Clean Architecture in .NET: The Complete Guide

Clean Architecture in .NET: The Complete Guide
Understand the reasoning. Enforce the rules. Build software that survives change.

Course Summary

This course teaches Clean Architecture the way almost no resource does: not as a diagram to memorize or a template to clone, but as a set of decisions you understand well enough to defend — and to break on purpose when the situation calls for it.

You build one real application — an Event Ticketing system — from a working-but-terrible starting point into a clean, fully-tested, production-shaped solution, by hand and from scratch, in .NET 10 and C# 14. Every layer, interface, and abstraction is introduced only when a concrete pain demands it, and each one is put on trial with the question that runs through the entire course: did this abstraction earn its place?

But building the architecture is only half the challenge. The course also trains the judgment that separates developers who follow the diagram from developers who reason about it — with hands-on exercises in every module, a decision procedure for where any piece of code belongs, a fair hearing for the rival Vertical Slice approach, a catalogue of anti-patterns that look clean but rot, and an honest guide to when not to use any of this.

What’s Included?

• 16 modules, 85 lessons — from the “feel the pain” starting app to a finished, clean, fully-tested system
• One complete application built by hand — an Event Ticketing system in .NET 10 and C# 14, with real business rules (capacity, pricing, refunds, concurrency) that force a real domain
• Downloadable .NET solution with a runnable checkpoint at every module — start any module from the previous one’s finished code, or grab the completed solution to check your work
• Before-and-after throughout — the messy starting app runs beside the clean code and is retired feature by feature, so you see the transformation, not just the destination
• Real, runnable code with real output at the key moments — failing tests, HTTP responses, logs, and the exact behavior each change produces
• A hand-rolled mediator, pipeline, and Result type — you build the core machinery yourself, so nothing in the final system is a black box
• Four complete test suites — pure domain tests, handler tests with fakes, architecture tests that enforce the Dependency Rule, and full integration tests against a real database
• Diagrams for the load-bearing ideas — the rings, the dependency arrow, the architecture landscape, the testing pyramid, and the code-placement decision flow
• Hands-on exercises in every module — recognition, refactoring, choosing between options, and spotting misuse, each with worked solutions
• Honest coverage of the .NET ecosystem’s licensing shifts — MediatR, AutoMapper, and FluentAssertions going commercial, and exactly what to do about it
• Regular updates aligned with the latest .NET releases
• Lifetime access
• Progress tracking

What Will You Learn?

• The Dependency Rule — the single idea the entire architecture rests on — and how to make the compiler and CI enforce it for you
• A rich domain layer: aggregates that guard their own invariants, value objects, domain events, and the Result pattern — so the bugs you meet on day one become impossible to write
• A clean application layer: use cases, CQRS, a hand-rolled mediator, and a pipeline of validation, logging, and unit-of-work behaviors
• EF Core behind honest boundaries: when a repository earns its place and when it is ceremony, plus the Specification pattern, the adapter pattern, and the composition root
• The API edge: DTOs and which boundaries deserve a separate model, manual mapping versus libraries, and minimal APIs versus controllers
• Errors done right: the difference between expected failures and genuinely exceptional ones, and the Result pattern mapped cleanly to HTTP ProblemDetails
• Domain events dispatched after the transaction commits, and a complete purchase-and-refund feature built end to end through every layer
• Testing that the architecture makes easy: from microsecond domain tests to integration tests with Testcontainers
• When not to use Clean Architecture — and Vertical Slice Architecture as the serious alternative, plus the hybrid most real systems should actually use
• A repeatable decision procedure for where any piece of code belongs, for the cases the diagrams never cover
• How to recognize the anti-patterns that pass code review but quietly rot — the generic repository, the leaky abstraction, the anemic model, and more — and how to fix them
• How to talk about the architecture in interviews and code reviews, and how to introduce it to a team without a doomed big-bang rewrite

You can find an entire TOC with preview lessons in the Course Content section below.