Developer tools that run in the browser have one major advantage over desktop software: they're always available, on any machine, without installation. Here's a roundup of the most useful free developer utilities available.
Data Formatting
JSON Formatter — Paste unformatted JSON and get back clean, indented, readable output in milliseconds. Also validates your JSON and highlights errors. Essential for anyone working with APIs.
Regex Tester — Write a regular expression and test it against sample text in real time. Highlights all matches and capture groups. Supports flags (global, case-insensitive, multiline). One of the most-used tools for backend and frontend developers alike.
SQL Formatter — Format messy SQL queries into readable, properly indented statements. Handles SELECT, INSERT, UPDATE, DELETE, and JOINs.
HTML Formatter — Beautify compressed or poorly formatted HTML. Useful when working with minified templates or debugging rendered markup.
Security & Tokens
Password Generator — Generate cryptographically secure passwords with full control over length and character types. Uses the Web Crypto API for true randomness — not pseudo-random.
Hash Generator — Compute MD5, SHA-1, SHA-256, and SHA-512 hashes from any text. Useful for checksum verification, creating content hashes, and testing hash functions.
UUID Generator — Generate RFC 4122 v4 UUIDs in bulk. Essential for database primary keys, API identifiers, and session tokens.
JWT Decoder — Decode and inspect JSON Web Tokens without verification. View the header, payload claims, and expiration time. Everything stays client-side — never paste production tokens into a third-party server.
Generators
QR Code Generator — Convert any text or URL into a downloadable QR code PNG. Works offline after page load.
Lorem Ipsum Generator — Generate placeholder text in paragraphs, sentences, or words. Configurable length and style.
Cron Expression Builder — Build cron job schedules visually without memorizing the syntax. Shows a plain-English description of when your cron will run.
CSS & Design
CSS Gradient Generator — Create linear and radial CSS gradients with a visual picker. Copy the ready-to-use CSS code directly.
CSS Button Generator — Design custom buttons visually and export the CSS. Adjust colors, borders, shadows, hover effects, and more.
CSS Glassmorphism Generator — Generate the frosted-glass CSS effect popular in modern UI design. Adjust blur, transparency, and border with live preview.
Color Picker — Pick any color with a visual selector and get the HEX, RGB, and HSL values instantly.
All tools are completely free, run client-side with no data collection, and require no account or installation. They work in any modern browser.