The screening call was conducted by a senior manager. I passed that, and they emailed me a challenge problem. After that, I came on site for an interview. I met with the manager who had conducted the phone screen and the lead programmer, then with two additional programmers. After that, the head of HR, followed by the senior manager. Everyone involved was obviously very intelligent, and they showed cordial respect to me and to one another. This was my first technical interview, and in retrospect was super easy, though at the time I found it challenging. Mostly I learned from it where I needed to improve, but was very impressed with the company and would have been glad to work with them.