Securing Web APIs: A Practical Guide to Authentication & Authorization Methods
Most API security incidents don't happen because attackers found a clever zero-day. They happen because a developer grabbed the first auth pattern that came to mind, shipped it, and moved on.
I've seen API keys committed to public repos, JWTs without expiry running in production, and OAuth flows that skip PKCE on mobile clients. These aren't exotic mistakes — they're the default outcome when engineers don't have a clear map of what each method does, when it fits, and where it breaks down.
This guide gives you that map. We'll cover every major authentication and authorization method used to secure web APIs today, with code examples in Python and a decision matrix at the end so you can match the right tool to your specific context.
Authentication vs. Authorization — Get This Right First
