JWT Expiry Checker
Check exactly when a JWT expires in your local timezone. Paste a JSON Web Token (JWT) and see expiration instantly, processed 100% client-side.
How ZeroData protects your privacy
- ✓ No Uploads: Processing happens entirely via client-side JavaScript.
- ✓ No Storage: We do not have a database. We physically cannot save your data.
- ✓ No Tracking: We don't log what you process or track your inputs.
- ✓ Verifiable: Check your DevTools Network tab. You will see 0 outbound requests.
Understanding the JWT "exp" Claim
The exp (expiration time) metadata claim is one of the most critical parts of the JSON Web Token standard (RFC 7519). It represents a numeric Unix timestamp indicating exactly when the token becomes invalid. Because computers read Unix epoch seconds easily but humans do not, checking token lifetimes manually requires constant timezone conversions and decoding.
This tool is a browser-native JWT expiry checker designed to remove that friction. It extracts the exp timestamp from the payload segment and compares it directly with your machine's current time, converting the epoch value into your exact local timezone.
Stop Decoding JWTs Manually
Every developer has done it: copy a JWT from a response header, open a new browser tab, navigate to some random JWT website, paste the token, and then manually calculate whether the exp timestamp has passed. Even worse, most tools display the time in UTC, forcing you to do timezone math in your head.
This tool does one thing and does it perfectly. Paste a token, and you immediately see the expiry time in your own timezone with a clear EXPIRED or VALID badge. No full debugger complexity, no signature verification prompts — just the answer to the question you actually have: "Has this token expired?"
Because this is a ZeroData tool, your JWT — which may contain user IDs, roles, and session information — never touches a server. The entire decode happens via JavaScript's atob() in your browser.
Want to understand exactly how the exp claim works under the hood? Read our deep dive on the JWT exp claim — including common bugs like clock skew, timezone confusion, and choosing the right token lifetime.
Common Use Cases
- Quickly checking if a JWT has already expired during API debugging.
- Verifying token lifetimes match your auth server's configuration.
- Debugging 401 Unauthorized errors by confirming the token is still valid.
- Checking 'iat' and 'exp' claims without decoding the full payload manually.
Frequently Asked Questions
What is the JWT exp claim?
The 'exp' (expiration time) claim in a JWT is a JSON number representing a Unix timestamp (seconds since Epoch). It defines the exact date and time after which the JWT must not be accepted for processing. Because it is a raw Unix timestamp, our JWT expiry checker converts it into a human-readable local time.
How does this JWT expiry checker work?
It base64url-decodes the JWT payload section and reads the 'exp' (expiry) and 'iat' (issued at) Unix timestamp claims. It then converts them to your local timezone and calculates whether the token has already expired.
Does this verify the JWT signature?
No. This is a lightweight expiry checker, not a full debugger. It only reads the payload claims to tell you when a token expires. For full header/payload/signature inspection, use our JWT Debugger tool.
Is my JWT token safe here?
Yes. The decoding happens entirely in your browser using JavaScript's built-in atob() function. Your token is never transmitted to any server. Check your DevTools Network tab to verify.
What timezone does it display?
It displays the expiry time in YOUR local timezone as detected by your browser. This is one of the main reasons this tool exists — most online JWT tools show UTC, which is confusing when debugging auth flows locally.
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