Over the past few years, I’ve built and maintained several production APIs. Here are the patterns and practices that have consistently delivered maintainable, high-performance services.
Clean Architecture Matters
Splitting your application into distinct layers — API, Application, Domain, and Infrastructure — keeps concerns separated and makes your codebase testable and adaptable. The domain layer should have zero external dependencies.
Efficient Data Access
Entity Framework Core is powerful, but raw performance requires attention. Use projection with Select() to avoid over-fetching, enable query splitting for complex includes, and always measure with ToQueryString() during development.
Validation at the Edge
Validate incoming requests as early as possible. FluentValidation combined with ASP.NET Core’s built-in model validation gives you clean, reusable validation logic that doesn’t clutter your controllers.
Authentication & Authorization
JWT-based authentication with refresh tokens is the standard for stateless APIs. Use policy-based authorization to keep access control declarative and centralized rather than scattered across controllers.
Observability
Structured logging with Serilog, health checks, and basic metrics give you visibility into production behaviour without needing a full observability stack from day one.
Key Takeaways
- Clean architecture pays off as the project grows — don’t skip it.
- Measure query performance early; don’t optimize blind.
- Good validation and auth are non-negotiable for production APIs.