JWT generator (HS256)

Build and sign a JWT with HMAC-SHA256 from a JSON payload and a secret — or verify one.

Payload (JSON object)Header (JSON, optional — alg is always HS256)Signing secret

Registered claimsAdd iat (issued now)Add nbf (valid from now)Expires in

Signed with WebCrypto HMAC-SHA256 in this browser. The secret and token never leave your device.

HS256 only. This creates test tokens — anyone holding the secret can forge them, so use a throwaway secret, not a production one.

How to use

Paste a JSON payload (and optional header overrides).
Enter the secret and optional iat/nbf/exp claims.
Copy the signed token or verify an existing one.

What it supports

HS256 only — RS256, ES256, and other algorithms are not supported. The secret never leaves the page; signing and verification use the Web Crypto API. Payload up to 100 KB, secret up to 1,024 characters.

Related tools

JWT decoder
HMAC generator
Hash calculator

Related guides

Sign a test JWT for local development
Make a signing key pair for JWTs or APIs