An API gateway can simplify authentication and routing, but it can also become a centralized application full of business logic. When every team depends on gateway changes, the component intended to decouple services becomes a release bottleneck.
Useful gateway design begins with a clear responsibility boundary. This guide compares common patterns and shows where routing, security, aggregation, and resilience controls should live.
Keep edge responsibilities at the edge
Gateways are well suited to TLS termination, authentication enforcement, rate limiting, routing, request limits, and standardized telemetry. Authorization that depends on business state usually belongs in the service that owns that state, even if coarse access checks happen earlier.
Choose the right gateway shape
A shared gateway supports common policy; a backend-for-frontend can tailor contracts to web, mobile, or partner consumers. Aggregation can reduce client round trips, but excessive orchestration couples the gateway to multiple service internals and magnifies downstream failures.
Design failure behavior
Apply deadlines, bounded retries, circuit breaking, and load shedding with knowledge of operation semantics. Preserve correlation context and return consistent errors. Avoid retrying non-idempotent requests unless a reliable idempotency mechanism exists.
Govern without centralizing delivery
Provide reusable policies and self-service configuration with validation, review, and ownership. Track route dependencies and deprecated consumers. Start by documenting what the gateway must enforce and what it must not own; then test those boundaries against one representative client journey.