A free, open-source developer toolkit that provides essential everyday utilities right in your browser. Built with Python Flask, DevTools Online offers a clean, fast interface for common encoding, decoding, formatting, and conversion tasks — no sign-up required.
- Entirely browser-based — works offline after initial load
- No data leaves your machine — all processing happens client-side
- Clean, distraction-free UI — get in, get the job done, get out
- Single lightweight server — one command to start
| Tool | Description |
|---|---|
| JSON Formatter | Pretty-print, minify, and validate JSON with syntax highlighting and error reporting. |
| Base64 Encoder / Decoder | Encode text to Base64 or decode Base64 back to plain text. Supports UTF-8. |
| JWT Decoder | Decode JSON Web Tokens to inspect the header, payload, and signature without verification. |
| Hash Generator | Generate MD5, SHA-1, SHA-256, and SHA-512 hashes from arbitrary text input. |
| UUID Generator | Create random v4 UUIDs instantly, with bulk generation support. |
| Regex Tester | Write and test regular expressions with real-time match highlighting and capture-group display. |
| URL Encoder / Decoder | Percent-encode or decode URLs and query-string parameters. |
| Timestamp Converter | Convert between Unix timestamps and human-readable dates in multiple formats and time zones. |
| Text Diff | Compare two blocks of text side-by-side and see additions, deletions, and changes highlighted. |
- Python 3.8+
- Flask (
pip install flask)
pip install flask
python server.pyThe application starts on http://localhost:9001.
This project is open source and available under the MIT License.
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