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API Gateways

An API Gateway is the "front door" to your applications. It sits between your users and backend services, acting as a reverse proxy that routes requests to the appropriate service.

What it handles ​

  • Authentication — validating credentials and managing sessions
  • Authorization — ensuring clients can access what they are requesting
  • Request transformation — modifying paths, headers, or protocols (e.g., HTTP to gRPC)
  • Rate limiting — protecting services from abuse or overload
  • Load balancing — distributing requests across service replicas
  • Service discovery — routing requests to the right backend
  • Caching — speeding up repeated requests
  • Observability — logging, metrics, and distributed tracing

When to use one ​

API Gateways shine when you have:

  • Multiple backend services that need a unified entry point
  • Cross-cutting concerns like auth or rate limiting that should not be duplicated
  • Different client types (web, mobile, IoT) needing different API shapes
  • Microservices that evolve independently from client contracts

When to skip it ​

Do not add an API Gateway just because it sounds good. If you have a monolith or a small number of services, the gateway becomes unnecessary complexity. Start simple — you can always add one later when the pain points appear.

  • Cloud-native: AWS API Gateway, Google Cloud Endpoints, Azure API Management
  • Self-hosted: Kong, Traefik, NGINX, Envoy, HAProxy
  • Kubernetes-native: Istio, Linkerd (service mesh with gateway features)

Choose based on your deployment model, team expertise, and whether you need advanced features like request transformation or just basic routing.

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