JWT generator & signer

Build and sign a JSON Web Token with HMAC-SHA256, or paste a token to decode its header and payload. Signing uses your browser’s built-in Web Crypto — nothing is uploaded.

Mode
Header
Payload (claims)
Quick-add claim
exp in
Secret (HS256)

Everything runs in your browser. No upload, no sign-up.

How it works

STEP 1

Choose Generate or Decode

Generate signs a new token from a header, payload and secret. Decode reads any token you paste and shows its parts — no secret needed.

STEP 2

Fill claims and secret

Edit the payload JSON and tap to add iat / exp. Enter your HS256 secret. Everything is validated as you type.

STEP 3

Copy the token

The signed token (header.payload.signature) appears instantly. Copy it with one click — the secret never leaves your device.