I applied via the "Jobs" section in Hackerrank, where I had to answer a simple statistics exam. I can't remember all the questions but they were related to regularization and p-values. Then I had a brief phone interview with HR so they could tell me more about the position. Then I had a technical phone interview with two scientists, where I talked about a project I had previously worked on, they asked a lot of technical questions. Then they asked how I would implement a "best value for money" offer on their website and afterwards how I would test it. Then I flew to Amsterdam (they paid for everything) to have an on-site interview. I had three interviews: in the first one I had to give a presentation that they had asked me to prepare about a destination recommender; in the second one (with different people) they asked me how I would implement a recommender system in their website; and in the third one I talked with a manager about myself and past projects, this last one wasn't technical. In the end they told me that they were looking for someone with more experience and that I was more suitable for a junior position, which they didn't have at the time so they didn't give me an offer.