How do you decide between REST and GraphQL for your API?

REST and GraphQL are different paradigms for building APIs, each with strengths suited to different scenarios.

REST uses multiple endpoints, each returning a fixed data structure. It's simple, well-understood, and leverages HTTP semantics and caching. However, it can lead to over-fetching (getting more data than needed) or under-fetching (needing multiple requests for related data).

GraphQL provides a single endpoint where clients specify exactly what data they need through queries. This eliminates over/under-fetching and allows clients to get related data in one request. The strongly-typed schema serves as documentation and enables powerful tooling.

Choose REST when: you have simple, well-defined resource relationships; you need robust HTTP caching; your team is more familiar with REST; you're building a public API for external developers; or you have resource-oriented operations.

Choose GraphQL when: clients need flexibility in data fetching; you're serving multiple clients with different data needs (mobile vs. web); you have complex, interconnected data; you want to reduce the number of network requests; or you need real-time updates via subscriptions.

GraphQL adds complexity: you need to handle query optimization (N+1 problems), implement authorization per-field, and handle caching differently. REST is simpler to implement and debug. Many successful applications use REST, and the "REST vs GraphQL" choice depends on specific project needs rather than one being universally better.