API gateways consolidate cross-cutting concerns to simplify microservice communication

Mobile applications requiring data from user, order, and recommendation services face excessive round trips and authentication overhead when calling each service directly (Arslan Ahmad from System Design Nuggets). An API gateway acts as a single entry point that routes external paths to internal services while offloading cross-cutting concerns like TLS termination, rate limiting, and request logging (Arslan Ahmad from System Design Nuggets). By validating tokens at the edge and passing identity downstream as trusted headers, the gateway prevents teams from reimplementing security logic in every service.

Engineers at X replaced three legacy servers with one unified system built on Fastify and Platformatic Watt, running worker threads on Node 26 to manage streaming architecture (Node Weekly). This transition required fixing event loop stalls to improve performance on the web. Teams using gateways often adopt a Backend for Frontend pattern to shape payloads specifically for mobile or web clients, rather than forcing a single compromise API for all consumers.

Systems relying on gateways must remain stateless and replicated because the component resides on the critical path of every request. Developers should avoid placing business logic inside the gateway, instead delegating complex aggregation to a dedicated composition service to maintain team velocity.