JWT Decoder Checklist for Authentication Bugs

Many auth incidents come from expired tokens or mismatched system time. Review exp, iat, and nbf claims before deeper investigation.

If mobile or distributed systems are involved, add safe clock skew tolerance in verification middleware.

A valid signature is not enough. Ensure aud and iss match the exact values your service expects for the target environment.

Staging tokens being used in production is a common cause of intermittent authorization failures.

Role-based bugs usually come from missing or renamed custom claims. Decode payload claims and map them directly to policy checks in your API.

Treat claim names as contracts and version them carefully when changing identity providers.