OAuth 2.1

As security threats evolve, new best practices emerge (PKCE, expiring tokens, refresh token restrictions) but enforcement is inconsistent. OAuth 1.0a is still in use alongside 2.0, and upgrading security requirements breaks backward compatibility, forcing developers to support multiple outdated security models simultaneously.

OAuth 2.0 is defined across 17 different RFCs covering OAuth framework, Bearer tokens, threat models, and private key JWTs. Developers must navigate this massive standard even for simple third-party-access use cases, and no two API providers implement the same subset consistently.