A collection of free, browser-based developer utility tools built with React and TypeScript. All processing happens entirely in your browser — no data is sent to any server.
- JSON Formatter & Validator — Format, minify, and validate JSON with syntax highlighting
- YAML Schema Validator — Validate YAML documents against JSON Schema definitions
- JWT Decoder — Decode and inspect JSON Web Tokens (header & payload)
- Text / File Compare — Compare two text inputs or uploaded files side-by-side with diff highlighting
- Encode / Decode — Base64, URL, and HTML encode/decode strings
- CSV Delimiter Changer — Upload a CSV file and convert its delimiter (e.g., comma to semicolon)
- Cron Expression Tester — Parse and test cron expressions with next occurrence previews
- JSON to YAML Converter — Convert JSON documents to YAML format
- YAML to JSON Converter — Convert YAML documents to JSON format
- React 19 with TypeScript
- Vite 8 — Build tool
- MUI 9 — Material Design component library
- Monaco Editor — Code editor (via @monaco-editor/react)
cd web
npm install
npm run devThe app will be available at http://localhost:5173.
cd web
npm run buildThe build output will be in web/dist.
See LICENSE for details.