A fast, private set of everyday developer tools that runs entirely in your browser. Nothing you paste is ever sent to a server, so it stays safe to use with tokens, payloads, and other sensitive data.
Live demo · built with React
Most online developer tools send whatever you paste to a backend, which is a real problem the moment you drop in a live JWT or an internal API response. DevToolbox does all of its work locally with native browser APIs, so your data never leaves the page, and it keeps working offline once loaded.
- JSON Formatter and Validator: pretty-print, minify, and validate JSON with clear error messages.
- JWT Decoder: inspect the header and payload of a token and see its expiry, all locally.
- Base64 Encoder and Decoder: full Unicode support in both directions.
- URL Encoder and Decoder: percent-encode text for safe use in query strings.
- Hash Generator: SHA-1, SHA-256, and SHA-512 using the Web Crypto API.
- UUID Generator: bulk generation of cryptographically random version 4 UUIDs.
- Unix Timestamp Converter: move between timestamps and human dates in both directions.
- React 18
- Native browser APIs only. Web Crypto for hashing,
crypto.randomUUIDfor UUIDs, and no third-party network calls. - No build step, so it deploys to any static host.
There is no build step, so a static file server is all you need:
# from the project folder
python3 -m http.server 8080
# then open http://localhost:8080Push the folder to a repo and turn on GitHub Pages for the main branch. The app is fully static.
MIT