Free Online Developer Tools
Format, encode, generate, and convert data. Essential developer utilities that run in your browser.
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About DevKit
DevKit provides essential developer tools that run entirely in your browser. Format JSON, decode JWTs, generate UUIDs, test regex patterns, convert colors, and much more. No data ever leaves your machine.
What Is DevKit?
DevKit is a browser-based collection of utilities that developers use daily. It covers four main categories: formatting (JSON, XML, SQL, CSS beautification and minification), encoding and decoding (Base64, URL encoding, JWT decoding, HTML entities), generation (UUIDs, passwords, regex testing, color conversion), and hashing and data tools (MD5/SHA hashing, diff checking, timestamp conversion). Every tool runs entirely in your browser — no API calls, no server-side processing, no data leaving your machine.
These tools replace the scattered collection of bookmarks most developers maintain. Instead of visiting six different sites to format JSON, decode a JWT, generate a UUID, and test a regex, DevKit puts them all in one place with a consistent interface. The tools are built for speed — results appear as you type, and there are no ads blocking your workflow.
Why DevKit?
- 100% Client-Side: Your data never leaves your browser
- No Registration: Use any tool instantly, no account needed
- Developer-Focused: Built by developers, for developers
- Always Free: No premium tiers or usage limits
Frequently Asked Questions
How does the JSON formatter work?
The JSON formatter parses your input using JavaScript's native JSON.parse() function and then re-serializes it with configurable indentation (2 spaces, 4 spaces, or tabs). It detects and highlights syntax errors with line numbers, validates the structure, and supports both beautification (expanding minified JSON) and minification (compressing formatted JSON). It handles nested objects, arrays, and all JSON data types.
What is a regex tester and how do I use it?
The regex tester lets you write a regular expression pattern and test it against sample text in real time. It highlights all matches, shows capture groups, and supports JavaScript regex flags (global, case-insensitive, multiline, dotAll, unicode). This is useful for debugging patterns before using them in code, validating email formats, extracting data from log files, or learning regex syntax.
Are UUIDs generated by DevKit truly unique?
The UUID generator creates version 4 UUIDs using the Web Crypto API (crypto.randomUUID() or crypto.getRandomValues()). V4 UUIDs contain 122 random bits, giving a probability of collision so low (about 1 in 5.3 x 10^36) that it is effectively zero for any practical application. You can safely use these UUIDs as database primary keys, session identifiers, or any other context requiring unique identifiers.
Is it safe to decode JWTs with DevKit?
Yes. The JWT decoder runs entirely in your browser — no tokens are transmitted to any server. It decodes the header and payload sections of a JWT (which are Base64URL-encoded, not encrypted) and displays them as formatted JSON. Note that decoding a JWT does not verify its signature; for signature verification, you need the signing key and a backend library.
What hash algorithms are supported?
The hash generator supports MD5, SHA-1, SHA-256, SHA-384, and SHA-512. SHA-256 and SHA-512 are the most commonly used for security purposes today. MD5 and SHA-1 are provided for legacy compatibility and checksum verification but should not be used for security-sensitive applications as they have known collision vulnerabilities.