Design Patterns that Deliver

You know the theory.

But the code still looks wrong.

You've read the Gang of Four. You've watched YouTube tutorials. You can name patterns on a whiteboard.

But when you open your IDE and face a real problem, you freeze:

• "Should this be a Strategy or a Factory?"

• "Am I overengineering this with a Decorator?"

• "How does this pattern even work with DI?"

• "The example online is a Pizza class... how does that help me?"

The gap between knowing a pattern and using it in production is massive.

That's what this ebook closes.

What Changes After You Read This

Before

❌ Copy-paste pattern examples from StackOverflow

❌ Can't decide which pattern fits the problem

❌ Overengineer simple features with wrong abstractions

❌ Struggle to explain patterns in interviews

❌ Every tutorial uses Pizza or Animal classes

❌ Don't know how patterns work with dependency injection

After

✔ Choose the right pattern in minutes

✔ Refactor messy code into clean, maintainable architecture

✔ Know exactly when to use - and when NOT to use - each pattern

✔ Speak confidently about patterns in any interview

✔ Have production-ready C# code you can adapt immediately

✔ Understand advanced variants (Fluent Builder, Scrutor Decorators, MediatR)

5 Patterns. Real Problems. Real Code.

Each pattern starts with a real-world problem, not a textbook definition

Builder Pattern

Stop creating objects with 10-parameter constructors. Learn to build complex objects step by step - from basic Builder to Fluent Builder, Director Class, and Step Builder with validation.

• Fluent Builder • Director Class • Nested Builders

• FluentValidation integration • Step Builder

Decorator Pattern

Add logging, caching, or retry logic without touching the original class. Learn how Scrutor makes decorators effortless with .NET dependency injection.

• Composing Decorators • Scrutor + DI

• Resilient API Service (Retry Policy) • Cross-cutting concerns

Strategy Pattern

Swap algorithms at runtime without if-else chains. Combine Strategy with Factory, dependency injection, and configuration-based selection.

• DI with Strategy • Strategy + Factory

• Config-based selection • Runtime algorithm swap

Adapter Pattern

Integrate third-party APIs and legacy systems without rewriting everything. Learn both Object and Class Adapter with a real cloud providers example.

• Object vs Class Adapter • Cloud Provider integration

• Legacy system wrapping • Interface compatibility

Mediator Pattern

Decouple your components and orchestrate communication cleanly. From basic mediator to MediatR with pipeline behaviors for Clean Architecture.

• MediatR in Clean Architecture • Pipeline behaviors

• Cross-cutting concerns • Event Aggregation

You Don't Just Get a PDF

📖 The Ebook

✔ 5 design patterns, explained from problem to production

✔ Real-world scenarios - not Pizza or Animal classes

✔ UML diagrams for every pattern

✔ Advanced variants for each pattern

✔ Pros, cons, and when NOT to use each one

💻 GitHub Repository

✔ 20 mini-projects with complete C# solutions

✔ Clone, run, and modify immediately

✔ Production-ready code structure

✔ Every pattern variation implemented

✔ Bonus: code in 4 additional languages

🎯 Interview Prep Mini-Ebook

✔ 100 design pattern interview questions

✔ Detailed answers with code examples

✔ Covers all major patterns (not just these 5)

✔ Perfect for senior-level interviews

⚡ Quick Reference

✔ Pattern decision guide - which pattern for which problem

✔ Cheat sheet with key implementation steps

✔ When to use vs. when NOT to use summary

✔ DI integration patterns at a glance

🎁 Bonuses Included

📚 EPUB Format

Read on any e-reader, tablet, or phone

🌓 Dark & Light Mode

Comfortable reading day or night

📄 100 Interview Q&As

With code examples for every answer

Total value: ebook + repo + interview prep + cheat sheets + EPUB

1250+ Developers Already Use These Patterns

Milan Jovanovic

Microsoft MVP

"Design Patterns ebook is a quick and enjoyable read about the most important design patterns in C#. The examples were refreshing, and I especially liked being able to access the source code. If you're just starting or need a refresher, this book will be your design patterns companion."

⭐⭐⭐⭐⭐

Raul Fernando Aillon Salinas

Software Developer

"I love the simplicity of how every pattern is explained. The real-life examples are an incredible way to provide context and understand why we are choosing this pattern. By providing the writer's point of view of preferences we are able to evaluate the pros and cons, to decide which is better for our particular use case."

⭐⭐⭐⭐⭐

Jeroen Opmeer

C#/.NET Senior Developer

"This ebook shows that good technical information doesn't have to be burried in hundreds of pages of fluff. Exactly what a developer wants to read, core information on what a specific technology is about and how to apply it."

⭐⭐⭐⭐⭐

Nikola Knezevic

Software Developer, Content Creator

"The book is packed with five important design patterns in C#. Each pattern is explained step by step, with access to a GitHub repository, making it easy for everyone to grasp the material."

⭐⭐⭐⭐⭐

Saeed Esmaeelinejad

Senior Software Engineer

"I just read the book and it's amazing with nice visualization which helps a lot for a better understanding of how patterns work. One of the points that I like is mentioning the Pros and Cons, they help you to decide which pattern is suitable for your case."

⭐⭐⭐⭐⭐

Stefan Milosevic

Senior Software Engineer

"This book is a very fun and interesting way to get into the world of design patterns. It also has everything that you need to start applying those patterns in your application. Highly recommended."

⭐⭐⭐⭐⭐

Written by a Developer, for Developers

Hi, I'm Stefan

Microsoft MVP and Senior Software Engineer with years of experience building production .NET systems. I teach 20,000+ subscribers through my newsletter, and 102k+ followers follow my content on LinkedIn.

I wrote this ebook because I was frustrated with pattern books that use toy examples. Every pattern in this book comes from a real problem I've solved in production code.

Newsletter

20,000+ subscribers

102k+ followers

Twitter

8000+ followers

Is This Ebook Right for You?

This is for you if...

✔ You're a .NET / C# developer (mid-level or senior)

✔ You know what design patterns are but struggle to apply them

✔ You want production-ready code, not textbook theory

✔ You're preparing for senior-level interviews

✔ You want to write cleaner, more maintainable architecture

✔ You're a tech lead looking for patterns your team can adopt

This is NOT for you if...

❌ You're a complete beginner still learning C# basics

❌ You want a reference for all 23 GoF patterns

❌ You prefer abstract theory over practical implementation

❌ You're looking for language-agnostic content only

Full Table of Contents

🛠 Builder Pattern

Real World Problem

Solution + Basic Builder Implementation

Definition + UML Diagram

Fluent Builder Pattern

Director Class

Nested Builder Objects (Hierarchical)

Builder Pattern + FluentValidation

Step Builder Pattern

Pros & Cons

When to & When NOT to Use It

🎨 Decorator Pattern

Real World Problem

Solution + Basic Decorator Implementation

Definition + UML Diagram

Composing Decorators

Adding Scrutor to Decorator Pattern

Real Problem - Resilient API Service (Retry Policy)

Pros & Cons

When to & When NOT to Use It

⚡ Strategy Pattern

Real World Problem

Solution + Basic Strategy Implementation

Definition + UML Diagram

Dependency Injection with Strategy Pattern

Combining Strategy Pattern with Factory Pattern

Using Configuration Settings for Strategy Selection

Pros & Cons

When to & When NOT to Use It

🔌 Adapter Pattern

Real World Problem

Solution + Basic Adapter Implementation

Definition + UML Diagram

Object Adapter Pattern

Class Adapter Pattern

Example: Cloud Providers Integration

Pros & Cons

When to & When NOT to Use It

🚀 Mediator Pattern

Real World Problem

Solution + Basic Mediator Implementation

Definition + UML Diagram

Cross-Cutting Concerns

MediatR Library in Clean Architecture

Event Aggregation

Pros & Cons

When to & When NOT to Use It

🎯 Bonus: Interview Prep

100 Design Pattern Interview Questions

Detailed Answers with Explanations

Covers All Major GoF Patterns

Frequently Asked Questions

What are design patterns in .NET?

Design patterns are reusable solutions to common software design problems. In .NET and C#, they help you structure code that is maintainable, testable, and scalable. The most practical ones include Builder, Decorator, Strategy, Adapter, and Mediator - which are the 5 covered in this ebook with production-ready implementations.

Which design patterns should I learn first as a C# developer?

Start with the patterns you'll use most in real projects: Builder for object creation, Strategy for swappable algorithms, Decorator for adding behavior without modifying classes, Adapter for integrating third-party code, and Mediator for decoupling components. These 5 cover 80% of real-world needs.

Are design patterns still relevant in modern .NET?

Absolutely. Modern .NET with dependency injection, middleware pipelines, and Clean Architecture relies heavily on design patterns. MediatR (Mediator), Scrutor (Decorator), Polly (Strategy), and HttpClientFactory (Builder) are all pattern implementations used daily in production .NET applications.

How is this different from other design patterns books?

Most pattern books explain theory with abstract examples (Pizza, Animal, Shape classes). This ebook starts every pattern with a real production problem, shows the solution in C#, then explores advanced variants. You also get a GitHub repo with 20 runnable mini-projects.

What knowledge level do I need?

You should be comfortable with C# and basic .NET development. The ebook is designed for intermediate to senior developers who know the language but want to level up their architecture and design skills. It's not for absolute beginners.

Do I get code I can use in my projects?

Yes. You get full access to a GitHub repository with 20 mini-projects - one for each pattern and each advanced variant. The code is structured, documented, and ready to clone, run, and adapt for your own projects.

How do I apply design patterns in real .NET projects?

Each pattern starts with a real-world scenario you'd encounter in production. The ebook shows you step-by-step how to identify the problem, choose the right pattern, implement it with proper dependency injection, and understand when NOT to use it. The GitHub repo gives you complete, runnable examples.

Is there a refund policy?

The ebook is a digital product delivered instantly. If you're not satisfied, reach out directly and we'll work it out. 1250+ developers have purchased it and the feedback has been overwhelmingly positive.

Start using the right one - with real C# code you can apply in your next PR.

You've read the Gang of Four. You've watched YouTube tutorials. You can name patterns on a whiteboard.

But when you open your IDE and face a real problem, you freeze:

• "Should this be a Strategy or a Factory?"

• "Am I overengineering this with a Decorator?"

• "How does this pattern even work with DI?"

• "The example online is a Pizza class... how does that help me?"

The gap between knowing a pattern and using it in production is massive.

That's what this ebook closes.

Before

❌ Copy-paste pattern examples from StackOverflow

❌ Can't decide which pattern fits the problem

❌ Overengineer simple features with wrong abstractions

❌ Struggle to explain patterns in interviews

❌ Every tutorial uses Pizza or Animal classes

❌ Don't know how patterns work with dependency injection

After

✔ Choose the right pattern in minutes

✔ Refactor messy code into clean, maintainable architecture

✔ Know exactly when to use - and when NOT to use - each pattern

✔ Speak confidently about patterns in any interview

✔ Have production-ready C# code you can adapt immediately

✔ Understand advanced variants (Fluent Builder, Scrutor Decorators, MediatR)

Each pattern starts with a real-world problem, not a textbook definition

Builder Pattern

Stop creating objects with 10-parameter constructors. Learn to build complex objects step by step - from basic Builder to Fluent Builder, Director Class, and Step Builder with validation.

• Fluent Builder • Director Class • Nested Builders

• FluentValidation integration • Step Builder

Decorator Pattern

Add logging, caching, or retry logic without touching the original class. Learn how Scrutor makes decorators effortless with .NET dependency injection.

• Composing Decorators • Scrutor + DI

• Resilient API Service (Retry Policy) • Cross-cutting concerns

Strategy Pattern

Swap algorithms at runtime without if-else chains. Combine Strategy with Factory, dependency injection, and configuration-based selection.

• DI with Strategy • Strategy + Factory

• Config-based selection • Runtime algorithm swap

Adapter Pattern

Integrate third-party APIs and legacy systems without rewriting everything. Learn both Object and Class Adapter with a real cloud providers example.

• Object vs Class Adapter • Cloud Provider integration

• Legacy system wrapping • Interface compatibility

Mediator Pattern

Decouple your components and orchestrate communication cleanly. From basic mediator to MediatR with pipeline behaviors for Clean Architecture.

• MediatR in Clean Architecture • Pipeline behaviors

• Cross-cutting concerns • Event Aggregation

📖 The Ebook

✔ 5 design patterns, explained from problem to production

✔ Real-world scenarios - not Pizza or Animal classes

✔ UML diagrams for every pattern

✔ Advanced variants for each pattern

✔ Pros, cons, and when NOT to use each one

💻 GitHub Repository

✔ 20 mini-projects with complete C# solutions

✔ Clone, run, and modify immediately

✔ Production-ready code structure

✔ Every pattern variation implemented

✔ Bonus: code in 4 additional languages

🎯 Interview Prep Mini-Ebook

✔ 100 design pattern interview questions

✔ Detailed answers with code examples

✔ Covers all major patterns (not just these 5)

✔ Perfect for senior-level interviews

⚡ Quick Reference

✔ Pattern decision guide - which pattern for which problem

✔ Cheat sheet with key implementation steps

✔ When to use vs. when NOT to use summary

✔ DI integration patterns at a glance

🎁 Bonuses Included

📚 EPUB Format

Read on any e-reader, tablet, or phone

🌓 Dark & Light Mode

Comfortable reading day or night

📄 100 Interview Q&As

With code examples for every answer

Total value: ebook + repo + interview prep + cheat sheets + EPUB

Written by a Developer, for Developers

This is for you if...

✔ You're a .NET / C# developer (mid-level or senior)

✔ You know what design patterns are but struggle to apply them

✔ You want production-ready code, not textbook theory