Don't waste your time, they're looking for a slave and they don't seem like a company that cares about you as a person. Communication with the company wasn't smooth, I had to repeat my questions in a separate e-mail every time I wanted to ask about something. The only person who made a good impression was the engineer from the Step 4.
0) HackerRank with some basic coding questions + Leetcode easy.
1) 15 minute pre-screen interview.
2) 1 hour long interview with a senior engineer. Some basic SW Eng. questions + LeetCode medium. It was okay, nothing special.
3) 30 minute long interview with the Chief of Staff. Replying to my question, he said that he came to Kalepa randomly by applying to a job posting he found, which is funny considering that they ask you "Why Kalepa?" at every stage of the process and considering the feedback they gave me (I "didn't seem particularly interested in Kalepa"). Other than that, some questions about "intense environment".
4) 1 hour data science interview with a senior engineer and a manager. The part conducted by the engineer was the highlight of the process. We had a good discussion about an ML system design case study. The interviewer seemed like a really nice and knowledgeable person. The other part of the interview was conducted by the manager and it was the worst interview experience I have ever had. He started with some questions about Python and ML. He asked this question about the trailing zeros in 26! and mocked me me when I tried to think about the answer. He asked about the parameters fitting step of logistic regression and after I answered "MLE + Newton's method", he said that isn't true and there is a closed-form solution to this problem which is obviously not true (you asked the question, you should know the answer). There were also some "culture fit" questions like "What do you mean by long hours" that were said in a really mean way. At the end of the interview, when it was the time for my questions, I asked him a follow-up question about what those long hours look like in practice at Kalepa. Again, he began to mock me, saying that I had asked "a strange question". He then stated (in a very rude manner) that he doesn't care about how many hours his employees work. He followed up with things like "if something doesn't work, it's already 10pm and you're tired of working all day, you can't close your laptop and call it a day" or "the other interviewer hasn't ended up in a hospital because of overwork yet so it's doable" (this was said while the other interviewer was still there!). I guess that says a lot about their "culture" which they say are very open about, but there is a difference between what he said and "Kalepa is a very intense environment" which they communicated two times to me. At one point he even started to swear (and he talked about "American work culture" before lol). He was the least professional person and the biggest bully I have ever met in my entire IT career. I completely lost interest in the company at that point.
5) 30 minutes with another manager, it was right after the previous step. Again some variations of "Why Kalepa?'. He didn't seem to listen or care what I said.
After that, I got a rejection email. Plus for them for providing a feedback.