What is the exp claim in a JWT?

exp (ExpiresAt) is a Unix timestamp (seconds since epoch) after which the token must not be accepted. It is defined in RFC 7519. A value of 1700000000 corresponds to 2023-11-14 22:13:20 UTC.

What is the nbf claim in a JWT?

nbf (NotBefore) is a Unix timestamp before which the token must not be accepted. It allows issuing a token in advance, for example a token that becomes active in 5 minutes.

Can I test expiration at a specific date?

Yes. Open Advanced Options and set the Time Travel field to any date and time. The tool will evaluate exp and nbf as if the current time were the selected moment, so you can test whether a token is valid at a past or future point.

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JWT Expiration Checker

Q: How do I check if a JWT is expired?

Paste your JWT into the decoder. The tool reads the exp (expiration) claim and compares it to the current time. An expired token shows a red badge with the exact date and how long ago it expired.

Check if a JWT is expired — exp · nbf · iat · time travel — 100% local, no upload

Paste your JWT to instantly check whether it is expired. The tool reads the exp claim and shows the exact expiration date, how long ago it expired (or how long it remains valid), and displays nbf / iat badges. Use time travel to simulate any date.

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Understanding JWT time claims

JWT time claims are Unix timestamps (seconds since 1970-01-01 00:00:00 UTC):

exp — expiration time: token must be rejected after this timestamp
nbf — not before: token must be rejected before this timestamp
iat — issued at: when the token was created

The time travel feature lets you set a custom "current time" for validation. This is useful for testing whether a token will still be valid in 10 minutes, or investigating a past authentication failure.

Frequently asked questions

How do I check if a JWT is expired?

Paste the JWT. The tool reads the exp claim (Unix timestamp) and compares it to the current time. An expired token shows a red Expired badge along with the exact expiration date and how long ago it expired.

What is the exp claim?

exp (ExpiresAt) is a Unix timestamp after which the token must no longer be accepted. It is defined in RFC 7519 §4.1.4. A value of 1700000000 corresponds to November 14, 2023 at 22:13:20 UTC.

Can a JWT be expired but still have a valid signature?

Yes. The signature verifies authenticity and integrity, not freshness. An expired token with a valid signature was genuinely issued by the expected party but should no longer be trusted for access control.

How does time travel work?

Open Advanced Options and set the Time Travel field. The tool will evaluate exp, nbf, and iat as if the selected datetime were now. Useful for debugging "was this token valid at the time of the request?" scenarios.

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