Developer Tools Online for Free
Format JSON, encode, test code and API utilities. Everything works instantly with nothing to install, and your files are never kept longer than it takes to deliver your result.
All Developer Tools
JSON Formatter
Format and validate JSON code instantly
Base64 Encoder
Encode or decode text and files in Base64
Regex Tester
Test your regular expressions against real text instantly
Diff Checker
Compare two texts or code snippets and see the differences clearly
UUID Generator
Generate unique UUIDs (v4) with one click
Hash Generator
Compute MD5, SHA-1, SHA-256 and more for any text instantly
Password Generator
Generate strong, random passwords with the length and characters you choose
Color Converter
Convert between HEX, RGB and HSL instantly with a live preview
QR Code Generator
Turn any link or text into a QR code ready to download and print
JSON Validator
Instantly validate JSON code and find exactly where the error is
XML Formatter
Format XML code with clear indentation and validate it instantly
HTML Formatter
Format HTML code with clear, organized indentation instantly
CSS Beautifier
Beautify minified CSS into a clear, readable format instantly
CSS Minifier
Minify CSS code and reduce its size instantly
JS Beautifier
Beautify minified JavaScript into a clear, readable format instantly
JS Minifier
Minify JavaScript code and reduce its size instantly
SQL Formatter
Format SQL queries into a clear, readable layout instantly
JWT Decoder
Decode a JWT token and view its Header and Payload instantly
Live Code Playground
Write HTML, CSS and JavaScript and see the result instantly in a live split-screen preview
Frequently Asked Questions
Are Developer Tools completely free?
Yes, all Developer Tools on Fastols are 100% free with no usage limit, and no account sign-up required.
Are my files and data safe?
Your privacy matters to us — nothing is shared with third parties, and your files are never kept longer than it takes to deliver your result.
Do I need to install any software?
No installation needed — Developer Tools work instantly on any device, from desktop to mobile.