How should a scalable ASP.NET Core application be structured using Clean Architecture and domain-driven design principles?

A scalable ASP.NET Core application should separate business rules from infrastructure and delivery mechanisms, rather than allowing controllers, database code, and domain logic to become tightly coupled. A practical Clean Architecture structure typically separates the Domain, Application, Infrastructure, and API/Presentation layers. The Domain layer contains entities, value objects, domain rules, and business concepts; the Application layer coordinates use cases and defines abstractions; Infrastructure implements concerns such as Entity Framework Core, external services, messaging, and persistence; while the API handles HTTP requests and responses.

Domain-Driven Design (DDD) complements this approach by encouraging developers to model the application around the business domain and bounded contexts, rather than simply creating database tables and CRUD endpoints. Complex business rules should live close to the domain model, while application services orchestrate workflows without becoming a dumping ground for business logic.

Dependency inversion is critical: higher-level business layers should depend on abstractions rather than concrete infrastructure implementations. ASP.NET Core's built-in dependency injection can then wire these implementations at the application boundary.

For scalability, developers should additionally consider asynchronous processing, caching, database performance, observability, resilience, API versioning, authentication/authorization, and horizontal scaling. Clean Architecture does not automatically make an application scalable—it provides boundaries that make scalability, testing, and change easier to manage.

A strong enterprise structure should therefore achieve:
Clear boundaries → low coupling → domain-focused business logic → testability → replaceable infrastructure → scalable deployment.