Top .NET Core Developer Interview Questions

Introduction

Hiring the right .NET Core Developer is critical in Information Technology. A strong candidate can design scalable services, implement secure APIs, and maintain high-performance applications that support business objectives.

This guide includes role-specific .NET Core Developer interview questions across basic, intermediate, and advanced levels, plus five pre-screening one-way video interview questions ideal for ScreeningHive. Use these to standardize evaluation and accelerate hiring.

.NET Core Developer Interview Questions

Basic .NET Core Developer Interview Questions

• What are the main differences between .NET Core and the .NET Framework?
• Explain the role of the Kestrel web server in ASP.NET Core applications.
• What is dependency injection and why is it used in .NET Core?
• Describe how middleware works in the ASP.NET Core request pipeline.
• How does Entity Framework Core differ from Entity Framework 6?
• What are async and await and when should you use them?
• Where should configuration settings be stored in an ASP.NET Core app and how are they accessed?
• How do you manage environment-specific settings such as Development and Production?

Intermediate .NET Core Developer Interview Questions

• You need to design a RESTful API for a new microservice. What project structure, controllers, and DTO patterns would you use and why?
• A client reports slow responses on an endpoint that queries multiple tables. How would you troubleshoot and optimize the query?
• Explain strategies for handling exceptions and returning meaningful HTTP status codes in ASP.NET Core.
• How would you implement authentication and authorization using JWT tokens in an ASP.NET Core application?
• Describe caching approaches you can apply at the application level and at the HTTP level to improve performance.
• How do you write unit and integration tests for controllers and services that depend on EF Core?
• Explain database migrations with EF Core and how you would handle schema changes in production.
• How do you choose between scoped, transient, and singleton service lifetimes? Give examples of each in a web app.
• Describe a deployment workflow for an ASP.NET Core app to Azure App Service or a container platform.
• How would you implement structured logging and correlate logs across requests and microservices?

Advanced .NET Core Developer Interview Questions

• Design an architecture for a highly available microservices system built on .NET Core. How would you handle service discovery, load balancing, and fault tolerance?
• How do you approach profiling and optimizing CPU and memory usage in a .NET Core production service?
• Describe techniques for reducing cold start times in serverless .NET Core functions or containerized services.
• Explain how to implement distributed tracing across .NET Core microservices and what telemetry to collect.
• How would you design a data access layer to support multi-tenant scenarios while keeping performance predictable?
• Discuss strategies for handling large file uploads and streaming with ASP.NET Core without blocking threads.
• What are common GC considerations and tuning options for high-throughput .NET Core applications?
• How do you secure inter-service communication and secrets in a cloud environment? Provide examples using certificates or managed identity.
• Explain design patterns you apply for resilient systems such as circuit breaker, bulkhead, and retry policies. How do you implement them in .NET Core?
• Describe how you would build a CI/CD pipeline for .NET Core services that includes testing, security scanning, and blue-green or canary deployments.

Pre-Screening Video Interview Questions for .NET Core Developer

These pre-screening interview questions are optimized for one-way video interviews on ScreeningHive. They assess technical depth, communication, and approach so hiring teams can quickly shortlist candidates.

1. Describe a recent .NET Core project you led and the specific contributions you made.

   This question evaluates practical experience, ownership, and clarity in explaining technical work.

2. Explain how you implemented authentication and authorization in a web API and why you chose that approach.

   This assesses knowledge of security patterns, token handling, and real-world decision making.

3. Walk through a performance problem you resolved in an ASP.NET Core app and the steps you took to measure and fix it.

   This reveals problem solving, use of profiling tools, and ability to quantify improvements.

4. Show how you structure code for testability in a .NET Core service and give an example of a unit or integration test you wrote.

   This checks for clean architecture, dependency injection usage, and testing practices.

5. Describe how you would migrate a legacy .NET application to .NET Core and the biggest risks you would mitigate first.

   This evaluates migration planning, compatibility knowledge, and risk management skills.

Conclusion

Using these .NET Core Developer interview questions helps hiring managers, recruiters, and HR teams evaluate candidates consistently across technical levels. The structured basic, intermediate, and advanced lists guide interviews while the pre-screening video questions let teams quickly filter for fit and communication.

ScreeningHive supports one-way video interviews to speed up screening, deliver standardized evaluations, and reduce time to hire. Integrate these questions into your ScreeningHive workflow to screen more efficiently and identify the best .NET Core Developer candidates.