What are the trade-offs of using GraphQL vs REST for different use cases?

GraphQL excels in: (1) Complex data requirements: nested, relational data from multiple resources in one request. (2) Multiple clients: mobile, web, partner APIs each request exactly what they need. (3) Rapid iteration: frontend evolves independently — no need to deploy backend API changes for new field combinations. (4) Type safety + codegen: end-to-end typed clients. REST excels in: (1) Simple CRUD APIs: low overhead, HTTP caching works naturally. (2) File uploads/downloads: REST is more natural. (3) Public APIs: REST is more widely understood, better HTTP cache support, standard tools (Swagger/OpenAPI). (4) Event streaming: SSE, chunked transfer — REST is simpler. (5) CDN caching: REST GET requests are cacheable at the HTTP layer without extra tooling. Trade-offs: GraphQL requires more server infrastructure (DataLoaders, complexity limits), has a steeper learning curve, and HTTP caching is harder. For internal APIs with complex frontends, GraphQL often wins. For simple public APIs, REST is often simpler.