JWT Lab

Live: gray0072.github.io/jwt

JWT Lab is an open-source developer tool for generating, decoding, and validating JSON Web Tokens (JWT) — right in the browser, with no data leaving your machine.

All processing happens client-side. Your secrets and tokens never touch a server.

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Features

• Generate JWTs with any algorithm — HS256/384/512, RS256/384/512, ES256/384/512, PS256/384/512, EdDSA
• Decode any JWT: inspect header, payload, and signature at a glance
• Verify tokens against a secret or public key with clear pass/fail feedback
• Live editing — modify header/payload fields and get an updated token instantly
• Claim helpers — auto-fill standard claims (iat, exp, nbf, iss, sub, aud, jti) with smart defaults
• Key generation — generate RSA / EC / OKP key pairs directly in the browser
• Import/Export keys in PEM and JWK formats
• History — recent tokens saved locally in your browser (localStorage)
• Dark / Light theme — follows system preference, toggleable manually
• Copy to clipboard with one click everywhere

Supported Algorithms

Family	Algorithms
HMAC	HS256, HS384, HS512
RSA	RS256, RS384, RS512
RSA-PSS	PS256, PS384, PS512
ECDSA	ES256, ES384, ES512
EdDSA	Ed25519
None	none (unsigned)

Tech Stack

• React 18 + TypeScript
• MUI v6 (Material UI) — component library & theming
• Zustand — lightweight global state
• jose — JWT implementation (Web Crypto API)
• Vite — build tool
• GitHub Pages — hosting

Getting Started

git clone https://github.com/YOUR_USERNAME/jwt-lab.git
cd jwt-lab
npm install
npm run dev

Open http://localhost:5173 in your browser.

Deployment

npm run build
npm run deploy   # pushes to gh-pages branch

Contributing

Issues and PRs are welcome. The project is intentionally kept simple — no backend, no analytics, no tracking.

License

MIT