🔥 Trending Design Patterns in C#: From Theory to Practice
Master classic GoF design patterns in C#. Learn how to apply creational, structural and behavioral patterns to build clean, flexible and maintainable systems.
Oleksii Anzhiiak
Software Architect, Senior .NET Engineer & Co-Founder
By the end you'll be able to
- Apply design patterns only where they add value
- Refactor legacy code into cleaner architectures
- Avoid unnecessary abstraction and complexity
- Explain architectural decisions confidently
- Improve maintainability of C# codebases
Is this course for you?
This is right for you if you…
- You write C# professionally and the team reviews keep saying 'this works but it's hard to extend' — you want to know what they actually mean
- You're a Mid engineer being asked to design new modules and want a vocabulary for the trade-offs you're already making by gut
- You've read the GoF book once, didn't apply anything, and want it to actually click this time
Don't take this course if you…
- You're new to C# — the patterns won't make sense without the language fundamentals first (course #1)
- You think 'use a pattern wherever possible' is good advice — this course will frustrate you because we spend half of it explaining when NOT to use one
- You want a memorisation drill — patterns memorised without context become the cargo-cult code these patterns were invented to fix
Who teaches this
Oleksii Anzhiiak
Software Architect, Senior .NET Engineer & Co-Founder
Oleksii Anzhiiak is a Software Architect, Senior .NET Engineer, and Co-Founder of ToyCRM.com and ProfectusLab. With over 15 years of experience, he specializes in distributed systems, cloud infrastructure, high-load backend development, and identity platforms. Oleksii designs complex architectures, builds secure authentication systems, and develops modern engineering education programs that help students achieve real career results.
Currently leads architecture for ToyCRM.com — a multi-tenant CRM platform built on .NET by our team. The same patterns and design decisions used there appear directly in the courses: identity & auth, distributed services, code review culture. You learn from engineers actively shipping production code, not from a textbook.
Syllabus
This course covers the following design patterns grouped by creational, structural and behavioral categories:
- 1 Module 1: Creational — Abstract Factory
- 2 Module 2: Creational — Builder
- 3 Module 3: Creational — Factory Method
- 4 Module 4: Creational — Prototype
- 5 Module 5: Creational — Singleton
- 6 Module 6: Structural — Adapter
- 7 Module 7: Structural — Bridge
- 8 Module 8: Structural — Composite
- 9 Module 9: Structural — Decorator
- 10 Module 10: Structural — Facade
- 11 Module 11: Structural — Flyweight
- 12 Module 12: Structural — Proxy
- 13 Module 13: Behavioral — Chain of Responsibility
- 14 Module 14: Behavioral — Command
- 15 Module 15: Behavioral — Interpreter
- 16 Module 16: Behavioral — Iterator
- 17 Module 17: Behavioral — Mediator
- 18 Module 18: Behavioral — Memento
- 19 Module 19: Behavioral — Observer
- 20 Module 20: Behavioral — State
- 21 Module 21: Behavioral — Strategy
- 22 Module 22: Behavioral — Template Method
- 23 Module 23: Behavioral — Visitor
Prerequisites
Basic computer skills and willingness to learn. Course materials will guide you step by step.
Solid C# programming skills and understanding of OOP principles are required.
What you'll build
You finish with a portfolio of refactors — taking 'works but ugly' code and showing the before/after. The most useful interview artefact a Mid-level engineer can carry: 'here's the legacy code, here's what I did to it, here's why I picked Strategy over inheritance'.
- Creational patterns: Factory, Builder, Singleton
- Structural patterns: Adapter, Decorator, Facade
- Behavioral patterns: Strategy, Observer, Command
- Refactoring procedural code into patterns
- Identifying overengineering and anti-patterns
- Architectural decision-making
Where this fits in your career
Read alongside this course
OpenSpec in 2026: The Operating System for Spec-Driven Development
Six weeks ago I installed @fission-ai/openspec. Yesterday I shipped a 14-file change in 90 minutes from a 200-line spec, in a brownfield codebase three engineers have been editing for two years — no merge conflicts, no review escalation. This is the senior-architect deep-dive on why OpenSpec is the first SDD tool that doesn't collapse under production reality.
Evals in 2026: The Test Suite for Systems That Aren't Deterministic
Your AI feature worked yesterday and fails today. No code change, no prompt change, no model change. That's what life without evals looks like. This is the third leg of the spec → context → evals trinity — and the discipline most teams skip.
Context Engineering: The Discipline That's Replacing Prompt Engineering in 2026
Prompt engineering was never the real skill. After two years of shipping AI features in production, the discipline that actually moves the needle is context engineering — state, tools, retrieval, history, and constraints assembled into the model's window at the right moment. Here's the senior-engineer's frame.
First lesson on us. Decide after meeting your instructor.
Sit in on the first session. If after lesson 1 you decide the instructor isn't the right fit, you don't pay for it — and no awkward conversation. (Trial offer applies to courses with more than 5 lessons; this one qualifies.)
Pricing & what's included
What's included
- 13 live sessions × 2 hours each — taught by the instructor, not a recording playback
- Slide deck for every session — yours to keep and refer back to
- Working code files and any data files used in class — cloned to your machine
- Weekly homework with personal code review from the instructor
- Recording on request — give the teacher a heads-up ("can't make Tuesday, please record it") and the session is recorded for you
Frequently asked questions
How much time per week will this take?
Plan for the live sessions plus roughly 1.5–2 hours of practice per session. Most students who finish on schedule put in 4–6 hours a week total. If you put in less, you still finish — it just takes longer.
What if I miss a class?
Tell the teacher BEFORE the session — "I can't make Tuesday, please record it" — and the teacher records that lesson and sends it to you. Recordings aren't a default catch-up archive; they're produced on request when you give a heads-up. After the lesson you do the homework, bring questions to the next session.
What's included in the price?
Live sessions with the teacher; the slide deck for each session (yours to keep); the working code files and any data files used in class; weekly homework with code review; and recordings of the sessions you give advance notice for. Anything beyond that — a certificate, alumni access, mock interviews — is listed explicitly in "What's included" above the FAQ for the courses where it applies.
What if I sign up and the teacher isn't a fit?
For courses with more than 5 lessons, the first session is effectively a trial — if after lesson 1 you decide the teacher isn't a fit, you don't pay for it. We'd rather you walk away after one lesson than push through 9 weeks of bad chemistry. (Courses with 5 or fewer lessons are short enough that the standard pricing applies — the trial offer doesn't make sense at that length.)
Can I get a refund partway through?
Yes, while more than half the course is still unused — i.e. you've attended fewer than 50% of the lessons. The refund covers the unused portion proportionally. Past the halfway point we don't refund, on the assumption that the value has been delivered.
Can I switch the language of instruction?
The live sessions run in the language listed under "Available Languages" above. Slides and code files are typically available in all four (English, Russian, Ukrainian, Georgian). Many students attend sessions in one language and read materials in another — that's normal.
Will I be ready for a real job after this course?
One course rarely gets anyone hired by itself — for any field. What this course gives you is the foundation a junior hiring manager expects: working code you wrote yourself, the vocabulary to read other people's code, and the practice habits that make you employable. The honest answer to "am I ready?" is on our roadmap (link in the page header) — open the level you want to reach and read the "You're ready when" checklist.
Can I pay in instalments?
Yes for courses with a "Monthly Payment" option in the at-a-glance ribbon — usually two or three equal monthly payments. Courses without that option are paid in one go. If the price is the blocker, write to us — we look at every case.
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