Security & Encoding
JWT Expiration Calculator
Paste a JWT to see when it was issued, when it becomes valid, and exactly how long until it expires. Everything runs in this page — your token is never uploaded.
Encoded token
header.payload.signature
Only the registered time claims — iat (issued at),
nbf (not before) and exp (expiration) — are read.
Status
waitingNo token yet
Paste a JWT to calculate its issued, not-before and expiration times.
Timing claims
UTCCalculated durations
liveEvaluate at a specific time (optional) offline testing
Leave empty to follow the real clock. Set a time to see how the token behaves at that instant; the matching UTC time is shown under Calculated durations.
How it works
The payload is Base64URL-decoded and parsed as JSON on this device. Timing is measured against your browser clock unless you set a reference time. Decoding only reads the token’s contents; it does not prove the token is genuine, so never treat a “valid” result as authentication. Never paste a token you do not trust into a page you do not control.