TL;DR — API Gateway

Design an API Gateway that serves as the single entry point for all client requests to a microservices backend. The gateway handles cross-cutting concerns -- authentication, rate limiting, request routing, protocol translation, response transformation, and circuit breaking -- so that individual microservices do not need to implement these themselves. Think of it as a smart reverse proxy that understands your API contracts. Key features: Route requests to appropriate backend services based on path, host, headers, and method. Authentication: validate JWT tokens, API keys, OAuth2 tokens at the gateway.