Very casual. Was essentially a conversation where the single interviewer asked me to explain my past experience, career trajectory and any relevant experience. I felt like I had the opportunity to explain my reasoning for the application and support it with examples. Interview was around an hour. I was then called back for a second interview with upper management, which was again a short, casual conversation (around 30 mins) and was offered the job during this interview. They were very accommodating to my time constraints and the interview process could have been under a week, had I been available.