It included a number of challenging coding questions, behavioral questions, and system design questions. They are willing to move through the process fairly quickly. There were only a few stages: initial screen, coding screen, and on-site.
I applied through a recruiter. I interviewed at Meta (New York, NY) in Feb 2020
Interview
Very long and grueling process. They literally give you PDFs of material to study for your interviews. You are expected to do 5 one-hour interviews in a single day, solving programming challenges nonstop the entire time. You get a lunch break but that's also a "friendly interview" with an employee to learn about company culture.
They are amongst the highest paying in tech and they know it - you sure have to work to get in.
Interview questions [1]
Question 1
Know your data structures and algorithms off the top of your head!