First I had a pre-interview with the HR company, then I had an interview with the department manager. At the next stage, I was sent an assignment. I solved it and presented it. There was another interview with my line manager along with the presentation. I talked to colleagues and their hiring stages were a bit different. The questions asked included regular HR questions (motivation, previous experience, etc.) and also questions on my level of expertise (examples, explanations, etc.) The interviewers were friendly and smiled.
