Mocking.Dev

JWT Decoder

Decode JWT header and payload JSON while debugging auth flows, API tests, and mock tokens.

JWT input

Paste a JWT to decode its header and payload.

Decoded JWT

Header and payload JSON appear after a short delay. Signature is not verified.

{
  "header": {
    "alg": "HS256",
    "typ": "JWT"
  },
  "payload": {
    "sub": "1234567890",
    "name": "John Doe",
    "iat": 1516239022
  },
  "signature": "present"
}

Frequently asked questions

What does this JWT decoder do?

It splits a JWT into parts and decodes the Base64URL header and payload into readable JSON.

Does it verify the JWT signature?

No. This tool decodes token contents for inspection only. Signature verification requires the correct secret or public key.

How is this useful for API testing?

It helps inspect claims like subject, issuer, role, issued-at time, and expiry while debugging authenticated mock requests.

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