Security incidents keep growing. AI makes some attacks easier to run at scale. This means API security is not a checkbox anymore. It is something that keeps moving. I keep seeing the same shortcut on projects: teams pick one authentication method and think the job is done.
Client ID Enforcement, JWT, mTLS, OAuth2 — these do not all answer the same question. They are not levels where higher is always better. Good API security uses more than one of them at the same time.
Here is how I break it down.