Software engineer mock interviews with an AI interviewer
A software engineering loop is several different interviews in a row: one or two coding rounds, a system design round from mid-level up, a behavioral round, and at some companies a newer round where you work in an existing codebase or alongside an AI assistant. Each one tests something different, and being strong at one doesn't carry over to the others.
PrepLinx lets you rehearse each round on its own, out loud, with an AI interviewer that behaves like a real one: it presents the problem, asks follow-up questions and keeps its verdict until the end. Then you get a scored report on every dimension the round is graded on.
6 software engineer rounds to practice
Each round has its own AI interviewer, problem and scoring. Practice them one at a time, at the difficulty you choose.
System Design
Design a large system, such as a URL shortener or a chat service, on a whiteboard. The interviewer reads your diagram and pushes on bottlenecks, failure modes and scale.
Up to 60 minutesBehavioral
Real examples from your work: conflict, ownership, decisions under pressure, learning from failure. The interviewer follows up until it has the specifics.
Up to 30 minutesCoding
Algorithm and data structure problems in a shared editor. Run your code in any of 17 languages; the interviewer reads the code and its output and asks about complexity and edge cases.
Up to 60 minutesAI-Assisted Coding
Solve a problem with an AI coding assistant in a side panel. You're graded on how you break up the work, prompt the assistant and verify what it gives you.
Up to 60 minutesCode Comprehension
An unfamiliar codebase with planted bugs is loaded in your editor. Explain it, trace it, find the defects and fix them without breaking anything else.
Up to 60 minutesTechnical
A technical discussion across data structures, databases, system architecture and performance trade-offs, with an editor and whiteboard on hand.
Up to 30 minutesWhat interviewers look for
Problem solving out loud
Interviewers grade your reasoning, not just the final answer. Talking through options before you commit is what they listen for.
Correct, tested code
Working code, handled edge cases, and a time and space complexity you can defend.
Design judgment
Clear requirements, a sensible architecture and explicitly stated trade-offs, especially from mid-level up.
Ownership and collaboration
Specific stories where you made a call, worked through a disagreement or recovered from a mistake.
Practice questions
Examples of the questions and follow-ups you can expect. Practice saying your answers out loud, not just reading them.
- Given a list of meeting time intervals, return the minimum number of rooms needed.
- Design a URL shortener that handles 100 million new links a month.
- Here's a rate limiter with a failing test. What's wrong with it, and how would you fix it?
- Use the assistant to implement an LRU cache, then show me how you know it's correct.
- What happens between typing a URL into the browser and the page rendering?
- Tell me about a time you disagreed with a technical decision your team made.
How a PrepLinx session works
- 1
Choose the round
Pick the role, the interview type and a difficulty (easy, medium or hard). Optionally add a job profile with your resume and the job description, so the questions relate to that job.
- 2
Interview out loud
The AI interviewer speaks, listens to your answers and asks follow-ups. It doesn't give hints or say whether you're right, just like the real thing.
- 3
Get scored feedback
A report with a 0–10 score for each dimension the round is graded on, strengths quoted from your own words, weaknesses, concrete improvements and an overall hiring signal, plus the full transcript.
How to prepare
Practice your weakest round first
It is easy to drill coding problems and walk into system design or behavioral rounds cold. Run one session of each round, see where your score is lowest, and put your hours there.
Match the difficulty to your target level
Easy suits internships and new-grad roles. Hard is closer to senior loops, where you're expected to drive the design and raise trade-offs without being asked.
Talk before you type
Restate the problem, confirm the constraints and outline your approach before writing code. Coding in silence leaves the interviewer nothing to credit but the final answer.
Bring the job description
Add a job profile with your resume and the posting, and the interviewer relates its questions to that job and to your own experience.
Frequently asked questions
Which software engineering rounds can I practice?
Six: coding, system design, AI-assisted coding, code comprehension, technical discussion and behavioral. You choose the round and the difficulty (easy, medium or hard) when you set up each session.
Can I code in my own language?
Yes. The editor supports 17 languages, including Python, Java, C++, JavaScript, TypeScript, Go and Rust, and you can run your code during the interview. The interviewer sees your code and its output.
Does the AI interviewer give hints?
No. Like a real interviewer, it presents the problem, answers short clarifying questions and asks follow-ups, but it won't tell you whether you're on the right track. All the feedback comes in the report at the end.
Is it useful for senior engineers?
Yes. Hard difficulty and the system design round are closest to senior loops, and with a job profile the interviewer draws on your resume to ask about systems you've actually built.
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Practice your next software engineer interview
4 full interviews free, with scored feedback. No credit card, and they don't expire.
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