Interview format

Core Expertise

Overview

Perplexity’s Core Expertise interview evaluates a candidate’s mastery of a technical discipline. We administer two types of Core Expertise interviews:

Early career candidates: we administer Core Expertise interviews for candidates who haven’t worked closely yet on large-scale production systems. In these cases, a System Design interview provides very noisy signal due to the candidate’s limited exposure to the concepts tested. Therefore, we instead test for technical depth on the candidate’s home turf (i.e., a technical discipline chosen directly by you).

Experienced candidates with specialized expertise: we administer Core Expertise interviews to assess candidates (including very senior candidates) for specialized roles that require particularly sharp mastery of a particular domain.

Logistics

Core Expertise interviews typically last 30-60 minutes. If you have an upcoming Core Expertise interview, here’s what you can expect:

For early career candidates

Before the interview: you’ll be presented with at least four choices of disciplines, typically drawn from computer science and applied mathematics. You’ll confirm your choice of discipline with your recruiter.

During the interview: you’ll work through multiple problems in your chosen discipline with your interviewer. These problems will vary in length and complexity, allowing you to showcase your depth of knowledge and command over your chosen discipline. You’ll spend between 25 and 50 minutes on these problems, and you’ll have access to a physical or virtual whiteboard.

For experienced candidates

Before the interview: your recruiter will share with you the technical domain of focus. Because we’re interested in understanding the expertise you’ve built up over your career (not what you’ve crammed over a few days), we do not provide detailed study syllabi.

During the interview: much of the previous section’s guidance holds for experienced candidates. The main difference is that the questions will be much deeper and may require you to discuss your own body of work (e.g., papers, systems, open-source contributions) in precise detail.

Evaluation criteria

There’s no strict rubric for a Core Expertise interview, and there’s no magic number of questions that must be solved for a positive evaluation. Ultimately, the interviewer is looking to understand your technical depth, the rigor of your thinking, and the clarity of your solution approaches.

Tips

Here are some tips for success on the Core Expertise interview:

• [For early career candidates] You should choose a discipline based on your own strengths, not what you perceive is most important to Perplexity. We don’t use the Core Expertise interview for team or project assignment.
• If a particular question seems so alien that you don’t know where to start, it’s 100% OK to say “I don’t know” and move on. Doing this is preferable to spending 10 minutes guessing in the dark.
• At the same time, many questions will require deep thinking to solve. It’s OK to take a minute or two to gather your thoughts before starting to solve a problem.
• Asking clarifying questions is welcome (and, in many cases, necessary).
• Remember to communicate openly! Your interviewer is permitted and encouraged to collaborate with you in solving these problems.