Technical Interviewing Portal

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 whiteboard, virtual whiteboard, or scratch paper.

A note on topic selection:

Of all the disciplines we offer to early career candidates, algorithms has the lowest pass rate by a wide margin. Our understanding is that some candidates choose algorithms because they’ve been practicing LeetCode-style problems and believe that practice will help them succeed in this round. We’ve generally observed the opposite: candidates who overprepare LeetCode recipes often find themselves quite unprepared for the rigor and depth that the Core Expertise interview demands.

Therefore, we strongly advise choosing your discipline based on your overall command of the subject matter, rather than on any preparation you may have been doing for other companies’ interviews.

Finally, 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.

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: