.NET Developer Interview Questions and Structured Evaluation Guide
Knowing C# syntax isn't enough to call someone a strong .NET developer. Good .NET developers understand the runtime, write async and testable code, build secure APIs with ASP.NET Core, use Entity Framework wisely, and deploy and operate services in the cloud.
This guide gives you 40 .NET Developer interview questions for junior, mid-level, and senior hiring, organized by skill area and experience level, plus a ready-to-use scorecard so every interviewer rates candidates against the same criteria.
What to Evaluate in a .NET Developer Interview
Ten skill areas cover what separates a candidate who knows C# from one who can build and operate reliable .NET services.
| Skill Area | What to Assess |
|---|---|
| C# Language and OOP | Types, generics, delegates, LINQ, records, nullable references |
| Async and Concurrency | async/await, tasks, threading, synchronization |
| ASP.NET Core | Middleware, controllers, minimal APIs, DI, configuration |
| Data Access | Entity Framework Core, Dapper, SQL, transactions, migrations |
| Runtime and Performance | Garbage collection, memory, profiling, allocations |
| Security | Authentication, authorization, data protection, secure coding |
| Testing and Code Quality | xUnit, mocking, integration tests, clean code |
| Cloud and DevOps | Azure services, containers, CI/CD, monitoring |
| Problem Solving | Debugging, diagnosing production issues |
| Communication | Code review, design discussions, collaboration |
The 40 Questions
Pick a topic to open its questions. Each one includes a quick answer and what to listen for.
Questions by Experience Level
Same topics, different depth. Adjust what you ask based on seniority.
Junior .NET Developer questions: Foundations first
C# fundamentals, OOP, collections, LINQ basics, exceptions, simple ASP.NET Core APIs, Git
- What is the difference between .NET Framework and .NET Core?
- What is a class and an object?
- What is LINQ?
- What is the difference between a struct and a class?
- How do you handle exceptions in C#?
- What is dependency injection?
- How do you connect to a database?
Mid-level .NET Developer questions: Independent delivery
Async/await, dependency injection, Entity Framework Core, REST APIs, middleware, unit testing, debugging
- How would you build a REST API in ASP.NET Core?
- How do you use async/await correctly?
- How do you use Entity Framework Core efficiently?
- How do you write unit tests with xUnit?
- What are service lifetimes in dependency injection?
- How do you handle authentication in an API?
- How do you debug a production issue?
Senior .NET Developer questions: System and team level
Architecture, performance, cloud deployment, security, microservices, code quality, mentoring
- How would you design a scalable .NET architecture for a large system?
- How do you decide between monolith and microservices?
- How do you improve performance across a .NET application?
- How do you design a secure API platform?
- How do you lead a migration from .NET Framework?
- How do you mentor developers on code quality?
- How do you plan cloud deployment and monitoring?
.NET Developer Interview Scorecard
Use this so every interviewer scores candidates against the same criteria instead of relying on gut feel.
| Evaluation Area | Weight | What Good Looks Like |
|---|---|---|
| C# Language and OOP | 15% | Explains language features and writes clean code |
| LINQ, Collections, and Async | 15% | Uses LINQ and async programming correctly |
| ASP.NET Core | 15% | Builds well-structured, configurable APIs |
| Data Access | 15% | Uses EF Core or SQL efficiently and safely |
| Performance and Security | 10% | Diagnoses performance issues and applies secure practices |
| Testing and Design | 10% | Writes tested, maintainable, well-designed code |
| Cloud and DevOps | 10% | Deploys and monitors applications effectively |
| Communication and Collaboration | 10% | Explains decisions and reviews code constructively |
| Rating | Meaning |
|---|---|
| 1 · Weak | Cannot explain core .NET Developer concepts or apply them reliably |
| 2 · Below Expected | Knows some fundamentals but struggles applying them |
| 3 · Meets Expectations | Sound working knowledge, can contribute independently |
| 4 · Strong | Depth, judgment, clear problem-solving, reliable ownership |
| 5 · Exceptional | Expert-level depth, system thinking, strong technical leadership |
What Strong .NET Developer Candidates Demonstrate
Look for candidates who can:
- Explain C# language features with practical examples
- Use async/await correctly and avoid common pitfalls
- Build ASP.NET Core APIs with proper DI, configuration, and error handling
- Use EF Core efficiently and avoid N+1 queries
- Apply authentication, authorization, and secure coding practices
- Write meaningful automated tests
- Deploy and monitor .NET applications in the cloud
For senior roles, go deeper on architecture, performance, cloud deployment, security, microservices, code quality, and mentoring.
Turn this into a structured interview
Turning a question list into a consistent, evidence-based interview process is the hard part. VProPle helps hiring teams build structured scorecards, guide interviewers with the right questions in real time, record and transcribe interviews, and compare candidate feedback objectively.
With VProPle, this .NET Developer question set becomes:
- A structured technical screening interview
- An expert-led .NET Developer assessment
- A role-specific scorecard for junior, mid-level, or senior hiring
- A recorded, transcribed interview for later review
- A consistent process across internal and external interviewers
Frequently Asked Questions
Common questions from hiring teams building a .NET Developer interview process.
Enough to assess the role without turning the interview into a checklist. Most structured interviews work well with 20 to 30 targeted questions across C#, ASP.NET Core, Entity Framework, async programming, dependency injection, testing, and Azure, plus scenario-based problem-solving.
No. Syntax matters, but strong interviews also cover async behavior, ASP.NET Core, data access, testing, security, and how the candidate designs and operates services.
Many organizations still run legacy .NET Framework applications, so strong candidates should understand both and how to migrate to modern .NET.
Ask about architecture, performance, cloud deployment, security, microservices, code quality, and mentoring.
Yes, adjust the depth. Junior interviews should focus on fundamentals and practical implementation. Senior interviews should weigh design judgment, complex problem-solving, and technical leadership more heavily.
VProPle helps teams standardize .NET Developer interviews with structured scorecards, expert interviewers, AI-supported interviewer guidance, recorded conversations, and evidence-based evaluation. Learn more about Interview as a Service.