitepapers, and printable PDFs with 1-click browser export.
Finance & Money
๐น Markup vs Margin Calculator
Convert cost, selling price, markup and profit margin. Markup is profit รท cost; margin is profit รท selling price. Mix them up and you under-price. Nothing is stored.
Science & Engineering
Materials Science Tools & Facts
Calculate material properties and explore fascinating facts about metals, polymers, and composites. Uses real material properties from established databases.
Mathematics
๐ Fibonacci & Special Sequences
Calculate arithmetic and geometric sequences and series. Includes step-by-step solutions and visual representations.
Mathematics
๐ Math Universe Explorer
Step beyond calculation into mathematical discovery. Visualize concepts, see proofs unfold, find connections humans have never seen.
Mathematics
๐งฎ Maths Flashcards
Generate random maths flashcards for quick practice. Perfect for studying, teaching, or mental math warm-ups. ๐ฏ Interactive โข Timed practice โข Multiple topics โข Progress tracking
Mathematics
Math Helper
Solve mathematical expressions, equations, and practice calculations. Supports arithmetic, algebra, trigonometry, and more!
Home & DIY
๐๏ธ Mattress Size Converter
UK, US and EU bed names are not the same size. A UK king is 150 ร 200 cm; a US king is 193 ร 203 cm. Fitted sheets do not stretch that gap. Depth (deep-fitted) is separate.
Culinary & Food Science
Meal Cost Calculator
Calculate total and perโserving meal costs, split bills, and track ingredients. Perfect for meal planning, budgeting, and sharing costs with friends!
Culinary & Food Science
Weekly Meal Planner
Plan your meals for the entire week, track nutrition, generate shopping lists, and save your plans. Perfect for healthy eating, budget planning, and reducing food waste!
Health & Fitness
โค๏ธ Mean Arterial Pressure
MAP โ (systolic + 2 ร diastolic) / 3, plus pulse pressure. A resting MAP near 70โ100 mmHg is often cited as adequate organ perfusion. This is arithmetic, not a diagnosis โ chest pain or a very high...
Mathematics
๐ Mean, Median, Mode & Std Dev
Paste numbers separated by commas, spaces or new lines. Sample standard deviation uses n โ 1 (Bessel); population uses n. Mode lists every most-frequent value.
Mathematics
๐ Mean, Median, Mode & Range Trainer
Work out the mean, median, mode and range of a data set, see the full working, and learn when each average is the right tool. 5 rounds, instant feedback, all on your device.
Culinary & Food Science
๐ง Meat Brine & Cure Salinity
Osmotic equilibrium brining & charcuterie cure engine. Calculates exact salt weights, curing salt (Prague Powder #1) 156 PPM food safety thresholds, and time windows.
Culinary & Food Science
๐ก๏ธ Meat Internal Temperature Guide
Probe the thickest part, away from bone. UK FSA safe-cook figures are listed beside common chef doneness for beef/lamb. Poultry and mince should hit the safe column. Carry-over cooking after rest c...
Productivity & Lifestyle
๐ฏ Corporate Meeting Bingo
Mark off buzzwords as your colleagues say them. First to get 5 in a row wins (and loses, because you're still in the meeting).
SaaS & Business Killers
๐ธ Meeting Cost Ticker
Track real-time company salary burn during meetings. Keep discussions focused, respect employee time, and visualize the true cost of every minute.
Productivity & Lifestyle
๐ World Meeting Time Zone Planner
Find a meeting slot that works across cities. Add up to eight time zones, drag the slider through the day and see each city's local time colour-coded as working hours, early/late, or asleep. Daylig...
Productivity & Lifestyle
Meeting Planner & Scheduler
Find optimal meeting times across multiple time zones, track availability, and generate meeting agendas. Perfect for remote teams, interviews, and collaborative scheduling!
Science & Engineering
๐ฅ Melting Point Explorer
Explore melting points of hundreds of substances. Compare materials, convert units, and learn about phase changes.
Writing & Language
๐ญ Meme Translator
The ultimate internet language decoder. Translate memes, slang, acronyms, and internet speak with context, origins, and examples. ๐ Real-time translation across internet cultures
Productivity & Lifestyle
โณ Memento Mori Life Ticker
Your life, visualised as a grid of weeks โ then converted into how many summers, books and Sunday roasts you have left. Not to scare you. To make the next one count.
Productivity & Lifestyle
๐ฏ Memorization Helper
Add items to memorize, then test yourself by revealing them later. Perfect for studying, learning vocabulary, or remembering important facts. ๐ก Click items to hide/reveal โข Drag to reorder โข Expor....
Productivity & Lifestyle
๐๏ธ Memory Palace Builder
Memorise anything with the 2,500-year-old method of loci used by memory champions. Build rooms, place vivid images at each stop, walk your palace, then test your recall.
Mathematics
๐งฎ Mental-Math Sprint
A 60-second arithmetic workout with three difficulty levels, streak bonuses and a review of every question you missed. Sharpens everyday number sense โ tips, change, discounts.
Astronomy & Space
๐ The Messier Gallery
Charles Messier was hunting comets. These 110 smudges kept fooling him, so he numbered them (1771โ81). The hall is now a rite of passage for amateur astronomers. Magnitudes are visual; distances ar...
Health & Fitness
โก Metabolic Age Estimator
Estimate your metabolic age based on your Basal Metabolic Rate (BMR) compared to population averages. ๐ก Lower metabolic age indicates better metabolic health
Science & Engineering
๐ฎ Metamaterials & Negative Index Cloaking Device
In standard materials, the refractive index is always positive ($n > 0$). But engineered metamaterials achieve negative permittivity ($\epsilon < 0$) and permeability ($\mu < 0$), reversin...
Interactive Art & Living Worlds
โ๏ธ Meteor Shower Sky Lab
Stargaze a live meteor shower: pick a real shower (Perseids, Geminids, Leonidsโฆ), set radiant altitude, observing skill and light pollution โ the model converts the catalogue Zenithal Hourly Rate i...
Music & Audio
๐ต Professional Metronome
Precise audible & visual metronome with subdivisions, tap tempo, and tempo presets. โ ๏ธ Enable sound in your browser
Science & Engineering
๐ฌ Microbiology Tools & Facts
Calculate essential microbiology values and explore fascinating facts about the invisible world of microbes. ๐งซ Growth rates โข Dilutions โข Microbial facts โข Educational insights
Lucid Dreaming & Sleep
๐ง MILD Lucid Dream Mantra Lab
Mnemonic Induction of Lucid Dreams (Stanford / Dr. Stephen LaBerge). Primes prospective memory to recognize the dream state right before entering REM sleep.
Algorithms & Computer Science
๐ MIME Type Lookup
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.
Home & DIY
๐ Miter & Bevel Angle Calculator
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.
SaaS & Business Killers
๐งช Mock Data Generator
Create repeatable sample customer, product or analytics-event datasets as JSON, CSV or SQL inserts. Names and example.test emails are deliberately fictional, so you can prototype safely without upl...
Museum & Collection
๐ The Mohs Gallery
Friedrich Mohs, 1812: a mineral of higher number scratches one of lower number. The steps are not equal โ corundum to diamond is a canyon. Pick two specimens (or a thumbnail and a steel file) and t...
Science & Engineering
ใฐ๏ธ Moirรฉ Optical Interference
Kinetic optical interference exhibit. Overlay geometric optical gratings and rotate them to observe emergent macro-scale moirรฉ superlattices.
Museum & Collection
๐งช The Moisture Lab
Watch water migrate through building materials via capillary action โ the same force that makes a sponge soak up water and makes your walls draw moisture from the ground. See why rising damp happen...
Science & Engineering
โ๏ธ Molecule 3D Viewer
Eleven molecules and crystals as true ball-and-stick 3D โ from water to a salt lattice to a diamond unit cell. Bonds are detected automatically from atomic distances, double/triple bonds included. ...
Mind-Blowing Demos
๐ฏ Monte Carlo ฯ Estimator
Watch π emerge from pure chance: random points rain on a square with a circle inside, and the ratio that lands in the circle is exactly π/4. No formula โ just probability converging o...
Astronomy & Space
๐ Moon Phases & Eclipse Geometry
Why do phases exist, and why are eclipses so rare? Spin the Moon around Earth (its real orbital inclination is 5.14ยฐ) and rotate the line of nodes โ the place where the Moon's tilted orbit crosses ...
Writing & Language
๐ก Morse Code Translator
Translate text to Morse code and back. Listen to the Morse code audio and learn the international standard.
Finance & Money
๐ฆ Mortgage Overpayment Calculator
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...
Finance & Money
๐ Mortgage Calculator
Calculate detailed mortgage payments with amortization schedules, extra payments analysis, and regional comparisons. ๐ฐ Monthly payments โข Total interest โข Payoff time โข Amortization schedule โข Reg....
Science & Engineering
โก Motor Startup Calculator
Calculate motor running/starting currents, cable sizing, protection devices, and voltage drop analysis for electrical installations. ๐ง Running current โข Starting current โข Cable sizing โข Protectio....
Sports
๐๏ธ Motorsport Lap Time & Stint Calculator
Turn a lap time into an average speed and a full race duration, see how much each pit stop costs, and โ if you have a rival's lap time โ watch the gap grow lap by lap.
Productivity & Lifestyle
๐ Ultimate Moving Planner
Complete moving organization tool: Create checklists, track inventory, manage budget, schedule tasks, and coordinate with family/friends. Make your move stress-free!
MrProphecy Arcade
๐ง MrProphecy: Beat Memory
Simon-style pad memory that grows by one step each round, scored over real MrProphecy tracks. Audio starts with the game.
MrProphecy Arcade
๐ MrProphecy: Beat Runner
Endless runner starring MrProphecy. Jump the gaps, build speed, and the soundtrack is real MrProphecy tracks โ playback only begins when you hit start.
MrProphecy Arcade
๐ค MrProphecy: Crowd Surf
Ride the crowd, collect gold notes and dodge flying drinks. Three lives, endless festival. Real MrProphecy tracks start with the game.
MrProphecy Arcade
๐ค MrProphecy: Title Scramble
Unscramble real MrProphecy track titles against a sixty-second clock. Music kicks in on start, not before.
MrProphecy Arcade
๐๏ธ MrProphecy: Mix Board Challenge
Five faders, five rounds, shrinking tolerance. Hit the target mix from the written cue. Real MrProphecy tracks run on the desk.
MrProphecy Arcade
๐ง MrProphecy: Name That Track
A real MrProphecy track plays from a random point โ pick the title from four options. Ten rounds, no audio until you press start.
MrProphecy Arcade
๐ฅ MrProphecy: Rhythm Tap
Four-lane rhythm game scored on timing and combo, running over real MrProphecy tracks. Nothing plays until you start.
MrProphecy Arcade
๐ก๏ธ MrProphecy: Studio Defender
Bad takes rain down on the studio โ pop them before they land. Waves get faster. Real MrProphecy tracks play once you start.
MrProphecy Arcade
๐บ๏ธ MrProphecy: Tour Manager
Twelve weeks to take MrProphecy from a Luton bedroom to a headline slot. Balance fans, cash and energy. Real tracks play while you decide.
MrProphecy Arcade
๐ฟ MrProphecy: Vinyl Catch
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.
Home & DIY
๐ Mulch Coverage Calculator
Volume = area ร depth. A 50 litre bag is 0.05 mยณ. Bark mulch is usually 5โ8 cm; paths can be 10 cm. Order a little extra for settling โ bags are sold by loose volume.
Writing & Language
๐ 10-Language Phrasebook
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.
Music & Audio
๐ค Multi-Syllabic Rhyme & Cadence Flow Architect
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...
Museum & Collection
๐ท๏ธ The Tombstone Desk
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...
Music & Audio
๐ต Ultimate Music Quiz
Interactive music knowledge challenge: Test your expertise across theory, history, instruments, and pop culture. Complete with scoring, explanations, and shareable results!
Music & Audio
๐ผ Circle of Fifths Explorer
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.
Science & Engineering
๐ Physarum Slime Mold & Mycelium Biocomputer Maze Solver
The single-celled organism Physarum polycephalum (slime mold) and fungal mycelium have no brain or neurons, yet they solve complex mathematical mazes, Steiner tree networks, and traveling salespers...
Algorithms & Computer Science
๐ชช Nano ID Generator
URL-safe IDs from crypto.getRandomValues. Default alphabet is AโZaโz0โ9_- (64 symbols). Collision odds are about (nยฒ) / (2 ร 64^size) for n IDs โ this is not a password manager.
Writing & Language
๐ก NATO Phonetic Alphabet Trainer
Master the international radio alphabet โ Alfa, Bravo, Charlie โ used so letters can never be misheard. Spell words out loud, test yourself letter by letter, and see the pronunciation table. Runs e...
Writing & Language
๐ก NATO Phonetic Speller
Spell a name, postcode or booking reference the way air-traffic and support desks do. ICAO/NATO alphabet (Alfa, Bravoโฆ). Digits stay as words.
Natural Remedies & Herbs
โก Natural Electrolyte Tonic Lab
Formulate whole-food isotonic rehydration elixirs matching World Health Organization (WHO) cellular osmolarity standards (245 mOsm/L) for sickness recovery, fevers, and intense heat.
Science & Engineering
๐ Nature ID Trainer
Learn to spot 24 common UK/European plants and fungi from the features that actually matter in the field โ leaf shape, flower colour, stem, habitat, season and a safety-relevant lookalike. Three mo...
Productivity & Lifestyle
๐ถ๏ธ ND Filter Exposure
New shutter = old shutter ร 2^(stops). ND8 is 3 stops, ND64 is 6, ND1000 is 10. Use it for silky water and daytime video at 180ยฐ shutter. Recheck highlights โ filters are not perfectly even.
SaaS & Business Killers
โ๏ธ Contract & NDA Builder
Generate legally-binding Non-Disclosure Agreements (NDA) and Independent Contractor Service Agreements. Customize IP assignment, confidentiality duration, non-solicitation, and jurisdiction with ze...
Sports
๐ Netball Scorekeeper
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.
Finance & Money
๐ฐ Personal Finance Dashboard
Complete personal finance dashboard: Track net worth, analyze assets vs liabilities, set financial goals, project future growth, and monitor your journey to financial freedom.
Algorithms & Computer Science
๐ง Neural Network Playground
Watch a tiny neural network learn XOR โ the task that killed the first wave of neural networks, because a straight line can't separate the points. As it trains, the decision boundary curls into a c...
Science & Engineering
โช Kinetic Momentum Cradle
Conservation of momentum and kinetic energy exhibit. Demonstrates compressive acoustic stress wave transmission across elastic collision chains.
Music & Audio
๐น Note Frequency Calculator
12-tone equal temperament: f = fโ ร 2^(n/12). Default A4 = 440 Hz. MIDI note 69 is A4. Period = 1/f.
Finance & Money
๐
Notice Period End Date
Add weeks or months to the day you hand in notice. UK statutory minimums are 1 week after a monthโs service and 1 week per year after two years (capped at 12) โ contracts are often longer. This is ...
Mathematics
๐งฎ Advanced Number Theory Toolkit
Comprehensive number theory laboratory: Explore prime numbers, factorization, modular arithmetic, sequences, and advanced mathematical properties. Perfect for students, educators, cryptography enth...
Finance & Money
โ๏ธ Number to Words (Cheque Writer)
Spell out a number in British or American English, including the cheque / check form with fractional currency. Handles values from 0 to 999,999,999,999.99. Nothing is sent off this device.
Science & Engineering
๐ Ocean Waves โ The Secret Orbital Motion
Water in a swell doesn't travel โ each parcel runs in a circle while the wave shape races on. Watch the orbit shrink with depth, then shallow the water until orbits squash and the wave breaks.
Science & Engineering
โก Ohm's Law Calculator
Instant voltage, current, resistance, and power calculations.
Health & Fitness
๐๏ธ One-Rep Max Calculator
Instantly estimate your maximum lifting capacity across multiple formulas.
Science & Engineering
๐ Soliton Wave Flume Tank
John Scott Russell's 1834 hydrodynamic flume exhibit. Simulates the Kortewegโde Vries (KdV) equation where nonlinear steepening balances dispersion to form permanent solitons.
Science & Engineering
๐ฌ Optics Calculator & Explorer
Calculate optical properties, simulate light behavior, and explore fascinating physics of light.
Science & Engineering
๐ฌ Optical Tweezers & Trapping
Arthur Ashkin's 2018 Nobel Prize optical trap. Focused Gaussian laser beam gradient forces trap micro-particles and counter thermal Brownian diffusion.
Science & Engineering
๐ฐ๏ธ Orbital Mechanics Lab
Calculate orbital velocity, Keplerian period, and gravitational escape speed around celestial bodies. Analyze Low Earth Orbit, GPS altitudes, and Geostationary synchronization.
Astronomy & Space
๐ Orbital Mechanics Playground
Fly a probe through a real gravity field. Set your starting speed and direction, hit Launch, and watch the trajectory obey Newton's law (a = โGM/rยฒ, integrated semi-implicitly). Get a circle at cir...
Mathematics
๐ง BODMAS Step-by-Step Trainer
Type any expression and see it solved one operation at a time with the reason for each step โ no calculator tricks, no guessing. Then take the 5-question practice round with worked solutions. Every...
Science & Engineering
๐ก Oscilloscope Visualizer
Visualize and analyze waveforms in real-time. Generate signals, adjust parameters, and explore waveforms.
Culinary & Food Science
๐ฅ Oven Gas Mark Converter
Convert British gas marks to ยฐC, ยฐF and a typical fan/convection setting. Gas mark 4 is a moderate 180ยฐC / 350ยฐF oven. Fan ovens usually run about 20ยฐC cooler than the recipeโs conventional figure.
Productivity & Lifestyle
๐ Overnight Shift Duration
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 โ not a payroll system.
Productivity & Lifestyle
๐งฎ The Overthinker's Calculator
Calculate exactly how many ways a situation can go wrong. Spoiler: it's more than you think.
Finance & Money
๐ท Hourly Wage, Overtime & Take-Home Estimator
Enter your hourly rate and hours (including overtime at 1.5ร or 2ร, night or weekend premiums) to see weekly, monthly and annual gross pay, an approximate UK take-home after Income Tax, National In...
Health & Fitness
๐ธ Ovulation & Fertile Window
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...
Productivity & Lifestyle
๐งณ Smart Packing List
Create intelligent packing lists with categories, trip types, weather considerations, and shareable checklists. Never forget an essential item!
Home & DIY
๐จ Paint Calculator
Calculate exactly how much paint you need for any room. No more buying 5 tins for a cupboard.
Productivity & Lifestyle
๐จ Advanced Palette Swapper
Advanced color manipulation with multiple effects, palette extraction, and real-time preview. Transform images with professional color tools!
Productivity & Lifestyle
๐ฅ Pan Size Converter
Convert between different baking pan sizes and adjust recipes. Calculates volume differences and ingredient scaling.
Productivity & Lifestyle
๐ Paper Size Converter
ISO A/B/C series, US Letter/Legal/Tabloid and pixels at print DPI. A4 is 210 ร 297 mm; Letter is 8.5 ร 11 in. Sizes are the ISO 216 trimmed sheet, not the printable area.
Writing & Language
๐ง Parts of Speech Trainer
Name the eight parts of speech โ noun, verb, adjective, adverb, pronoun, preposition, conjunction, interjection โ in 10-question rounds with hints and a reference guide.
Productivity & Lifestyle
Party Planner
Plan your party with date, location, and guest list.
Productivity & Lifestyle
๐ง Passive Aggressive Email Translator
Type what you actually want to say. We'll make it sound professional. Ish.
Productivity & Lifestyle
๐ Passport Photo Size Guide
Official print sizes and pixel dimensions for UK, US, Schengen, Canada, Australia, India and China visa photos. Face-height rules are listed โ a home print can still be rejected if lighting or back...
Productivity & Lifestyle
๐ก๏ธ Password Strength & Crack-Time Estimator
Type a password to see its entropy in bits, estimated time to crack at online, offline and GPU-cluster speeds, and specific weaknesses โ dictionary words, keyboard walks, dates, repeats and common ...
Productivity & Lifestyle
Password Generator
Create strong, random passwords instantly. Customize length and character sets.
Algorithms & Computer Science
๐บ๏ธ Pathfinding Algorithm Visualizer
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...
Science & Engineering
โก PCB Trace Width Calculator
Estimate minimum PCB trace width for a given current, copper thickness, and temperature rise.
SaaS & Business Killers
๐ PDF Toolkit Pro โ Merge, Split, Compress & Extract
Premium-grade PDF studio that replaces Smallpdf / Adobe Acrobat for everyday jobs โ 100% offline, no uploads, no watermarks. Merge, split by pages, compress images โ PDF, and extract text. Uses you...
Science & Engineering
๐ฐ๏ธ Pendulum Wave Array
Kinetic museum wave array. Independent pendulums with calibrated lengths execute serpentine traveling waves, choreographing standing waves and unified reconstitution.
Mathematics
๐ Percentage Change Calculator
Work out the percentage increase or decrease between two numbers, plus reverse percentages and a worked price-change example.
Mathematics
๐ Advanced Percentages Explorer
Master percentages with advanced calculations, visualizations, and real-world applications. From basic math to financial analysis!
MrProphecy Arcade
โ๏ธ Periodic Table Quiz
Learn all 118 elements โ symbol to name, name to symbol, or number to name โ with multiple choice, instant feedback and a searchable reference table. The whole periodic table is embedded; nothing l...
Productivity & Lifestyle
๐ข Permutations & Combinations
Calculate permutations (nPr) and combinations (nCr) โ how many ways to arrange or select items.
Survival & Emergency Readiness
๐ก Personal Safety & Awareness Planner
Most personal-safety advice is about what to do when something is already going wrong. The useful part is earlier: noticing a situation while it is still a choice. Score a journey you are about to ...
Productivity & Lifestyle
Pet Care Tracker
Log pet care tasks like feeding, walking, or grooming.
Productivity & Lifestyle
๐ Petty Revenge Idea Generator
Hilariously harmless revenge ideas for life's minor annoyances. All legal. All petty. All satisfying.
Interactive Art & Living Worlds
๐ธ Phenology & Growing Degree-Day Lab
Phenology is the study of seasonal timing โ when leaves open, flowers bloom and swallows return. This lab models it with real growing degree-days (GDD): heat accumulated above a species-specific ba...
Science & Engineering
๐ท Exposure, Depth of Field & Filter Lab
Four things photographers work out in their heads and get wrong under pressure: what shutter speed balances a change of aperture, how long an ND filter needs, how much of the frame is actually shar...
Science & Engineering
๐ฌ Quantum Energy Calculator
Calculate electromagnetic photon energy ($E = h\nu = hc/\lambda$), momentum ($p = h/\lambda$), and matter wave de Broglie wavelengths across the entire electromagnetic radiation spectrum.
Science & Engineering
๐ฟ Photosynthesis โ Leaf Cross-Section Lab
Zoom into a leaf: light hits chloroplasts, COโ slips in through stomata, water arrives from the roots โ and sugars plus the oxygen you're breathing come out. Drive it with light and COโ and find th...
Science & Engineering
๐ Universal Unit Matrix
High-precision bidirectional converter across engineering, data storage, scientific physics, and everyday measurements.
Science & Engineering
๐ฌ Physics Toolkit
Calculate common physics formulas: motion, forces, energy, and more. Select a formula to begin.
Home & DIY
๐ผ๏ธ Picture Hanging Calculator
Calculate the perfect height and hook position so your pictures hang straight and look professional.
Museum & Collection
๐จ The Pigment Cabinet
Colour as a dated substance. Each pot is a first-use, a chemistry, and a verdict: still on the palette, replaced, or locked in the poison cupboard. Swatches are screen approximations โ never a spec...
Museum & Collection
๐ง The Pipe Lab
Watch water flow through pipes in real time. See Bernoulli's principle in action โ where the pipe narrows, water speeds up and pressure drops. Particles show laminar vs turbulent flow. Adjust diame...
Interactive Art & Living Worlds
๐จ PixelVerse Canvas
An evolving communal pixel art tapestry. Paint with friends over time, record generational brushstrokes, watch the creation time-lapse from inception, and export high-res artwork without paywalls.
Culinary & Food Science
๐ Pizza Dough Ferment Master
Artisan pizza dough formula engine supporting Neapolitan (AVPN), New York Style, Detroit Pan, and Roman Al Taglio. Computes baker's percentages, cold fermentation schedules, and yeast scaling.
Writing & Language
๐ Plagiarism Checker
Check text for originality and similarity with common phrases. Local processing only โ no data sent online.
Wellbeing & Community
๐ Plain Language Decoder
Paste a letter, contract clause, medical note or official notice and get it back in ordinary English, with the obligations and deadlines pulled out separately. Runs entirely on your device โ nothin...
Astronomy & Space
๐ช Planet & Ring Designer 3D
Build your own ringed world: gas giants with racing storms, lava planets with glowing cracks, tilted Keplerian rings where inner particles genuinely orbit faster, and up to three moons. Every world...
Astronomy & Space
๐ Planet Surface 3D Explorer
Land on every world like an astronaut with a telescope: a real 3D sphere you can spin, tilt and zoom, textured per planet from real features โ Mercury's craters, Venus's hidden iron-peaked clouds, ...
Science & Engineering
๐ฟ Plant Encyclopedia (Live)
Comprehensive plant database with real-time data from multiple sources. Search for any plant to get detailed information.
Home & DIY
๐ชฃ Plastering Calculator
Calculate how much plaster, render, or screed you need for walls, ceilings, or floors. Includes bags, coverage, and estimated cost.
Science & Engineering
๐ Plate Boundaries โ Tectonics Lab
Four boundary types, four very different landscapes: spreading ridges, subduction volcanoes, Himalaya-scale collisions and stick-slip transform faults โ with earthquakes and mantle convection drivi...
Home & DIY
๐ง Pipe Sizing Guide
Look up the right pipe diameter for any domestic plumbing job. Covers hot/cold water, central heating, and waste.
Interactive Art & Living Worlds
๐พ Pip: The Pocket Joy & Calming Companion
Meet Pip, your zero-maintenance procedural companion designed to bring instant comfort and warmth. Pet Pip to hear soothing purrs, drop delicious treats, play bouncy ball fetch, or slow down and co...
Survival & Emergency Readiness
โฃ๏ธ Poison & Chemical Exposure Response
The first ninety seconds after a poisoning are mostly about not making it worse, and most of the folk advice is actively dangerous. Find the substance, pick how it got in, and get the specific firs...
Science & Engineering
๐ Photoelasticity & Birefringence: See Hidden Stress in Glass
Transparent plastics and tempered glass appear perfectly clear to our eyes, yet conceal massive internal structural stresses. When placed between crossed polarizers, anisotropic stress splits light...
Virtual Worlds & Gaming
๐ฒ Polyhedral Dice 3D Roller
Real tumbling 3D dice โ D4 through D20 โ rendered as true platonic solids. The die physically rotates so your rolled face lands front-and-centre. Includes roll history, fairness stats and a 100-rol...
Productivity & Lifestyle
โฑ๏ธ Pomodoro Flow Timer
Level up your daily productivity with science-backed 25-minute focus intervals, audio finish chimes, streak tracking, and gamified XP rewards for completed sprints.
Home & DIY
๐ Pool & Spa Volume
Litres and gallons from length, width and average depth. Rectangular, circular and oval. Chemical dosing is per 1,000 litres โ this is volume only, not a treatment plan.
Natural Remedies & Herbs
๐ฉน Herbal Poultice & Compress
Topical acute botanical applications (fomentations & cataplasms). Formulates venom drawing pastes, bone-healing comfrey packs, and castor oil compresses.
Science & Engineering
โก Power Calculator
Calculate electrical power values with multiple calculation modes. โ ๏ธ Educational purposes only โ consult licensed electrician for actual installations.
Sports
๐๏ธ Powerlifting DOTS & Wilks Score
Compare lifters across weight classes. Enter a bodyweight and total (or the three lifts) and get both the modern DOTS score and the classic Wilks score, so a 60 kg lifter and a 120 kg lifter can be...
Productivity & Lifestyle
๐ฏ Practice Tracker
Track and analyze your practice sessions with detailed metrics and progress visualization. Set goals, track habits, and measure improvement.
Health & Fitness
๐คฐ Pregnancy Due Date & Week-by-Week Calculator
Estimate your due date from the first day of your last period, conception date, IVF transfer or a scan-dated due date. See how many weeks and days pregnant you are today, the current trimester, key...
Health & Fitness
๐คฐ Pregnancy Weight Gain Guide
IOM/NAM ranges by pre-pregnancy BMI for a singleton: underweight 12.5โ18 kg, healthy 11.5โ16 kg, overweight 7โ11.5 kg, obese 5โ9 kg. A sketch for conversations with a midwife โ not a target you mus...
Sports
โฝ Premier League Live
Live Premier League data scraped from current online sources. Teams update automatically.
Productivity & Lifestyle
โฑ๏ธ Price Tag in Hours of Your Life
Money is frozen time. Convert any price into how many hours (and minutes) of your actual working life it costs โ after tax, before snacks. That latte is cheaper once you've seen it in minutes.
Mathematics
๐งฎ Prime Factorisation Trainer
Break any number into its prime factors with a full working ladder, learn the divisibility rules, then practise finding the next prime factor yourself. Primes are the building blocks of every whole...
Productivity & Lifestyle
๐จ๏ธ Print Size & DPI Calculator
Convert pixel dimensions to print size at a chosen DPI, or the other way around. 300 DPI is typical photo-lab quality; 150 DPI is fine for posters viewed from a few feet.
Science & Engineering
๐ Prism Optics & Snell's Law
Interactive optical bench simulating chromatic dispersion, Snell's law refraction, and total internal reflection (TIR) through a triangular prism.
Finance & Money
๐ท Pro Rata Salary Calculator
Scale a full-time equivalent salary to part-time hours, or the other way. Uses working hours only โ not tax, NI, or pension. UK job ads often quote FTE then โpro rataโ.
Mathematics
๐ฒ Probability Paradox Lab
Your gut feeling about chance is usually wrong โ prove it to yourself. Simulate the Monty Hall problem, the birthday paradox and coin-flip streaks with thousands of instant trials.
Mathematics
๐ฒ Probability Calculator
Calculate probabilities for dice, cards, distributions, and real-world scenarios.
Productivity & Lifestyle
๐ Procrastination Justifier
Scientifically* valid reasons why you should absolutely do that thing tomorrow instead. *Not scientifically valid.
Productivity & Lifestyle
๐ Productivity Score
Calculate and analyze your daily productivity with detailed insights and actionable recommendations. Track progress and optimize your workflow.
Finance & Money
๐ Project Profitability Estimator
Quote client projects from real labour, expenses and contingency while protecting a target profit margin. All calculations stay in your browser.
Productivity & Lifestyle
๐
Project Deadline Calculator
Calculate project timelines with buffer days, weekend exclusions, and milestone planning. Plan realistically and track progress.
Science & Engineering
๐ฏ Projectile Motion Simulator
Simulate parabolic ballistic trajectories in real time across different planetary gravitational fields. Computes flight time, apex altitude, total ground range, and impact velocity.
Home & DIY
๐ฝ๏ธ Projector Throw Distance
Throw ratio = distance to screen รท image width. A 1.5:1 lens 3 m from the wall makes a 2 m wide picture. 16:9 assumed unless you change it. Check the projectorโs own min/max zoom range.
Productivity & Lifestyle
โก AI Prompt Studio
Turn vague thoughts into high-performance AI prompts used by senior prompt engineers. Constructs rigorous prompts with Chain-of-Thought reasoning, XML delimiters, output schemas, and anti-hallucina...
Writing & Language
โ๏ธ Proofreading & Style Checker
Advanced text analysis for grammar, style, readability, and clarity. Get detailed suggestions with explanations.
Health & Fitness
๐ฅฉ Daily Protein Intake
Estimate a daily protein target from body weight and how hard you train. Sedentary adults often sit near 0.8 g/kg; strength athletes commonly use 1.6โ2.2 g/kg. Not a prescription โ kidney disease n...
Writing & Language
๐ค Public Speaking Coach
Improve your speeches with AI-powered analysis, practice tools, and personalized feedback. Practice timing, structure, delivery, and confidence.
Writing & Language
๐ Punctuation Mastery Guide
Master the art of punctuation with this comprehensive guide. Learn rules, see examples, and test your knowledge. Perfect for writers, students, and professionals!
Dogs & Canine Care
๐พ Puppy Adult Weight Forecaster
Canine Gompertz growth velocity forecaster. Predicts final adult weight based on current puppy weight, age in weeks, and breed skeletal frame category.
Algorithms & Computer Science
โ๏ธ px โ rem โ em Converter
Convert CSS lengths between pixels, rem and em for a chosen root and parent font size. Defaults to the browser 16 px root. Copy-ready declarations, no build step.
Mathematics
๐ Pythagoras Calculator
Find the missing side of a right-angled triangle with the Pythagorean theorem โ plus the area, perimeter and both acute angles.
Productivity & Lifestyle
๐ฑ QR Code Generator
Generate QR codes instantly โ all processing happens in your browser. No data leaves your device. Supports URLs, text, WiFi, email, and more.
Productivity & Lifestyle
๐ท Instant QR & Image Reader
Decode QR codes instantly from uploaded screenshots, images, or your live camera feed. 100% private in-browser decoding โ photos never leave your device.
Productivity & Lifestyle
๐ Barcode Check Digit Validator
Validate or generate the check digit for EAN-13, UPC-A, EAN-8, ISBN-13, ISBN-10, GTIN-14 and ITF-14 barcodes. Shows the arithmetic so you can see exactly why a code passes or fails.
Productivity & Lifestyle
๐ณ Advanced QR Generator
Create scannable QR codes for URLs, text, Wi-Fi, contacts, email and SMS โ custom colours, optional logo, batch ZIP. Everything is generated on your device; nothing you encode is sent anywhere.
Health & Fitness
โค๏ธ QTc Interval (Bazett)
QTc (Bazett) = QT รท โ(RR), with RR = 60 / heart-rate. Also shows Fridericia (QT รท RRโ
). Educational arithmetic from numbers you type โ not an ECG, not a diagnosis. Chest pain or syncope needs emerg...
Mathematics
๐งฎ Quadratic Equation Solver
Solve axยฒ + bx + c = 0 with the quadratic formula โ real or complex roots, with every step shown.
Science & Engineering
โ๏ธ Quantum Superposition & Bloch Sphere Intuition Engine
Unlike a classical binary bit (which is strictly 0 or 1), a quantum qubit exists as a continuous vector pointing anywhere on the 3D Bloch Sphere. Apply quantum gates ($H$, $X$, $Z$, $S$), observe c...
Science & Engineering
โ๏ธ Quantum Tunneling: Why the Sun Actually Shines
According to classical physics, the Sun should not shine! Its core temperature (15 million Kelvin) provides only ~1 keV of kinetic energyโten times too weak to overcome the 1,000 keV electrostatic ...
Science & Engineering
โ๏ธ Quantum Wave Tunneling
Quantum mechanical wavepacket simulator solving the time-dependent Schrรถdinger equation across an impenetrable classical potential barrier.
Algorithms & Computer Science
๐ Query String Parser
Split a URL or a raw ?a=1&b=2 into keys. Duplicate keys become arrays. Build the other way from JSON. Uses the platform URLSearchParams โ stays on this device.
Interactive Art & Living Worlds
๐งต QuiltWeaver Tapestry
Weave an evolving mathematical patchwork tapestry with friends. Design geometric quilt blocks using wallpaper group symmetries, Truchet curves, and Islamic rosettes, then stitch them into a shared ...
Productivity & Lifestyle
๐ฏ Smart Quiz Generator
Create custom quizzes, track progress, and test your knowledge. Perfect for studying, training, or self-assessment. Add multiple choice, true/false, or open-ended questions!
Sports
๐ Race Pace Predictor & Training Paces
Enter one recent race you actually ran, honestly, and this predicts the rest, gives you the pace to hold per kilometre or mile, and turns it into the five training paces you actually need. Predicti...
Mathematics
โ Radians โ Degrees Converter
ฯ rad = 180ยฐ. Also shows revolutions and a reduced ฯ-fraction when it is close to a simple multiple of ฯ.
Science & Engineering
โข๏ธ Radioactive Decay Lab
Model exponential nuclear decay, remaining isotope fractions, and radiometric carbon dating via the fundamental decay law $N(t) = N_0 (1/2)^{t / t_{1/2}}$.
Interactive Art & Living Worlds
โฐ๏ธ Rain Shadow & Orographic Lift Lab
Push a parcel of air over a mountain and watch geography make weather. This lifts your air dry-adiabatically to the cloud base, integrates a proper saturated adiabat over the summit โ the lapse rat...
Science & Engineering
๐ How Rainbows Form โ Raindrop Ray Lab
A real ray trace: sunlight enters a raindrop, bends (refracts), bounces once (or twice) off the back, and comes back at ~42ยฐ โ split into colours because each wavelength bends a different amount.
Home & DIY
๐ง๏ธ Rainwater Harvest
1 mm of rain on 1 mยฒ is 1 litre. Multiply by a runoff coefficient (tiles ~0.85, felt ~0.8). UK roofs often yield more than a water-butt can hold โ size the tank, not just the dream.
Interactive Art & Living Worlds
๐ชฃ Rainwater Harvesting & Tank Simulator
Everyone sizes a water butt by guessing. This runs a day-by-day simulation of a whole year โ rain falling on your roof, water drawn off, the tank filling, overflowing and running dry โ then sweeps ...
Productivity & Lifestyle
๐ฒ Random Number, Dice & Name Picker
Cryptographically random numbers in any range (with or without repeats), dice rolls in D&D notation like 3d6+2, coin flips, and a fair picker that draws a winner or shuffles a list of names. No...
Mathematics
โ Ratio & Proportion
Solve a/b = c/d for the blank, simplify a ratio, and scale a recipe-style mix. Leave exactly one of A, B, C, D empty. Cross-multiply: A ร D = B ร C.
Virtual Worlds & Gaming
๐๏ธ Raycast Pocket Dungeon
A Wolfenstein-style 3D dungeon in pure maths โ no game engine. Procedurally generated maze, glowing orb collectibles, a portal exit, minimap and touch controls. Click the view, then use WASD or arr...
Science & Engineering
โฒ๏ธ RC Time Constant
ฯ = R ร C. A capacitor charges to ~63% in one ฯ and ~99% in 5ฯ. Cut-off of a first-order RC low-pass is fc = 1 / (2ฯRC). R in ohms, C in farads (enter ยตF).
Science & Engineering
๐ Turing Reaction Diffusion
Alan Turing's 1952 morphogenesis simulator. Nonlinear chemical reaction-diffusion equations generating biological spots, stripes, and coral textures.
Writing & Language
๐ Readability Analyzer
Analyze text readability with multiple scoring systems. Get actionable insights to improve your writing for any audience. Supports 8+ readability formulas with visual feedback!
Productivity & Lifestyle
โฑ๏ธ Pace Reading Timer
Time yourself reading a passage to measure your words-per-minute rate.
Writing & Language
๐ Reading Time Calculator
Calculate precise reading time estimates with multiple input methods, audience presets, and detailed breakdowns. Perfect for writers, editors, and content creators!
Science & Engineering
๐ Dimensions of Reality
We live in 3 spatial dimensions โ but why 3? Explore what life would be like in 1D, 2D, 4D, and beyond. Each dimension changes the laws of physics.
Science & Engineering
๐ Emergence โ Simple Rules, Infinite Complexity
Watch Conway's Game of Life: 4 simple rules create self-replicating patterns, computation, and open-ended complexity from nothing.
Science & Engineering
๐ Entropy & The Arrow of Time
Why does time only flow forward? Watch entropy increase in real-time as ordered systems dissolve into disorder โ the fundamental law that gives time its direction.
Science & Engineering
๐ข The Constants of Reality
The universe is governed by a handful of numbers. Change any one of them slightly โ and atoms, stars, chemistry, and life cannot exist. Why these numbers?
Science & Engineering
๐๏ธ The Observer Effect
Does observation change reality? Explore the measurement problem, Schrรถdinger's cat, and the role of the observer in quantum mechanics.
Science & Engineering
โ๏ธ The Quantum World
Explore wave-particle duality, superposition, and the measurement problem. Fire particles through slits and watch reality behave impossibly.
Science & Engineering
๐ Scale of Reality
Zoom from the Planck length (10โปยณโตm) to the observable universe (10ยฒโทm). Drag the slider to see where you exist in the full scale of reality.
Science & Engineering
๐ณ๏ธ Spacetime Curvature
See how mass warps the fabric of spacetime. Drag the mass slider to watch gravity bend space, slow time, and curve the paths of light.
Science & Engineering
โณ Timeline of Everything
From the Big Bang to the heat death of the universe. Slide through 13.8 billion years of cosmic history and see how reality unfolded.
Science & Engineering
๐ง What Is Consciousness?
The hardest problem in science. Explore the mystery of subjective experience โ how does matter become aware? Interactive exploration of the leading theories.
Science & Engineering
๐ณ๏ธ Why Is There Something Rather Than Nothing?
The deepest question philosophy has ever asked. Explore the mystery of existence itself โ why does anything exist at all?
Culinary & Food Science
๐ณ Recipe Converter
Scale recipes, convert measurements, and adjust serving sizes. Supports metric, imperial, cups, spoons.
Music & Audio
๐ค Recording Basics
Learn fundamental recording techniques. โ ๏ธ Educational only โ always verify with professional resources.
Algorithms & Computer Science
๐ณ Recursion & Memoization Explorer
The same Fibonacci function, two ways: naive recursion recomputes the same subproblems a staggering number of times, while memoization remembers each answer once. Watch the call tree fill with dupl...
Astronomy & Space
๐ด Redshift & Cosmic Distance
Put in a redshift and get the recession velocity, Hubble distance, light-travel time and the wavelength a known spectral line is shifted to. Distinguishes Doppler motion from cosmological expansion...
Finance & Money
๐ Redundancy & Notice Entitlement Calculator
Work out your UK statutory redundancy pay, notice period, accrued holiday and how much of a settlement is tax-free โ with the full age-banded breakdown, year by year. Nothing you enter leaves your ...
Algorithms & Computer Science
๐ Regex Cheat Sheet & Tester
Complete regex reference with live testing. Pattern syntax, flags, character classes, quantifiers, and groups โ all in one place.
Writing & Language
โก Regex Transform Studio
Search, replace, extract capture groups, and batch-transform text with real-time regular expression pattern matching.
Productivity & Lifestyle
โฐ Reminder Tool
Create reminders that stay saved in your browser. Works offline โ data saved locally.
Finance & Money
๐ Rent Calculator
Split rent among roommates, calculate per-person costs, and account for room size differences. Supports multiple currencies and custom splits.
Finance & Money
๐ Rental Yield Deal Analyser
Compare gross yield, net yield and monthly cash flow for a prospective rental property. All calculations stay in your browser.
Science & Engineering
๐จ Resistor Color Code
Decode resistor color bands into resistance values. โ ๏ธ Educational only โ verify with multimeter.
SaaS & Business Killers
๐ฏ Resume ATS Scanner Pro โ Beat the Bots
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) โ 100% offline, no upload, no AI API. ...
SaaS & Business Killers
โฑ๏ธ Retainer Capacity Planner
Check whether monthly client retainers fit your available hours and reveal effective revenue per hour. All calculations stay in your browser.
Finance & Money
๐ฐ Retirement Calculator
Estimate your retirement savings growth with compound interest. โ ๏ธ Educational only โ consult a financial advisor.
Music & Audio
๐ Reverb Pre-Delay & RT60 Decay BPM Calculator
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...
Finance & Money
๐ธ Reward Site Earnings Reality Check
Work out what survey and get-paid-to sites are actually worth per hour before you give them your evenings. Uses realistic rate bands rather than the โearn £500 a month from your sofaโ num...
Science & Engineering
๐ก RF Link Budget & Fresnel Zone Planner
Will the link work? Radio needs more than line of sight โ it needs a clear ellipse of space around the beam, and the Earth quietly bulges up into it. This adds up every gain and loss in the chain, ...
Writing & Language
๐ช Rhyme Finder
Find true rhymes and near rhymes for any word โ powered by an embedded CMU pronunciation dictionary, no network needed.
Music & Audio
๐ฅ Rhythm Generator
Generate rhythm patterns for practice and composition. โ ๏ธ Educational only โ verify with professional resources.
Culinary & Food Science
๐ Rice-to-Water Ratio Calculator
Absorption method volumes. Rinse until the water runs clearer; aged basmati wants a little more water; brown rice needs time, not only liquid. A rice cooker may want its own cup marks.
Mind-Blowing Demos
๐ง Riley: Goblin Smasher
A free, offline 3D arena battler in raw WebGL โ no assets, no downloads. Riley the wizard smashes endless goblin waves with wand shots, charged blasts, dashes and double jumps โ and the goblins evo...
Productivity & Lifestyle
๐ Ring Size Converter
Convert UK letters, US numbers, EU/ISO circumference and inner diameter. Based on a circular inside; wide bands often need a half-size up. Measure a well-fitting ring, not a string if you can help ...
Interactive Art & Living Worlds
๐๏ธ River Meander Lab
A free channel migrates by the IkedaโParkerโSawai law: banks erode on the outside of a bend and deposit on the inside. Raise discharge and the bends fatten; raise cohesion and they freeze. When a n...
SaaS & Business Killers
๐บ๏ธ Robots.txt & Sitemap Generator
Draft a valid robots.txt and XML sitemap from your own URL list. Add paths or full URLs, set crawl rules and download the result. This is a local generator, not a crawler: it never visits or upload...
Interactive Art & Living Worlds
๐ชจ Rock Cycle & Mineral ID Lab
Two ways to learn geology hands-on: drive a rock through the full cycle (weather it, bury it, metamorphose it, melt it) with real pressureโtemperature conditions and metamorphic facies, then play M...
Finance & Money
๐ ROI Calculator
Calculate Return on Investment with advanced metrics and comparisons. Supports annualized returns and multiple currencies.
Museum & Collection
๐ช The Coin Room
Early Imperial bronze and silver, counted in asses. 4 asses = 1 sestertius; 4 sestertii = 1 denarius; 25 denarii = 1 aureus. A legionary under Augustus took 225 denarii a year (before stoppages). E...
Mathematics
๐๏ธ Roman Numeral Converter
Convert numbers to Roman numerals and back, with a step-by-step breakdown of how each numeral is built. Handles 1โ3,999 in standard notation and up to 3,999,999 with overline (vinculum) notation. I...
Home & DIY
๐ Roof Pitch & Rafter Calculator
Roof pitch is the rise in inches for every 12" of run. Enter the pitch and half-span (run), and get the rafter length, angle and roof-area multiplier.
Museum & Collection
๐ The Echo Chamber
Watch sound bounce around a room in real time. See wavefronts propagate from a source, reflect off walls, and decay as materials absorb their energy. Adjust room size, wall material, and source pos...
Home & DIY
๐ก๏ธ Room BTU & HVAC Sizing Calculator
Estimate the heating and cooling load for a room: area, ceiling height, insulation, sun exposure, occupancy and climate all move the number of BTUs you need.
Home & DIY
๐๏ธ Room Layout Planner
Drag and drop furniture to plan your room layout. Scale-accurate 2D top-down view.
Sports
๐
Round-Robin Fixture Generator
Generate a full league schedule where every team plays every other team โ once, or twice home and away. The circle method guarantees no team plays twice in a round, and odd numbers get a bye.
Mathematics
๐ Rounding & Estimation Trainer
Master rounding rules and quick estimation. Round any number to a chosen place, then estimate answers to real-life word problems with 5-round quizzes and full working.
Sports
๐ฃ Rowing Erg Pace Calculator
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...
Sports
๐ Rugby Points Score Builder
Try 5, conversion 2, penalty 3, drop goal 3. Add up a score, or work backwards: give a points gap and this lists every combination of tries, conversions, penalties and drop goals that closes it โ f...
Finance & Money
โณ Rule of 72 Doubling Time
Years to double โ 72 รท annual %. At 6% thatโs 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 โ not a guarantee.
Sports
๐ Running Cadence & Stride Length
Cadence, pace and stride length are locked together โ 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...
Sports
๐ Running Split Pace Calculator
Target time for a race distance โ pace per km and per mile, plus even kilometre splits. Negative splits are a planning aid, not a training plan.
SaaS & Business Killers
๐ SaaS Churn Revenue Impact
Model recurring revenue lost to churn and the customers needed to maintain or grow monthly revenue. All calculations stay in your browser.
SaaS & Business Killers
๐ SaaS LTV & CAC Calculator
Calculate core SaaS unit economics, Customer Lifetime Value (LTV), Customer Acquisition Cost (CAC), payback period, and cash burn runway. Replaces expensive subscription analytics dashboards.
Finance & Money
๐ฐ Salary Calculator
Calculate net salary after taxes, deductions, and contributions. โ ๏ธ Estimates only โ consult a tax professional.
Finance & Money
๐ผ Sales Commission Calculator
Commission from a sale amount and rate, with an optional second-tier rate above a threshold (common in sales plans). Gross figures โ tax is not deducted.
Music & Audio
โ๏ธ Sample Chop Slice & Bar Marker Calculator
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...
Interactive Art & Living Worlds
๐๏ธ Sand Dune Lab
A saltation cellular automaton of a sand sea. Wind above Bagnold's threshold picks up grains, slip faces (34ยฐ) trap them, vegetation anchors the sand, and supply + wind variability decide whether b...
Interactive Art & Living Worlds
โณ Sandpile Mandala
An emergent self-organized criticality simulator. Drop grains of sand into an abelian lattice. When cells exceed four grains, they topple into cascading avalanches, spontaneously forming hyper-comp...
Finance & Money
๐ฐ Savings Calculator
Calculate how much your savings will grow with regular deposits and compound interest.
Music & Audio
๐น Scale Trainer
Practice scales in different keys. Educational only โ always verify with a music teacher or professional resource.
Wellbeing & Community
๐ก๏ธ Scam Sense Checker
Paste a text, email or message and see which warning signs it contains. Everything is analysed on your own device โ the message is never uploaded, which matters because pasting a scam into a websit...
Productivity & Lifestyle
๐ช๐บ Schengen 90/180 Calculator
Short-stay visitors can spend 90 days in any rolling 180-day window in the Schengen area (unless a visa or residence permit says otherwise). Add trips; days of entry and exit both count. Not immigr...
Science & Engineering
๐ฅ Schlieren Optics Airflow
August Toepler's 1864 Schlieren photography system. Visualizes invisible thermal convection plumes and supersonic shockwaves via refractive index gradients.
Science & Engineering
Science Quiz Generator
Generate science quiz questions and test your knowledge with fun facts.
Science & Engineering
๐ฌ Science Study List
Build your science study list. Add topics and notes, then test yourself by hiding the notes. Saved locally in your browser.
Mathematics
๐งฎ Scientific Calculator
Full-featured scientific calculator with trigonometry, logarithms, powers, and memory functions. Works offline.
Science & Engineering
๐ฌ Scientific Method Helper
Work through the scientific method. Enter your experiment idea and generate a structured outline.
Mathematics
๐ฌ Scientific Notation & Sig Figs
Convert a number to scientific / engineering notation and round to significant figures. 1.23 ร 10โด is 12300. Trailing zeros in 1000 are ambiguous โ say how many sig figs you want.
MrProphecy Arcade
๐ค Scrabble Score Calculator
English (Hasbro / Mattel) tile values. Type a word, mark double/triple letter on a character with 2 or 3 after it (C3AT = C on a TL). Word multipliers apply after letters. Bingo +50 for 7 tiles.
Productivity & Lifestyle
๐ฅ๏ธ Screen PPI Calculator
Pixels per inch from diagonal size and resolution. Also shows pixel pitch, aspect ratio and whether the display is โRetinaโ at a typical viewing distance (1 arc-minute).
Productivity & Lifestyle
๐ On-Screen Ruler & Pixel-to-Physical Converter
Turn your screen into a ruler. Calibrate once with a bank card (85.6 mm wide) or by entering your screen's diagonal size, then measure real objects in mm, cm and inches โ and convert between CSS pi...
Home & DIY
๐ฉ Screw & Drill Bit Size Chart
Look up the right drill bit for any screw size, wall plug colour, and pilot hole diameter. No more guessing.
Astronomy & Space
๐ Seasons & Earth's Tilt โ 3D Explainer
Drag to orbit a 3D SunโEarth model and discover why seasons happen. It is not distance โ it is the 23.4ยฐ tilt of Earth's axis, which changes the Sun's noon altitude and the length of the day.
Science & Engineering
๐ Seawater Salinity & Density
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...
Virtual Worlds & Gaming
๐ Second Life Surnames Encyclopedia
Explore the rich tapestry of Second Life surnames. Discover origins, cultural associations, and roleplay inspiration. A living encyclopedia with search, filters, and favorite tracking.
Virtual Worlds & Gaming
๐ Visit Supadupaman Sapphire in Second Life
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.
Productivity & Lifestyle
๐ Secret Santa Generator
Organize a perfect Secret Santa gift exchange with automatic matching, restrictions, and wish lists! โ
Supports: Family restrictions, wish lists, budget tracking, email notifications
Science & Engineering
๐ฑ Seed Germination Calculator
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 .
Algorithms & Computer Science
๐ฆ SemVer Compare & Bump
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.
Writing & Language
๐ SEO & Content Optimizer
Professional SEO analysis, optimization, and content planning. Get actionable insights and comprehensive reports.
SaaS & Business Killers
๐ SEO Meta Tag Previewer
Generate and preview Open Graph, Twitter Cards, and SEO meta tags in real time. Simulate Google SERP snippets and social media feed cards before deploying. Replaces expensive monthly SEO subscripti...
Mathematics
๐ข Sequences & Series Calculator
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.
Wellbeing & Community
๐ Secret Kindness Mission & Joy Ripple Engine
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...
Museum & Collection
๐บ The Seven Wonders
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 ...
Music & Audio
๐ผ Sheet Music Reference Generator
Generate detailed sheet music references with proper notation guidance. โ ๏ธ Educational only โ always verify with a teacher or professional resource.
Home & DIY
๐ Shelf Bracket Calculator
Calculate the right bracket size, spacing, and load capacity for your shelf project.
Interactive Art & Living Worlds
๐๏ธ Shift Labour Cost Planner
Price a staffed shift including breaks, employer on-costs and overtime before publishing the rota. All calculations stay in your browser.
Productivity & Lifestyle
๐ Shoe Size Converter
Convert adult shoe sizes between US, UK, EU and Mondopoint (mm). Based on standard last-length charts โ brands still vary by a half size, so treat this as a starting point, not a fitting.
Productivity & Lifestyle
๐ Smart Shopping List
Add items, organize by category, track quantities, and manage your shopping efficiently. โ
Features: Categories, quantity tracking, budget calculator, shareable lists
Sports
๐ Showjumping Faults Calculator
Faults add up fast: 4 for a knockdown, 4 for a refusal, and 1 for every second over the time allowed. Enter a round and get the total, then use a rival's faults and time to settle a jump-off.
Home & DIY
๐๏ธ Skip Hire Volume Calculator
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 โ many yards cap weight before the skip looks full. Not a quote.
Virtual Worlds & Gaming
๐ SL Avatar Height & Proportion Calculator
Calculate your avatar's true height, body proportions, and get recommendations for realistic or stylized looks
Virtual Worlds & Gaming
๐๏ธ Second Life Builder's Mate
Professional toolkit for Second Life builders: prim allowance, object sizing, weight calculation, grid alignment, and LOD optimization. โ
Features: Prim/LI calculation, mesh optimization, physics a...
Virtual Worlds & Gaming
๐
Live Second Life Events
๐ข LIVE Real-time events from Second Life. Updates automatically.
Virtual Worlds & Gaming
๐ฐ Linden Dollar Exchange
Convert Linden Dollars (Second Life virtual currency) to real-world currencies using market rates. Rates are estimates โ actual exchange rates may vary.
Virtual Worlds & Gaming
๐ฅ SL Group Slot Calculator
Track your group memberships โ manage the 42-group limit and plan which groups to keep or drop
Virtual Worlds & Gaming
๐ SL Land Tier Calculator
Calculate monthly tier costs, prim budgets, and land area โ for mainland, private regions, and homesteads
Virtual Worlds & Gaming
๐ต L$ Linden Dollar Converter
Convert between Linden Dollars (L$) and real-world currencies โ USD, GBP, EUR, JPY, AUD, CAD
Virtual Worlds & Gaming
๐ LSL Script Generator
Generate ready-to-use Linden Scripting Language scripts โ security, teleport, dance, auto-response, and more
Virtual Worlds & Gaming
๐ Second Life Marketplace Search
Search and browse Second Life Marketplace items. Demo data shown โ in production, connect to actual Marketplace API.
Virtual Worlds & Gaming
๐บ SL Mesh Upload Cost Calculator
Estimate Land Impact and upload cost for mesh objects โ input triangle counts and physics shapes
Virtual Worlds & Gaming
๐ SL Outfit Planner
Plan and organize your Second Life outfits โ track body parts, clothing layers, accessories, and color coordination
Virtual Worlds & Gaming
๐งฑ SL Prim Budget Planner
Plan your land's prim usage โ add objects, track LI (Land Impact), and stay within your budget
Virtual Worlds & Gaming
๐บ๏ธ Second Life Region Map
View Second Life region maps with interactive pan/zoom, coordinates, and debugging tools. Uses multiple data sources with automatic fallback.
Virtual Worlds & Gaming
๐ SL Teleport & SLURL Planner
Build teleport notecards, generate SLURLs, and plan region visits with coordinate calculations
Virtual Worlds & Gaming
๐ผ๏ธ SL Texture Upload Cost Calculator
Calculate upload costs, memory usage, and get recommendations for optimal texture sizes in Second Life
Virtual Worlds & Gaming
๐ผ๏ธ Second Life Texture Tool
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...
Virtual Worlds & Gaming
๐ SL Time Converter
Convert between Second Life Time (SLT/PST) and your local time โ never miss an event again
Lucid Dreaming & Sleep
๐ด Sleep Debt Calculator
Need minus hours actually slept, summed over the week. Most adults are in the 7โ9 h band; you are not. This is arithmetic, not a sleep clinic. If you stop breathing at night, talk to a GP.
Lucid Dreaming & Sleep
๐ก๏ธ Sleep Paralysis Navigator
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.
Health & Fitness
๐๏ธ Sleep Cycle Calculator
Calculate optimal wake-up times based on 90-minute sleep cycles for better rest. No affiliate links - this site is supported by user contributions .
Algorithms & Computer Science
๐ Slug Generator
Convert any text into URL-friendly slugs. Perfect for blog posts, filenames, and SEO-friendly URLs.
Finance & Money
๐ Small Claims Letter Before Action Builder
Build a proper Letter Before Action for an unpaid debt โ 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...
Finance & Money
โฝ Web3 Gas Fee Estimator
Compare real-time decentralized transaction fees, DEX swap overhead, and smart contract execution costs across Solana, Base, Ethereum L1, and Polygon.
Sports
๐ฑ Snooker Snookers-Required Calculator
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 ...
Interactive Art & Living Worlds
โ๏ธ Snowflake Crystal Lab
Grow an ice crystal from the real Nakaya diagram: temperature and supersaturation decide its habit โ plates, needles, columns, sectored plates or fern-like dendrites. Vapour is consumed by the crys...
SaaS & Business Killers
๐จ Social Image Resizer
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...
Productivity & Lifestyle
๐ผ๏ธ Social Preview Generator
Create perfectly sized Open Graph and Twitter preview images with custom branding, layouts, and auto-generated HTML meta tags.
SaaS & Business Killers
๐ Testimonial Card Generator
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 P...
Writing & Language
๐๏ธ Socratic Thinking Coach
Sharpen your reasoning: stress-test any claim with Socratic questions, steelman the other side of an argument, and learn to spot 10 classic logical fallacies with a quiz.
Science & Engineering
๐ฑ Soil & pH Guide
Soil pH and type determine nutrient availability and plant success. Match plants with their preferred conditions. This tool is supported by user contributions .
Science & Engineering
โ๏ธ Solar Panel Calculator
Estimate solar panel requirements for your energy needs. Educational tool only โ always consult a professional installer.
Astronomy & Space
๐ช 3D Solar System Orrery
A real 3D orrery of the whole solar system with true orbital mechanics โ Kepler's equation is solved every frame, so Mercury visibly speeds up at perihelion and retrograde Halley's comet dives insi...
Science & Engineering
๐ Solar System Simulator
Interactive 2D simulation of the Solar System. Adjust time speed and scale, toggle orbits and labels, click planets for details.
Astronomy & Space
๐ช Solar System Size Comparator
See the planets side by side to true relative scale, compare them by distance, day length, gravity or moons โ and find out what you'd weigh on each. All the figures are built in; nothing is fetched...
Music & Audio
๐ต Song Writer (General Advice)
Brainstorm song ideas, lyrics, and structure. โ ๏ธ Educational only โ always verify with a teacher or professional resource.
Algorithms & Computer Science
๐ Sorting Algorithm Visualizer
Watch six classic sorting algorithms race on the same shuffled data โ see exactly why O(nยฒ) sorts crawl while merge and quick sort fly. Every comparison and swap is counted live.
Science & Engineering
๐ Sound Decibel Calculator
Calculate sound pressure level (SPL dB) drop over distance using the acoustic inverse-square law $L_2 = L_1 - 20\log_{10}(r_2/r_1)$, acoustic pressure in Pascals, and NIOSH/OSHA safe daily exposure...
Culinary & Food Science
๐ Sourdough Baker's Math Lab
Baker's percentage formula engine for artisanal sourdough. Factors in starter hydration, flour water absorption, and ambient room temperature bulk fermentation kinetics.
Culinary & Food Science
๐ฅฉ Sous Vide Time & Temperature
Precision immersion cooking guide based on thermal conductivity & USDA/FSIS pasteurization curves. Calculates exact bath temperatures, heating time to core, and searing parameters.
Writing & Language
๐ช๐ธ Spanish Verb Conjugator
Master Spanish verb conjugations, conquer the notorious Ser vs Estar dilemma (permanent essence vs temporary state), and master Por vs Para with native Spanish audio playback.
Science & Engineering
๐ Speaker Ohm Wiring
Series adds ohms; parallel is the reciprocal sum. Never present an amp with a lower load than it is rated for โ that is how output stages die. Passive crossovers are not modelled.
Science & Engineering
๐ Special Relativity Simulator
Calculate relativistic time dilation, length contraction, and kinetic energy via Einstein's Special Relativity equations. Compare spaceship crew time against stationary observer time.
Mathematics
๐ Speed Distance Time Calculator
Fill in any two of speed, distance and time; the third is calculated. Swap units without changing the physics: metres, kilometres, miles, knots, hours, minutes, seconds.
Writing & Language
โก Speed-Reading RSVP Trainer
Train your brain to read faster with rapid serial visual presentation โ while absorbing fascinating true passages about science and history. Includes a comprehension quiz so speed never beats under...
Writing & Language
โก Speed Reading Trainer
Measure your words-per-minute, then train with guided pacing where your eye is told where to look. Includes recall questions and live WPM tracking. Nothing is stored online.
Writing & Language
๐ Smart Spelling Checker
Advanced spelling checker using multiple open-source dictionary APIs combined for maximum accuracy. โ ๏ธ Requires internet connection for online dictionary checks.
Mathematics
โช Sphere, Cylinder & Cone Volume
V_sphere = 4/3 ฯ rยณ, A = 4 ฯ rยฒ. Cylinder ฯ rยฒ h. Cone (1/3) ฯ rยฒ h. Enter radius and height in the same units; volume comes out in those units cubed.
Science & Engineering
๐ฅ Firefly Kuramoto Synchronization
Yoshiki Kuramoto's nonlinear synchronization model. Independent bioluminescent fireflies spontaneously phase-lock into simultaneous collective pulsing.
Productivity & Lifestyle
๐ฎ Sprite Sheet Studio
Advanced sprite sheet cutter for game developers. Slice, preview, animate, and export sprite sheets with professional tools. โจ Supports PNG, JPG, GIF, and WebP formats
SaaS & Business Killers
๐๏ธ SQL Formatter & Query Helper
Make a dense SQL query readable without sending it to a database. This formatter understands common SELECT, INSERT, UPDATE and DELETE clauses, preserves quoted strings/comments, and can output comp...
Algorithms & Computer Science
๐ฌ SRT Subtitle Time Shifter
Shift every HH:MM:SS,mmm timestamp in an .srt by milliseconds (negative to go earlier). Runs in this page โ files stay on your device.
Home & DIY
๐ช Stair Stringer Calculator
Size a straight staircase: enter the total rise and your preferred riser height, and get the number of steps, the tread depth, total run and the stair angle โ checked against the comfortable 2รrise...
Mind-Blowing Demos
๐ Starfield Warp Drive
A retro warp-speed starfield with real flight feel: steer with your pointer, throttle from sublight to Warp 9, punch through hyperspace jumps, and watch the light-years stack up as famous exoplanet...
Interactive Art & Living Worlds
๐ฆ Starling Murmuration
Reynolds boids with the three forces starlings actually use: short-range separation, local alignment, and a weaker cohesion. Click to drop a hawk โ the flock folds, splits and re-forms. The ribbon ...
SaaS & Business Killers
๐ Cap Table & Dilution
Model startup equity dilution across funding rounds. Calculates Y Combinator post-money SAFEs, valuation caps, employee option pool (ESOP) expansion, and founder equity value without paying thousan...
SaaS & Business Killers
๐ซ Runway & Burn Simulator
The question that ends startups: which month does the bank account hit zero? Enter your cash, your costs and your revenue growth, and it projects 36 months forward, finds your break-even month, cal...
Science & Engineering
๐ง States of Matter โ Particle Simulator (HโO)
One substance, three behaviours: a vibrating lattice (ice), molecules that slide but stick (water), and a fast free-for-all (steam). Drag the temperature and watch the same particles reorganise โ w...
Museum & Collection
๐ญ The Illusion Gallery
Three statistical traps you can run with your own eyes: survivorship bias (the WW2 planes), Simpson's paradox (the kidney-stone study where one treatment wins overall yet loses everywhere), and reg...
Mathematics
๐ Statistics Calculator
Comprehensive statistical analysis tool with descriptive statistics, probability distributions, hypothesis testing, and data visualization. This tool is supported by user contributions .
Science & Engineering
โ๏ธ Steam Tables Lab
Industrial steam table thermodynamics (IAPWS formulation). Calculate saturation pressure ($P_{sat}$), specific enthalpy ($h$), entropy ($s$), specific volume ($v$), and latent heat ($h_{fg}$) for s...
Health & Fitness
๐ถ Steps to Calories Converter
Convert steps walked to calories burned with precision. Calculate energy expenditure based on steps, weight, and walking pace. See equivalent activities and track progress toward daily goals. This ...
Science & Engineering
๐ป Stochastic Resonance: Reveal Hidden Signals With Noise
In classical engineering, noise is the enemy. But in non-linear physics and sensory biology, Stochastic Resonance proves that adding the exact right amount of random noise allows a sub-threshold, i...
Science & Engineering
โ๏ธ Stone, Pounds โ kg
Convert body weight between stone & pounds, pounds, kilograms and grams. One stone is 14 lb; one avoirdupois pound is exactly 0.45359237 kg.
Writing & Language
๐ฒ Story Dice Plot Twister
Roll story dice for a hero, a setting, a mysterious object and a plot twist โ then write the tale. With challenge-mode constraints, story starters and saved prompts for classrooms and young writers...
Wellbeing & Community
๐๏ธ Street Sharing Planner
Neighbourly sharing usually fails for two unglamorous reasons: nobody wants to be the one who knocks on a door first, and nobody knows who has what. This builds the sheet and writes the awkward mes...
Finance & Money
๐ณ Stripe & PayPal Fee Calculator
Reverse a published percentage + pence fee so you know what you keep, or what to charge to net a target. Default rates are the common UK consumer-card / PayPal numbers โ your contract may differ.
Museum & Collection
๐๏ธ The Stress Gallery
Apply loads to a beam and watch stress propagate in real time. See shear force and bending moment diagrams update live. The colour map shows where failure begins โ red zones are where your shelf, j...
Home & DIY
๐งฑ Stud & Wall Framing Calculator
Frame a wall the way a carpenter would: enter the wall length, stud spacing, openings and corners, and get the stud count, plate lumber and headers to order.
Productivity & Lifestyle
๐ Study Planner
Plan your study sessions, track progress, and stay focused with a built-in Pomodoro timer. All data saved locally in your browser.
Science & Engineering
๐ Subnet & CIDR Calculator
Calculate IPv4 subnets, network boundaries, usable host ranges, and binary bit allocation. Essential for cloud VPCs, DevOps, and network routing.
Finance & Money
Subscription Tracker
Track your subscriptions, manage renewals, and optimize spending
MrProphecy Arcade
๐งฉ Sudoku Trainer (unique puzzles, hints & solver)
Play a freshly generated Sudoku with a guaranteed unique solution, get hints, or reveal the solution. Every puzzle is built on your device โ nothing is fetched or sent.
Writing & Language
AI-Style Summary Generator
AI-Style Summary Generator Generate intelligent summaries using advanced text analysis algorithms
Astronomy & Space
๐ Sundial Designer
A sundial only works at the latitude it was cut for, which is why the garden-centre ones are decorative rather than accurate. Give it your latitude and this lays out the hour lines properly โ the a...
Astronomy & Space
๐ Daylight & Twilight Atlas
A whole year of light for any point on Earth, computed offline with the NOAA solar equations: sunrise, sunset, solar noon, the three twilights, golden hour, the compass bearing the sun rises on, ho...
Algorithms & Computer Science
โก SVG Path Optimizer & Minifier
Minify and clean SVG markup, remove metadata, editor bloat and unused namespaces, round decimal precision, preview live, and copy optimized SVG.
Productivity & Lifestyle
๐ SVG Path Visualizer
Inspect, edit, and optimize SVG path data (d="...") in real time. Visualizes anchor nodes, control handles, bounding box, and minified code.
Sports
๐ Swimming Pace & CSS Calculator
Turn a swim time into pace per 100 m, per length and full splits, then โ if you have a 200 m and a 400 m test time โ get your Critical Swim Speed and the training zones built around it.
Interactive Art & Living Worlds
๐ค Syllable Counter
Heuristic English syllable count (vowel groups, silent e, -le, some -ed/-es). Good enough for haiku drafts and readability checks โ not a dictionary.
Interactive Art & Living Worlds
๐ง NeuroSynapse Graph
An organic neural graph where thoughts, insights, and memories connect via pulsating synaptic axons. Fire bio-electric action potentials, watch ideas resonate across clusters, and author collective...
Writing & Language
๐ Synonym Finder
Find better words โ synonyms and near-synonyms for 100+ common English words, with usage tips for the tricky ones.
Health & Fitness
๐ฅ Tabata Timer
Classic Tabata is 8 rounds of 20 s work / 10 s rest (4 minutes). Phone speakers optional. If you prefer reduced motion, the digits still count without the pulse.
Sports
๐ Table Tennis Scorer
Rally scoring to 11, win by two โ 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.
Science & Engineering
๐ฉ Tap Drill Size
Close-enough tap drill โ major diameter โ pitch (75% thread). Metric coarse plus a few UNC sizes. For production work use the machinistโs table for your material.
Productivity & Lifestyle
๐ Task Prioritizer Matrix
Use the Eisenhower Matrix to prioritize tasks by urgency and importance. Based on the time management framework.
Finance & Money
๐ฐ Tax Estimator & Calculator
Estimate income tax, national insurance, student loan repayments, and take-home pay for UK taxpayers โ by week, fortnight, month, quarter or year. Based on 2026/27 UK tax bands.
Science & Engineering
๐ Tectonic Plate Drift Calculator
The ground under you is moving right now. Pick a place and its tectonic plate and this rotates it about the plate's Euler pole โ the real way plate motion is described โ to give the present-day spe...
Astronomy & Space
๐ญ Telescope Collimation Check
How precisely your secondary and primary need to be aligned for the images you want, and what a star test tells you about the error you actually have. Based on the wavefront tolerance criteria from...
Astronomy & Space
๐ญ Eyepiece & Magnification Calculator
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.
Astronomy & Space
๐ Resolution & Limiting Magnitude
What can your aperture actually split, and how faint can it go? Computes the Dawes and Rayleigh limits, the theoretical limiting magnitude, and the doubles and deep-sky targets that fall within rea...
Music & Audio
๐ต Tempo & BPM Map
Create tempo maps for musical compositions with BPM calculations and time conversions. Educational tool for musicians and composers.
Finance & Money
๐ Tenancy Deposit Calculator (England)
Check your deposit against the statutory cap, see when it must be protected and returned, and understand the remedies if the landlord gets it wrong. England rules; ask for full compliance history b...
Sports
๐พ Tennis Match Scorer
Score a match point by point with the correct rules handled for you: deuce and advantage, sets to six with a two-game lead, a seven-point tiebreak at six-all, and best-of-three or best-of-five matc...
Algorithms & Computer Science
๐ก Text Case Converter
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 ...
SaaS & Business Killers
๐ Text Diff Checker
Compare two versions of text and see additions, removals and unchanged passages in a clean unified diff. Choose line-by-line for documents and code, or word-by-word for short edits. Everything is c...
Writing & Language
โ๏ธ Text to Handwriting
Convert typed text into realistic handwriting. Choose styles, sizes, and colors. Download as image.
Writing & Language
๐ผ๏ธ Text to Image Generator
Create images from text. Choose fonts, colors, backgrounds, and sizes. Perfect for social media posts and headers.
Writing & Language
๐ Text-to-Speech Reader (Offline Browser Voices)
Paste any text and have your device read it aloud using the voices already built into your browser or operating system โ no upload, no account. Choose voice and language, adjust speed and pitch, fo...
Wellbeing & Community
๐ฃ๏ธ Talk to Your Body (It's Been Trying to Tell You Something)
Your body stores emotions your mind has suppressed. Tension, pain, fatigue โ these aren't random. They're messages. This guided dialogue helps you listen to what your body has been holding.
Wellbeing & Community
๐งฌ The Emotions You Inherited (But Never Chose)
Some of your deepest patterns โ guilt, anxiety, people-pleasing, scarcity fear โ aren't yours. They were passed down through your family like heirlooms you never asked for. This tool helps you iden...
Wellbeing & Community
๐ฏ๏ธ The Grief No One Validates
You've been carrying losses that don't have funerals โ the friendship that faded, the version of yourself you thought you'd be, the childhood you deserved but didn't get. This tool validates the gr...
Wellbeing & Community
๐ The Identities You're Dragging Behind You
You're carrying identities that expired years ago โ "the shy one," "the responsible one," "the one who doesn't need help." They were useful once. Now they're cages. This tool helps you see which on...
Wellbeing & Community
๐ก๏ธ Your Inner Critic Is Trying to Save You
Your inner critic isn't your enemy โ it's a terrified protector stuck in the past. Meet it, understand what it's protecting you from, and gently update its threat model.
Wellbeing & Community
โ Tiny Revolts Against Your Own Prison
You don't need a life overhaul. You need a micro-act of defiance against the rules you've been following that were never yours. One small, deliberate act of "I'm allowed" can crack open years of se...
Wellbeing & Community
๐ You're Already Living Your Dream (You Just Forgot)
Five years ago, you wished for what you have now. This tool reconnects you with the gap between longing and having โ the most overlooked source of gratitude that exists.
Wellbeing & Community
๐ See Your Life Through a Narrator's Eyes
When you're inside your own story, everything feels overwhelming. This tool reframes your situation as a chapter in a novel โ creating the psychological distance that turns suffering into narrative...
Wellbeing & Community
๐ Learning to Swim in Not Knowing
Most of your suffering comes not from bad outcomes, but from the gap between "I need to know" and "I can't know yet." This tool trains your tolerance for uncertainty โ the single most underrated me...
Wellbeing & Community
โฐ Your Life Is Telling a Different Story Than You Think
You say you value family, health, creativity. But where does your time actually go? This tool reveals the gap between your stated values and your lived values โ the most honest mirror there is.
Museum & Collection
๐งฑ The Thermal Wall
Watch heat flow through building materials in real time. A thermal wave propagates from a warm room through brick, insulation, glass or wood โ Fourier's law made visible. See why a 100mm air gap is...
Science & Engineering
๐ฅ Thermodynamics Calculator
Calculate heat transfer, efficiency, entropy, and explore thermodynamics principles. Essential tool for physics, engineering, and chemistry.
Productivity & Lifestyle
๐ท๏ธ The Thing Namer
Naming things is one of the two hard problems in computer science (along with cache invalidation and off-by-one errors). Point it at a thing and it will name it โ band, pet, D&D character, star...
Productivity & Lifestyle
๐ผ๏ธ Universal Thumbnail Generator
Generate perfectly sized thumbnails for any platform with advanced editing tools. No upload required - all processing happens locally.
Productivity & Lifestyle
๐ฎ Tic Tac Toe Game
Play Tic Tac Toe against the computer or a friend. Features three difficulty levels and game statistics. Classic strategy game reimagined.
Science & Engineering
๐ Tidal Window & Crossing Planner
Two kinds of people watch the tide: sailors who need enough water under the keel, and everyone crossing a causeway, ford or sandbar who needs the water gone. Give it one high water and one low wate...
Home & DIY
๐งฑ Tile & Flooring Estimator
Calculate tiles, planks, or carpet needed for any room โ including waste and cuts.
Science & Engineering
โณ Einstein's Light Clock & Relativistic Time Dilation
Albert Einstein derived special relativity with an astonishingly simple thought experiment: a "light clock" bouncing a photon between two mirrors. Because the speed of light $c$ is constant for all...
Productivity & Lifestyle
โฑ๏ธ Timelapse Interval
Shots needed = clip length ร frame rate. Real time covered = shots ร interval. Leave the battery and a bigger card than you think. Sunset clouds often want 2โ5 s; construction days want 30โ60 s.
Productivity & Lifestyle
โฑ๏ธ Advanced Timer & Stopwatch
Advanced timer with countdown, stopwatch, intervals, lap times, and multiple alarms. Perfect for workouts, cooking, study sessions, and productivity.
Mathematics
๐ข Times Tables Drill Trainer
Drill the 1โ12 times tables with instant feedback, streak tracking and a review of the facts you get wrong. Includes a full 12ร12 grid and memory tricks. Everything runs in your browser โ no sign-u...
Productivity & Lifestyle
๐ Time Zone Converter
Convert any date and time between time zones. Supports all major world time zones.
Finance & Money
๐ธ Tip & Split Calculator
Calculate tips, split bills, and see exactly how much everyone owes. Supports multiple currencies!
Finance & Money
๐ฝ๏ธ Restaurant Bill Splitter with Itemised Shares
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...
Productivity & Lifestyle
๐ Tyre Size Comparison
Compare two metric tyre sizes (e.g. 225/45R17 vs 235/40R18): overall diameter, circumference, sidewall and the speedometer error if you swap them. Not a load or speed-rating check.
Writing & Language
๐ค Tongue Twister Trainer
Practise classic tongue twisters at your own pace, then beat the clock: read as many as you can in 30 seconds.
Interactive Art & Living Worlds
๐ช๏ธ Tornado & EF-Scale Lab
Build a supercell in real time. CAPE (buoyant energy), 0โ6 km wind shear, core radius and surface roughness control rotation, funnel formation, damage and the Enhanced Fujita rating โ with the live...
Science & Engineering
โก Torsional Vibration Lab
Calculate torsional stiffness ($k_t = \frac{GJ}{L}$), natural angular frequencies ($\omega_n = \sqrt{k_t/I}$), and critical whirling RPM. Analyze engine harmonic orders ($1\times, 2\times, 3\times,...
Sports
๐ Tournament Bracket Generator
Knock out a single-elimination draw in seconds. Pick how many teams, name them if you like, and get a seeded bracket with the right number of byes, in a form you can read or copy out.
Algorithms & Computer Science
๐ผ Towers of Hanoi
Move the stack from peg A to peg C, never putting a bigger disk on a smaller one. The catch: the optimal solution is 2โฟ โ 1 moves, so 8 disks means 255 moves โ recursion made visible. Solve it your...
Science & Engineering
๐ธ TR-3B Flight Simulator
Simulate the theoretical physics of the triangular TR-3B aerospace platform. Calculates Mercury-based Magnetic Field Disruptor (MFD) plasma acceleration, inertial mass reduction percentage, and sup...
SaaS & Business Killers
๐๏ธ Transcribe & Subtitle Studio Pro
Offline transcription workspace that replaces Otter.ai / Descript โ upload audio/video, auto-transcribe with Web Speech API where available, hand-correct on a waveform, and export SRT / VTT / TXT. ...
Science & Engineering
โก Transformer Sizing Calculator
Estimate transformer size for electrical loads. โ ๏ธ EDUCATIONAL ONLY โ Always verify with a qualified engineer and local standards.
Writing & Language
๐ Translation Helper
Translate text between languages with style and tone analysis. Includes language detection and clarity checking!
Music & Audio
๐ต Music Transposer
Transpose chords, melodies, and entire progressions between keys. โ ๏ธ EDUCATIONAL TOOL โ Verify with music teacher or professional resources.
Music & Audio
โก Trap & Drill Hi-Hat Roll Pattern Generator
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...
Productivity & Lifestyle
โ๏ธ Travel Trip Planner
Plan your perfect trip with detailed itineraries, budget tracking, and smart recommendations. Get personalized suggestions based on your preferences!
Sports
๐โโ๏ธ Triathlon Race Planner
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.
Mathematics
๐ฏ Foundation & Unit Circle
Sin = Opposite / Hypotenuse Cos = Adjacent / Hypotenuse Tan = Opposite / Adjacent
Astronomy & Space
๐ True Scale of Space
Every body is drawn at its real size and real distance โ no compression. Start at the EarthโMoon system (the Moon's orbit is 60 Earth radii across!) and zoom out through the inner planets, the gian...
Algorithms & Computer Science
๐งฎ Truth Table Generator
Generate truth tables for logical expressions. Supports AND, OR, NOT, XOR, IMPLIES, and IFF operators.
Interactive Art & Living Worlds
๐ Tsunami Runup Simulator
A real 1D shallow-water wave solver (c = โgh, leapfrog scheme) running a subduction-zone tsunami from seafloor rupture to the coast. Watch the wave slow, shoal and amplify โ Green's law emerges nat...
Music & Audio
๐ธ Instrument Tuner Reference
Reference notes for tuning your instrument. Educational only โ verify with your ear or a professional tuner.
Culinary & Food Science
๐ฆ Turkey Thaw & Cook Time
Fridge thaw ~24 h per 2โ2.5 kg (FSA: 24 h per 2 kg is a safe extra). Oven times are a starting point โ always probe 75 ยฐC in the thickest thigh and stuffing. Not a substitute for the label on your ...
Home & DIY
๐บ TV Viewing Distance Calculator
Recommend a sofa distance from screen diagonal and resolution. Uses SMPTE 30ยฐ field-of-view, THX 40ยฐ, and a sharpness seat where 4K/1080p pixels sit at about 1 arc-minute. Advice, not a living-room...
Writing & Language
โจ๏ธ Typing Speed Test
Measure your typing speed and accuracy with live feedback. Type the passage, watch your WPM build as you go, and see exactly which characters you missed. Your keystrokes never leave this page.
Writing & Language
โจ๏ธ Typing Story Sprint
Build typing speed by retyping fascinating true mini-stories โ bees, pyramids, photosynthesis. Live WPM, accuracy, tricky-key analysis and personal bests.
Finance & Money
๐ UCAS Tariff Points
Add A-level, AS and T Level grades to a running UCAS tariff total. Offers are often โBBB (120)โ โ this is the current A-level band (A* = 56). Always check the course page; some universities ignore ...
Health & Fitness
๐บ UK Alcohol Units Calculator
UK units = ABV (%) ร volume (ml) รท 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.
MrProphecy Arcade
๐บ๏ธ UK Counties & Regions Quiz
Learn the 48 English counties plus Scotland, Wales and Northern Ireland โ match counties to regions in ten-question rounds. Runs entirely in your browser.
Museum & Collection
๐ฅ The Hallmark Bench
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...
Finance & Money
๐ด Holiday Entitlement & Pro-Rata Calculator
Work out statutory UK holiday for part-timers, mid-year starters and leavers, and irregular-hours staff โ including the 12.07% accrual method. Employers get this wrong constantly. Nothing you enter...
Productivity & Lifestyle
๐ฎ UK Postcode Formatter
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 โ it does not look up addresses.
Science & Engineering
๐ฌ Underwater Acoustics Lab
Investigate acoustic wave mechanics in water. Calculate high-precision sound velocity ($c \approx 1,482\text{ m/s}$, 4.3ร faster than air), bulk modulus incompressibility ($K_s = \rho c^2 \approx 2...
Algorithms & Computer Science
๐ Unicode Converter
Convert text to Unicode code points, HTML entities, and escape sequences. Supports all Unicode characters.
Science & Engineering
๐ฌ Scientific & Everyday Unit Converter
Convert between common scientific and everyday units โ length, mass, temperature, energy and pressure. Runs entirely in your browser.
Finance & Money
๐ Unit Price Comparator
Shops price things so you cannot compare them: 340 g here, 12 ร 30 g there, "3 for ยฃ5" on the shelf edge. Put in what is actually on the shelf and this reduces everything to one number. Handles mul...
Algorithms & Computer Science
โฑ๏ธ Unix Timestamp Converter
Convert Unix epoch timestamps (seconds, milliseconds, microseconds or nanoseconds โ auto-detected) to human dates and back. Shows UTC, your local time, ISO 8601, relative time and the weekday. A li...
Wellbeing & Community
๐ธ Origami Fortune & Uplifting Destiny Weaver
Relive the tactile magic of schoolyard origami fortune tellers (cootie catchers). Pick a vibrant outer flap, watch the paper chatterbox fold and pinch in real-time with crisp paper sounds, choose y...
Algorithms & Computer Science
๐ URL Encoder, Decoder & Parser
Percent-encode or decode any text (full encodeURIComponent or URL-safe encodeURI), and break a URL into protocol, host, port, path, hash and an editable table of query parameters. Edit a value and ...
Algorithms & Computer Science
๐ต๏ธ User Agent & Browser Client Inspector
Inspect your browser's user agent string, client hints, screen geometry, GPU WebGL renderer, touch capabilities, color depth, and networking status.
SaaS & Business Killers
๐ UTM Campaign URL Builder
Generate standardized Google Analytics 4 (GA4) tracking URLs across multiple marketing channels simultaneously. Enforces lowercase slugification, auto-encodes illegal spaces, and exports batch CSVs...
Algorithms & Computer Science
๐ UUID / GUID & Random ID Bulk Generator
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...
Science & Engineering
โก Van de Graaff Generator
Electrostatic museum exhibit. Rubber belt triboelectric charge transport accumulates up to 400 kV on the metal dome, firing high-voltage atmospheric sparks.
Finance & Money
๐ท VAT / GST / Sales Tax Calculator
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 โ not tax advice.
Algorithms & Computer Science
๐ชช vCard Generator
Build a vCard 3.0 you can save as .vcf and open on a phone. Stays in the browser โ no address book is uploaded.
Mathematics
๐ต Venn Diagram Visualiser
Type two lists and watch the Venn diagram draw itself โ union, intersection, symmetric difference and per-zone items are listed.
Science & Engineering
๐ก๏ธ Vibration Isolator Designer
Design mechanical vibration isolators and shock mounts using force transmissibility ($T_R$). Calculate required static deflection ($\delta_{st}$), isolation efficiency ($\eta$), and operating frequ...
Algorithms & Computer Science
๐ฌ Video Bitrate File Size
Estimate video file size from duration and video/audio bitrates, or solve for the bitrate that fits a size budget. Formula: size โ (video + audio) ร time. Container overhead is ignored.
Music & Audio
๐๏ธ Vinyl Sample Pitch & Semitone BPM Shifter
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...
Health & Fitness
๐ VOโ Max Calculator
Estimate your VOโ Max โ a measure of aerobic fitness. The higher the value, the better your cardiovascular endurance.
Writing & Language
Vocabulary Trainer
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.
Music & Audio
๐๏ธ Hip Hop Vocal & Sidechain Compressor Calculator
Compressors that aren't mathematically timed to your beat either choke punchy transients or pump unnaturally. Calculate tempo-synced Attack, Release, and Hold times for kick-to-808 sidechain duckin...
Interactive Art & Living Worlds
๐ Volcano Eruption Simulator
A living cross-section of a stratovolcano. Magma viscosity, dissolved gas, vent width and slope drive the real eruption style โ Hawaiian fountains, Strombolian bursts or Plinian columns โ with buoy...
Sports
๐ Volleyball Score Sheet & Rotation
Rally scoring to 25 (win by two, up to 30), with the fifth set to 15 โ plus a rotation tracker: list your six players in serving order and they rotate every time the side that wins the rally was re...
Science & Engineering
โก Voltage Divider
Vout = Vin ร R2 / (R1 + R2). R1 is the top resistor from the supply; R2 is the bottom resistor to ground. Unloaded โ a low-impedance load pulls the output down.
Science & Engineering
โก Voltage Drop Calculator
Estimate voltage drop across a conductor run. Educational only โ always verify with a qualified electrician and local standards.
Interactive Art & Living Worlds
๐ฟ VoxelMonolith 3D
An isometric 3D voxel monument sculpted across time. Place obsidian, glowing crystal, gold, and marble blocks layer by layer. Scrub the chronological time slider to watch historical construction fr...
Health & Fitness
๐ Waist-to-Height Ratio
NICE NG246 uses waist รท 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.
Health & Fitness
๐ Waist-to-Hip Ratio Calculator
Calculate your waist-to-hip ratio and see your health risk category based on WHO guidelines.
Home & DIY
๐ฉ Wall Anchor Selector
Not sure what fixings to use? Tell us your wall type and what you're hanging โ we'll tell you exactly what to buy.
Home & DIY
๐งป Wallpaper Estimator
Calculate how many rolls of wallpaper you need โ accounting for pattern repeat, doors, and windows.
Science & Engineering
๐ง Water Cycle Simulator
Watch Earth's water engine run: the Sun lifts water from the ocean as vapour, clouds build, rain falls, and every drop finds its way back to the sea. Step through the four stages or let it flow.
Science & Engineering
๐ง Water Density Anomaly Lab
Investigate water's famous thermodynamic density anomaly ($\rho_{max}$ at $3.98^\circ\text{C}$). Explore negative thermal expansion, the $+9\%$ ice phase transition volume expansion, and ecological...
Science & Engineering
โก Water Dielectric Lab
Investigate water's molecular dipole moment ($\mu = 1.854\text{ Debye}$) and huge dielectric permittivity ($\epsilon_r \approx 80.1$). Model Debye relaxation ($\epsilon^*(\omega) = \epsilon_\infty ...
Science & Engineering
๐ฐ Water Hardness (LSI) Lab
Assess water hardness and mineral stability using the Langelier Saturation Index ($\text{LSI} = \text{pH} - \text{pH}_s$) and Ryznar Stability Index ($\text{RSI}$). Predict calcium carbonate precip...
Science & Engineering
๐งช Water Ionization & pH Lab
Investigate water's auto-protolysis equilibrium ($2\text{H}_2\text{O} \rightleftharpoons \text{H}_3\text{O}^+ + \text{OH}^-$). Discover why neutral water is $\text{pH } 7.00$ only at $25^\circ\text...
Science & Engineering
๐๏ธ Water Phase Diagram Lab
Navigate water's complete thermodynamic $P$-$T$ phase space across Solid, Liquid, Vapor, and Supercritical regimes. Explore the Triple Point ($0.01^\circ\text{C}, 611.65\text{ Pa}$), Critical Point...
Survival & Emergency Readiness
๐ง Water Purification Planner
You can live weeks without food and about three days without water. This works out how much to store, how many containers that is, and โ the part people get wrong โ exactly how to make a questionab...
Science & Engineering
๐งช Water Surface Tension Lab
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...
Lucid Dreaming & Sleep
๐ WBTB Lucid Dream REM Planner
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%.
Sports
๐๏ธ Weightlifting Sinclair Score
The Sinclair coefficient lets lifters of different bodyweights be compared. Enter sex, bodyweight and total, and this computes the 2025โ2028 Sinclair coefficient and Sinclair Total.
Productivity & Lifestyle
Which Year Are You? ๐ฐ๏ธ
Discover your internet personality era based on your tastes, habits, and vibes. โ Share your result!
Science & Engineering
๐ Wheelbuilding Spoke Length & Tension Calculator
Spoke length is a three-dimensional problem: the spoke runs from a hole in the hub flange, sideways to the rim centreline and around by however many crossings you lace. Get it wrong by two millimet...
Finance & Money
๐ท๏ธ Wholesale Pricing & Margin
Set retail and wholesale prices while seeing your margin and the retailerโs margin side by side. All calculations stay in your browser.
Science & Engineering
๐ Why Is The Sky Blue? โ Rayleigh Scattering Lab
Air molecules scatter sunlight in every direction โ and short wavelengths scatter about 4ร more than long ones. Slide the Sun down and watch the same physics hand the sky back as a sunset.
Productivity & Lifestyle
๐ถ Wi-Fi QR Pass Generator
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. ๐ Genuin....
Algorithms & Computer Science
๐ถ WiFi Speed & Download Time Calculator
Calculate exact file download and upload durations, test bandwidth capacity for simultaneous 4K streams and video calls, and estimate mobile data cap exhaustion.
Lucid Dreaming & Sleep
๐ WILD Hypnagogia Transition
Wake-Initiated Lucid Dreaming (WILD) mental anchor simulator. Ride the borderline hypnagogic transition directly from conscious waking state into full REM dream creation.
Interactive Art & Living Worlds
๐ฅ Wildfire Behaviour Lab
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...
Science & Engineering
๐ฌ๏ธ Wind Chill Calculator
NWS/JAG/TI wind-chill (2001): valid when air is โค 10 ยฐC and wind โฅ 4.8 km/h. It estimates how cold exposed skin feels โ not a frostbite timer, and not for indoor fans.
Science & Engineering
โ๏ธ Wind Triangle & Flight Leg Planner
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 โ heading t...
Science & Engineering
๐ฌ๏ธ Wind, Fetch & Wave Forecaster
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...
Science & Engineering
โก Wire Gauge Calculator
Professional wire sizing calculator for electrical installations with NEC/IEC compliance checks and safety recommendations.
Productivity & Lifestyle
๐ Text Statistics Analyzer
Comprehensive text analysis: word count, character count, sentence count, reading time, readability score, and more.
Writing & Language
๐ Keyword Density & Word Frequency
Paste copy and see word count, the densest terms, and an optional target keywordโs density. Counts are local and crude (no stemming). Density is a diagnostic, not a Google ranking lever โ stuffing ...
Productivity & Lifestyle
โฑ๏ธ Work Hours & Pay Calculator
Calculate work hours, breaks, overtime, and pay. Track multiple shifts, different pay rates, and generate detailed timesheets. Perfect for freelancers, contractors, and employees!
MrProphecy Arcade
๐ World Capitals Quiz
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 โ nothing is sent anywhere, it all r...
Wellbeing & Community
๐ The 3am Worry Sorter
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 โ with a kind word for each. Nothing is saved.
Productivity & Lifestyle
โ๏ธ XMAS Card Writer Assistant
Struggling with what to write? Get personalized Christmas card messages for everyone on your list! Save time, spread joy!
Productivity & Lifestyle
๐ Christmas Countdown
Count down to Christmas with real-time tracking, festive facts, and daily suggestions! ๐
Shows days, hours, minutes until Christmas morning
Finance & Money
๐ฐ Christmas Gift Budget Planner
Plan, track, and optimize your Christmas gift spending. Avoid overspending with smart budgeting! โ
Features: Gift ideas, price tracking, comparison shopping, receipt scanning
Productivity & Lifestyle
๐
Santa Tracker & Message Center
Track Santa's journey and send him a message! Get a personalized response from the North Pole. Perfect for kids and kids-at-heart!
Algorithms & Computer Science
๐ XML Formatter & Validator
Format, minify, validate, and explore XML. Paste messy XML, get clean indented output with syntax highlighting.
Culinary & Food Science
๐ Yeast Converter
Swap fresh cake yeast, active dry and instant/fast-action using the bakerโs 1 : 1.25 : 3 rule (instant : active dry : fresh by weight). Teaspoons assume 3.1 g instant per level tsp.
Museum & Collection
แ The Rune Cabinet
Sixteen staves, not twenty-four. After about 700 CE the north dropped Elder Futhark down to this tighter case โ one rune now stands for several Latin letters. Stones from Jelling to Rรถk speak it. T...
Writing & Language
โจ Aesthetic Bio Generator
Generate stylish bios for Instagram, TikTok, Discord, Twitter/X, and more โ with fonts, symbols, and vibes
Writing & Language
๐ฑ Caption Generator
Generate Instagram, TikTok, and selfie captions โ funny, aesthetic, savage, or wholesome
Productivity & Lifestyle
๐จ Aesthetic Color Palette Generator
Generate beautiful color palettes for designs, social media, and vibes โ click to copy hex codes
Finance & Money
๐ธ Money Tracker
Track your spending, set a budget, and see where your money goes โ simple enough for your first budget
Productivity & Lifestyle
๐ต Playlist Name Generator
Generate creative playlist names for Spotify, Apple Music, and YouTube โ match the vibe of your music
Writing & Language
๐ First Resume Builder
Build your first CV or resume โ even with no experience. Fill in what you have, get a clean, professional resume
Productivity & Lifestyle
๐ Study Timer (Pomodoro)
Focus timer with study/break cycles, session tracking, and motivational quotes โ ace your exams
Sports
๐ง Youth Team Rotation Planner
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...
Productivity & Lifestyle
๐ฎ Username Generator
Generate unique, cool usernames for gaming, social media, and streaming โ check availability vibes
Productivity & Lifestyle
๐ฌ What Should I Watch?
Can't decide what to watch? Answer 3 quick questions and get personalized movie/show recommendations
Music & Audio
๐๏ธ YouTube DJ Mixer
Mix YouTube videos live like a professional DJ. Crossfade between tracks, apply effects, and create seamless mixes. ๐ง Live mixing โข Crossfader โข EQ โข Effects โข YouTube integration
Health & Fitness
๐ซ Arterial Blood Gas Interpreter
pH, PaCOโ 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...
Wellbeing & Community
๐ง ADHD Time & Task Lab
Time blindness is not laziness, it is a broken odometer: the guess is wrong in a consistent direction, so it can be measured and corrected. Log a few estimate-vs-actual pairs and this learns your o...
Home & DIY
๐งด Adhesive Selector โ Which Glue Sticks This to That?
Pick the two things you are joining and the conditions it has to survive, and this works out which adhesive will actually hold โ with open time, clamp time, full cure and the surface prep that make...
AI & Autonomous Agents
๐ง Advanced RAG Playground โ BM25 + Embeddings + Re-ranking
Launcher for the standalone AI: hybrid retrieval over documents you paste in โ BM25, hashed dense vectors, HyDE, reciprocal rank fusion and MMR โ with per-pass scores and a trace.
AI & Autonomous Agents
๐ค AI Agent Orchestrator โ Multi-Agent ReAct & Tool-Use
Launcher for the standalone AI: a planner, retriever, reasoner, actor and verifier pipeline that really executes local tools, then reviews the answer constitutionally. In-browser, no key.
AI & Autonomous Agents
๐ธ๏ธ Graph-of-Thought Lab โ Aggregation, Transformation, GoT Reasoning (Besta 2023/2024)
Launcher for the standalone AI: thoughts as a graph โ merge, refine and loop back over candidate ideas with per-node scoring, instead of one linear chain. Runs in your browser.
AI & Autonomous Agents
๐ง Browser Vector Memory โ IndexedDB + Semantic Search
Launcher for the standalone AI: vector memory in IndexedDB scored like Generative Agents โ relevance, importance and recency โ with tiers, reflections, consolidation and import/export.
AI & Autonomous Agents
๐ญ AI Realistic Face Avatar โ Procedural Canvas, FACS, Eye-Tracking, Lip-Sync
Byte 3.0's realistic face live โ 100% procedural Canvas 2D, no images, no external models. Skin subsurface scattering, iris texture with flecks, micro-saccades, FACS action units (AU1, AU2, AU4, AU...
AI & Autonomous Agents
๐ง AI Reasoning Trace Visualizer โ Chain-of-Thought & Self-Critique
Launcher for the standalone AI: every reasoning run emits a step-by-step trace plus a tree, graph, DAG, vote or iteration visualisation. Export any trace as JSON. In-browser, no account.
AI & Autonomous Agents
๐ AI Super Realistic Face v4 โ FACS Continuous Blending, Micro-Expressions 1/25s, 12 Visemes, GoT Eye-Tracking
Byte 4.0 super face v4 โ upgrade from v3 discrete emotions to continuous FACS blending (happy 0.12 + thinking 0.34), micro-expressions 80ms flashes 1/25s (Ekman 2003), 12 viseme phoneme groups, eye...
AI & Autonomous Agents
๐ง AI Thinking Machine Lab โ ToT, Reflexion, HyDE, RRF, Generative Memory (Research Stack 2022-2026)
Launcher for the standalone AI: 18 implemented reasoning methods with an automatic router that picks the method that fits your question, and an honest label on every answer. In-browser.
AI & Autonomous Agents
๐ง AI Tool-Use Simulator โ Function Calling & Byte 2.0 Integration
Launcher for the standalone AI: 13 local tools with JSON schemas โ calculator, units, dates, text stats, encoders, JSON, regex, hashing, retrieval and memory. Run or parse any call. In-browser.
Health & Fitness
๐ง Anion Gap & Corrected Electrolytes
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 ...
Health & Fitness
๐ถ APGAR Score Calculator
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 โ nothing is written to this browser.
Finance & Money
๐ Appliance Running Cost Calculator
The kettle costs pennies and the tumble dryer costs a fortune โ build your house as a list, see what each appliance really costs per day, month and year, and find the ones worth changing first.
SaaS & Business Killers
๐ท๏ธ Barcode & Label Studio
Produce real, scanner-readable barcodes โ Code 128, Code 39, EAN-13, UPC-A and ITF-14 โ and download them as vector SVG or a print-resolution PNG. Barcode generator sites charge a subscription for ...
Wellbeing & Community
๐ค Bulk-Buy Co-op Splitter: Halve Your Food Bills Together
One household cannot buy a 25 kg sack of rice โ but ten can. Start a street buying club: pick wholesale packs, split them fairly between households, and see exactly what everyone pays and saves, wi...
SaaS & Business Killers
๐ท๏ธ Business & Domain Name Generator
Type one or two words that describe what you do and get a few dozen names built from the tricks naming agencies actually use โ blends, compounds, prefixes, suffixes, alliteration and invented words...
Productivity & Lifestyle
๐ฏ๏ธ Candle Making Supplies Calculator
Fill a jar with water, weigh it, and youโve measured your candle. Enter vessel size and fragrance load โ get wax grams, fragrance grams, wick guidance and a full batch shopping list.
Health & Fitness
โค๏ธ CHAโDSโ-VASc & HAS-BLED Calculator
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...
Health & Fitness
๐ Clinical Fluid Requirements Calculator
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 ...
Wellbeing & Community
๐ง Community Fridge Starter Kit: Feed Your Street
A community fridge turns a neighbourhoodโs surplus food into free meals for anyone. This kit gives you the setup checklist, the food-safety rules, an allowed-foods checker, volunteer rotas and read...
Home & DIY
๐ฑ Compost Carbon:Nitrogen Balancer
Slimy and smelly means too much nitrogen; dry and stubborn means too much carbon. Tell it whatโs gone into the heap and it estimates your C:N ratio and exactly what to add next.
SaaS & Business Killers
๐ช Cookie Consent Banner Builder
Build a self-hosted cookie banner with real accept / reject / granular choices โ the thing Cookiebot, OneTrust and Termly charge a monthly fee for, and the thing most "free" generators only half do...
Finance & Money
๐ Council Tax Band Checker & Bill Estimator
Bands come from your homeโs value on a fixed historic date โ 1991 in England and Scotland, 2003 in Wales. Find your band, estimate the real bill from your councilโs Band D figure, and see what the ...
Productivity & Lifestyle
โณ Countdown to Any Date
Holidays, exams, releases, birthdays, notice periods or a deadline you are trying to respect: pick a date and watch the days, hours, minutes and seconds tick down live. Also tells you the working d...
Writing & Language
โ๏ธ Daily Writing โ Streak & Word Goal
A blank page, a word goal and a streak you do not want to break. Write every day โ 750 words is the classic target, but any goal works โ and this counts the words, keeps your streak, shows you the ...
Fire & Rescue Service
๐ Drafting & Static Water Supply
Lift, theoretical and dependable lift at your elevation, the intake pressure correction, net pump discharge pressure, and how much of your rated capacity you actually keep at that lift.
Health & Fitness
๐งช eGFR & Creatinine Clearance Calculator
Race-free CKD-EPI 2021 eGFR plus Cockcroft-Gault creatinine clearance side by side, with KDIGO G-stage and the renal dosing bands that hang off them. Runs offline in your browser.
Culinary & Food Science
๐ฅ Perfect Egg Timer
Soft, jammy or hard, from the fridge or the counter, at sea level or in the hills โ tell it about your eggs and it gives you a time and a live countdown. No more grey-green yolks.
SaaS & Business Killers
๐ EPUB & eBook Builder
Turn a set of chapters into a real EPUB 3 file your reader can actually open โ the job Vellum charges a couple of hundred pounds for and Designrr sells as a subscription. Write in plain text with l...
Fire & Rescue Service
๐ฅ Fireground Hydraulics โ Friction Loss & Pump Pressure
Friction loss, elevation, appliance loss, pump discharge pressure, solid-stream flow and nozzle reaction for up to five hose sections, with the supply-line hand methods alongside.
Fire & Rescue Service
๐ก๏ธ Firefighter Rehab & WBGT Heat Stress
Wet-bulb globe temperature from your three thermometer readings, the ACGIH screening TLV and action limit for your work/rest cycle, and why the tables stop short of turnout gear.
Fire & Rescue Service
๐ซง Foam Proportioning & Application Rate
Foam solution flow for an area, concentrate per minute and total concentrate for the run time, for Class A and Class B hydrocarbon and polar-solvent spills.
Culinary & Food Science
๐ฆ Food Parcel Stretcher: A Week of Meals From a Food Bank Box
Got a food bank parcel or pantry box? Enter what is inside and get a 7-day meal plan that uses it all up โ plus the cheapest fresh top-ups that unlock the most extra meals. Parcel first, money seco...
SaaS & Business Killers
๐ Gantt & Timeline Studio
Draw a real project timeline โ tasks, dates, progress, milestones and dependencies โ and export it as a clean SVG or a print-resolution PNG. TeamGantt and Microsoft Project charge per user per mont...
Mathematics
๐ Geometry Calculator
Calculate the area, perimeter, or volume of common shapes.
Finance & Money
๐ Gift Aid Calculator
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...
Health & Fitness
๐ง Glasgow Coma Scale Calculator
Adult and pre-verbal paediatric GCS with the 2014 wording, "not testable" handled properly, the E-V-M string for the notes, and the NICE deterioration thresholds. Nothing is stored or sent anywhere...
Fire & Rescue Service
๐ช Ground Ladder Placement & Reach
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.
Productivity & Lifestyle
๐งพ Group Expense Splitter & Settle Up
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...
Wellbeing & Community
๐งญ Hard Times Navigator: No Food, No Money โ Start Here
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...
Finance & Money
โ๏ธ Hardship Letter Writer: Ask for Breathing Space
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 โ in UK, US or ...
Fire & Rescue Service
โฃ๏ธ Hazmat Concentration Converter
ppm to mg/mยณ 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.
Fire & Rescue Service
๐ง Hydrant Flow Test & Water Supply
Read your pitot gauge and your two hydrant gauges, and get the percentage method, the first-digit method, the available fire flow at 20 psi residual, and whether the test is even valid.
Algorithms & Computer Science
๐จ Image Colour Picker & Palette Extractor
Drop in a photo, logo or screenshot and hover to read any pixel as HEX, RGB and HSL โ with a magnifier for precision. The tool also pulls out the image's dominant palette, ready to copy as CSS vari...
Health & Fitness
๐ท๏ธ Ingredient Label Allergen Decoder
Allergens hide behind nicer names: โcaseinateโ is milk, โarachis oilโ is peanut, โhydrolysed vegetable proteinโ is often wheat, and E220โE228 are sulphites. Paste an ingredient list โ from a packet...
Health & Fitness
๐ง IV Drip Rate & Infusion Calculator
mL/h โ 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.
Culinary & Food Science
๐ฅ Kitchen Converter & Baking Swaps
The four things every recipe makes you look up: cups to grams (per ingredient, because a cup of flour is not a cup of sugar), oven temperatures between ยฐC, ยฐF, fan and gas mark, the equivalents tha...
Productivity & Lifestyle
๐งถ Knitting & Crochet Yarn Studio
The four sums every knitter and crocheter does on the back of a pattern envelope: how many stitches to cast on at your gauge, how much yarn to buy, whether that leftover ball is enough, and which h...
Survival & Emergency Readiness
๐ชข Knot Tying Guide โ 18 Knots Worth Knowing
Every knot you actually need, with a diagram, step-by-step tying instructions, what it is for, how much rope strength it costs you and whether it jams solid afterwards. Filter by job, search by nam...
Writing & Language
๐ LaTeX Table & Maths Studio
Building a tabular by hand is the most reliably irritating ten minutes in academic writing: alignment letters to count, & and \\ to escape, and one unescaped % or _ to break the whole build. Pa...
Culinary & Food Science
โป๏ธ Leftover Rescue Kitchen: Waste Nothing
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...
SaaS & Business Killers
๐ Link-in-Bio Page Builder
Build the one-page hub you put in your social bio and download it as a single self-contained HTML file you can host anywhere for free. Linktree charges a monthly fee for themes, analytics and remov...
Music & Audio
Loop Seam Checker
Check a sampleโs end-to-start jump and slope mismatch before setting a loop in your sampler.
Music & Audio
LUFS Target & Headroom Planner
Use measured integrated LUFS and true peak to plan a gain change and see whether your chosen peak ceiling permits it.
Productivity & Lifestyle
๐ Mean, Median & Mode
Paste a list of numbers separated by commas, spaces, or new lines.
Productivity & Lifestyle
๐ Meme Generator โ Your Image, Top & Bottom Text, No Watermark
Drop in any picture, add classic Impact captions or a modern white caption bar, and download a clean PNG. Text wraps and shrinks to fit automatically. The image never leaves your device and there i...
Algorithms & Computer Science
๐๏ธ Mic, Speaker & Webcam Test โ Pre-Meeting Device Check
Check everything before the call: see your microphone level move, hear a tone from the left and right speaker, and preview your camera with its real resolution. Audio and video stay inside this tab...
Home & DIY
๐ฑ Micro Garden: Grow Food With No Land
Turn a balcony, windowsill or tiny yard into real food. Tell it your space, sun and season and it ranks what to grow by calories per square metre โ with a sowing calendar, harvest forecast and mone...
Productivity & Lifestyle
๐ง Mind Map Studio
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...
Finance & Money
๐ฆ Mortgage Affordability โ How Much Can You Borrow?
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...
Science & Engineering
๐บ๏ธ MostUsefulMaps โ Distance & Place Finder
The site's own map, right here in the card. Drop two points โ a town name, a coordinate pair, a Plus Code, a UK grid reference, a UTM coordinate, a Maidenhead locator or a geohash โ and get the geo...
Home & DIY
๐ฆ Moving House Box & Supplies Estimator
Everyone under-buys boxes by half. Tell it the size of the place, the people in it and how long youโve been there โ get a realistic shopping list plus the packing timeline removal crews wish everyo...
Productivity & Lifestyle
๐ค Negotiation Prep Studio
Most negotiations are lost in the ten minutes before them, in the negotiatorโs head: no written walk-away, no BATNA, no plan for the first number. Fill in six fields and this produces the one-page ...
Health & Fitness
๐ NEWS2 Early Warning Score
Royal College of Physicians National Early Warning Score 2 with both SpOโ scales, the single-parameter-of-3 rule and the RCP escalation table. Shows which band each observation landed in so the sco...
Productivity & Lifestyle
๐ Online Notepad โ Autosave, Word Count & Download
A plain, fast notepad that saves itself as you type. Several notes in tabs, live word and character counts, find & replace, and one-click download as .txt โ all stored in this browser, never on...
Finance & Money
๐ Payday Stretch: Make Your Last Pounds Last
Broke before payday? Enter what you have left and what is due, and get a day-by-day survival budget that protects rent, heat and food first โ and tells you honestly which bills can be paused or neg...
Music & Audio
Peak Normalizer & WAV Export
Normalize mono or stereo samples to a chosen sample-peak ceiling, with linked-channel gain and a downloadable 24-bit PCM WAV.
Culinary & Food Science
๐ฒ Penny Meals: Survival Food Planner
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 ...
Productivity & Lifestyle
๐ Percentage Calculator
Work out percentages, increases, decreases, and discounts in seconds.
Finance & Money
๐ฑ Phone Contract vs SIM-Only Calculator
Networks hide the handset price inside the monthly figure. Put the two deals side by side, apply the annual April price rise, and see the real total โ then haggle or walk.
SaaS & Business Killers
๐๏ธ Photo Watermark Studio
Stamp a logo or a text signature across a whole folder of photos in one pass โ tiled, angled and faded so it survives a crop but does not ruin the picture. Desktop watermark apps charge a licence a...
Wellbeing & Community
๐ Police & Legal Speak, Decoded
Police, court and bailiff jargon, translated into plain English. 80+ terms โ from "stop and search" to "warrant of control" โ each tagged UK, US or both, with what it actually means for you. Runs o...
Productivity & Lifestyle
๐ Prime Factor Finder
Break a whole number into its prime factors and see whether it is prime.
Productivity & Lifestyle
๐ Printable Paper Generator
Make your own graph paper, dot grid, ruled refill, manuscript paper, storyboard sheets, Cornell notes, week planners and wall calendars โ sized for real paper, drawn on the device and downloaded as...
SaaS & Business Killers
๐๏ธ Pro Audio Studio โ Record, Edit & Master in Browser
Professional audio workstation that replaces Audacity, Adobe Audition & Descript โ 100% offline. Record mic, import audio/video, visualize waveform, trim, normalize, fade, adjust gain/speed, an...
SaaS & Business Killers
๐จ Pro Color Theme Studio โ Palette, WCAG, Gradients & Export
Professional color system that replaces Coolors, Adobe Color & Stark โ 100% offline. Extract palette from any image via k-means, generate harmonies, test WCAG contrast, simulate color blindness...
SaaS & Business Killers
๐๏ธ Pro Database Grid Studio โ Airtable & Notion Killer
Professional database studio that replaces Airtable $20/mo, Notion Database & Coda โ 100% offline. Spreadsheet grid with types (text, number, select, checkbox, date, formula), filters, sort, vi...
SaaS & Business Killers
๐จ Pro Design Canvas Studio โ Thumbnail, Poster & Social Maker
Professional drag-drop design studio that replaces Canva Pro $13/mo, Adobe Express & Figma โ 100% offline. Templates for YouTube thumbnail, Instagram post/story, OG image, poster, with layers, ...
SaaS & Business Killers
๐ Pro Doc Scanner Studio โ OCR, PDF & Image to Text
Professional document scanner that replaces Adobe Scan, CamScanner & OnlineOCR โ 100% offline in browser. Scan images, enhance, crop/rotate, OCR via built-in engine, export PDF/TXT, batch proce...
SaaS & Business Killers
โ๏ธ Pro Email Visual Builder โ BeeFree & Mailchimp Killer
Professional email builder that replaces BeeFree $30/mo, Mailchimp builder & Stripo โ 100% offline. Drag blocks, edit copy, inline CSS, dark mode, mobile/desktop preview, spam score, export HTM...
SaaS & Business Killers
๐ง Pro Flashcard Studio โ Spaced Repetition (Anki Killer)
Professional spaced repetition studio that replaces Anki $25 & Quizlet Plus $36/yr โ 100% offline. Create decks, import CSV, study with SM-2 algorithm, bury/leech detection, stats, heatmap, exp...
SaaS & Business Killers
๐ Pro Form Builder Studio โ Typeform & Google Forms Killer
Professional form builder that replaces Typeform $25/mo, Tally & Google Forms โ 100% offline. Drag-drop fields, validation, logic, themes, collect responses in localStorage, export CSV/JSON, em...
SaaS & Business Killers
๐ผ๏ธ Pro Image Compressor Studio โ Batch Resize, Convert & Optimize
Production-grade image studio that replaces TinyPNG, Squoosh & Photoshop batch โ 100% offline. Batch compress, resize, convert to WebP/JPEG/PNG, strip EXIF, add watermark, and download. No uplo...
SaaS & Business Killers
๐งพ Pro Invoice & Recurring Studio โ Estimates, Invoices, Subscriptions
Production invoicing studio that replaces FreshBooks, HoneyBook & Stripe Invoicing โ 100% offline. Create invoices, estimates, recurring subscriptions, track paid/overdue, taxes, discounts, mul...
SaaS & Business Killers
๐งฉ Pro JSON & API Workbench โ Format, Query, Diff & Convert
Production-grade JSON studio that replaces Quicktype, JSONPath Online & Postman scratchpad โ 100% offline. Format, validate, minify, query with JSONPath, diff, convert to YAML/CSV/XML/TypeScrip...
SaaS & Business Killers
๐ Pro Landing Page Builder โ Carrd & Webflow Killer
Professional landing page builder that replaces Carrd $19/yr, Webflow $14/mo & Framer โ 100% offline. Drag sections (hero, features, pricing, FAQ, CTA), edit copy, themes, responsive preview, e...
SaaS & Business Killers
๐ Pro Password Vault Studio โ Generator, Encrypted Vault & TOTP
Military-grade password manager that replaces 1Password / Bitwarden for local use โ 100% offline, zero-knowledge. Generate high-entropy passwords, check strength, store in AES-GCM vault locked by m...
SaaS & Business Killers
โก Pro Regex Studio โ Tester, Builder, Explainer & Code Export
Professional regex workbench that replaces Regex101, RegExr & Debuggex โ 100% offline. Live highlighting, match groups table, replace preview, explainer, cheatsheet, common-pattern library, and...
SaaS & Business Killers
๐ Pro SEO Audit Toolkit โ On-Page, OG, Schema & Performance
Professional SEO auditor that replaces Screaming Frog, Ahrefs Site Audit & Yoast โ 100% offline. Paste HTML or enter URL, get 40+ checks: title, meta, headings, images alt, OG, Twitter, canonic...
SaaS & Business Killers
๐ฌ Pro Video Toolkit โ Trim, Compress, GIF, Thumbnail & Metadata
Professional browser video studio that replaces HandBrake, Kap, EZGIF & Adobe Media Encoder โ 100% offline. Trim, compress preview, extract frames, generate thumbnails, GIF preview, mute, rotat...
SaaS & Business Killers
๐งฉ Pro Whiteboard Studio โ Infinite Canvas, Sticky Notes & Drawing
Professional infinite whiteboard that replaces Miro $10/mo, FigJam & Mural โ 100% offline. Pan, zoom, sticky notes, freehand drawing, shapes, connectors, text, image upload, layers, export PNG/...
Finance & Money
๐ Rail Delay Repay Calculator
Delay Repay pays you for arriving late โ but the clock runs on your arrival at your final destination, not on the departure board, and single, return and season tickets are compensated on three dif...
Productivity & Lifestyle
๐ฅ Random Team Generator & Group Splitter
Paste a list of names and split it into fair random teams โ by number of teams or people per team. Add an optional skill rating to balance sides, pick captains, and copy the result to the group cha...
Sports
โก Reaction Time, Click Speed & Aim Test
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...
Finance & Money
๐ Rent vs Buy Calculator
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 โ not financial advice.
Fire & Rescue Service
๐ Required Fire Flow Calculator
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.
Writing & Language
โ๏ธ Resignation Letter Generator
One minute of form, one courteous letter. It works out your contractual last day, keeps the door open, and never says anything youโll regret โ fill it in and copy it out.
Productivity & Lifestyle
๐ Rules of Thumb โ 80 Shortcuts That Actually Work
A working library of the short, memorable rules people use to make decisions without doing the maths: how long money takes to double, how to season a sauce, how many copies a backup needs, how far ...
Music & Audio
Sample-Delay Alignment Calculator
Translate a measured timing offset into DAW sample nudges, acoustic path difference, and predicted comb-filter notches.
Fire & Rescue Service
๐ซ SCBA Air Management & Turnaround Pressure
Rule of thirds, EOSTI activation pressure, the actual duration your cylinder will last at a real consumption rate, and how long your air has been going based on how much you have used.
SaaS & Business Killers
๐ฅ Screen & Camera Recorder Studio
Record your screen, your webcam, or your webcam as a picture-in-picture over your screen โ free, unlimited and watermark-free. Loom puts recording length and viewer counts behind a plan and Screenc...
Culinary & Food Science
๐ Seasonal Produce Calendar โ What to Buy This Month
A month-by-month seasonality chart for fruit, vegetables, herbs and foraged finds, with the peak weeks picked out, storage notes and a shopping list you can copy or print. Eating to the season is c...
SaaS & Business Killers
๐ Secure Vault โ Text & File Encryption
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...
SaaS & Business Killers
โ๏ธ Signature Pad โ Draw or Type, Save as PNG or SVG
Sign with a mouse, a finger or a stylus โ the line thickens as you slow down, the way a real pen does โ or type your name and get a script version. Save it as a transparent PNG to drop into a docum...
Productivity & Lifestyle
โ
To-Do List โ Simple, Offline, Remembers Itself
Type a task, press Enter, tick it off. Priorities, due dates with overdue warnings, reorder, filter and search โ and the list is still there tomorrow because it is saved in this browser. No account...
Health & Fitness
๐ญ Smoking Cost & Quit Savings Planner
A pack a day is a used car every year. Set what you actually smoke, pick a quit date, and watch the money timeline โ plus the recovery milestones your body hits along the way.
Culinary & Food Science
๐ถ๏ธ Spice Blend Scaler โ Homemade Mix Recipes
Supermarket blends are mostly salt and filler, and they go stale in the jar. Twelve classic blends as simple ratios here โ pick one, choose how much to make, and weigh it out.
Productivity & Lifestyle
๐ก Spin the Wheel โ Random Name & Decision Picker
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...
Music & Audio
Stereo & Mono Compatibility Analyzer
Measure stereo correlation, side energy, and mono fold-down loss from your mix without uploading it.
Productivity & Lifestyle
โฑ๏ธ Stopwatch & Precision Timer
Stopwatch with lap splits, countdown timer, and interval beeps โ all offline, no install. Great for workouts, cooking, presentations, and lab timing.
Fire & Rescue Service
๐ Tanker Shuttle Delivery Rate
How many gallons per minute a water tender shuttle can actually put on the fire โ NFPA 1142 cycle time, the 10 % unusable capacity allowance, and how many tenders you need for the flow you want.
Culinary & Food Science
๐ต Tea Brew Temperature & Steep Guide
Most โbadโ tea is just burnt tea. The right water temperature and steep time matter more than the brand โ pick your leaf and get the numbers, a steep timer and a re-steep plan.
SaaS & Business Killers
โ๏ธ Terms of Service Generator
Write a real set of terms for a small site, shop or SaaS product โ the document Termly, iubenda and Shopify's policy apps charge a monthly subscription to generate and re-host. Answer a dozen quest...
Productivity & Lifestyle
โฑ๏ธ Time Calculator โ Add, Subtract & Convert Hours and Minutes
Add up a list of times like 1:30 + 2h45m, find the hours and minutes between two clock times (overnight shifts included), add a duration to a start time, and convert decimal hours to h:mm or 24-hou...
SaaS & Business Killers
โฑ๏ธ Time Tracker & Timesheet Studio
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...
Health & Fitness
๐ Tinnitus & Hearing Relief Studio
Nothing here cures tinnitus โ 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...
Trucking & Freight
โ๏ธ Axle Weight & Bridge Formula Checker
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 โ in inches and in holes โ based ...
Trucking & Freight
๐ง Roadside Breakdown Triage
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...
Trucking & Freight
๐ต Cost Per Mile & Break-Even Rate
What a mile actually costs you to run โ fixed costs spread over the miles you really do, plus fuel, tyres, maintenance and driver pay โ and the rate per mile that leaves a profit rather than a stor...
Trucking & Freight
๐ Driving Hours & Duty Clock Planner
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...
Trucking & Freight
๐๏ธ Grade, Climb & Descent Calculator
What a grade actually means in degrees and feet, how fast your truck can hold it, and โ the part that ends careers โ how much heat a descent puts into your brakes, whether your retarder can carry i...
Trucking & Freight
๐ Load Offer Decider & Counter-Offer
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 ...
Trucking & Freight
๐ฆ Trailer Load & Pallet Planner
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 53โ van...
Trucking & Freight
๐งพ Pre-Trip Walkaround & DVIR Builder
A walkaround that follows the order you actually walk: paperwork, engine, cab and air brake tests, lights, tyres and brakes, coupling and trailer, securement. Tick what passes, flag what does not, ...
Trucking & Freight
๐ Stopping Distance & Following Gap
Where your truck actually stops โ thinking, brake lag and rubber on the road, added up โ and the following gap in seconds that goes with it. Change the surface, the grade or the load and watch the ...
Trucking & Freight
๐ Truck Tyre Load, Pressure & Temperature Check
Three checks a driver actually does: is this axle over its tyres' rating, is the pressure rise on the road normal or is something dragging, and do the tyres on a set of duals match closely enough t...
Health & Fitness
๐๏ธ 20-20-20 Eye Rest Timer
Optometristsโ rule for screen strain: every 20 minutes, look at something 6 metres (20 feet) away for 20 seconds. This runs the cycle for you โ start it when you sit down to work.
Finance & Money
๐ง UK Childcare Cost Calculator
Funded hours, Tax-Free Childcare and Universal Credit childcare stack in ways nobody explains at the nursery door โ and the difference between them is often more than a car payment. Put in what you...
Finance & Money
๐
ฟ๏ธ UK Parking Appeal Builder
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...
Finance & Money
๐ Prescription Prepayment (PPC) Checker โ England
More than one prescription a month? An NHS prepayment certificate caps the cost โ but only past the break-even point. Enter your items and see whether paying per item, 3-month or 12-month PPC wins.
Finance & Money
๐ UK Stamp Duty Land Tax Calculator
Estimate SDLT on residential purchases in England & Northern Ireland using HMRC bands. Covers standard, first-time buyer relief and additional-property surcharge. Estimates only โ not tax advic...
Science & Engineering
๐ Math Unit Converter
Convert length, area, mass, and temperature without hunting for formulas.
Finance & Money
๐ Wedding Budget Planner
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...
Health & Fitness
๐ Weight-Based Dose & Volume Calculator
mg/kg to milligrams, milligrams to millilitres at the strength you have, split across divided doses, with a hard-stop check against the maximum dose you set. No account, no data leaves the page.
Lucid Dreaming & Sleep
๐ง๏ธ White, Pink & Brown Noise โ Sleep & Focus Sound Machine
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 ...
Writing & Language
โ๏ธ Word Cloud Generator
Paste any text โ an article, a meeting transcript, a speech, your own journal โ and see what it is really about. Common filler words are stripped out, the survivors are sized by how often they appe...
Productivity & Lifestyle
๐ World Clock & Time Zone Board
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...
Science & Engineering
๐บ๏ธ World Map Geography Trainer
An interactive world map with all 195 countries (UN members + observers) โ every marker is a capital city. Explore flags, capitals and continents, then quiz yourself three ways: find the country on...
Finance & Money
๐ผ Zero-Capital Income Starter
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 โ with pricing maths, a 7-day launch plan ...
Mathematics
๐ Complex Function Landscape 3D
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...
Science & Engineering
๐ท Crystal Lattice & Unit Cell 3D
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...
Science & Engineering
โก Electric Field Lines 3D
Place point charges in 3D space and watch Coulomb field lines trace themselves from + to โ. Includes a potential heat-map plane, a movable probe that gives the exact field E, potential V and force ...
Science & Engineering
๐ Electromagnetic Wave & Polarization 3D
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...
Science & Engineering
โ๏ธ Hydrogen Atom Orbitals 3D
See the real quantum wavefunctions of hydrogen as glowing 3D probability clouds sampled from |ฯ|ยฒ, coloured by phase. Pick n, l and m, slice the cloud to reveal nodes, and calculate the energy, mea...
Astronomy & Space
๐ช Lagrange Points & Gravity Well 3D
See the five Lagrange points of any two-body system on a 3D effective-potential surface in the rotating frame. Computes L1โL5 distances, the Hill sphere and stability for SunโEarth, EarthโMoon, Sun...
Mathematics
๐ง Linear Transformation 3D Visualizer
Type any 3ร3 matrix and watch it smoothly warp space: the unit cube becomes a parallelepiped whose volume is the determinant, and real eigenvectors light up as the lines that only stretch. Computes...
Mathematics
๐ Polyhedra 3D Lab โ Platonic, Duals & Truncations
Explore the five Platonic solids and their Archimedean cousins in shaded 3D. Morph any solid into its truncation, overlay its dual, and get exact volume, surface area, in/mid/circumradius and dihed...
Mathematics
๐บ Solids of Revolution Volume Calculator 3D
Spin any curve y = f(x) around the x- or y-axis and watch the 3D solid form. Get the volume by disc/washer and shell methods, the surface area and centroid, with an optional inner curve for washers...
Mathematics
๐ Vector Field, Divergence & Curl 3D
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...
Science & Engineering
๐ Lorentz Force 3D โ Charged Particle in E & B Fields
Fire an electron, proton or ion into electric and magnetic fields and watch F = q(E + v ร B) carve glowing 3D paths โ cyclotron circles, helices, EรB drift and magnetic-mirror style spirals. Get th...
Mathematics
๐๏ธ Surface Curvature 3D โ Gaussian Curvature, Gradient & Critical Points
Type any surface z = f(x, y) and see its curvature painted onto it: warm where it bends like a dome (K > 0), cool where it curves like a saddle (K < 0). Move a probe to get the tangent plane,...
Mathematics
โ 3D Vector Calculator โ Dot, Cross & Triple Product Visualised
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...
Culinary & Food Science
๐พ Grow Your Calories
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 โ staples, protein and high-value veg โ with yields, calories, money s...
Wellbeing & Community
๐ค Mutual Credit Ledger
A working money system for a street, a club or a community โ with no bank in the middle. Every member starts at zero. Every exchange debits one member and credits another by exactly the same amount...
Home & DIY
๐ง Repair or Replace?
The throwaway economy wants you to bin it and buy another. This decider weighs the three things that actually matter โ cost per useful year, embodied carbon and remaining life โ and tells you hones...
Mathematics
๐งญ 3D Coordinate Converter โ Cartesian, Cylindrical & Spherical
Type a point in any system and the other two update instantly, with the point drawn in 3D and its radius and angles traced out so you can see what each number means. Switch between the physics (ISO...
Mathematics
๐ 3D Lines & Planes Calculator โ Distance, Intersection & Angle
Pick two objects โ point, line or plane โ and get the shortest distance, the intersection point or line, the angle between them and the closest points, all drawn in 3D. Handles parallel, skew, coin...
Mathematics
๐ง 3D Shape Volume & Surface Area Calculator
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 โ with the formula and work...
Use these tools on your own site
Embedding is free, forever, no account โ the small credit line under each tool is the entire price of the free tier, and it doubles as your backlink. A licence removes the credit line and puts your brand on the tool instead. Annual, and you cancel by simply not renewing.
Free embed
ยฃ0 / year
- All 1279 tools, any site
- Small credit line (required)
- No ads, no accounts, no paywalls
- Your branding
Single tool
ยฃ99 / year
- One tool, one site
- Credit line removed
- Your logo on the tool
- Statutory updates included
Most picked
Category
ยฃ299 / year
- Every tool in one category โ e.g. Finance & Money: 80 calculators
- Credit line removed, your logo
- Up to 3 sites
- Statutory updates included
Full white-label
ยฃ899 / year
- All 1279 tools, unlimited sites
- Your branding throughout
- Self-host option
- Statutory updates + priority fixes
Prices are per year and include all statutory updates while active. The finance tools are estimating tools, not financial advice: the statutory figures they use (tax bands, National Insurance, student-loan thresholds) are maintained against HMRC's published 2026/27 rules and enforced by automated checks that run on every deploy โ see the changelog for the update history. Visitors' inputs are processed in their own browser; the embeds collect nothing for us.
๐ Already bought a licence?
Paste the key we emailed you โ it starts with MUS1. Activation happens entirely in this browser: every snippet on this page switches to your licensed version (credit line removed, licence-checked against your domain) until you forget the key. Nothing is sent anywhere.
Licence activation isn't configured on this deployment yet โ the site owner hasn't published a verification key, so snippets below are the free credited tier. Email us about licences.