JWT Decoder & Verifier — Read Header, Payload & Signature
Paste a JWT to see its Header, Payload, expiration (exp), and verify the signature with your secret key
Decodes any JWT into readable Header and Payload JSON, checks the exp claim against the current time, and verifies HS256 signatures right in your browser.
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🔒 Everything runs 100% in your browser. Your files and input are never uploaded to any server.
How to use
- Paste the encoded JWT string into the input box.
- Review the decoded Header and Payload JSON and check whether it's expired.
FAQ
- Does my token get sent to a server?
- No — decoding happens entirely client-side with Base64Url, so nothing ever leaves your browser.
- How do I know if a token is expired?
- The tool compares the exp claim to the current time automatically and shows a clear valid/expired badge.
- Can it verify the signature too?
- Yes for HS256 — enter the secret key and it verifies instantly in your browser. RS256 and other asymmetric algorithms are decode-only for now.