I was first contacted by an Amazon recruiter via LinkedIn. I was kind of hesitant to interview with them, since I had been rejected by them in the past. But I spoke to a manager -- I liked the stuff his team was working on, and I decided to give it another shot.
The first interview was on the phone with this manager. It was behavioral in nature, but still technical. What I mean by this is that the questions all started off as "Tell me about a time when..." and finished with detailed questions about the code behind my solutions. I don't personally think what I said was THAT cool, but I must know how to sell it because I got a request for an online test and onsite interview the next day. The test was actually really hard! Maybe if I was halfway through an undergrad junior level algorithms course, it would have gone easier. But I wasn't. So I did what I could, commented on what I couldn't, and left some notes about how I would approach the problems given more time.
Anyway, on to the on site interview! The interviewers were very nice, they made me feel right at home. I was asked a little bit about what kind of code I worked on at my current job and what working at Amazon would be like. I knew going in that Amazon had a reputation for being a bit of a sweat shop, but going through a bit of a workaholic phase in my life, I didn't really mind.
For the most part, the questions were technical. I was given some questions on trees, graphs, distributed systems, and object oriented design. They were fairly standard questions, with slight twists as followups. Basically they'd give me a standard question and I'd give them a standard answer. Then they'd grin and change the question and make it significantly harder. Then I'd struggle, get nervous, take a deep breath and calm myself, and work through it and get to the correct answer.
Being calm is just as important as having strong technical prowess in these interviews. This was a big challenge for me when I was graduating college. I got interviews from all the big tech companies: Amazon, Microsoft, Apple, Facebook, and Google. And I failed every single one of them even though the the questions were surprisingly doable, because I couldn't control my nerves. I secretly had an anxiety and panic disorder back then, so this was easier said than done.