# toolhub

> Free online tools, calculators and converters. Every tool is also a JSON API (POST /api/<name>) and a web UI (/tools/<name>). No auth, no rate limits, privacy-friendly.

toolhub is a collection of fast, free, browser-based utilities. Each tool has:
- A human-friendly web page at /tools/<id>
- A machine-friendly JSON API at /api/<id> (or a per-operation endpoint) accepting POST with a JSON body and returning {"ok":true,"result":{...}}
- A copy-paste AI prompt and skill snippet on its web page

## Tools
- [Age Calculator](https://toolhub-5eo.pages.dev/tools/age-calculator): Calculate exact age in years, months, days from a birth date.. API: https://toolhub-5eo.pages.dev/api/age-calculator (POST)
- [BMI Calculator](https://toolhub-5eo.pages.dev/tools/bmi-calculator): Body Mass Index calculator with metric & imperial units.. API: https://toolhub-5eo.pages.dev/api/bmi-calculator (POST)
- [Percentage Calculator](https://toolhub-5eo.pages.dev/tools/percentage-calculator): Percentage of a number, percent change, increase/decrease.. API: https://toolhub-5eo.pages.dev/api/percentage-of (POST)
- [Password Generator](https://toolhub-5eo.pages.dev/tools/password-generator): Strong, random passwords generated locally in your browser.. API: https://toolhub-5eo.pages.dev/api/password-generator (POST)
- [Word Counter](https://toolhub-5eo.pages.dev/tools/word-counter): Count words, characters, sentences and reading time.. API: https://toolhub-5eo.pages.dev/api/word-counter (POST)
- [QR Code Generator](https://toolhub-5eo.pages.dev/tools/qr-code-generator): Create QR codes for links, text, Wi-Fi and more.. API: https://toolhub-5eo.pages.dev/api/qr-code-generator (POST)
- [Length Converter](https://toolhub-5eo.pages.dev/tools/length-converter): Convert meters, feet, inches, miles, km and more.. API: https://toolhub-5eo.pages.dev/api/length-converter (POST)
- [Loan Calculator](https://toolhub-5eo.pages.dev/tools/loan-calculator): Calculate monthly payments, total interest, and total cost for any loan.. API: https://toolhub-5eo.pages.dev/api/loan-calculator (POST)
- [Tip Calculator](https://toolhub-5eo.pages.dev/tools/tip-calculator): Calculate tips and split bills between any number of people.. API: https://toolhub-5eo.pages.dev/api/tip-calculator (POST)
- [Color Converter](https://toolhub-5eo.pages.dev/tools/color-converter): Convert between hex, RGB, and HSL color formats instantly.. API: https://toolhub-5eo.pages.dev/api/color-converter (POST)
- [Case Converter](https://toolhub-5eo.pages.dev/tools/case-converter): Convert text to uppercase, lowercase, title case, camelCase, and more.. API: https://toolhub-5eo.pages.dev/api/case-converter (POST)
- [Date Difference Calculator](https://toolhub-5eo.pages.dev/tools/date-difference): Calculate the number of days, weeks, and months between two dates.. API: https://toolhub-5eo.pages.dev/api/date-difference (POST)
- [Base64 Encoder & Decoder](https://toolhub-5eo.pages.dev/tools/base64-encoder): Encode text to Base64 or decode Base64 back to text instantly.. API: https://toolhub-5eo.pages.dev/api/base64-encoder (POST)
- [JSON Formatter](https://toolhub-5eo.pages.dev/tools/json-formatter): Format, validate, and beautify JSON with custom indentation.. API: https://toolhub-5eo.pages.dev/api/json-formatter (POST)
- [Temperature Converter](https://toolhub-5eo.pages.dev/tools/temperature-converter): Convert between Celsius, Fahrenheit, and Kelvin instantly.. API: https://toolhub-5eo.pages.dev/api/temperature-converter (POST)
- [Weight Converter](https://toolhub-5eo.pages.dev/tools/weight-converter): Convert between kilograms, pounds, ounces, grams, and more.. API: https://toolhub-5eo.pages.dev/api/weight-converter (POST)
- [Hash Generator](https://toolhub-5eo.pages.dev/tools/hash-generator): Generate SHA-1, SHA-256, SHA-384, and SHA-512 hashes instantly.. API: https://toolhub-5eo.pages.dev/api/hash-generator (POST)
- [URL Encoder & Decoder](https://toolhub-5eo.pages.dev/tools/url-encoder): Encode text for URLs or decode URL-encoded strings instantly.. API: https://toolhub-5eo.pages.dev/api/url-encoder (POST)
- [Number to Words](https://toolhub-5eo.pages.dev/tools/number-to-words): Convert any integer to its English word representation.. API: https://toolhub-5eo.pages.dev/api/number-to-words (POST)
- [Lorem Ipsum Generator](https://toolhub-5eo.pages.dev/tools/lorem-ipsum-generator): Generate placeholder Lorem Ipsum text for designs and mockups.. API: https://toolhub-5eo.pages.dev/api/lorem-ipsum-generator (POST)
- [Data Size Converter](https://toolhub-5eo.pages.dev/tools/data-size-converter): Convert between bytes, kilobytes, megabytes, gigabytes, and terabytes.. API: https://toolhub-5eo.pages.dev/api/data-size-converter (POST)
- [Random Number Generator](https://toolhub-5eo.pages.dev/tools/random-number-generator): Generate random numbers within a range using cryptographic randomness.. API: https://toolhub-5eo.pages.dev/api/random-number-generator (POST)
- [Markdown to HTML Converter](https://toolhub-5eo.pages.dev/tools/markdown-to-html): Convert Markdown text to clean HTML instantly in your browser.. API: https://toolhub-5eo.pages.dev/api/markdown-to-html (POST)
- [Text Reverser](https://toolhub-5eo.pages.dev/tools/text-reverser): Reverse text by characters, words, or lines instantly.. API: https://toolhub-5eo.pages.dev/api/text-reverser (POST)
- [Slug Generator](https://toolhub-5eo.pages.dev/tools/slug-generator): Convert text to URL-friendly slugs for web pages and blog posts.. API: https://toolhub-5eo.pages.dev/api/slug-generator (POST)
- [HTML Entity Encoder & Decoder](https://toolhub-5eo.pages.dev/tools/html-entity-encoder): Encode HTML entities or decode entity-encoded text instantly.. API: https://toolhub-5eo.pages.dev/api/html-entity-encoder (POST)
- [Compound Interest Calculator](https://toolhub-5eo.pages.dev/tools/compound-interest-calculator): Calculate compound interest with optional regular contributions.. API: https://toolhub-5eo.pages.dev/api/compound-interest-calculator (POST)
- [Discount Calculator](https://toolhub-5eo.pages.dev/tools/discount-calculator): Calculate sale prices, discounts, and savings instantly.. API: https://toolhub-5eo.pages.dev/api/discount-calculator (POST)
- [Sales Tax Calculator](https://toolhub-5eo.pages.dev/tools/sales-tax-calculator): Calculate sales tax on any purchase, before or after tax.. API: https://toolhub-5eo.pages.dev/api/sales-tax-calculator (POST)
- [Volume Converter](https://toolhub-5eo.pages.dev/tools/volume-converter): Convert between liters, gallons, cups, milliliters, and more.. API: https://toolhub-5eo.pages.dev/api/volume-converter (POST)
- [Area Converter](https://toolhub-5eo.pages.dev/tools/area-converter): Convert between square meters, square feet, acres, hectares, and more.. API: https://toolhub-5eo.pages.dev/api/area-converter (POST)
- [Speed Converter](https://toolhub-5eo.pages.dev/tools/speed-converter): Convert between mph, km/h, knots, meters per second, and more.. API: https://toolhub-5eo.pages.dev/api/speed-converter (POST)
- [Time Converter](https://toolhub-5eo.pages.dev/tools/time-converter): Convert between seconds, minutes, hours, days, weeks, months, and years.. API: https://toolhub-5eo.pages.dev/api/time-converter (POST)
- [UUID Generator](https://toolhub-5eo.pages.dev/tools/uuid-generator): Generate random UUID v4 identifiers instantly in your browser.. API: https://toolhub-5eo.pages.dev/api/uuid-generator (POST)
- [Fraction to Decimal Calculator](https://toolhub-5eo.pages.dev/tools/fraction-calculator): Convert fractions to decimals and simplify fractions instantly.. API: https://toolhub-5eo.pages.dev/api/fraction-calculator (POST)
- [GCD Calculator](https://toolhub-5eo.pages.dev/tools/gcd-calculator): Find the Greatest Common Divisor of two or more integers.. API: https://toolhub-5eo.pages.dev/api/gcd-calculator (POST)
- [Prime Number Checker](https://toolhub-5eo.pages.dev/tools/prime-checker): Check if a number is prime and find its smallest factor if not.. API: https://toolhub-5eo.pages.dev/api/prime-checker (POST)
- [Average Calculator](https://toolhub-5eo.pages.dev/tools/average-calculator): Calculate mean, median, and mode of any set of numbers.. API: https://toolhub-5eo.pages.dev/api/average-calculator (POST)
- [Roman Numeral Converter](https://toolhub-5eo.pages.dev/tools/roman-numeral-converter): Convert numbers to Roman numerals and Roman numerals to numbers.. API: https://toolhub-5eo.pages.dev/api/roman-numeral-converter (POST)
- [Character Counter](https://toolhub-5eo.pages.dev/tools/character-counter): Count total characters, unique characters, and frequency of each character.. API: https://toolhub-5eo.pages.dev/api/character-counter (POST)
- [LCM Calculator](https://toolhub-5eo.pages.dev/tools/lcm-calculator): Find the Least Common Multiple of two or more integers.. API: https://toolhub-5eo.pages.dev/api/lcm-calculator (POST)
- [Factorial Calculator](https://toolhub-5eo.pages.dev/tools/factorial-calculator): Calculate the factorial of any non-negative integer up to 170.. API: https://toolhub-5eo.pages.dev/api/factorial-calculator (POST)
- [Exponent Calculator](https://toolhub-5eo.pages.dev/tools/exponent-calculator): Calculate powers and exponents: base raised to any exponent.. API: https://toolhub-5eo.pages.dev/api/exponent-calculator (POST)
- [Ratio Calculator](https://toolhub-5eo.pages.dev/tools/ratio-calculator): Calculate and simplify ratios between two numbers.. API: https://toolhub-5eo.pages.dev/api/ratio-calculator (POST)
- [Circle Calculator](https://toolhub-5eo.pages.dev/tools/circle-calculator): Calculate the area, circumference, or diameter of a circle.. API: https://toolhub-5eo.pages.dev/api/circle-calculator (POST)
- [Savings Goal Calculator](https://toolhub-5eo.pages.dev/tools/savings-goal-calculator): Calculate how long it takes to reach your savings goal.. API: https://toolhub-5eo.pages.dev/api/savings-goal-calculator (POST)
- [Net Worth Calculator](https://toolhub-5eo.pages.dev/tools/net-worth-calculator): Calculate your net worth: total assets minus total liabilities.. API: https://toolhub-5eo.pages.dev/api/net-worth-calculator (POST)
- [Token Counter](https://toolhub-5eo.pages.dev/tools/token-counter): Estimate token count for LLM prompts (GPT-4, Claude, Llama, Mistral).. API: https://toolhub-5eo.pages.dev/api/token-counter (POST)
- [Regex Tester](https://toolhub-5eo.pages.dev/tools/regex-tester): Test regular expressions with live match highlighting and groups.. API: https://toolhub-5eo.pages.dev/api/regex-tester (POST)
- [JWT Decoder](https://toolhub-5eo.pages.dev/tools/jwt-decoder): Decode JSON Web Tokens and inspect header, payload, and expiry.. API: https://toolhub-5eo.pages.dev/api/jwt-decoder (POST)
- [Cron Expression Generator](https://toolhub-5eo.pages.dev/tools/cron-generator): Generate cron expressions for scheduled tasks with human-readable descriptions.. API: https://toolhub-5eo.pages.dev/api/cron-generator (POST)
- [CSS Gradient Generator](https://toolhub-5eo.pages.dev/tools/gradient-generator): Create CSS gradients (linear, radial, conic) with live preview.. API: https://toolhub-5eo.pages.dev/api/gradient-generator (POST)
- [Meta Tag Generator](https://toolhub-5eo.pages.dev/tools/meta-tag-generator): Generate SEO meta tags, Open Graph, Twitter Cards, and JSON-LD schema.. API: https://toolhub-5eo.pages.dev/api/meta-tag-generator (POST)
- [Hashtag Generator](https://toolhub-5eo.pages.dev/tools/hashtag-generator): Generate relevant hashtags from your text for social media posts.. API: https://toolhub-5eo.pages.dev/api/hashtag-generator (POST)
- [Password Strength Checker](https://toolhub-5eo.pages.dev/tools/password-strength-checker): Check how strong your password is and estimate crack time.. API: https://toolhub-5eo.pages.dev/api/password-strength-checker (POST)
- [BMR Calculator](https://toolhub-5eo.pages.dev/tools/bmr-calculator): Basal Metabolic Rate calculator using Mifflin-St Jeor or Harris-Benedict.. API: https://toolhub-5eo.pages.dev/api/bmr-calculator (POST)
- [Calorie Calculator](https://toolhub-5eo.pages.dev/tools/calorie-calculator): Daily calorie needs and TDEE calculator with activity levels and goals.. API: https://toolhub-5eo.pages.dev/api/calorie-calculator (POST)
- [Ideal Weight Calculator](https://toolhub-5eo.pages.dev/tools/ideal-weight-calculator): Ideal body weight calculator from four medical formulas.. API: https://toolhub-5eo.pages.dev/api/ideal-weight-calculator (POST)
- [Simple Interest Calculator](https://toolhub-5eo.pages.dev/tools/simple-interest-calculator): Simple interest calculator for loans, deposits, and investments.. API: https://toolhub-5eo.pages.dev/api/simple-interest-calculator (POST)
- [ROI Calculator](https://toolhub-5eo.pages.dev/tools/roi-calculator): Return on Investment calculator with annualized ROI.. API: https://toolhub-5eo.pages.dev/api/roi-calculator (POST)
- [Time Zone Converter](https://toolhub-5eo.pages.dev/tools/time-zone-converter): Convert a date and time between any two time zones.. API: https://toolhub-5eo.pages.dev/api/time-zone-converter (POST)
- [Mortgage Calculator](https://toolhub-5eo.pages.dev/tools/mortgage-calculator): Mortgage calculator with monthly payment, total paid, and interest.. API: https://toolhub-5eo.pages.dev/api/mortgage-calculator (POST)
- [Inflation Calculator](https://toolhub-5eo.pages.dev/tools/inflation-calculator): Inflation calculator: see how money loses value over time.. API: https://toolhub-5eo.pages.dev/api/inflation-calculator (POST)
- [Salary Calculator](https://toolhub-5eo.pages.dev/tools/salary-calculator): Convert hourly wage to annual, monthly, weekly, and daily salary.. API: https://toolhub-5eo.pages.dev/api/salary-calculator (POST)
- [Hex to RGB Converter](https://toolhub-5eo.pages.dev/tools/hex-to-rgb-converter): Convert hex colors to RGB and HSL with a live swatch.. API: https://toolhub-5eo.pages.dev/api/hex-to-rgb-converter (POST)
- [Binary Converter](https://toolhub-5eo.pages.dev/tools/binary-converter): Convert between binary, octal, decimal, and hex.. API: https://toolhub-5eo.pages.dev/api/binary-converter (POST)
- [Standard Deviation Calculator](https://toolhub-5eo.pages.dev/tools/standard-deviation-calculator): Standard deviation, variance, mean, and median of a dataset.. API: https://toolhub-5eo.pages.dev/api/standard-deviation-calculator (POST)
- [Permutation and Combination Calculator](https://toolhub-5eo.pages.dev/tools/permutation-combination-calculator): Calculate permutations (nPr) and combinations (nCr).. API: https://toolhub-5eo.pages.dev/api/permutation-combination-calculator (POST)
- [Quadratic Equation Solver](https://toolhub-5eo.pages.dev/tools/quadratic-equation-solver): Solve ax² + bx + c = 0 and find roots, discriminant, and nature.. API: https://toolhub-5eo.pages.dev/api/quadratic-equation-solver (POST)
- [Triangle Calculator](https://toolhub-5eo.pages.dev/tools/triangle-calculator): Solve a triangle from its three sides: area, perimeter, and angles.. API: https://toolhub-5eo.pages.dev/api/triangle-calculator (POST)
- [CSS Box Shadow Generator](https://toolhub-5eo.pages.dev/tools/css-box-shadow-generator): Generate CSS box-shadow with a live preview.. API: https://toolhub-5eo.pages.dev/api/css-box-shadow-generator (POST)
- [Dice Roller](https://toolhub-5eo.pages.dev/tools/dice-roller): Roll any number of dice with any number of sides.. API: https://toolhub-5eo.pages.dev/api/dice-roller (POST)
- [Lottery Number Generator](https://toolhub-5eo.pages.dev/tools/lottery-number-generator): Generate random lottery numbers from a range.. API: https://toolhub-5eo.pages.dev/api/lottery-number-generator (POST)
- [Morse Code Translator](https://toolhub-5eo.pages.dev/tools/morse-code-translator): Translate text to Morse code and Morse code back to text.. API: https://toolhub-5eo.pages.dev/api/morse-code-translator (POST)
- [Caesar Cipher](https://toolhub-5eo.pages.dev/tools/caesar-cipher): Encrypt and decrypt text with a Caesar (shift) cipher.. API: https://toolhub-5eo.pages.dev/api/caesar-cipher (POST)
- [Pig Latin Translator](https://toolhub-5eo.pages.dev/tools/pig-latin-translator): Translate English text into Pig Latin.. API: https://toolhub-5eo.pages.dev/api/pig-latin-translator (POST)
- [Email Validator](https://toolhub-5eo.pages.dev/tools/email-validator): Check if an email address is valid and well-formed.. API: https://toolhub-5eo.pages.dev/api/email-validator (POST)
- [URL Parser](https://toolhub-5eo.pages.dev/tools/url-parser): Break a URL into protocol, host, path, query, and fragment.. API: https://toolhub-5eo.pages.dev/api/url-parser (POST)
- [Scientific Notation Converter](https://toolhub-5eo.pages.dev/tools/scientific-notation-converter): Convert between decimal and scientific notation.. API: https://toolhub-5eo.pages.dev/api/scientific-notation-converter (POST)
- [Decimal to Fraction Converter](https://toolhub-5eo.pages.dev/tools/decimal-to-fraction-converter): Convert any decimal to a simplified fraction.. API: https://toolhub-5eo.pages.dev/api/decimal-to-fraction-converter (POST)
- [Remove Duplicate Lines](https://toolhub-5eo.pages.dev/tools/remove-duplicate-lines): Remove duplicate lines from a list, keeping the first.. API: https://toolhub-5eo.pages.dev/api/remove-duplicate-lines (POST)
- [Find and Replace Text](https://toolhub-5eo.pages.dev/tools/find-and-replace-text): Find and replace text with literal or regex matching.. API: https://toolhub-5eo.pages.dev/api/find-and-replace-text (POST)
- [JSON to CSV Converter](https://toolhub-5eo.pages.dev/tools/json-to-csv-converter): Convert a JSON array of objects to CSV.. API: https://toolhub-5eo.pages.dev/api/json-to-csv-converter (POST)
- [CSV to JSON Converter](https://toolhub-5eo.pages.dev/tools/csv-to-json-converter): Convert CSV data to a JSON array of objects.. API: https://toolhub-5eo.pages.dev/api/csv-to-json-converter (POST)
- [Color Contrast Checker](https://toolhub-5eo.pages.dev/tools/color-contrast-checker): Check WCAG color contrast between two colors.. API: https://toolhub-5eo.pages.dev/api/color-contrast-checker (POST)
- [Fraction Simplifier](https://toolhub-5eo.pages.dev/tools/fraction-simplifier): Reduce a fraction to its simplest form.. API: https://toolhub-5eo.pages.dev/api/fraction-simplifier (POST)
- [LCM Calculator](https://toolhub-5eo.pages.dev/tools/least-common-multiple-calculator): Find the least common multiple of two or more numbers.. API: https://toolhub-5eo.pages.dev/api/least-common-multiple-calculator (POST)
- [Decimal to Percent Converter](https://toolhub-5eo.pages.dev/tools/decimal-to-percent-converter): Convert between decimals and percentages.. API: https://toolhub-5eo.pages.dev/api/decimal-to-percent-converter (POST)
- [Aspect Ratio Calculator](https://toolhub-5eo.pages.dev/tools/aspect-ratio-calculator): Reduce width and height to a simple aspect ratio.. API: https://toolhub-5eo.pages.dev/api/aspect-ratio-calculator (POST)
- [CSS Minifier](https://toolhub-5eo.pages.dev/tools/css-minifier): Minify CSS by removing comments and whitespace.. API: https://toolhub-5eo.pages.dev/api/css-minifier (POST)
- [JavaScript Minifier](https://toolhub-5eo.pages.dev/tools/js-minifier): Minify JavaScript by removing comments and whitespace.. API: https://toolhub-5eo.pages.dev/api/js-minifier (POST)
- [Fraction to Decimal Converter](https://toolhub-5eo.pages.dev/tools/fraction-to-decimal-converter): Convert a fraction to a decimal and detect repeating cycles.. API: https://toolhub-5eo.pages.dev/api/fraction-to-decimal-converter (POST)
- [HTML Minifier](https://toolhub-5eo.pages.dev/tools/html-minifier): Minify HTML by removing comments and whitespace.. API: https://toolhub-5eo.pages.dev/api/html-minifier (POST)
- [SQL Formatter](https://toolhub-5eo.pages.dev/tools/sql-formatter): Format and beautify SQL queries with indentation.. API: https://toolhub-5eo.pages.dev/api/sql-formatter (POST)
- [Leap Year Checker](https://toolhub-5eo.pages.dev/tools/leap-year-checker): Check whether any year is a leap year.. API: https://toolhub-5eo.pages.dev/api/leap-year-checker (POST)
- [HTML to Text Converter](https://toolhub-5eo.pages.dev/tools/html-to-text): Strip HTML tags and convert to plain text.. API: https://toolhub-5eo.pages.dev/api/html-to-text (POST)
- [Word Frequency Counter](https://toolhub-5eo.pages.dev/tools/word-frequency-counter): Count how often each word appears in text.. API: https://toolhub-5eo.pages.dev/api/word-frequency-counter (POST)

## API usage
Send a POST request with a JSON body. Example:
```
curl -X POST https://toolhub-5eo.pages.dev/api/percentage-of -H "Content-Type: application/json" -d '{"x":20,"y":50}'
# => {"ok":true,"result":{"result":10}}
```
GET on any endpoint returns its schema and example.

## Machine-readable specs
- OpenAPI 3.1: https://toolhub-5eo.pages.dev/openapi.json
- OpenAI function-calling definitions: https://toolhub-5eo.pages.dev/functions.json
- AI manifest: https://toolhub-5eo.pages.dev/ai.json
- Sitemap: https://toolhub-5eo.pages.dev/sitemap.xml

## Notes
- All compute runs on Cloudflare's edge (free tier). No data is stored.
- CORS is enabled (`Access-Control-Allow-Origin: *`).
- The full, detailed guide for LLMs is at https://toolhub-5eo.pages.dev/llms-full.txt