First, I had a phone call where the recruiter told me a little bit about the job offer, the company and about the home task I will have to do first before passing to the office interview day. After this test, they will give you a feedback (very helpful, I have to say, because you know what you can improve the next time). I went to Barcelona for one day to make some interviews in their office. Every interview lasted about 1 hour. They consist in: one presentation about anything you want (about 10-15 mins and then they'll ask you some questions about it), a logical test that lasts 1 hour, a culture interview about different topics, a pair programming session with two of their developers, where you have to explain the code you made previously (this home task). I didn't get the job, but only because I met Giulia (the recruiter) I think it was worth it. She was a really helpful and nice person who provides you all the information you will need and some articles you can read to be prepared for those interviews.