JWT Encoder
Sign JWTs with an HMAC secret.
Signing runs entirely in your browser with the Web Crypto API. Don’t paste production secrets into any web tool.
How to use the JWT Encoder
- 1 Pick the HMAC algorithm (HS256, HS384 or HS512).
- 2 Enter your secret and edit the JSON payload.
- 3 Click Sign token and copy the resulting JWT.
Frequently asked questions
Is the signing secret sent anywhere?
No. The token is signed locally with the Web Crypto API, so your secret never leaves the browser. Still, avoid pasting real production secrets into any online tool.
How is this different from a JWT decoder?
A decoder only reads an existing token’s header and payload. This encoder builds a new token and signs it with your secret so the signature verifies.
Which algorithms are supported?
Symmetric HMAC algorithms: HS256, HS384 and HS512. Asymmetric algorithms (RS/ES) require a private key and are out of scope for a client-side tool.