I met a representative at a career fair (wasn't even planning talking to them, but they seemed bored), and applied right there at the career fair on their ipad (followed up by an email with some questions to answer). I was contacted for a phone interview shortly after. The phone interview was very relaxed; it seems like they're really just trying to draw in talent. After the phone interview, I was contacted to set up an on-site interview.
up until this point, everything was fairly ordinary.
Prior to the on-site interview, they had me complete a series of online assessments (personality stuff, "IQ test" questions, reading / data comprehension, coding exercise (in a made up language, to see how well you can learn)). These were done via ProctorU, so you'll need a windows/mac computer with a webcam.
A day before the on-site interview, I was contacted asking if I would also be interested in another position (Integration Engineer), since I had indicated that I would be interested in a role more directed at development. I said yes, so they set up interviews for that as well during my on-site interview.
On-site interview was nearly a full day, along-side several other candidates. The day included an intro presentation about the company (with snacks), a Q&A with other people in the position(s) being applied for, a short "what would you do in this situation" assessment, lunch (on their dime), a short HR personality interview, and a programming assessment. I was informed that the programming assessment was actually just to give them an idea of your abilities and where to place you, rather than something that would qualify you or disqualify you from the position. They let you use whatever language you wanted, to complete a series of small programming assignments.
Following the on-site interview, I was contacted 2 days later with an offer.
Overall, the interview process seemed more focused on convincing you to work for them, rather than judging what you are capable of, and they seem more concerned with "can you learn" than "what do you know" or "what have you done".
One note on dress code. Their invitation for the on-site interview says "casual" as the dress code. They mean it; employee dress code is pretty casual. "Startup casual" for the interview is probably about the right level to look good for the interview, but not stick out like a sore thumb. My dress shirt, jeans, and nice loafers were about right, and I fit in with the other candidates as well.