How to Build Scalable REST APIs in .NET

Introduction

Building scalable REST APIs is fundamental to the success of modern applications. In this article, I share the practices I use in my .NET projects.

Project Structure

I always organize projects following Clean Architecture:

• API Layer: Controllers and middleware
• Application Layer: Use cases and DTOs
• Domain Layer: Entities and business rules
• Infrastructure Layer: Data access and external integrations

API Versioning

I always use versioning to maintain compatibility:

[ApiVersion("1.0")]
[Route("api/v{version:apiVersion}/[controller]")]
public class ProductsController : ControllerBase
{
    // ...
}

Validation and Error Handling

I implement validation with FluentValidation and a global middleware for error handling.

Conclusion

These practices ensure more robust, testable and maintainable APIs.