JWT Expiry Checker
The JWT Expiry Checker reads the exp claim from your token, compares it with your current system time and tells you immediately whether the token is still valid or has already expired — with the exact time remaining or elapsed.
What This Tool Does
The exp (expiration time) claim is a NumericDate: seconds since the Unix epoch. This tool decodes the payload, extracts exp, converts it to a readable date and computes the difference against the current time. Tokens without an exp claim are reported explicitly, since they never expire on their own.
How to Use
- Paste your JWT into the input field.
- Read the verdict: valid or expired, with the exact expiration date.
- Check the remaining lifetime (or how long ago the token expired).
- Copy the result or reset the editor to check another token.
Key Features
- Instant valid/expired verdict based on the exp claim
- Exact expiration timestamp in readable local time
- Time remaining or time since expiry calculated for you
- Clear reporting for tokens without an exp claim
- Sample data, copy, download and reset actions
- Fully client-side — tokens are never transmitted
Common Use Cases
- Diagnosing unexpected 401 responses from an API
- Checking how long an issued access token remains usable
- Verifying that your issuer sets sensible token lifetimes
- Testing refresh-token logic during development
- Auditing tokens captured in logs or bug reports
The exp Claim and Token Lifetimes
RFC 7519 defines exp as the time after which the token must not be accepted. Validators typically allow a small clock skew, but an expired token should otherwise be rejected and replaced — usually through a refresh token flow.
Short-lived access tokens limit the damage a leaked token can do. If you find tokens with very long or missing expirations, review the issuer configuration.
Frequently Asked Questions
How is token expiration determined?
The tool reads the exp claim (seconds since the Unix epoch) and compares it with your current system time. If exp is in the past, the token is expired.
What if my token has no exp claim?
The tool reports that explicitly. Such tokens do not expire on their own, which many security guidelines discourage for access tokens.
Does an unexpired token mean it is valid?
Not necessarily. Expiration is only one check — the signature, issuer, audience and nbf claim should also be validated before trusting a token.
Why does my token look expired here but work in my app?
Check your device clock — the comparison uses your local system time. Some servers also allow a clock-skew tolerance.
What is the difference between exp and iat?
iat records when the token was issued; exp records when it stops being valid. The JWT Lifetime Calculator shows the span between them.
Is my token sent anywhere for checking?
No. The comparison happens entirely in your browser using JavaScript.
Related JWT Tools
- JWT Lifetime Calculator — Calculate JWT token lifetime duration
- JWT Timestamp Converter — Convert JWT timestamps to readable dates
- JWT Inspector — Comprehensive analysis of JWT token structure and claims
- JWT Decoder — Decode JWT tokens to view header and payload