Interview steps:

• 30 min HR screener
• 1 hr technical screener
• Technical challenge
• 1 hr technical review
• A couple of days later, a rejection.

I was invited for the first round around 3 months after my CV reached them. I believe they could not find a suitable candidate.

Following the technical screener, I was invited to take a 4-hour HackerRank test. After asking to double-check the language choice, the challenge was now time-unlimited. After asking for clarification of the change, I was told that you are given 30 days, but candidates typically take 8-16 hours to do it.

The requirement is to make it scalable and extensible. You are asked to send your questions to a group of people including HR and technical staff, who would then help clarify the answers. They did correspond with me on the questions with good answers, and I submitted a full solution with benchmarks, documentation, and similar.

Afterwards, I was invited to a technical interview with 2 developers to review the solution. This was one of the hardest interviews I have had. I definitely could have done better in terms of communicating with them to understand what they meant, and my feeling at the end was that I would likely be rejected. A couple of days later, I received an automated rejection email, but what I did not expect at all was to be told that in my solution 'there were a few issues that did not meet the bar'.

I asked HR to clarify, and they kindly offered to go on a call to discuss, which I really appreciate (some companies would not bother). Over the phone, I was told that the solution was good, and the rejection was due to not being able to answer a question at the last round of the interview, which is fair enough.

Based on my experience, apply only if you have solid Computer Science fundamentals (I am not of a CS background), or if you have no other low-hanging fruit opportunities (due to time investment in the challenge).

I am not saying this in a bitter way, but simply because of what they do, they really need that solid understanding of algorithms and low-level details, constantly, every day.

Do ask for a high starting salary with this company because if they hire you, you are one of the select few that they are really looking for.

How could you make this faster?