API Gateway vs Service Mesh

Two infrastructure patterns that look similar but solve completely different problems — one handles external traffic in, the other handles internal traffic between services.

Key Takeaways

1. API gateways handle north-south traffic (client to service) — routing, authentication, rate limiting, and request transformation
2. Service meshes handle east-west traffic (service to service) — mTLS, retries, circuit breaking, and observability between internal services
3. They solve different problems and complement each other — use an API gateway for external traffic and a service mesh for internal traffic
4. Istio, Linkerd, and Consul Connect are the major service mesh options — each trades operational complexity for infrastructure-level reliability features