Free Developer Tools

A collection of free online tools for software developers and engineers. Format, validate, encode, decode, and test — all from your browser, nothing to install.

Why Every Developer Needs These Tools

Software development involves countless small, repetitive tasks: formatting JSON responses, testing regular expressions, encoding strings for URLs, decoding Base64 data, formatting SQL queries, and validating data structures. You could write one-off scripts for each task — or you could use these tools and get back to building features.

Most of these tools process data entirely in your browser. No data leaves your device. This is critical for developers working with proprietary code, API keys, or sensitive configuration data — you can't risk pasting that into a random website.

Available Developer Tools

JSON Formatter & Validator

The most-used tool on Supertools. Paste minified JSON, get syntax-highlighted, properly indented output. Validates structure, detects errors, and supports collapsible tree view. Essential for debugging API responses, reading config files, and reviewing data exports.

Regex Tester

Write, test, and debug regular expressions with real-time match highlighting. Supports JavaScript, Python, and PCRE flavors. See exactly what your pattern matches — no more guess-and-check in the console.

Base64 Encoder/Decoder

Encode text to Base64 and decode it back. Supports UTF-8, binary data, and handles the edge cases that trip up command-line tools. Used for data URIs, email attachments, JWT tokens, and API authentication headers.

JWT Decoder

Decode JSON Web Tokens to inspect header, payload, and signature claims. All processing is local — your tokens never hit a server. Essential for debugging authentication issues.

SQL Formatter

Take unformatted SQL and turn it into clean, readable, properly indented queries. Supports PostgreSQL, MySQL, SQL Server, and SQLite. Capitalizes keywords, aligns clauses, and makes complex queries maintainable.

Additional Tools

URL Encoder/Decoder · MD5/SHA Hash Generator · UUID Generator (v4 and v1) · Text Diff (side-by-side comparison) · Cron Parser (human-readable cron expressions) · HTML Entity Encoder · HTML Minifier · XML & YAML Formatters · JSON Converter · CSS Grid & Flexbox Generators · and more.

Developer Workflow Tips

Bookmark the tools you use most. Keep JSON Formatter, Regex Tester, and Base64 Encoder one click away. They replace several command-line utilities and are instantly available.

Use during code reviews. When reviewing a PR, paste complex regex patterns into the tester to understand what they match. Format messy JSON or SQL to verify correctness before approving.

Pair with AI tools. Found a bug? Use the AI Error Explainer to understand it. Need code? Use AI Code Generator. Then format the output with the developer tools.