Free Online Developer Tools
Everyday utilities for software engineers. Tokens, payloads and code stay in your browser, which matters when you are debugging real credentials or production data.
Developer Tools (16)
JSON Formatter
Beautify, validate and pretty-print JSON with clear error locations.JSON Validator
Check whether JSON is valid and see the exact line, column and caret of any syntax error.JSON Minifier
Strip all whitespace from JSON and see how many bytes you save.JWT Decoder
Read a JSON Web Token's header and claims, with readable expiry times. Signatures are not verified.Base64 Encoder
Encode UTF-8 text or any file up to 10 MB to Base64, with URL-safe and 76-column options.Base64 Decoder
Decode Base64 or Base64URL to text, or save binary data as a file with its type detected.URL Encoder
Percent-encode text for URLs using component, full-URL or HTML form rules.URL Decoder
Decode percent-encoded text and break any URL down into host, path and query parameters.UUID Generator
Generate up to 1,000 random v4 or time-ordered v7 UUIDs and inspect any UUID's version.Regex Tester
Test JavaScript regular expressions with live highlighting, capture groups and replace preview.HTML Formatter
Beautify HTML with Prettier, including embedded CSS and JavaScript, with configurable indentation.CSS Formatter
Beautify CSS, SCSS or Less with Prettier, or minify plain CSS and see the bytes saved.JavaScript Formatter
Format JavaScript, JSX, TypeScript and TSX with Prettier and your preferred style options.YAML to JSON Converter
Convert YAML to JSON (multi-document aware) or JSON back to YAML with precise error locations.Unix Timestamp Converter
Convert Unix epoch timestamps to dates and back, with unit auto-detection and time zones.HTML Entity Encoder
Escape text into HTML entities or decode named, decimal and hex entities back to characters.
About these developer tools
Many online developer tools send whatever you paste to a server. That is a real risk when the input is an access token, an API response containing customer data or proprietary source code. Every tool in this category runs entirely client-side.
Formatters use Prettier, the same formatter many teams run in their editors, so output matches common code style. Validators report precise error positions, and the regex tester runs patterns in an isolated worker with a timeout to protect against catastrophic backtracking.
Frequently asked questions
Does the JWT decoder verify signatures?
No. It decodes the header and payload, which are only Base64URL-encoded, and checks expiry times. Verifying a signature requires the signing secret or public key and should be done by your server.
Is code I format executed?
No. Code is parsed and re-printed by Prettier. Nothing you paste is evaluated or executed.