JWT Generator

Build and Sign a JSON Web Token in Your Browser

Edit the header and payload as plain JSON, pick a signing algorithm, provide a secret or key, and get a ready-to-use token. The JWT Generator supports HMAC (HS256/384/512) with a shared secret, and RSA and elliptic-curve signatures (RS, PS, and ES at 256/384/512) with a pasted PKCS#8 private key — or generate a throwaway test key pair with one click. One-tap helpers add the common registered claims (iat, exp, nbf, sub, iss, aud, jti) so you do not have to remember the epoch math.

Everything — the claims, the secret, the private key, and the signing itself — happens locally in your browser using the Web Crypto API. Nothing is uploaded, logged, or sent to a server, which is exactly what you want when a signing key is involved. Many online JWT tools sign on their backend and see whatever key you paste; this one never does.

These are test tokens. The tool is for development, debugging, and learning — not for minting production credentials. Treat any secret or key you paste here the way you would anywhere: only on a machine you trust, and never a live production signing key.

Common Use Cases

• API testing: Mint a token with a specific subject or scope claim to exercise an authenticated endpoint from Postman, curl, or your test suite.
• Debugging auth flows: Set an expiry (exp) in the past or a not-before (nbf) in the future and watch how your middleware handles an expired or premature token.
• Learning how JWTs work: Switch the algorithm or edit a claim and see the three-part token, plus its decoded header and payload, update instantly.
• Local key pairs: Generate an ES256 or RS256 key pair, sign with the private key, then verify with the printed public key in your own service.
• Test fixtures: Produce consistent tokens for integration tests without standing up a real identity provider.

Privacy: The JWT Generator runs entirely in your browser. Your header, payload, secret, and private key never leave your device — no upload, no network request, no storage.