Software engineer interviews test how you think, how you build and how you work with other people. Expect questions about past projects, design choices, debugging and teamwork, often alongside a coding exercise. To prepare, pick three projects you know well, practise explaining each in plain words, and say your reasoning out loud.
Ten questions, with sample answers
The sample answers are original examples. Change the details so they describe your own work, and never claim experience you do not have.
1. Tell me about a project you are proud of.
What they look for: your own part in it, clear thinking and the reason it mattered.
Sample answer: “I led a rewrite of our job-processing service, which kept stalling when traffic grew. I split it into smaller workers, added retries and wrote tests around the parts that had failed before. I’m proud of it because the team stopped dreading releases.”
2. How do you approach debugging a problem you have not seen before?
What they look for: a calm, repeatable method instead of guessing.
Sample answer: “I first reproduce it, then shrink it to the smallest case. I read the logs, form one guess at a time and test it. If I am stuck after a set time, I explain the problem to a colleague, which often shows me the gap.”
3. Describe a time you disagreed with a teammate about a technical choice.
What they look for: respect, evidence and a willingness to commit once a decision is made.
Sample answer: “A colleague wanted a new database for a small feature. I listed what it would cost us in running and learning, and suggested a short trial first. We tried it, the extra work was not worth it, and we kept what we had.”
4. How do you decide between a quick fix and a proper solution?
What they look for: judgment about risk and time, and honesty about trade-offs.
Sample answer: “I ask what breaks if I wait and how long the quick fix will live. If users are blocked, I ship the small fix and write down the proper one as a task. I do not let a temporary fix sit without an owner.”
5. How do you test your code?
What they look for: that you treat tests as part of the work.
Sample answer: “I write tests for the behaviour people rely on, with extra care at boundaries and error cases. I prefer a few fast, reliable tests over many fragile ones, and I run them before every review.”
6. Walk me through how you would design a simple URL shortener.
What they look for: that you clarify requirements first, then reason step by step.
Sample answer: “I would ask about expected traffic and whether links expire. Then a service creates a short code, stores the mapping and redirects on lookup. I would discuss how to generate unique codes, how to cache popular links and what to do if the store is down.”
7. What do you do in a code review, as the author and as the reviewer?
What they look for: kindness, clarity and care for the codebase.
Sample answer: “As an author I keep changes small and explain why. As a reviewer I read for correctness first, then clarity, and I ask questions instead of giving orders. I thank people when they catch something.”
8. Tell me about a mistake you made in production.
What they look for: ownership, learning and no blame.
Sample answer: “I once shipped a change that skipped a check on empty input, and a page failed for some users. I rolled it back, fixed it with a test, and we added a step to our release checklist so the same gap could not return.”
9. How do you learn a new technology quickly?
What they look for: curiosity with a method.
Sample answer: “I build something small and real with it, read the official documentation and look at how experienced people structure projects. Then I ask someone who uses it daily to review what I made.”
10. Why do you want to work here?
What they look for: that you read the job post and thought about the work.
Sample answer: “Your team builds tools for [kind of users], and the post mentions [a technology or problem]. That matches what I have done in my last role and what I want to go deeper into.”
How to practise this with PrepHint AI
Every account starts with 15 free minutes of live help and 1 mock interview of up to 10 minutes. No card needed.
- Add your resume. Sign up at PrepHint AI, then add your resume, or build one first in Resume Maker, which is free forever with an account.
- Create a mock interview for this job. Add the job post, choose your resume and pick a length from 5 to 30 minutes. The questions are built from the job post and your resume.
- Practise out loud by voice. The AI interviewer asks its questions aloud and listens to your spoken answers. Answer as you would in the room, including your reasoning.
- Read the transcript. The transcript of every mock interview is saved, so you can read your own answers afterwards and tighten the weak ones.
- For live answers in a call, use live answers in the app.
Use it where AI help is allowed. PrepHint AI is made for practice and for conversations where help from AI is allowed. Check the rules of the employer and the interviewer before you use it in a real interview. If the answer is no, use it to practise.
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