Process includes few stages/rounds with some tricky questions (in positive sense): first tip you can find watching a video, next round contains open ended questions mostly (+code samples) that I found pretty interesting! I was rejected on 2nd round so I didn't see their code challenge. But I also asked for a feedback why I was rejected and their provided me a comprehensive list of reasons (most of them were related to my code sample) and I agree with 100% of them. I guess I'm not as good as I thought, but it's fair: they are looking for a candidate with 6 years of experience, I have 4 years only. Anyway, I really like their compony culture and will keep an eye on their open positions.