JWT Decoder
Paste a JSON Web Token to decode the Base64URL header and payload and inspect common claims such as exp.
JWT needs at least header and payload segments.
How this tool works
A JWT is split at periods; the first two Base64URL segments are decoded as JSON. Signature verification is deliberately not performed by this utility.
Example
Paste a token to see its algorithm header, subject or issuer claims and whether the exp timestamp is already in the past.
Common questions
Does decoding prove the JWT is authentic?
No. Anyone can create an encoded token. Trust requires cryptographic signature verification with the correct key and algorithm.
Is the signature sent anywhere?
No. This decoder processes the token in the browser and only reads the first two segments.