50+ Free Tools for Developers | Utilko
The best free online tools for web developers and software engineers — JSON formatters, code minifiers, regex testers, UUID generators, hash tools, and more. No sign-up required.
Free Online Tools for Developers
Utilko is the developer's toolbox for quick, browser-based utilities that don't require installing packages or signing up for accounts. Every tool runs locally in your browser — your code and data never leave your machine.
JSON Tools
- JSON Formatter — Beautify and validate JSON instantly. Identifies syntax errors before you paste into your app.
- JSON Minifier — Strip whitespace from JSON to reduce API payload size.
- JSON to CSV — Export JSON arrays to spreadsheet-ready CSV files.
- JSON to YAML — Convert JSON configs to YAML for Kubernetes, Docker Compose, and CI pipelines.
Encoding & Decoding
- Base64 Encoder/Decoder — Encode binary data or images to Base64 for embedding in JSON or HTML.
- URL Encoder/Decoder — Percent-encode query strings for safe URL transmission.
- HTML Encoder/Decoder — Escape HTML entities to prevent XSS in template strings.
- JWT Decoder — Decode and inspect JSON Web Token payloads without verifying the signature.
Code & Formatting Tools
- Diff Checker — Compare two code snippets or text files and see the differences highlighted.
- Regex Tester — Test regular expressions with real-time match highlighting and capture group output.
- SQL Formatter — Beautify SQL queries for readability in code reviews and documentation.
- XML Formatter — Format and validate XML documents with proper indentation.
- Code Beautifier — Format JavaScript, CSS, HTML, and other languages.
Minifiers
- CSS Minifier — Compress CSS files for faster page loads.
- JavaScript Minifier — Strip whitespace and comments from JS for production bundles.
- HTML Minifier — Remove unnecessary whitespace from HTML templates.
Utility Tools
- UUID Generator — Generate UUID v4 values for database primary keys and session tokens.
- Hash Generator — Generate MD5, SHA-1, SHA-256, and SHA-512 hashes for checksums and security.
- Color Converter — Convert between HEX, RGB, HSL, and CMYK color codes.
- Unix Timestamp Converter — Convert Unix timestamps to human-readable dates and back.
- Cron Expression Generator — Build cron schedules visually and verify they run when expected.
- HTTP Status Codes — Full reference for all HTTP response codes with descriptions.
Markdown & Documentation
- Markdown to HTML — Convert Markdown to HTML for READMEs, blogs, and documentation sites.
- HTML to Markdown — Convert webpage HTML back to clean Markdown.
Featured Tools
Try these free tools directly in your browser — no sign-up required.
JSON Formatter
Format, beautify, and validate JSON instantly. Paste raw JSON and get a clean, indented, human-readable output with syntax error detection.
JSON Minifier
Minify and compress JSON by removing whitespace and comments. Reduce JSON payload size instantly for faster API responses and smaller storage footprint.
Regex Tester
Test and debug regular expressions in real time. Highlights matches, capture groups, and supports JavaScript regex flags for instant pattern validation.
UUID Generator
Generate UUID v1, v4, and v5 universally unique identifiers instantly. Create single or bulk UUIDs for databases, APIs, and distributed systems.
Hash Generator
Generate cryptographic hashes for any text using MD5, SHA-1, SHA-256, SHA-512, and more. Verify data integrity and create checksums instantly online.
Diff Checker
Compare two texts or code files side by side and highlight differences. Find added, removed, and changed lines instantly with colour-coded diff output.
Base64 Encoder / Decoder
Encode text or decode Base64 strings instantly online. Convert between plain text and Base64 encoding for data URLs, authentication headers, and API tokens.
URL Encoder / Decoder
Encode or decode URLs and query strings instantly. Convert special characters to percent-encoding and back for safe URL transmission and debugging.
JWT Decoder
Decode and inspect JSON Web Tokens (JWTs) instantly. View header, payload, and signature without a secret key. Debug authentication tokens safely.
Color Converter
Convert colors between HEX, RGB, RGBA, HSL, HSLA, and HSV formats instantly. Pick colors visually and get all format values at once for CSS and design work.