The process is well described on their website (email exercises, phone interview with live coding and culture contribution, then a day in their office).

The experience was great, for the in office they will send you a mail describing what you'll do there (rounds of 45min with different engineers for technical talks and other for culture, your past work, and chat about products you like/dislike). I was rejected because they had some other stronger candidates

Tell me when you had a big feature to deliver (estimated time > 1 month): How did you take the problem?