Dev tools — Free Online Dev Tools
Format, convert and inspect things developers need every day.
Developer utilities — formatters, encoders, generators, validators — that you'd normally piece together from a dozen one-off sites. Every tool here works offline once the page is open and never sends your data anywhere.
Compare Dev tools — Free Online Dev Tools
| Tool | Input | Output | Max size | Runs in browser? |
|---|
| JSON Formatter | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| PX to REM Converter | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| JSON Minifier | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| JSON to CSV Converter | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| CSV to JSON Converter | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| CSV Viewer | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| CSV Cleaner | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| Base64 File Encoder & Decoder | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| URL Parser | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| Query String Builder | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| JWT Decoder | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| UUID Generator | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| ULID Generator | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| Hash Generator (MD5, SHA-1, SHA-256, SHA-512) | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| HMAC Generator (SHA-1, SHA-256, SHA-512) | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| Unix Timestamp Converter | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| Cron Expression Generator | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| Regex Cheatsheet | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| HTML Entity Encoder/Decoder | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| HTML Minifier | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| CSS Minifier | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| robots.txt Generator | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| YAML Formatter & Validator | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| XML Formatter & Minifier | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| JSON ↔ YAML Converter | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| JSON ↔ XML Converter | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| SQL Formatter | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| JSON Diff | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
| JSON Schema Generator | Code, JSON or text | Code, JSON or text | 10 MB | Yes |
Frequently asked questions
- Can I use these dev tools at work?
- Yes — because everything runs locally in your browser, even payloads you can't paste into ChatGPT or other cloud tools are safe to use here.
- Do you store my JSON / JWT / hash inputs?
- No — the input never leaves your device. Closing the tab deletes everything.
- Are the JSON tools strict or forgiving?
- The formatter accepts trailing commas and comments while warning about them; the minifier and CSV converter require strict, valid JSON.
- Can I bookmark a tool with my input pre-filled?
- Yes — most tools persist input in the URL hash so a bookmark restores your state on the next visit.
- Do you support API endpoints I can curl?
- No — every tool here is a UI for client-side work, not a public API. If you need an API for a tool, drop us an email.