API Gateway Responsibilities & Edge Architecture

In a microservices architecture, a backend system may consist of dozens or hundreds of discrete services. Having client devices (browsers, iOS, Android) communicate directly with individual microservices creates severe architectural hazards:

• Exposed Attack Surface: Every microservice must expose a public IP, manage its own TLS certificates, and handle DDoS mitigation.
• Client-Service Coupling: Changing an internal service port or splitting a service breaks external client code.
• Redundant Code Duplication: Every service team must independently write and maintain identical code for JWT parsing, CORS headers, rate limiting, and access logs.

The API Gateway Solution:

An API Gateway acts as the single reverse-proxy entry point for all external traffic. It intercepts incoming requests, applies cross-cutting security and traffic policies at the network perimeter, and routes sanitized requests to downstream internal services over a high-speed private network.