JWTs are easy to use, but small security mistakes can turn them into a serious authentication problem.
A JWT is only as secure as the way your application creates, stores, sends, and verifies it. Problems such as weak signing secrets, accepting unexpected algorithms, ignoring expiration, storing tokens unsafely, or putting sensitive information in the payload can create vulnerabilities.
JWT security also involves thinking about token theft and revocation. Short-lived access tokens, secure token storage, refresh-token rotation, HTTPS, strong cryptographic keys, and careful validation can reduce the impact if a token is compromised.
What you'll walk away knowing