The process took 4 weeks. I interviewed at Block (San Francisco, CA) in May 2012
Interview
I was contacted directly by one of the Square recruiters. After solving the initial coding test, a phone screen and phone interviews followed. After three interviews, I was flown on a short notice to the company HQ and interviewed onsite in a combination of pair programming exercises, semi-academic whiteboards, and meals with the employees. Generally I had a very positive experience. The questions were interesting and rather skill- and thinking-testing than testing how much of "Introdiction to Algorithms" you have crammed in college. The recruiter remained in touch even after (unfortunately a generic Jobvite one) "deciding to pursue other candidates", so I might revise this option in a while.
Interview questions [1]
Question 1
Questions pertaining directly to your development platform and frameworks of choice.
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.