Engineering
Software Engineer mock interview
Designs, writes, tests and maintains software, turning product requirements into working code. Day to day they build features, fix bugs, review teammates' code and keep systems running in production. Hiring teams for this role tend to ask for specific examples of the work above.
Ava, the AI interviewer, will ask you questions on coding fundamentals & data structures, debugging & troubleshooting, system design and testing & code quality and 4 more skills, follow up on what you say, and finish with a report that quotes your own words back to you.
Skills assessed in a software engineer interview
Coding fundamentals & data structures
Role skillPicks data structures for stated reasons, talks about time and memory costs plainly, and describes measuring before optimising.
Debugging & troubleshooting
Role skillDescribes a methodical process: reproduce, narrow down with logs or a debugger, form and test hypotheses, and confirm the root cause rather than patching symptoms.
System design
Role skillStarts from requirements and scale, sketches the main components, names trade-offs like consistency versus availability, and explains what they would change as load grows.
Testing & code quality
Role skillExplains what deserves tests and why, distinguishes unit from integration tests, and treats readability and refactoring as part of the job.
Code review & collaboration
Role skillReviews for correctness, clarity and risk rather than style nitpicks, gives specific and kind feedback, and accepts feedback on their own code without defensiveness.
Version control & delivery
Role skillUses branches, small commits and pull requests fluently, understands continuous integration, and knows how to roll back or fix forward safely.
Communication
BehaviouralExplains technical ideas in terms the listener cares about, checks for understanding, and uses concrete examples rather than jargon.
Ownership
BehaviouralTalks about owning outcomes not just tasks, follows through after shipping, admits mistakes and describes the fixes and prevention they drove.
Sample software engineer interview questions
8 of the 13 questions Ava can ask for this role, one or more per skill. In a real session she adapts them to your level and follows up on your answers.
- Q1Coding fundamentals & data structuresEntry level
When would you pick a hash map over a list to store data, and what does that choice cost you?
A strong answer: Fast average lookup by key versus linear search, the extra memory and lack of ordering in a hash map, and matching the structure to how the data is accessed.
- Q2Debugging & troubleshootingEntry level
Imagine your code works on your laptop but fails in the test environment. Walk me through how you would start figuring out why.
A strong answer: Reading the actual error and logs, comparing configuration, versions, data and environment variables, reproducing the failure, and changing one thing at a time.
- Q3Version control & deliveryEntry level
How do you usually use Git day to day, from starting a piece of work to getting it merged?
A strong answer: Creating a branch, small meaningful commits, keeping up to date with main, opening a pull request, responding to review, and resolving conflicts calmly.
- Q4Testing & code qualityMid level
How do you decide what to test in a new feature, and how do you balance unit tests against integration tests?
A strong answer: Focusing on business logic, edge cases and risky paths, fast unit tests for logic and fewer integration tests for wiring, and avoiding brittle tests of implementation details.
- Q5Code review & collaborationMid level
When you review a teammate's pull request, what do you look for, and how do you give feedback they will actually act on?
A strong answer: Correctness, edge cases, readability, tests and risk before style, separating blocking issues from suggestions, asking questions, and keeping a respectful tone.
- Q6System designSenior
How would you design a link shortening service that has to handle millions of redirects a day? Talk me through the main pieces and trade-offs.
A strong answer: Clarifying requirements, generating unique codes, choice of storage, heavy caching for reads, handling scale and hot links, and discussing analytics and abuse.
- Q7CommunicationAny level
Tell me about a time you had to explain a technical problem or trade-off to someone non-technical. How did you make it land?
A strong answer: Framing in terms of the listener's goals, plain language and analogies, offering options with trade-offs, and checking they understood.
- Q8OwnershipAny level
Tell me about a time something you shipped broke in production. What did you do in the moment and afterwards?
A strong answer: Taking responsibility without blame, fast mitigation, clear communication, a root cause analysis, and specific changes made to prevent it happening again.
What a strong software engineer answer looks like
Coding fundamentals & data structures
Picks data structures for stated reasons, talks about time and memory costs plainly, and describes measuring before optimising.
Debugging & troubleshooting
Describes a methodical process: reproduce, narrow down with logs or a debugger, form and test hypotheses, and confirm the root cause rather than patching symptoms.
Communication
Explains technical ideas in terms the listener cares about, checks for understanding, and uses concrete examples rather than jargon.
How the practice works
- Step 1
Choose your level
Pick intern through lead. The software engineer question bank is labelled for 3 entry-level, 5 mid-level and 3 senior questions (plus 2 for any level), and Ava leans toward the ones that fit.
- Step 2
Answer out loud or by typing
Ava asks 4 or 7 main questions, depending on the length you choose, such as the coding fundamentals & data structures question above. You can also add a short coding exercise. Typing is always available if you can't speak.
- Step 3
Get feedback you can act on
Each skill is scored against the evidence you gave, with the specific points from your answers. In practice mode you also get a check against the situation, task, action and result structure, a stronger version of each answer built only from what you said, and what to practise next.
Frequently asked questions
- Which skills does the Software Engineer mock interview cover?
- Coding fundamentals & data structures, Debugging & troubleshooting, System design, Testing & code quality, Code review & collaboration, Version control & delivery, Communication and Ownership. The first 6 are role skills; communication and ownership are the behavioural part.
- What kind of questions will I get?
- Questions come from a bank of 13 written for this role. An entry-level one is “When would you pick a hash map over a list to store data, and what does that choice cost you?” and a senior one is “How would you design a link shortening service that has to handle millions of redirects a day? Talk me through the main pieces and trade-offs.”.
- How will my system design answer be judged?
- Against what strong evidence looks like for that skill: starts from requirements and scale, sketches the main components, names trade-offs like consistency versus availability, and explains what they would change as load grows. Anything you don't mention is not credited, and nothing is invented for you.
- Is this useful for SDE or SWE roles?
- Yes. SDE, SWE, application developer and coder are treated as close to software engineer, so the same skills and questions apply. You can also type any other role on the setup screen.
- Is it free, and do I need an account?
- Starting practice is free, and a free account is required before the interview begins. The feedback is guidance for your preparation, not a prediction of any hiring decision.