JWT Expiry Checker

Check JWT Expiration

JWT Expiry Checker is a developer tool that tells you whether a JSON Web Token is expired. Paste a JWT below to see the exp, iat, and nbf claims, time remaining, and a live countdown.

About JWT Expiry Checker

JWT Expiry Checker is a free browser-based tool that decodes a JSON Web Token and checks whether it has expired. It reads the exp (Expiration Time), iat (Issued At), and nbf (Not Before) claims from the token payload and compares them against the current time. It does not verify the token signature — it only inspects the time-related claims.

How JWT Expiration Works

A JWT is three Base64URL-encoded segments separated by dots: header.payload.signature. The payload contains claims — key-value pairs with information about the token. Three claims control timing:

• exp (Expiration Time) — Unix timestamp after which the token must be rejected. Required for most use cases.
• iat (Issued At) — Unix timestamp recording when the token was created. Optional but widely used.
• nbf (Not Before) — Unix timestamp before which the token must not be accepted. Optional.

All timestamps are Unix epoch seconds — the number of seconds since January 1, 1970 00:00:00 UTC. To check expiration: if current_time > exp, the token is expired.

Worked Example

Given this JWT payload (decoded):

{
  "sub": "user_42",
  "iat": 1704063600,
  "exp": 1704067200,
  "nbf": 1704063600
}

• iat = 1704063600 → 2024-01-01 00:00:00 UTC (issued at midnight)
• exp = 1704067200 → 2024-01-01 01:00:00 UTC (expires 1 hour later)
• nbf = 1704063600 → 2024-01-01 00:00:00 UTC (valid from issuance)
• Lifetime = 1704067200 − 1704063600 = 3,600 seconds = 1 hour

If the current time is 2024-01-01 00:30:00 UTC (1704065400), the token is valid — 30 minutes remain. If the current time is 2024-01-01 02:00:00 UTC (1704070800), the token expired 1 hour ago.

Common JWT Expiration Periods

Privacy and Limitations

All decoding runs in your browser. Your JWT is never sent to any server, stored, or logged. This tool does not verify the token signature — it only checks expiration claims. For signature verification, use a library like jsonwebtoken (Node.js) or PyJWT (Python) with the appropriate secret or public key.

JWT Expiry Checker FAQ