⭐ Most-used · 60 picks

Popular free tools, ready in one click

The 60 tools people open the most — calculators, converters, generators, and a few delightful surprises. Every one is free, runs in your browser, and never asks for an account.

🎲 Surprise Me (Random Tool) Explore All 1424 Tools →

The ＋ on any card saves that tool into your toolbox — a private shortlist kept in this browser, no account, and the whole catalogue is filterable here →

💰 Money & finance 12 tools

Mortgage Calculator

Monthly payments, total interest, full amortisation schedule.

Compound Interest

See exactly how your savings grow year by year.

Loan Calculator

Personal, auto, or student loans with extra-payment scenarios.

Salary Calculator

Hourly to annual, take-home pay, gross/net breakdown.

Tax Calculator

UK income tax, National Insurance, and pension estimates.

Tip Calculator

Split the bill fairly, with custom tipcalculator percentages.

Currency Converter

Live exchange rates for 150+ currencies, no signup.

Discount Calculator

Sale price, savings, and the actual percentage off.

Inflation Calculator

What was £100 in 1990 worth in 2024? Find out.

ROI Calculator

Return on investment with time, cash flow and IRR.

Break-Even Calculator

How many units until you cover your costs?

FIRE Calculator

Financial Independence Retire Early — your number, your date.

📐 Math & conversion 10 tools

Percentage Calculator

Increase, decrease, difference, percent of.

Universal Unit Matrix

Length, mass, volume, area, time, speed, energy.

Scientific Units

Newtons, joules, pascals, watts, kelvin and more.

Algebra Solver

Solve linear, quadratic, and cubic equations step by step.

Equation Solver

Symbolic math — single variable, polynomials, radicals.

Graphing Calculator

Plot functions, intersections, derivatives, on a real grid.

Hex / Decimal / Binary

Convert between bases 2, 8, 10, 16 — and ASCII.

Date Calculator

Days between dates, add/subtract, age on a date.

Statistics Calculator

Mean, median, mode, std dev, quartiles, regression.

Probability Calculator

Combinations, permutations, distributions, Bayes.

🛠️ For developers 10 tools

JSON Formatter & Linter

Pretty-print, validate, minify, sort keys, escape.

JWT Decoder

Decode header, payload and signature. No data leaves your browser.

Image to Base64

Convert any image to a data URL — for inline embedding.

Hash Generator

MD5, SHA-1, SHA-256, SHA-512 — for files and text.

Subnet CIDR Calculator

Network, broadcast, usable range, host count from any CIDR.

SEO Studio

Audit a page, then preview how it looks in Google and on social media.

Social Preview Generator

Open Graph & Twitter card preview, all platforms.

ASCII Banner Generator

Big text for READMEs, terminals, commit messages.

SVG Path Visualizer

Edit SVG paths with a live preview, copy the result.

Prompt Injection Lab

Test your prompts against common injection techniques.

📝 Writing & productivity 8 tools

Password Generator

Strong random passwords, length and character set control.

UUID Generator

v1, v4, v7 — bulk generate, format, copy.

Invoice Generator

Branded PDF invoices, no signup, no watermark.

Markdown Live Editor

Side-by-side editor + preview, export to HTML.

Apology Builder

Honest, specific, short — the parts of an apology that work.

Habit Streak Grid

GitHub-style year heatmap for your daily habits.

Resume ATS Scanner

Check whether your resume gets past the bot filter.

Blame Deflector

Polite phrasing for the workplace — when it's not your fault.

🎵 Music & audio 6 tools

BPM Tapper

Tap to the beat — instant tempo, no signup.

Tone Generator

Pure sine/square/saw tones, 20Hz–20kHz, save as WAV.

Metronome

Adjustable tempo, time signatures, accent patterns.

Chord Finder

Find chords by name, see fingerings, hear them.

Chord Transposer

Move any song into the key that suits your voice.

Ear Trainer

Intervals, chords, scales — practice mode with scoring.

🏥 Health, fitness & food 6 tools

BMI Calculator

Body Mass Index with healthy range, metric and imperial.

BMR & TDEE Calculator

Basal metabolic rate and Total Daily Energy Expenditure, by activity level.

Calorie Calculator

Maintenance, deficit, surplus — based on your real TDEE.

Macro Calculator

Protein, fat, carb split for any goal.

Sous Vide Cooker

Time & temperature tables for every cut of meat.

Sourdough Hydration

Flour, water, salt — by weight, not guesswork.

🎨 Design & visual 4 tools

Color Palette Extractor

Drop in an image, get the dominant colours with hex codes.

WCAG Contrast Checker

AA/AAA contrast, plus colour-blindness simulation.

Aspect Ratio Resizer

16:9, 1:1, 4:5 — keep what matters, crop the rest.

Favicon Generator

Multi-resolution .ico + Apple touch + manifest icons.

🔮 A few delightful surprises 4 tools

Black Hole Lensing

Real-time general-relativity ray tracer in your browser.

Turing Patterns

Reaction-diffusion morphogenesis — like real animal coats.

Van de Graaff 400kV

Interactive electrostatic generator simulation.

Aurora Borealis

Magnetic-field-driven atmospheric plasma simulation.

See the full 1424-tool catalogue

Search, filter by category, or browse directory view. Every tool is free, runs offline once loaded, and never asks for an account.

Browse all 1424 tools → By use case Just added Help & FAQ