JWT Encoder
Build and sign an HS256 JSON Web Token.
Signing happens in your browser via the Web Crypto API. Don’t paste production secrets into any online tool.
Free JWT encoder. Provide a header, payload and secret to build and sign an HS256 JSON Web Token, with the HMAC-SHA256 signature computed in your browser via the Web Crypto API. Nothing is uploaded.
How to use the JWT Encoder
- 01Edit the header and payload as JSON.
- 02Enter your HS256 secret.
- 03Click Encode to get the signed token, then copy it.
Frequently asked questions
How is the token signed?
The header and payload are base64url-encoded and the signature is an HMAC-SHA256 of them using your secret, computed locally with the Web Crypto API. The result is a standard HS256 JWT.
Is it safe to enter my secret?
The signing happens entirely in your browser and nothing is transmitted. Even so, never paste real production secrets into any online tool.