C#/.NET - 50 Essential Interview Questions (Mid Level)

Design principles, patterns and advanced C#. Built on 250+ tech interviews I conducted. Do not memorize, understand.

Why this course?

I've conducted over 250 technical interviews as a .NET Technical Lead. I know what interviewers ask, how they evaluate answers, and what separates a "good enough" response from one that actually impresses.

This course teaches you exactly what you need for a mid-level C# interview. We go through 50 essential questions in depth, plus 100 bonus questions — 150 real-world questions total. Each one is explained so you understand why the answer is correct, not just what to say.

What makes this course different?

Most interview prep courses are question dumps — here's the question, here's the answer, memorize it. This course takes a different approach:

• We learn by coding. Topics are explained with hands-on examples, and the course includes 10 in-browser coding exercises to reinforce your understanding.

• We go deep. Each topic is broken down so you can handle follow-up and trick questions with confidence.

• We cover what actually gets asked. The questions in this course are based on real interviews, not pulled from a textbook.

What's inside?

8 hours of video covering the advanced topics interviewers expect mid-level candidates to know:

• Advanced C# mechanisms — reflection, the dynamic keyword, pattern matching, nullable reference types

• Design principles and best coding practices — with real-world reasoning, not just definitions

• 5 popular design patterns — when and why to use each one

• C# collections in depth — differences, trade-offs, and the follow-up questions interviewers love to ask

• Events, lambda expressions, and more — the topics that separate junior answers from mid-level ones

Included with the course

• Two free e-books — one with all mid-level questions and answers, one reviewing 15 essential junior-level topics (just in case you need a refresher)

• Printable flashcards + Anki deck — study on the go, anywhere, anytime

• Full Git repository with all the code from the lectures

• 10 in-browser coding exercises to practice as you learn

Coming from the junior level?

No problem. This course picks up where junior-level knowledge ends. And just in case there are any gaps, a free e-book reviewing 15 essential junior-level topics is included — so you can get up to speed before diving into the advanced material.

Not preparing for an interview right now?

That's fine too. Many students take this course to deepen their understanding of C# and fill knowledge gaps. Interview questions are a great framework for learning — they force you to think about the "why" behind every concept, which makes you a better programmer regardless of whether you have an interview coming up.

This course is covered by Udemy’s 30-day Refund Policy, so you can try it out risk-free.