20+ free developer tools that run entirely in your browser. No signup. No tracking. No ads.
🌐 Live at: mellowmarshall.github.io/devtoolbox
| Tool | Description |
|---|---|
| JSON Formatter | Format, validate, and minify JSON |
| Base64 Encoder/Decoder | Encode and decode Base64 strings |
| URL Encoder/Decoder | Encode and decode URL components |
| UUID Generator | Generate random UUIDs (v4) |
| Hash Generator | SHA-1, SHA-256, SHA-384, SHA-512 |
| JWT Decoder | Decode and inspect JSON Web Tokens |
| Regex Tester | Test patterns with live matching |
| Color Converter | Convert between HEX, RGB, HSL |
| Unix Timestamp | Convert timestamps to dates and back |
| Text Diff | Compare two texts side by side |
| Lorem Ipsum | Generate placeholder text |
| Markdown Preview | Live markdown rendering |
| HTML Entities | Encode/decode HTML entities |
| CSV ↔ JSON | Convert between CSV and JSON |
| QR Generator | Generate QR codes from text |
| Cron Parser | Parse and explain cron expressions |
| Password Generator | Secure random password generation |
| Character Counter | Count chars, words, lines, bytes |
| JS Minifier | Basic JavaScript minification |
| SQL Formatter | Format SQL queries |
- ⚡ Instant — No loading, no server calls
- 🔒 Private — Everything runs client-side, nothing leaves your browser
- 📱 Responsive — Works on desktop and mobile
- 🌙 Dark mode — Easy on the eyes
- 🆓 Free forever — No signup, no limits
Deep-dive cheatsheets for professional developers:
- 🧠 Prompt Engineering Mega Pack — 50+ battle-tested prompt templates ($4.99)
- 🔀 Git Power User Cheatsheet — Advanced workflows & recovery ($3.99)
- 🐳 Docker Compose Cheatsheet — Production-ready patterns ($2.99)
- 🔍 Regex Mastery Cheatsheet — Patterns & recipes ($3.99)
- 🐧 Linux CLI Essential Reference — 150+ commands ($4.99)
- 💻 VS Code Productivity Guide — Shortcuts & extensions ($3.99)
- 🐚 Shell Scripting Cookbook — 50+ Bash recipes ($4.99) NEW
- 🔗 API Design Patterns Guide — REST, GraphQL & beyond ($4.99) NEW
- 🗃️ SQL Query Optimization Guide — PostgreSQL & MySQL ($3.99) NEW
- 🐍 Python One-Liners Reference — 100+ snippets ($2.99) NEW
Browse all: devtoolsmarket.gumroad.com
- Pure HTML/CSS/JavaScript
- No frameworks, no dependencies
- Hosted on GitHub Pages
- < 50KB total page weight
MIT — use it however you want.
Made by @mellowmarshall