4 Essential Work Sample Exercises for Evaluating .NET Full Stack Developer Candidates

The .NET Full Stack Developer role is pivotal in modern software development teams, requiring a unique blend of front-end aesthetics, back-end logic, and architectural understanding. Finding candidates who truly possess these multifaceted skills can be challenging when relying solely on traditional interviews and resume reviews. Technical interviews often reveal theoretical knowledge but fail to demonstrate how candidates apply that knowledge in real-world scenarios.

Work samples provide a window into a candidate's practical abilities, problem-solving approach, and coding style. For .NET Full Stack Developers, these exercises should evaluate both breadth and depth of technical knowledge across the stack. Well-designed work samples reveal not just what candidates know, but how they think, collaborate, and adapt to feedback – critical skills for success in development teams.

The exercises outlined below are specifically crafted to evaluate core competencies required for .NET Full Stack Developers: code quality and refactoring skills, API development capabilities, front-end implementation expertise, and database design knowledge. Each exercise simulates real-world challenges developers face daily, providing authentic insight into how candidates would perform in your environment.

By implementing these structured work samples, you'll gain objective data points to compare candidates fairly, reduce hiring bias, and significantly increase the likelihood of identifying developers who will excel in your specific technical environment. Additionally, these exercises give candidates a realistic preview of the work they'll be doing, helping ensure mutual fit and reducing early turnover.

Activity #1: Code Review and Refactoring Exercise

This exercise evaluates a candidate's ability to identify code quality issues, understand existing codebases, and implement improvements following best practices. Code review skills are essential for maintaining high-quality software and collaborating effectively with team members. This activity reveals how candidates approach legacy code, their understanding of .NET patterns and practices, and their ability to communicate technical concepts clearly.

Directions for the Company:

• Prepare a C# code sample (approximately 100-200 lines) containing deliberate issues such as:
• Performance inefficiencies (e.g., unnecessary loops or memory usage)
• Poor error handling
• Violation of SOLID principles
• Security vulnerabilities
• Lack of proper logging
• Provide the code in a GitHub repository or as a downloadable solution
• Include a brief description of what the code is supposed to do functionally
• Allocate 45-60 minutes for this exercise
• Have a senior developer available to discuss the candidate's approach afterward

Directions for the Candidate:

• Review the provided code sample and identify issues related to performance, security, maintainability, and adherence to best practices
• Refactor the code to address the identified issues while maintaining the original functionality
• Document your changes and explain your reasoning for each significant modification
• Be prepared to discuss alternative approaches you considered
• Submit your refactored code and documentation before the deadline

Feedback Mechanism:

• After submission, the interviewer should review the refactored code with the candidate
• Provide specific feedback on one aspect the candidate handled well (e.g., "I appreciated how you simplified the error handling by…")
• Offer one constructive suggestion for improvement (e.g., "One thing to consider is how this approach might scale when…")
• Allow the candidate 10-15 minutes to implement the suggested improvement or explain how they would approach it differently

Activity #2: RESTful API Development

This exercise assesses the candidate's ability to design and implement back-end services using .NET technologies. It evaluates their understanding of API design principles, data modeling, authentication, and error handling – all critical skills for modern web application development. The activity reveals how candidates structure their code, handle edge cases, and document their work for other developers.

Directions for the Company:

• Create a specification for a simple RESTful API with 3-4 endpoints (e.g., a basic product catalog or task management API)
• Specify requirements including:
• Entity relationships
• Authentication requirements (if any)
• Expected response formats
• Business rules to implement
• Provide any necessary starter code or database scripts
• Allow candidates to use their preferred .NET version (Core/.NET 5+)
• Allocate 2-3 hours for completion (can be done as a take-home exercise)

Directions for the Candidate:

• Implement the API according to the provided specifications using ASP.NET Core
• Create appropriate models, controllers, and services following clean architecture principles
• Implement proper error handling and status codes
• Include basic input validation
• Write at least one unit test for a critical component
• Document your API using Swagger/OpenAPI or equivalent
• Include instructions for running your solution locally
• Be prepared to explain your architectural decisions

Feedback Mechanism:

• Review the submitted API implementation with the candidate
• Highlight one strength in their implementation (e.g., "Your approach to validation was particularly robust…")
• Provide one area for improvement (e.g., "Consider how you might improve the error responses to be more client-friendly…")
• Ask the candidate to implement the suggested improvement or explain how they would approach it
• Observe how receptive they are to feedback and their ability to incorporate suggestions

Activity #3: Front-End Integration Challenge

This exercise evaluates the candidate's ability to implement user interfaces and integrate them with back-end services. It tests their proficiency with modern front-end technologies in the .NET ecosystem, understanding of asynchronous programming, and UI/UX sensibilities. This activity reveals how candidates balance technical requirements with user experience considerations.

Directions for the Company:

• Prepare a simple API endpoint (or mock) that returns data (e.g., a list of products, users, or tasks)
• Create a wireframe or mockup of a desired UI component that will display and interact with this data
• Specify any required interactions (sorting, filtering, editing)
• Provide access to any design assets or CSS frameworks you typically use
• Decide whether to use Blazor, ASP.NET MVC with JavaScript, or allow the candidate to choose
• Allocate 1-2 hours for this exercise

Directions for the Candidate:

• Implement the UI component according to the provided design
• Connect to the API endpoint to retrieve and display data
• Implement the required interactive features (sorting, filtering, etc.)
• Ensure the component is responsive and follows accessibility best practices
• Handle loading states and error scenarios appropriately
• Use appropriate state management techniques
• Implement at least one unit test for your component
• Be prepared to explain your implementation choices

Feedback Mechanism:

• Review the implementation with the candidate, focusing on both functionality and code quality
• Provide positive feedback on one aspect of their implementation (e.g., "I like how you handled the loading states…")
• Suggest one improvement (e.g., "The error handling could be enhanced by…")
• Give the candidate 15 minutes to implement the suggested improvement
• Discuss how their solution might scale to handle more complex requirements

Activity #4: Database Design and Implementation

This exercise assesses the candidate's ability to design efficient database schemas and implement data access patterns in a .NET environment. It evaluates their understanding of Entity Framework (or other ORMs), SQL, data relationships, and performance considerations. This activity reveals how candidates approach data persistence, a critical foundation for most business applications.

Directions for the Company:

• Prepare a business scenario requiring a database with 3-5 related entities (e.g., an order management system)
• Outline the business rules and relationships between entities
• Specify any performance considerations or constraints
• Decide whether to focus on Entity Framework, Dapper, or raw SQL approaches
• Provide any starter code or project templates
• Allocate 1-2 hours for this exercise

Directions for the Candidate:

• Design a database schema that satisfies the business requirements
• Create entity models and implement the data access layer using the specified approach
• Implement at least one complex query (e.g., joining multiple tables with filtering)
• Consider and implement appropriate indexing strategies
• Document any assumptions made during implementation
• Include migration scripts or Entity Framework migrations
• Be prepared to explain your design decisions and discuss alternatives

Feedback Mechanism:

• Review the database design and implementation with the candidate
• Provide positive feedback on one aspect of their design (e.g., "Your indexing strategy shows good understanding of performance considerations…")
• Suggest one area for improvement (e.g., "Consider how this relationship might be optimized for…")
• Ask the candidate to implement the suggested improvement or explain their approach
• Discuss how their solution would handle increased scale or additional requirements

Frequently Asked Questions

Q: Should we use all four activities for every .NET Full Stack Developer candidate?
A: Not necessarily. Select the activities most relevant to your specific role requirements. For a position heavily focused on API development, you might prioritize Activities #2 and #4. For more front-end focused roles, Activities #1 and #3 might be more appropriate. Using 2-3 targeted activities is often more effective than using all four.

Q: How should we evaluate candidates who use different approaches than we expected?
A: Focus on the reasoning behind their choices rather than strict adherence to your preferred patterns. Strong candidates should be able to articulate why they chose a particular approach and understand the tradeoffs involved. Different approaches often reveal valuable diverse thinking that can benefit your team.

Q: What if a candidate doesn't complete the exercise within the allocated time?
A: Partial completion can still provide valuable insights. Evaluate what they prioritized, the quality of what was completed, and their communication about what they would have done with more time. Consider whether time constraints were realistic and adjust if necessary for future candidates.

Q: How do we ensure these exercises don't disadvantage candidates from different backgrounds?
A: Provide clear instructions and necessary context for all exercises. Allow reasonable accommodations when requested. Focus evaluation on problem-solving approach and core skills rather than knowledge of specific libraries or frameworks that can be quickly learned. Consider providing exercises as take-home options when possible to accommodate different schedules and working styles.

Q: How should we weight these technical exercises compared to other interview components?
A: Work samples should be a significant factor in your evaluation but not the only one. Consider using a structured scorecard that weights technical skills, problem-solving ability, communication, and collaboration appropriately for your team needs. Yardstick's Interview Orchestrator can help design a balanced evaluation process.

Q: Can these exercises be adapted for remote hiring processes?
A: Absolutely. All these exercises can be conducted remotely using screen sharing, collaborative coding environments (like VS Live Share), and video conferencing. For take-home exercises, provide clear submission instructions and follow up with a discussion about their solution.

Finding exceptional .NET Full Stack Developers requires a thoughtful, structured approach to evaluation. By implementing these work samples, you'll gain deeper insights into candidates' practical abilities and significantly improve your hiring outcomes. Remember that the best technical evaluations not only assess skills but also give candidates a realistic preview of the work they'll be doing at your company.

For more resources to enhance your hiring process, check out Yardstick's AI Job Description Generator, AI Interview Question Generator, and AI Interview Guide Generator. You can also view the complete job description for this role at .NET Full Stack Developer Job Description.

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