Developer
JWT Decoder & Claims Analyzer
Decode JWT headers and claims locally in your browser.
Decoding does not validate the cryptographic signature.
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What is JWT Decoder & Claims Analyzer?
JWT Decoder & Claims Analyzer decodes the header and payload of a JSON Web Token directly inside your browser. It also highlights common time-based claims such as exp, nbf and iat.
What this tool checks
- JWT header decoding
- JWT payload decoding
- Algorithm declaration
- Issuer and subject claims
- Expiration time
- Not-before time
- Issued-at time
- alg=none warning
How to use it
- Paste the JWT into the decoder.
- Click Decode JWT.
- Review the header and claims.
- Verify the signature separately using the correct trusted key.
Important:
Decoding is not cryptographic verification. A decoded token may still be forged or invalid. The token is processed locally in your browser by this tool.
Frequently asked questions
Is my JWT sent to the server?
No. This decoder runs in the browser.
Does a successful decode mean the signature is valid?
No. The tool intentionally does not claim signature verification.