Node.js is a fantastic platform for building APIs. Its event-driven, non-blocking I/O model makes it perfect for handling many concurrent connections.
Express.js remains the most popular framework for building APIs in Node.js. It's minimal, flexible, and has a huge ecosystem of middleware.
Structure matters. Organize your code into routes, controllers, services, and models. This separation makes your code easier to test and maintain.
Input validation is crucial for security. Use libraries like Joi or express-validator to validate incoming data before processing it.
Don't forget documentation. Tools like Swagger/OpenAPI make it easy to document your endpoints and even generate client libraries automatically.