API Design Best Practices: Building APIs Developers Love

API design is user experience design for developers. A well-designed API is intuitive, consistent, well-documented, and handles errors gracefully. Poor API design creates support burden and integration friction.

REST resource naming: use nouns for resources (/users, /orders), plural forms for collections, and hierarchical paths for relationships (/users/123/orders). Avoid verbs in URLs; HTTP methods convey the action.

HTTP methods: GET (read), POST (create), PUT (full update), PATCH (partial update), DELETE (remove). Use methods consistently and return appropriate status codes: 200 (success), 201 (created), 204 (no content), 400 (bad request), 404 (not found).

Pagination for collections: implement cursor-based pagination for large datasets (more efficient than offset-based). Return pagination metadata (next cursor, total count if feasible) in the response.

Filtering, sorting, and field selection: allow query parameters for filtering (?status=active), sorting (?sort=created_at&order=desc), and selecting specific fields (?fields=id,name,email) to reduce payload size.

Error responses should be consistent, informative, and actionable. Include error code, human-readable message, and specific details. Never expose internal stack traces or database errors to API consumers.

API versioning strategies: URL versioning (/v1/users), header versioning (Accept: application/vnd.api.v1+json), or query parameter versioning (?version=1). URL versioning is most explicit and widely used.

Authentication: use OAuth 2.0 for third-party access, API keys for server-to-server communication, and JWT tokens for user authentication. Implement rate limiting to prevent abuse and ensure fair usage.

Documentation is not optional. Use OpenAPI/Swagger for REST APIs. Include request/response examples, authentication instructions, error code references, and quickstart guides. Interactive documentation (Swagger UI) enables testing.

GraphQL considerations: define a clear schema with descriptive types, implement query complexity limits to prevent abuse, use DataLoader for N+1 query prevention, and provide schema documentation and a playground.