Applied online, got an initial 45 minute call with an engineer, all behavioural type questions. Some Qs are a bit more probing than standard HR stuff (like in the book Talent by Cowen and Gross), and I guess they are also interested to see how keen you are on the companies mission. I didn't get past this stage, but I appreciate this was an extremely rare company I applied to where the interviewer actually gave me some feedback instead of the dreaded canned rejection from a noreply.