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Software Engineer interview questions

You do not need to test language trivia or pretend to be a senior engineer. Your job is to collect concrete evidence about what the candidate shipped, how they reason about trade-offs, how they respond when work fails, and whether they can explain technical choices clearly. Use a qualified technical reviewer or a job-relevant work sample when the role requires deeper technical validation.

How to interview a software engineer as a non-technical founder

Use the agenda as written, then record the candidate’s evidence before choosing a 1, 3, or 5 score. The text is designed to copy into an interview document or print from your browser without a separate template.

30-minute interview agenda

  1. 0–3 min

    Set the evidence standard

    Explain the structure so both sides can use the short interview well.

    “We will cover one shipped project, one technical decision, one failure, and how you work with non-engineers. I will ask follow-ups about what you personally did.”

  2. 3–9 min

    Trace one shipped project

    Separate direct ownership from proximity to a team result.

    “Choose one production feature you know deeply. What problem did it solve, what did you personally build, and what changed after release?”

  3. 9–15 min

    Explain a technical decision

    Test reasoning and communication without requiring the founder to judge syntax.

    “Explain a technical choice from that project as if I were a customer or product manager. What alternatives did you consider, and why was this trade-off acceptable?”

  4. 15–20 min

    Inspect debugging and quality

    Look for a repeatable way to diagnose, verify, and prevent failures.

    “Tell me about a defect or incident you owned. How did you narrow down the cause, prove the fix worked, and reduce the chance of recurrence?”

  5. 20–25 min

    Test scope and collaboration

    See how the candidate handles ambiguity, disagreement, and constrained delivery.

    “Describe a time the requested scope was unsafe or unrealistic. How did you explain the constraint and agree on what to ship?”

  6. 25–28 min

    Verify the strongest claim

    Follow one answer down to an artifact, measure, or person who could corroborate it.

    “What artifact, metric, pull request, incident record, or reference could help us verify the result you described?”

  7. 28–30 min

    Candidate questions and close

    Leave room for the candidate to test the role and explain the next step.

    “What do you need to understand about the product, codebase, team, or decision process before deciding whether this role fits?”

Evidence rubric and interview scorecard

Score each criterion independently: 1 means the interview did not produce usable evidence, 3 means adequate evidence with open questions, and 5 means strong, specific, verifiable evidence. A high interview score is not proof of future performance.

Ownership of shipped work

Why score it: A small team needs clarity about what the candidate can own without hiding behind a team result.

Listen for evidence: A specific problem, the candidate’s personal decisions and implementation, the people they worked with, and an observable result after release.

Verification follow-up: Which part would not have happened without you, and which part was owned by somebody else?

Red flags to investigate:

  • • Uses only “we” after repeated requests to separate personal contribution
  • • Cannot name a user, operational, reliability, or delivery outcome

1 — weak evidence

Vague team story; personal contribution and outcome remain unclear.

3 — adequate evidence

Names a real contribution and result, but evidence or trade-offs are thin.

5 — strong evidence

Connects the problem, personal ownership, trade-offs, collaborators, and a verifiable result.

Evidence notes: ______________________________________________________________

Technical reasoning explained clearly

Why score it: A founder must be able to understand risks and choices well enough to make product and business decisions.

Listen for evidence: A plain-language explanation of constraints, at least one alternative, the chosen trade-off, and what would cause the candidate to revisit it.

Verification follow-up: What was the strongest alternative, and under what conditions would it have been the better choice?

Red flags to investigate:

  • • Uses jargon as a substitute for explaining the decision
  • • Presents one tool or architecture as universally correct

1 — weak evidence

The explanation stays opaque or treats preference as proof.

3 — adequate evidence

Explains the choice clearly but gives limited alternatives or decision criteria.

5 — strong evidence

Explains constraints, alternatives, trade-offs, and reversal conditions in accessible language.

Evidence notes: ______________________________________________________________

Debugging, quality, and safe delivery

Why score it: The useful signal is not whether something failed, but how the engineer found, fixed, and learned from it.

Listen for evidence: A concrete failure, a narrowing process using evidence, a validation step, and a lasting test, alert, review, or process improvement.

Verification follow-up: What evidence ruled out the first explanation, and how did you confirm the final fix in production?

Red flags to investigate:

  • • Claims never to have caused or owned a meaningful defect
  • • Stops the story at “we deployed a fix” with no verification or prevention

1 — weak evidence

Blames others or offers no reproducible diagnosis and verification process.

3 — adequate evidence

Explains the cause and fix, with basic validation.

5 — strong evidence

Shows disciplined diagnosis, safe remediation, verification, and a durable prevention step.

Evidence notes: ______________________________________________________________

Collaboration and scope judgment

Why score it: Early teams need engineers who surface constraints without blocking progress or silently accepting unsafe work.

Listen for evidence: Questions asked early, risk explained in business terms, options with different costs, and a documented decision the team could support.

Verification follow-up: What did you propose cutting or sequencing, and what did the non-technical stakeholder decide after hearing the options?

Red flags to investigate:

  • • Frames product or design partners as the problem
  • • Either agrees to everything or refuses work without proposing a path forward

1 — weak evidence

Avoids conflict, blames stakeholders, or cannot show a negotiated outcome.

3 — adequate evidence

Handled a real disagreement professionally and reached a workable decision.

5 — strong evidence

Made risk legible, offered scoped options, and helped the team reach and record a sound decision.

Evidence notes: ______________________________________________________________

Verification follow-up questions

Use these after a strong or vague claim. They help you collect more job-related evidence; they are not traps and should not become questions about protected or personal circumstances.

1. What did you personally implement, review, or decide in that example?

Listen for: A bounded contribution described with enough detail that another teammate could confirm it.

Red flag: The answer repeatedly returns to the team result without identifying personal work.

2. How did you know the change worked after it reached users?

Listen for: A relevant measure such as observed behaviour, support volume, errors, latency, reliability, or a clearly defined acceptance check.

Red flag: Treats deployment as proof of success or chooses a metric unrelated to the original problem.

3. What would you ask a senior technical reviewer to verify before we relied on this example?

Listen for: Awareness of the limits of the interview and a concrete artifact, test, design choice, or risk worth independent review.

Red flag: Claims there is nothing meaningful another engineer could inspect or challenge.

Compare another evidence-based interview kit

Role-specific questions

1. Walk me through the most complex system you’ve built. What would you do differently now?

Listen for: Concrete architecture decisions, honest trade-off talk, and self-criticism that shows growth since.

Red flag: Only "we" with no clear personal contribution, or no regrets at all.

2. Tell me about a production incident you caused. What happened and what changed afterwards?

Listen for: Ownership without excuses, a clear timeline, and a process or tooling change that outlived the incident.

Red flag: Claims to have never broken production — everyone senior has.

3. How do you decide when code is good enough to ship versus needs more polish?

Listen for: A pragmatic framework tied to user impact and reversibility, not perfectionism or recklessness.

Red flag: "I just know" or shipping standards that depend entirely on deadline pressure.

4. What’s a technology choice you argued against and lost? How did you handle it?

Listen for: Disagreement handled professionally, commitment after the decision, and honest reflection on who turned out right.

Red flag: Still relitigating the decision, or never having disagreed with anyone.

5. How do you use AI tools in your workflow today, and where do you not trust them?

Listen for: Real daily usage with specific examples plus a clear-eyed sense of failure modes.

Red flag: Either blanket rejection or blind trust — both age badly in a small team.

Closers that work for any role

6. What does a great first 90 days in this role look like to you?

Listen for: Learning before changing, early small wins, and questions about how you’d measure them.

Red flag: Grand transformation plans before understanding the context, or no ambition at all.

7. What part of this kind of role do people usually underestimate?

Listen for: Lived-experience insight that only someone who’s done the job would know.

Red flag: Generic answers that could come from reading the job description.

8. What would your last manager say is the thing they had to manage around?

Listen for: A real weakness stated plainly, plus the compensating system they’ve built.

Red flag: A humblebrag ("I care too much"), or claiming the manager would say nothing.

Take this Software Engineer hire from first conversation to offer.

Keep your job listing, applicants, relevant experience, and interview decisions together. Your team chooses what happens next.

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Software Engineer Interview Guide for Founders — Penroll