An alum from my school/major who works there reached out on LinkedIn to see if I was interested. We had a 30 minute phone screen (tell me about your resume/projects), and then the real interview process started.
Round 2: Take-home Hackerrank that you have 3 days to do. Medium-ish level on LC/hackerrank, and only takes a few hours to solve, but you're definitely expected to comment/structure everything very well since you have 3 days.
Rounds 3-5: 3x 45 min interviews over Bluejeans back-to-back-to-back with a senior FDSE, a younger FDSE, and a FDSE manager, respectively. First one was broad technical knowledge / general problem solving, second one was coding (again, medium level LC/HR), third was culture/behavioral/fit and data/object representations (i.e. DB normalization). Apparently the content of this interview round changes somewhat often but those will definitely be the general themes.
Round 6: I didn't ace the coding interview and I didn't provide the most optimal solution to the Hackerrank challenge (haven't taken a CS class in a while), so they scheduled another 45 min interview for data structures and algorithms (with a different entry level FDSE). Was a little more prepared for that one.
Round 7: 30 minute video chat with the VP of the department. This one took a week or two to schedule. More behavioral (definitely have a good answer to "Why c3?"), and you should bring some questions about the company's trajectory/business model.
Round 8: The VP round is normally the final round, but I'm getting hired right out of college so I am getting put on a 1-3 month training rotation when I start, and this round was with a manager of one of the teams I would be on. 30 min behavioral, a lot more laid back than previous rounds. Took 2-3 weeks to hear anything about scheduling it after the previous round.
Was told I have an offer the week after the last interview, then received the offer in writing two weeks after that. Like someone else on here said, it's a very competitive offer for Redwood city, but just a little below what you might expect after going through eight interviews.
Some closing thoughts: Everyone that I talked to was super friendly and very intelligent, and everyone just seemed genuinely excited to be working there (which is not something you see everywhere). The process takes foreverrrr (11 weeks from LinkedIn message -> written offer), but you really get to know the company and people very well and see how they operate. If your coding/technical knowledge is strong and you're a confident communicator, the process won't be too bad. I had to re-teach myself a large amount of CS in a few weeks (on top of school work too) which made my life pretty hectic, but that won't be everyone's experience. There might be long periods where you don't hear anything (especially toward the later rounds), but don't get too worried about it.