I applied online in February. After 5 weeks I had a Skype interview. The interviewer was very friendly. There were some behavior questions and some technical questions (not so detailed and difficult) to know what technologies I know about. After 4 days, I got an invitation to the HQ in Dusseldorf. In the email, it was just an invitation to "awesome workspace for a get2know day", but from what I read on Glassdoor, I know it was another interview.
Since I come from Asia, they pay for almost all expenses (hotel, plane, visa). It takes more than one month so I can get a Schengen visa, so I went to the interview in May. After some time waiting at the reception, a guy came and took me to their working table. There is no interview! It is a practical test. I don't want to tell in details about the content but in general, it related to the position. I did it all the day, skipped the lunch to try to finish it, but since I don't have much experience about the tasks, I did not do it well.
However, the thing which made me impressed is that everyone was so nice, many people from that department came and say hi to me, they known my name in advanced and asked about my long trip or if I need any help, some foods or drinks. I also saw people came around to help each other. In the end of the working day, the head of the department came and checked my result and say that the result should come to me in a week.
After that, I waited 2 weeks and there was nothing. I sent an email to ask and received a generic email saying that they found a better candidate. I still dissatisfy why HR (in many companies) never answer the result to failed candidates. A generic email should not take much time.
In general, I see that the office is pretty, people are nice so trivago should be a good place to work. In the end, I have learned a lot.