JWT Generator
Build and sign JSON Web Tokens online with editable headers, payload claims, and HS256/HS384/HS512 signatures generated locally.
The header is automatically updated to match the selected algorithm.
Toggle timestamp helpers to inject iat, nbf, and exp automatically.
Balanced security with SHA-256 HMAC.
Secrets never leave your browser; signing runs via Web Crypto.
How it works
- Header and payload JSON are Base64URL encoded, then concatenated with the signature.
- Signing uses the Web Crypto API so your secret never leaves the browser.
- Enable timestamp helpers to regenerate iat, nbf, and exp on every signing.
- Use long, random secrets for production tokens—at least 32 bytes for HS256.
- Keep private signing secrets in a vault; never paste production values on shared devices.
- Match algorithm and secret across services to avoid signature mismatches.
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