The interview process was very straightforward.

It started with a phone screen with the recruiter to learn more about the position and the company, and to ensure a good fit.

Next was a timed, take-home assessment. This involved working on a realistic assignment to prove your skills; it was not a typical LeetCode-style problem. You also needed to complete four stages, where each subsequent stage built upon your previous solution. Importantly, you did not need to complete the entire assessment within the timeframe to advance to the next stage of interviews. I was able to reach the final part of the assessment and didn't complete every test case before running out of time, but I was still moved on to the next round.

Following that was an interview with a hiring manager. During this, you discuss your background and do a deep dive into a project you've worked on, detailing how you designed and implemented your solution. They are looking for a lot of detail here and will ask follow-up questions about how and why you implemented the project the way you did, how it scaled, alerting and monitoring, single points of failure, what you learned, and so on. I recommend choosing a project where you were the lead engineer and heavily involved in the implementation.

Next were the final round interviews. The first interview was a live coding collaboration with a couple of Klaviyo developers. You are given a project that was already implemented by someone else and need to walk through the code, discussing how you would improve it. They are truly looking for how you work and collaborate with other developers and whether you can spot bad code and enhance it.

Then came yet another hiring manager interview, very similar to the previous one. The key difference here is that this hiring manager may actually be the one hiring for the role you're applying for and, in my case, would be my eventual manager. Again, they do a deep dive on a previous project you've worked on. You can pick the same one you discussed in the first HM interview. Be sure to also come prepared with your own questions about Klaviyo and how this HM approaches management, as this person may be your future boss.

Next was a system design interview with a Lead Engineer and another Senior Developer. In this interview, you are given an existing system design diagram and a prompt on how you'd improve upon it. So, you're not building something from scratch, just building upon an existing system. This was also just a discussion with the developers, and I did not need to draw anything out. For this one, just study and prepare for a regular system design interview; there are plenty of resources available.

Lastly, you interview with an Engineering Leader at Klaviyo to discuss your leadership skills. Expect a lot of classic "tell me a time when..." type of questions.

Overall, although the process involved six different interviews, it was very engaging. You truly felt they were ensuring you'd be a good fit for the company and that your skills would transfer over. Also, my recruiter was the best recruiter I've ever worked with – very involved in helping you succeed. He even did a prep call before your final round interviews, where he goes over exactly what to expect for each interview. This was immensely helpful in preparing.

Tell me about a project where you were the lead.

How did you design and implement the requirements?