Backend API

RESTful API design uses resource-based URLs with standard HTTP methods: GET retrieves data, POST creates, PUT updates, and DELETE removes resources. Structure endpoints like `/users` for collections and `/users/:id` for specific resources, applying appropriate status codes and validation to each operation.

HTTP status codes signal operation outcomes: 200 for successful GET/PUT, 201 for successful POST creation, 204 for successful DELETE, 400 for invalid requests, 404 for missing resources, and 5xx for server errors. Consistent status code handling ensures clients reliably interpret API behavior.

API versioning manages changes without breaking clients. Strategies include URL-based versioning like `/v1/users` and `/v2/users`, or header-based versioning. Choose a strategy early and document migration paths to help clients adopt new versions smoothly.

Yes. FastAPI and Express both support request validation through middleware and decorators. Validate incoming data against schemas, enforce consistent response formats, and return detailed error messages. Validation prevents malformed requests from reaching your business logic.

Use lowercase, plural nouns for resource collections (`/users`, `/products`) and consistent parameter names in URLs and query strings. Avoid verbs in URLs—let HTTP methods express the action. This consistency makes endpoints predictable and easier for clients to discover and use.

Rate limiting restricts requests per client to prevent abuse, typically applied via middleware that tracks request counts and returns 429 status codes when exceeded. Middleware also handles response formatting, logging, and authentication consistently across all endpoints.