Modern API Gateways Now Handle Security, AI, and Observability Far Beyond Routing

API gateways have evolved well beyond their original role as simple reverse proxies with basic authentication and rate limiting, a function that was sufficient around 2012 but is now considered inadequate. Today's gateways sit at the intersection of security, integration, observability, and AI, offering capabilities such as full OAuth 2.0/OIDC lifecycle management and fine-grained authorization at the route level. Early platforms like Apigee and Kong established solid fundamentals but suffered from static configurations, monolithic architectures, and an inability to handle protocols like gRPC or GraphQL natively. Modern implementations move authorization logic out of individual services and into a centrally managed gateway layer, allowing security policy updates to be applied once rather than across dozens of service repositories. Organizations that continue treating the API gateway as a basic routing tool risk missing significant operational and security capabilities now considered standard in enterprise architecture.