18Software Engineering · Interview Prep · Free
.NET Developer interview questions — and how to answer them.
These are the questions .NET Developer candidates are most likely to face, from openers to the hard ones — each with a note on what a strong answer covers. Want more, tuned to your level? Use the free generator below.
What interviewers look for in a .NET Developer
- Concrete examples of systems you've built, with the trade-offs you weighed
- How you debug — the process, not just the fix
- Collaboration signals: code review, disagreements, mentoring
Likely .NET Developer interview questions
1. Can you walk us through your experience with C# and .NET? What versions have you worked with?
Mention specific projects, frameworks (ASP.NET Core, .NET Framework), and your progression with the language.
2. Tell me about a time you had to debug a difficult issue in production. How did you approach it?
Describe systematic troubleshooting, tools used (debugger, logging, profiling), and how you communicated with stakeholders.
3. What's the difference between value types and reference types in C#? Can you give examples?
Explain structs vs classes, stack vs heap memory, boxing/unboxing, and performance implications.
4. Describe your experience with ASP.NET Core. How do you structure a web application?
Cover MVC/API patterns, dependency injection, middleware, routing, and how you organize projects.
5. How do you handle asynchronous programming in C#? When would you use async/await vs Task?
Explain async/await patterns, Task vs ValueTask, cancellation tokens, and common pitfalls like deadlocks.
6. Walk us through your experience with databases. How do you typically access data in .NET?
Discuss Entity Framework Core vs Dapper, LINQ, query optimization, migrations, and ORM trade-offs.
7. Tell me about a time you refactored legacy code. What was your approach and what challenges did you face?
Show understanding of technical debt, testing strategy before refactoring, maintaining functionality, and stakeholder communication.
8. How do you implement and use dependency injection in .NET? Why is it important?
Explain IoC containers, service lifetimes (singleton/scoped/transient), testability benefits, and real-world scenarios.
9. Describe your experience with unit testing and mocking frameworks. How do you ensure good test coverage?
Mention xUnit/NUnit, Moq, test pyramid, integration vs unit tests, and how you balance coverage with maintainability.
10. How would you design a scalable API to handle high traffic? What architectural patterns would you consider?
Discuss caching strategies, rate limiting, microservices vs monolith, API versioning, monitoring, and database optimization.
11. Tell me about your experience with cloud platforms (Azure, AWS). How have you deployed and maintained .NET applications?
Cover CI/CD pipelines, App Service/EC2, containerization (Docker), logging/monitoring, and infrastructure-as-code.
12. Describe a complex architectural decision you made in a .NET project. How did you weigh trade-offs and justify your choice?
Show strategic thinking, consideration of performance/maintainability/cost, communication with team, and evidence-based decision-making.
Want to practice answering live with scored feedback? Try the Mock Interview Coach.
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