## API Authentication & Authorization: An Engineering Deep Dive into Mechanisms, Trade-offs, and Failure Modes Every API has some form of authentication. But having authentication and getting it right are two completely different things. I've reviewed production systems where JWTs had no expiry. Systems where API keys were hardcoded in source code and committed to public repositories. Systems where OAuth redirect URIs used wildcards. Systems where Basic Auth was being used for financial APIs over what was supposed to be HTTPS but nobody checked. Every single one of those was a live…