Before you start
What you need
A JWT with optional numeric exp, nbf, and iat claims plus an agreed skew allowance.
Developer & Data
JWT Expiry Checker
Check exp, nbf, and iat time claims against this browser clock without trusting the token.
- 01Runs in this browser
- 02Limits are explicit
- 03Copy or download output
No black box
How this tool handles the input
The payload is decoded locally, numeric date claims are converted from Unix seconds, and exp/nbf are compared with the current browser time.
What you get
What the page gives back
A UTC time-claim report, status, and seconds until expiry, always marked unverified.
Keep in mind
Use the result responsibly
A token within its time window can still be forged, revoked, issued by the wrong party, or unauthorized.
Practical uses
Where this tool earns its place
- Explain why a test token appears expired.
- Convert numeric JWT dates to UTC.
- Compare service clock-skew assumptions.
Verified data boundary
Source text stays on this page.
The published contract marks these tools as client-only processing. Nirmion uses the API only to confirm that this workspace is enabled in MySQL; source values and results are not sent to Flask.