The interview consisted of multiple steps. Each step was about 1-2 weeks after the previous one. The communication was rather smooth up until the last step (more on this later).
1. The first step was an online test with some IQ test like questions.
2. The second step was a ~10 minutes phone screen, pretty standard.
3. Then I got a take-home assignment. It had 2 parts: software engineering and data science. Nothing sophisticated, I would even say that the software engineering one was too easy (although it seemed to me the instructions were vague and sloppy).
4. After ~2 weeks there was a 1 hour call with two managers. It was a very friendly call. The questions covered both software engineering and data science and seemed reasonable. I then had a short e-mail follow up with one of the interviewers.
5. The last step was a meeting with the CEO. It was one week after the previous step. He asked me the same questions as those listed on other Glassdoor reviews, and it was more like a questionnaire than a conversation. At the end, I was assured that I should expect hearing from the company very soon. The call lasted ~15 minutes.
Then the company stopped responding to my e-mails. I tried to contact the HR and the interviewer with whom I had previously exchanged a few messages, but no one replied. After two weeks, I received a generic e-mail from their recruitment system saying that they had chosen another candidate (even though the vacancy is still open today, more than a month after they rejected me). I asked for feedback, but they simply ignored me.