Step 1) answer some questions via email
Step 2) they ask you to make an assignment within a few hours
Step 3) interview at the office 09:00-17:00 where you meet some people and present the assignment and a project of your choosing in front of 4-5 people. For each of those projects you have to prepare presentations, for which you have to talk 20' each and then for another 20' they make questions like how would you sell it to a client in 10 seconds.
Advice:
Make sure you are a fit for the job before getting into trouble interviewing with them. They are a start-up so basically they are still discovering process (I think).
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I had no UX experience, it was very clear in my CV, however they asked me for an interview and I flew over there to have it. I spent days/nights, while already working, to prepare those presentations and money to fly over there - a cost I thought would be covered - as they wrote to their invitation that if you have to fly over there costs are covered by them, apparently that was not true..!
The outcome:
I didn't get the job and I was really fine with it, because I didn't enjoy the "environment" at the office, nor had a full understanding of the role, so it was really ok! I was actually happy when they said no, no matter the great effort I made to be as perfect as I could as this role is not my area of expertise!
It was very nice of them to call me and inform me of the rejection, rather than just send a cold email. I was informed by the first person that interviewed me, she explained fully why I didn't get the job and I really appreciated that! What I didn't appreciate though was the fact that apparently me CV wasn't read carefully from the beginning by them and I got into a situation where I spend many hours of my personal time and money, only for them to realise "at the very end" what already was in plain site through my CV, portfolio and answers from the first step.