Free Online Developer Tools
Format JSON, decode JWTs, generate hashes and UUIDs, test regex, and convert between number bases — everyday tools for building software.
JSON Formatter
Prettify, minify and validate JSON, with a collapsible tree view.
Base64 Encoder / Decoder
Encode or decode text and files to and from Base64, entirely in your browser.
Password Generator
Generate a strong random password with a configurable length and character set, plus a strength meter.
URL Encoder / Decoder
Encode or decode text for safe use in a URL.
JWT Decoder
Decode a JWT's header and payload live, entirely in your browser.
Regex Tester
Test a regular expression against sample text with live match highlighting.
Hash Generator
Generate MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes from text.
UUID Generator
Generate one or many random v4 UUIDs.
Timestamp Converter
Convert Unix timestamps to dates and back, with relative time.
Binary / Hex Converter
Convert between binary, octal, decimal, hex and a character, live.
Cron Expression Generator
Build a cron expression with a plain-English description and next run times.
HTML / CSS / JS Formatter
Beautify or minify HTML, CSS and JavaScript in your browser.
CSV ↔ JSON Converter
Convert between CSV and a JSON array of objects.
Fake Data Generator
Generate fake names, addresses, phones and emails for testing. Copy as JSON or CSV.
Frequently asked questions
- Yes — every tool in this category is free to use, with no sign-up and no usage limits.
- No. Everything runs in your browser (or through our server for the tools that need one) — no downloads, no extensions, no account.
- No. Files and inputs are processed to produce your result and are not stored afterward.