Layered Architecture vs Feature Folders

Choosing between Layered Architecture and Feature Folders in .NET is often framed as a simple folder-structure discussion. In practice, it’s a much deeper architectural decision that directly affects how your codebase grows, how quickly teams can ship features, and how much technical debt accumulates over time.

I’ve built and maintained production systems using both approaches. I’ve experienced the safety and predictability of classic layering, and I’ve also felt the friction it introduces when speed matters. I’ve enjoyed the flow and focus that Feature Folders enable, and I’ve also dealt with the chaos that can emerge without discipline. This post isn’t theoretical, it’s based on what actually broke, what slowed teams down, and what ultimately worked better in real projects.

The Classic: Layered (or Onion) Architecture

Most .NET developers encounter Layered or Onion Architecture early in their careers. The structure is familiar: Core, Infrastructure, Application, and Web or API. It’s easy to explain, easy to diagram, and widely accepted as a safe” architectural choice.

On paper, Layered Architecture ticks all the Clean Architecture boxes. Dependencies point inward, business logic is isolated, and infrastructure concerns are abstracted away. This creates a sense of order and predictability, especially in larger teams where clear ownership boundaries are important.

But here’s what tends to happen in real-world projects:

• Every new feature requires touching multiple layers, even when the change is conceptually small.
• Cross-layer leakage becomes hard to avoid. Infrastructure concerns slowly creep into application code.
• Onboarding slows as new developers struggle to understand where logic belongs.

Example: Adding a CreateOrder Endpoint

In a layered setup, adding a single endpoint often requires changes across the system:

• OrderController in Web/API
• CreateOrderCommand and handler in Application
• Order aggregate in Core/Domain
• OrderRepository in Infrastructure
• Mapping profiles and DTOs

The approach is safe and explicit, but also verbose and slow, particularly for small teams.

The Challenger: Feature Folders

Feature Folders take a different perspective. Instead of organizing by technical layer, they organize by business capability. Everything related to a feature lives together, making it easier to understand and modify behavior in one place.

When I adopted Feature Folders in production systems, the impact was immediate. Context-switching dropped, code reviews became easier, and developers spent less time navigating the project structure.

What I’ve learned using Feature Folders:

• Feature development becomes faster and more focused.
• Refactoring is easier for isolated features.
• Discipline is required to prevent duplication or uncontrolled sprawl.

Example: The Orders Feature Folder

/Features
  /Orders
    OrderController.cs
    CreateOrderHandler.cs
    OrderValidator.cs
    OrderRepository.cs
    OrderDto.cs

This structure reduces ceremony and minimizes debates about where code should live, allowing teams to focus on solving business problems.

Trade-Offs I’ve Actually Paid For

With Layered Architecture

• Pros: Strong boundaries, easier enforcement of SOLID principles, and suitability for large teams.
• Cons: Slower delivery, more boilerplate, and higher cognitive load for everyday changes.

With Feature Folders

• Pros: Faster iteration, easier onboarding, and better alignment with business concepts.
• Cons: Risk of duplicated logic and the need for clear conventions.

What actually broke?

On one project, we started layered because it was considered best practice. After six months, onboarding was painful and feature delivery slowed dramatically. Refactoring toward Feature Folders restored momentum, but only after introducing rules for shared logic.

How I Draw the Line Today

There’s no universally correct choice. Context determines the best approach.

• Small teams and fast-moving products benefit from Feature Folders.
• Platforms with heavy cross-cutting concerns may benefit from layering.
• Hybrid approaches often work best, combining both styles where appropriate.

Architecture should enable teams, not constrain them.

Now What?

For your next vertical slice, try Feature Folders, even within a layered project. Observe how it affects speed and clarity.

Avoid premature abstraction. Let duplication surface naturally before extracting shared components. Never create a Common folder without clear ownership and purpose.