GraphQL and Schema Federation

REST and gRPC return the response shape the server defines. GraphQL lets the client ask for exactly the fields it needs.

This is useful when different clients need different views of the same data. A mobile app, web dashboard, and internal tool can query one endpoint but receive different response shapes.

In microservices, GraphQL can also compose data from multiple services behind one schema.

This chapter covers GraphQL basics, schema federation, performance risks, and when GraphQL is or is not the right fit.