API Gateway
An API gateway is a server that acts as the single entry point for all API requests, handling cross-cutting concerns such as authentication, rate limiting, logging, and request routing.
API gateways sit between client applications and backend services, acting as a reverse proxy that centralizes security enforcement, traffic management, and observability. Popular API gateway solutions include Kong, AWS API Gateway, Azure API Management, and Apigee. They allow organizations to apply consistent security policies across all APIs without modifying individual services.
From a security perspective, API gateways provide several critical functions. They enforce authentication and authorization at the edge, preventing unauthorized requests from reaching backend services. They implement rate limiting and throttling to protect against denial-of-service attacks and abuse. They can transform and validate request payloads, rejecting malformed or malicious input before it reaches application logic.
API gateways also enable centralized logging and monitoring, giving security teams visibility into API traffic patterns and potential threats. Advanced gateways support mutual TLS for service-to-service authentication, IP allowlisting and blocklisting, request and response schema validation, and integration with web application firewalls. When deploying an API gateway, organizations should ensure that it does not become a single point of failure, that default configurations are hardened, and that administrative interfaces are properly secured with strong authentication.