First call was with Anastasia who is a Co-Founder. Confirming you are still looking, that your resume is accurate, and to get a baseline on your communication.
Second interview was with a Sr. Engineer and the CEO/Founder where I had to do a simple Javascript problem on paper (they left me in the room). It seemed easy but they are testing to see 1) if you can program basic JS without assistance from an editor and 2) how elegant your solution is. They showed me two alternative solutions that were 1/5 the length as mine, or 2-3x as good. The CEO is an engineer and so are a few of the non-technical team members, so be careful about lying about your abilities to them.
Third Interview was focused on culture fit and values and personality. They want people who stay a long time.
Before they make you an offer the CEO, COO, or VP of your department will call all of your references and will even email or call references you have not listed like the HR department or manager at your previous companies. They also asked really intense questions to the references and spent up to 45 minutes per call.
When they made me the offer it was the CEO who called me. He detailed the offer but actually gave me 3 options so I got to choose how much cash salary vs equity I wanted. The CEO does not negotiate the offers, which I like because now I know that they are the same offers he makes to everyone with similar experience and same job title.
Also, the offer was actually higher than I expected and even the low option was $15,000 higher than what I said I wanted in the interview.