tl:dr; I had a really great interview experience at Flatiron - I feel like they give a lot of thought and care to their process and it shows. I applied online as a new grad and received a small timed coding assignment (I think around 2 questions in 1 or 1.5 hours). After completing the code screen, I heard from a recruiter, who set up a time for a phone call with an engineer on their team. I went through a technical question with that engineer and also discussed some projects I'd worked on. After that, I heard from the same recruiter about setting up a time to come and interview on site. For the on site interview, I met with 4 different interviewers, with a break for lunch in the middle where I talked with a member of the Flatiron team. The questions in the interview involved coding on the white board, talking about how I would design a problem, and also my previous experiences/projects. I thought the questions were very reasonable and related to seeing how I thought as an engineer - not if I had certain things memorized. After the 4 interviews, two members of the team took me out for coffee to share more about working at Flatiron and answer any questions I had. After the on site interview, I received an offer. The recruiter shared more about what the offer entailed, and also set up time for me to do what they call a "reverse interview", where I met with a couple different members of the team so they could answer any questions I had. Overall, everyone I met throughout the process was kind and respectful, and seemed concerned about making sure Flatiron was a good fit both for me and them.

I had an online assessment first after applying, and after I passed it there was a pair programming session with one of their engineers. The online assessment was more difficult, the pair programming was more practical.