Building Scalable APIs with ASP.NET Core

As applications grow, keeping controllers, business logic and persistence responsibilities separated becomes increasingly important.

A clear architecture makes the system easier to maintain, test and extend without turning every new feature into a large refactor.

The API layer should focus on HTTP concerns while application services handle business workflows and infrastructure handles persistence and integrations.

This separation creates clear boundaries between responsibilities and keeps the codebase easier to reason about.

Input validation, authentication and authorization should be treated as first-class parts of the application rather than added after the core functionality is complete.