Applied online and got a general screening call from HR about my background, etc. The next stage was a phone interview with someone in their Seattle office in a similar role. Finally, I was brought in for an in-person sales loop, which is a full day's worth of 1-on-1 nterviews with 5-6 different people.
I read pretty much every single interview description on this site and it helped a lot. I suggest you do the same and don't take their interview process lightly. They're very intense about their process!
A lot of the questions asked throughout the interview process were 'situational' questions (ie. Tell me about a time...). And by a lot, I mean every interview except for the general HR phone screening consisted of these questions. During the in-person sales loop, I'm pretty sure I was asked the same question by every single person. It definitely helps to review the jobs description and have examples ready of when you did similar things. Also, study Amazon's list of core value/principles. You'll be asked situational questions based on those as well.
The entire process is long and tiring but I guess they just want to be thorough. Everyone I met with was pleasant and nice except for the VP from Amazon HQ. He was brash and a bit of an imbecile.
If you make it to the interview loop, HR will tell you that the 5-6 people you'll meet will act as a panel and each of them will vote on whether or not you're a good fit for the company. They'll stress that each person has an equal vote and their position doesn't hold any additional weight on their vote. This is completely inaccurate as the moment I started my interview with the VP (the one I mentioned earlier), he made a point to say: "i'm the lead hiring manager for the day". Well him and I obviously did not click, which would explain why I most likely didn't get the role. If I was offered the role, I probably wouldn't have accepted it due to the fact that i'd have to report in to him.
HR tells you at the beginning of the process that if you don't get the role, they're unable to provide any feedback as to why. I knew this going in, but after investing 8+ hours interviewing (one of which included me taking a vacation day from my existing job) it's still kind of frustrating to not even get a simple explanation (literally just a phone call saying you didn't get the role, thanks for your time, bye.)
I've heard mixed reviews about the company but I hear they pay well. I feel that their interview process is a bit too intense for a company that's barely in the top 30 of Fortune 500 companies. I'd expect a similar process for big tech companies like Google or Facebook, but not from a company with the 2nd highest turnover rate out of all Fortune 500 companies.