Tool · client-side · no signup
JWT Signer — mint signed JWTs locally.
Mint signed JSON Web Tokens in your browser for testing. Supports HS256, HS384, HS512, RS256, ES256. Your keys never leave your device — all signing happens client-side via WebCrypto.
Detected from header: HS256
Your key never leaves your browser. Signing runs in WebCrypto.
Signed JWT appears here
Fill in the header + payload + key, then click Sign. The signing runs locally — nothing is sent.
What this is good for
Typical use cases.
Mint a test JWT for an integration test against your API
Generate a forged token to verify your signature-validation code rejects it
Quickly sign a JWT for a local development environment