40 Interview Questions for Software Engineers (With What to Look For)

Engineering hiring is broken at most companies. Interviewers ask whatever comes to mind, candidates get inconsistent experiences, and hiring decisions end up based on gut feelings rather than evidence. Research from Google's own hiring data shows that structured interviews are twice as predictive of job performance compared to unstructured ones.

A structured interview means every candidate gets the same questions, evaluated against the same criteria. This does not mean robotic conversations — it means you have a framework that ensures you actually assess the skills that matter for the role.

The questions below are organized into categories so you can build a complete interview loop. Pick 8-12 questions per interview round and make sure you cover multiple categories across your hiring process.

If you want to generate role-specific questions instantly, try our free AI interview question generator — it creates categorized questions tailored to any engineering role in seconds.

These questions assess a candidate's core engineering knowledge and hands-on ability. Adjust complexity based on seniority level.

1. Walk me through how you would design the architecture for [a feature relevant to your product].

What to look for: Do they ask clarifying questions first? Can they break a complex problem into components? Do they consider trade-offs (performance vs. simplicity, build vs. buy)?

2. Describe a time you had to debug a production issue under time pressure. What was your process?

What to look for: Systematic debugging approach, familiarity with monitoring and logging tools, ability to stay calm and prioritize.

3. What is your approach to writing tests? When would you skip writing tests?

What to look for: Understanding of test levels (unit, integration, e2e), pragmatism about test coverage, awareness of when tests add vs. destroy value.

4. Explain a technical concept from your domain to me as if I were non-technical.

What to look for: Communication skills, ability to simplify without being condescending, patience in explanation.

5. How do you decide between using a library or building something from scratch?

What to look for: Pragmatic thinking, awareness of maintenance burden, understanding of dependency risks and licensing.

6. Tell me about a piece of code you wrote that you are proud of. What made it good?

What to look for: Technical taste, ability to articulate design decisions, values (readability, performance, elegance).

7. How would you handle a database query that is running 10x slower than expected?

What to look for: Knowledge of query optimization, indexing strategies, profiling tools, and systematic investigation approach.

8. What is the difference between SQL and NoSQL databases? When would you choose one over the other?

What to look for: Understanding of data modeling trade-offs, not just textbook definitions. Real-world examples are a plus.

These questions reveal how candidates approach ambiguous problems and think at a systems level. Especially important for mid-senior roles.

9. Design a URL shortener. What components would you need and how would they interact?

What to look for: Ability to scope the problem, identify key components (API, database, redirect logic, analytics), and discuss trade-offs around scale.

10. You join a team and the codebase has no tests, inconsistent patterns, and no documentation. What do you do first?

What to look for: Pragmatism over perfectionism. Do they prioritize understanding before changing? Do they propose incremental improvements rather than rewrites?

11. How would you migrate a monolithic application to microservices? Where would you start?

What to look for: Understanding that this is a gradual process, ability to identify service boundaries, awareness of pitfalls (distributed transactions, network latency, operational complexity).

12. A feature you built is causing performance issues in production. How do you investigate and resolve it?

What to look for: Use of monitoring, profiling, and logging tools. Ability to narrow down the problem space systematically rather than guessing.

13. How would you design a notification system that sends emails, push notifications, and SMS?

What to look for: Queue-based architecture thinking, handling failures and retries, template management, user preference handling.

14. Given unlimited time, what would you refactor in a codebase you have worked on?

What to look for: Technical debt awareness, ability to distinguish impactful refactors from cosmetic ones, understanding of when refactoring adds real value.

Technical skills get candidates in the door, but behavioral fit determines long-term success. These questions reveal how engineers work with others.

15. Tell me about a time you disagreed with a technical decision on your team. How did you handle it?

What to look for: Ability to disagree constructively, willingness to commit after a decision is made, respect for team dynamics.

16. Describe a project where requirements changed significantly mid-development. How did you adapt?

What to look for: Flexibility, communication with stakeholders, ability to reprioritize without frustration.

17. How do you handle code reviews? What makes a good code review?

What to look for: Respectful, constructive approach. Focus on the code not the person. Balance between thoroughness and not being a blocker.

18. Tell me about a time you had to learn a new technology or framework quickly for a project.

What to look for: Learning strategies, resourcefulness, ability to be productive while still learning.

19. How do you prioritize when you have multiple tasks with competing deadlines?

What to look for: Communication with stakeholders, ability to estimate effort, willingness to ask for help or push back on unrealistic timelines.

20. Describe a situation where you mentored a junior developer. What was your approach?

What to look for: Patience, structured teaching ability, investment in others' growth, and whether they actually enjoy mentoring.

21. Have you ever shipped something that broke in production? What happened and what did you learn?

What to look for: Ownership and accountability. Do they blame others or focus on what they could have done differently? Have they improved their process since?

22. How do you communicate technical trade-offs to non-technical stakeholders?

What to look for: Ability to translate technical concepts into business impact, patience, and clear communication.

These questions help you understand what drives the candidate and whether they will thrive in your specific environment.

23. What does your ideal engineering culture look like?

What to look for: Alignment with your company values. If your culture is fast-paced and scrappy, a candidate who needs extensive process may not be the right fit.

24. What kind of projects or problems excite you most?

What to look for: Alignment with the work your team actually does. Genuine enthusiasm versus rehearsed answers.

25. How do you stay current with technology trends?

What to look for: Genuine curiosity and continuous learning habits. Side projects, reading, conferences, or community involvement are all positive signals.

26. What would make you leave a job within the first year?

What to look for: Honesty and self-awareness. Their dealbreakers might flag misalignment early — which saves both sides time.

27. Describe a time you went above and beyond on a project. What motivated you?

What to look for: Intrinsic motivation signals — craftsmanship, customer impact, team success — rather than just external recognition.

28. How do you handle working on tasks you find boring or repetitive?

What to look for: Maturity and professionalism. Every role has mundane parts — you want someone who handles them reliably rather than dropping them.

For senior engineers, staff engineers, and tech leads, add these questions to assess strategic thinking and leadership ability.

29. How do you balance shipping fast with maintaining code quality?

What to look for: Nuanced thinking — not "always ship fast" or "always write perfect code." Context-dependent decision making.

30. Tell me about a technical strategy or direction you set for a team. How did you get buy-in?

What to look for: Ability to build consensus, present evidence-based arguments, and lead through influence rather than authority.

31. How do you evaluate whether to adopt a new technology on your team?

What to look for: Risk assessment, proof-of-concept approach, consideration of team skills and maintenance burden.

32. Describe how you have handled underperformance on your team.

What to look for: Empathy combined with accountability. Direct feedback, support plans, and clarity about expectations.

33. How do you make build-vs-buy decisions?

What to look for: Total cost of ownership thinking, understanding of maintenance and operational burden, alignment with core competencies.

34. What is the most impactful architectural decision you have made? What were the trade-offs?

What to look for: Ability to articulate trade-offs clearly, evidence that the decision was data-informed, and honest reflection on what they would do differently.

Tailor your final questions to the specific engineering role you are hiring for.

Frontend Engineers

35. How do you approach performance optimization in a web application? What metrics do you track?

36. Describe your approach to making a component accessible. What tools and standards do you follow?

Backend Engineers

37. How do you design an API that is easy to use and maintain? What principles guide your decisions?

38. Walk me through how you handle authentication and authorization in a multi-service architecture.

Full-Stack Engineers

39. When working across the stack, how do you decide where to put business logic — frontend, backend, or database?

40. How do you keep yourself productive when context-switching between frontend and backend work?

Do not ask all 40 questions in a single interview. Instead, build a structured interview loop:

1. Phone Screen (30 min) — 3-4 questions from Behavioral and Culture Fit to assess basic fit and communication
2. Technical Interview (60 min) — 4-6 questions from Technical Skills and Problem Solving
3. System Design (45 min) — 2-3 questions from System Design, especially for senior roles
4. Culture & Values (30 min) — 3-4 questions from Culture Fit and Leadership (if applicable)

Each interviewer should score candidates independently before any debrief to avoid anchoring bias.

Generate Custom Questions Instantly

Need questions tailored to a specific role, tech stack, or seniority level? Our free AI interview question generator creates structured, categorized questions in seconds — no signup required.

If you are building your entire hiring process from scratch, BorovaHR's free plan gives you job posting, applicant tracking, AI resume scoring, and interview scheduling — everything you need to hire your next engineer.