api-design-principles

REST API versioning establishes long-term compatibility through clear version paths in URLs or headers, paired with consistent endpoint design. Use URI-based versioning (e.g., `/v1/`, `/v2/`) or header-based approaches, document deprecation timelines, and maintain backward compatibility across major versions to reduce developer friction.

REST uses resource-oriented endpoints with fixed response shapes; GraphQL uses schema-first design where clients request exactly the fields needed. REST scales through versioning and caching; GraphQL reduces over-fetching and under-fetching. Choose REST for simple, cacheable resources; GraphQL for complex queries and flexible client requirements.

Consistent error handling includes standardized HTTP status codes, uniform error response formats with descriptive messages, and clear error documentation. Use schemas to define error objects, include request IDs for observability, and document which errors each endpoint can return so clients handle failures predictably.

Pagination patterns include offset-limit (simple, cursor-prone to gaps), cursor-based (stable, efficient), and keyset pagination (scalable). Select based on dataset size and sort stability. Document page size limits, default behavior, and whether sorting affects cursors to guide client implementation.

Yes. Schema definitions alone do not cover authentication flows, rate limits, error scenarios, or use-case examples. Developer documentation should include quick-start guides, endpoint walkthroughs, authentication/authorization patterns, and code samples to reduce integration time and support burden.

Authentication verifies identity (API keys, OAuth, JWT); authorization controls what authenticated users can access. Design APIs with clear scopes or permissions, document token formats and expiration, use consistent header conventions, and provide observability into access denials to help developers debug permission issues.