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JWT Decoder

Decode the header and payload of a JWT token.

What Is a JWT Decoder?

The JWT Decoder decodes the three parts of a JSON Web Token (JWT): the header, the payload, and the signature. It is an essential tool for developers to inspect the claims inside an access token. Note that decoding does not verify the cryptographic signature. This free online security tool is useful for JWT decoder, JSON Web Token decoder, decode JWT online. Common use cases include inspecting JWT headers and claims during API development, authentication debugging, and token troubleshooting. It is designed for quick browser-based analysis and development workflows. Security checks are signals rather than guarantees, so production systems should also be validated against current standards and their specific threat model.

How to Use This JWT Decoder

  1. 1
    Paste the JWTEnter the three-part JSON Web Token into the input field.
  2. 2
    Review the headerCheck the token type and declared signing algorithm.
  3. 3
    Inspect the payloadReview claims such as iss, sub, aud, exp, iat, and nbf.
  4. 4
    Check warningsLook for expired timestamps or suspicious configuration reported by the inspector.
  5. 5
    Remember signature validationDecoding and structural inspection do not prove that a token is authentic.

Frequently Asked Questions

No. This tool only decodes the base64url JSON payload. Verifying that the signature is valid requires the issuer's secret or public key, which this tool does not do.
A JWT has a header with the algorithm, a payload of claims (such as the subject, issuer, expiration), and a signature. The payload is only base64 encoded, not encrypted.
No. Decoding happens entirely in your browser. However, exercise caution: a JWT you can decode may contain sensitive claims, so pasting it into any untrusted site is risky.

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