One phone interview: Thirty minutes, very business-like, purely about factual knowledge and previous experience. One in-house interview: 4+ hour interview with 5 different people, one at a time for ~45 min each. Final person was director level for 1.5 hours. Interviewers were Senior Engineer level and above. Some factual questions, but mostly personality and experience questions. It was important to them to find an employee that would fit with company culture. Interview was relaxed and not stressful. Conversation with director was about career goals and company culture. The company moved very quickly from the phone interview forward. An offer letter was sent within two days of the in person interview.