Free Developer Tools
A fast toolbox for developers — format, encode, decode, hash and inspect data without leaving the browser.
JSON Formatter
Format, beautify and minify JSON instantly.
JSON Validator
Validate JSON and pinpoint syntax errors.
Base64 Encoder
Encode text to Base64 (UTF-8 safe).
Base64 Decoder
Decode Base64 back to readable text.
URL Encoder
Percent-encode text for safe use in URLs.
URL Decoder
Decode percent-encoded URLs back to text.
UUID Generator
Generate random v4 UUIDs in bulk.
Hash Generator
Generate SHA-1, SHA-256, SHA-384 and SHA-512 hashes.
Timestamp Converter
Convert Unix timestamps to dates and back.
JWT Decoder
Decode and inspect JWT header and payload claims.
Free Developer Tools that respect your privacy
These developer utilities cover the daily essentials: formatting and validating JSON, encoding and decoding Base64 and URLs, generating UUIDs and secure hashes, decoding JWTs and converting timestamps. Everything runs client-side using native web APIs, so large payloads and sensitive tokens never touch a server.
Every tool runs in your browser — nothing is uploaded.
Frequently asked questions
Is my data sent to a server?
No — all developer tools process data locally in your browser.
Can I use these for large payloads?
Yes, they handle large inputs because processing happens on your device.
Explore more collections
Looking for something specific? Browse all Crystal Toolkit tools or view tools by category.