I applied through college or university. The process took 3 weeks. I interviewed at Block (Waterloo, ON) in Feb 2015
Interview
Hour long "pair programming" sessions with square developers. They give you a simple programming task and you implement it in the language of your choice. "Pair" because some of them will sit with you and point out typos and let you bounce ideas and be helpful, while some will work on other things and hardly pay attention.
Interview questions [1]
Question 1
Find shortest uniquely identifying prefixes on a set of words. Eg "pineapple" "pinetree" "pill" has "pinea" "pinet" and "pil"
Inital take home, followed by extension interview, followed by a coding challenge, followed by system design interview.
The whole process took 3 months!
The interviewers are usually really nice and want you to do your best.
The interviewer was nice, and he is friendly and willing to give hint, the question has 2 follow-ups, it was hard to complete in time. The question was not a typical LeetCode
Phone screen and then a full day of interviews. 3 pair programming challenges, a system design review and a prior experience interview. There was also an onsite lunch with a person from the company.
Interview questions [1]
Question 1
To design a hotel booking system. Pick any part (backend, frontend, database, api etc) and deepdive into that, explaining the decisions along the way.