An API gateway is a middleware layer that sits between clients and backend services. It receives requests, applies policy, and routes traffic to the right service or upstream provider. Common functions include authentication, authorization, rate limiting, request validation, logging, and sometimes response shaping or protocol translation.
In cyber security, an API gateway matters because it becomes a high-value control point. If it is misconfigured, attackers may bypass access controls, abuse exposed endpoints, or harvest sensitive data from logs and traces. If it is compromised, the gateway can reveal API keys, tokens, and internal service details, or be used to redirect traffic. Defenders use gateways to enforce consistent security rules, monitor abuse, and reduce the attack surface by keeping backend services off the public internet. In modern AI and cloud systems, the gateway often becomes the chokepoint where routing, billing, and governance meet.