Free Online Developer Tools
8 tools
Format, compare, encode and inspect the data you handle every day without opening an editor. These tools treat your input strictly as text or data: it is never run or sent anywhere.
All Developer Tools
JSON Formatter & Validator
Format, validate and minify JSON, with exact error locations. Runs in your browser.
JSON Compare
Compare two JSON documents and see every added, removed and changed value by path.
Base64 Encoder & Decoder
Encode text to Base64 or decode Base64 back to text, with URL-safe and Unicode support.
URL Encoder & Decoder
Percent-encode or decode text and URLs, and see a URL split into parts and query parameters.
JWT Parser & Decoder
Decode a JSON Web Token to read its header, payload, claims and expiry. Nothing is uploaded.
Swagger / OpenAPI Editor
Edit OpenAPI or Swagger YAML and JSON with live checks and an endpoint preview.
HTML Formatter
Beautify messy HTML with clean indentation. Your code is never executed.
CSS Minifier
Remove comments and whitespace from CSS to reduce file size safely.
Safe by design
Pasting code, tokens or API definitions into a website can feel risky. These tools parse your input as plain text or data; they do not render HTML, evaluate scripts or load remote resources mentioned in your input. Even so, treat live secrets such as production tokens with care, and prefer test values when you can.
What the tools are, and are not
The decoders explain what is inside a value but do not verify it: a decoded JWT is not proof that a token is genuine, and Base64 is an encoding, not encryption. The API editor checks structure and previews your definition, but it is not a complete OpenAPI validator.
Frequently asked questions
Is my code sent to a server?
No. Formatting, comparing, encoding and decoding all happen in your browser, and your input is not stored.
Will the minifier break my CSS?
It only removes comments and unnecessary whitespace and keeps strings, URLs and calc() expressions intact. Even so, test minified files before deploying, as you would with any build step.