Everything You Need to Build, Learn & Calculate
Free developer tools, calculators, converters, an online code editor, and structured programming-language learning — all in one place, running entirely in your browser.
Everything, organized
Jump straight to the section you need — every tool, calculator, and lesson lives in one focused place.
Popular free tools
A few of the most-used tools — formatters, generators, and converters people reach for daily.
JSON Formatter
Pretty-print and indent minified or messy JSON.
JSON Validator
Check whether a JSON document is syntactically valid.
Word Counter
Count words, characters, sentences, and paragraphs.
UUID Generator
Generate random version 4 UUIDs.
Latest from our blog
Guides, tips, and behind-the-scenes notes from the team.
HTTP Status Codes Explained: A Practical Guide to Understanding 200, 301, 400, 401, 403, 404 and 500 Errors
Have you ever opened a website and suddenly encountered a 404 Not Found message? Or tried calling an API only to receive a confusing 401 Unauthorized or 500 Internal Server Error response?
Percentage Calculator – How to Calculate Percentages Online with Practical Examples
Percentages are used in everyday life, from calculating shopping discounts and sales tax to understanding exam results, business growth, and financial reports. Whether you want to find 15% of a number, calculate a percentage increase, or determine how much you saved during a sale, understanding percentages makes these calculations much easier.
HTML, CSS and JavaScript Minifier: How to Minify Code Online and Improve Website Performance
Website performance plays an important role in user experience, search engine optimization, and overall website efficiency. One way developers can improve frontend asset delivery is by reducing the size of HTML, CSS, and JavaScript files.
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A growing collection of useful tools and lessons designed to get things done quickly, without unnecessary complexity.
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