How do you run a developer interview?

Running a developer interview requires careful preparation, structured questioning, and effective evaluation to ensure that you assess both the technical and interpersonal skills of the candidate. Here’s a step-by-step guide to help you conduct an effective developer interview:

1. Understand the Role and Its Requirements

Before the interview, it’s essential to thoroughly understand the technical skills and qualifications required for the role. This helps you tailor your questions to assess the relevant abilities.

• Technical Requirements: Know the required programming languages, frameworks, tools, and technologies.
• Soft Skills: Be aware of the non-technical traits needed, such as teamwork, communication, problem-solving, and adaptability.
• Experience Level: Understand the level of experience you're looking for—junior, mid-level, or senior.

2. Prepare a Structured Interview Plan

A well-structured interview ensures you cover all key areas and don’t miss anything important. Your interview plan should include:

• Introductory Questions: Briefly discuss the candidate’s background, experience, and why they’re interested in the role.
• Technical Questions: Questions that assess the candidate’s coding skills, problem-solving, and knowledge of algorithms and data structures.
• System Design (for mid/senior roles): For more senior developers, system design questions assess their ability to design scalable, maintainable systems.
• Behavioral and Cultural Fit Questions: To understand the candidate’s interpersonal skills and how well they will fit into the team.
• Closing and Candidate Questions: Allow the candidate to ask questions about the role, team, or company.

3. Start with a Friendly Introduction

Create a relaxed and open atmosphere by starting with a friendly introduction.

• Introduce Yourself: Mention your role in the company and briefly explain the format of the interview.
• Set Expectations: Give the candidate an overview of how the interview will progress, including the types of questions you will ask (technical, behavioral, coding, etc.).
• Ask an Icebreaker Question: This could be something about their past experience, recent project, or what excites them about software development.

Example:

"Hi, I’m [Your Name], a lead developer here at [Company Name]. Today, we’ll go through some technical and behavioral questions to get a sense of your skills and experiences. At the end, I’ll give you time to ask any questions you might have about the role or the company."

4. Ask Behavioral and Background Questions

Start with some behavioral and background questions to get a sense of the candidate's experience, work style, and how they’ve handled challenges in the past. This also helps build rapport before diving into technical questions.

Example Questions:

• "Tell me about a project where you solved a difficult technical challenge."
• "How do you manage your time when you have multiple deadlines?"
• "Can you share an example of when you had to collaborate with other developers on a challenging project?"

Key Traits to Observe:

• Ability to explain their past experiences clearly.
• Problem-solving mindset.
• Communication skills and ability to work in teams.

5. Conduct a Coding Challenge

The coding challenge is often the heart of a developer interview. This should test the candidate’s ability to write clean, efficient, and bug-free code.

Example Coding Questions:

• "Write a function to reverse a linked list."
• "Find the longest substring without repeating characters."
• "Given a binary tree, implement an algorithm to check if it’s balanced."

How to Evaluate:

• Problem-Solving Skills: Does the candidate break down the problem logically and approach it step by step?
• Code Quality: Is the code clean, readable, and maintainable?
• Efficiency: Does the candidate consider the time and space complexity of their solution?
• Communication: Are they able to explain their thought process as they work through the problem?

Tools:

• In-Person Interviews: Use a whiteboard or pen and paper.
• Remote Interviews: Use online coding platforms like CoderPad, HackerRank, or CodeSignal.

Preparation Tip: Be sure to choose problems that are appropriate for the candidate’s experience level and align with the real work they’d be doing.

6. Ask System Design Questions (For Mid/Senior Roles)

If you’re hiring for a more senior position, system design questions are crucial. These questions assess the candidate’s ability to design scalable, maintainable systems and make high-level technical decisions.

Example Design Questions:

• "Design a URL shortening service like Bitly."
• "How would you design a scalable chat application like WhatsApp?"

How to Evaluate:

• Scalability and Performance: How well does the candidate design for large-scale systems? Do they consider performance and latency?
• Architecture Decisions: Do they choose the right components and justify their decisions? (e.g., database, caching, load balancing).
• Trade-Offs: How well do they handle trade-offs between different approaches (e.g., consistency vs. availability)?
• Communication: Can they clearly explain their design and rationale?

Preparation Tip: Grokking System Design Fundamentals is a valuable resource to help candidates and interviewers prepare for system design interviews.

7. Evaluate Soft Skills and Cultural Fit

Assessing soft skills is just as important as technical ability, especially in collaborative roles. Ask questions that reveal how the candidate interacts with others and fits within your company culture.

Example Questions:

• "How do you handle disagreements on a technical issue with your team?"
• "Can you describe a time when you had to learn a new technology or tool quickly?"
• "How do you stay up to date with the latest developments in software development?"

Key Traits to Observe:

• Communication and teamwork.
• Adaptability and willingness to learn.
• Problem-solving approach in non-technical situations.

8. Allow the Candidate to Ask Questions

At the end of the interview, give the candidate a chance to ask questions. This shows you’re open and transparent and gives them the opportunity to learn more about the role, team, and company.

Common Questions Candidates Might Ask:

• "What is the team’s development process like?"
• "What opportunities are there for professional growth?"
• "Can you describe the company’s culture?"

Allowing time for these questions also helps you gauge the candidate’s level of interest in the role.

9. Provide a Closing Summary and Next Steps

Wrap up the interview by thanking the candidate for their time and explaining what the next steps in the process will be. Let them know when they can expect to hear back, and be clear about what happens next.

Example:

"Thank you for your time today. We’ll be reviewing all the candidates over the next week and will get back to you with feedback soon. If you have any further questions in the meantime, feel free to reach out."

10. Provide Constructive Feedback (Optional)

If you're giving feedback after the interview, make sure it’s constructive and actionable. Focus on both strengths and areas for improvement. Constructive feedback helps candidates grow and leaves a positive impression of your company, even if they’re not selected.

Conclusion

Running a successful developer interview requires a mix of preparation, technical assessment, and evaluation of soft skills. By asking the right questions, providing a comfortable environment, and giving the candidate time to showcase their abilities, you can effectively determine whether they are a good fit for the role. Structured interviews that assess both technical proficiency and cultural fit ensure that you make well-rounded hiring decisions.