AI mock interview for software engineers, on real code
By Shilo Drot, software engineer (ex-Meta). Updated .
An AI mock interview on Cla64.ai opens a real project in your browser, not a list of questions. You work on the task and ask the AI when you need it. At the end, it asks about your decisions, and you get a written review of how you worked.
How an AI mock interview works here
- Choose an exercise and a language. Python, JavaScript, TypeScript, Java or C++.
- Start coding in the browser. You get a cloud workspace with an editor and a terminal, with nothing to install. The clock starts when the workspace is ready.
- Ask the AI when you want to. It answers when asked and doesn't interrupt you. It also won't add requirements partway through. Any optional next steps are already listed in the exercise's README.
- Answer a few questions. When you click Finish session, the AI asks 2-3 questions about your work, the way an interviewer would.
- Your work gets checked. Exercises with starting code run hidden tests. Blank-project exercises have no fixed tests: you demo your solution in the terminal, and the AI reviews your code, the demo and the conversation.
- Read your written review. It covers what went well, what to improve, how a strong solution would approach the task and how you used the AI. There's no score or ranking.
To see all of this before you try it, watch a full session.
What the AI will and won't do
The AI is both your assistant and your interviewer, so it doesn't behave like a coding assistant at work. Here's what to expect:
| If you ask... | The AI... |
|---|---|
| A language, library or tooling question | Answers directly, with a small generic example when one helps |
| What the task's rules mean | Gives you a clear answer, as an interviewer would |
| For help because you're stuck | Gives you a hint about the one thing you're stuck on |
| How to design something | Lays out the trade-offs and leaves the decision to you |
| "Fix it" or "solve it" | Asks what you mean, and doesn't guess |
| For specific code that you spell out | Writes what you described and nothing more. Some exercises limit it to words only, apart from language and syntax help |
On exercises that allow it, you can use AI code changes: the AI proposes edits to your files, and you accept or reject each one. It follows the same rule and writes only what you spell out. It can make mistakes, so check its suggestions before you accept them.
Some companies go further. Meta's AI-enabled round, for example, reportedly lets candidates ask the AI to generate code freely. Cla64.ai's AI holds back on purpose, so the thinking stays yours and your practice shows you what you can do. That also means it isn't a full rehearsal of reviewing large blocks of AI-written code. Read more about what AI coding interviews test.
What you can practice
- Debugging from a bug report. Start from a support ticket or incident report, read someone else's code, find the real cause and prove it with a regression test.
- Building on starting code. Add to a project that already exists, and make sure your changes hold up against its tests.
- Design in code. Start from a blank project, choose your own architecture and show it working in a live demo, as in the parking garage billing exercise.
Browse every exercise on the exercise list without an account. For how to behave in the room, read the interview guide.
Who it's not for
Cla64.ai covers one kind of interview, so another tool will suit you better if you need:
- Behavioral interview practice. The exercises are coding tasks, not "tell me about a time" questions.
- Speaking practice. The chat is typed, so nothing listens to how you sound.
- Algorithm drilling. LeetCode is built for algorithm puzzles. Cla64.ai tests different skills: understanding a codebase, debugging, designing and building, testing and explaining your decisions while using AI.
- Whiteboard system design. Design here happens in code, on a problem sized for one session.
- A specific company's questions. The exercises are general engineering tasks, not a question bank for any one company.
How to get the most from a session
- Treat it like the real thing. Keep other AI tools closed and plan your time around the clock.
- Run the tests early. If the project comes with tests, see where you stand before you change anything, and again after each change.
- Give the AI specific requests. Vague requests get a question back, just as they might from a colleague.
- Take the end questions seriously. Explaining your own decisions is a skill you can only build by doing it.
- Repeat with one goal. Pick one thing from your review to do differently next time.
What it costs
The Concert Tickets exercise is free, takes 15 minutes and needs no account to start. Sign up free to see your feedback and get one free attempt at each weekly challenge, which, unlike practice sessions, is scored and ranked.
Every other exercise needs a paid session: $5 for one, $15 for five, or $20 a month for up to 30 sessions, in your local currency where we price it. See the pricing page for details.
Frequently asked questions
What is an AI mock interview?
An AI mock interview is a practice interview where an AI plays the interviewer, then gives you feedback. Some tools focus on spoken answers and interview questions. On Cla64.ai, the practice is a coding task in a real project, with an AI you can ask for help and questions about your work at the end.
Is there a free AI mock interview?
Yes. One exercise, Concert Tickets, is free and takes 15 minutes. You can start it with no account, and you sign up free to see your feedback. A free account also gets one free attempt at each weekly challenge. Other exercises need a paid session.
Does the AI interviewer talk to me out loud?
No. On Cla64.ai you type to the AI in a chat next to your code. There's no voice conversation, so to practice speaking, say your reasoning out loud while you work or do a mock with another person.
Will the AI write the code for me?
It won't solve the task or decide the logic. Say "fix it" and it asks what you mean. If you spell out what you want, it can write that, and on exercises that allow it, AI code changes lets you accept or reject its proposed edits. Some exercises limit it to words only, apart from language and syntax help. Some companies, Meta among them, reportedly let candidates generate code more freely, so this is stricter than those rounds.
Is the AI watching me code?
It doesn't interrupt you or comment on your typing. It responds when you ask, and at that point it can see your project files and test runs, which is why you don't need to paste your code into the chat.
How long does an AI mock interview take?
60 minutes for most exercises, and 30-45 or 75-90 minutes for a few. The free one takes 15 minutes. The clock starts when your coding workspace is ready, and you can finish earlier.
Which programming languages can I use?
Python, JavaScript, TypeScript, Java and C++.
Is this the same as a live interview copilot?
No. A copilot feeds you answers during a real interview, which is usually cheating unless the company allows it. A mock interview is practice before the real thing. Cla64.ai is only for practice.
Is it as good as a mock interview with a person?
They do different jobs. An AI is available whenever you want and costs less, which makes it useful for repetition. An experienced interviewer can pick up on things it can miss, such as how you come across. If you have a big interview coming up, consider doing both.