API Gateways

An API gateway is an infrastructure component that sits between clients and backend services, handling cross-cutting concerns like authentication, rate limiting, routing, and protocol translation in one place rather than repeating them in every service.

itDistributed systems, messaging, and integration

API Gateways

An API gateway is the entry point between API clients and one or more backend services. For HTTP, it is a reverse proxy with API-aware policies. A client addresses the gateway. The gateway accepts the connection, applies configured policy, selects a backend, and relays the result.

The gateway does not become the backend. It sits on the request path and mediates access to backend capabilities. This position gives it useful context, but it also makes the gateway part of every request's latency and failure path.

Why put a gateway in the path

Without a gateway, each client may need to discover service endpoints and handle their different protocols or failure behavior. Every exposed service also needs its own edge controls. A gateway can present one stable API surface while backend services move, split, or use private addresses.

Routing is the core job. A route can select a backend from the request host, path, method, header, or other application-layer information. The gateway can also terminate TLS, validate credentials, enforce traffic policy, transform messages, cache eligible responses, and emit telemetry.

These features are optional. Start with the smallest policy set that solves a defined boundary problem. Each added policy changes request behavior and creates configuration you must test, deploy, observe, and recover.

API Gateways

Why put a gateway in the path

Relevant careers