The interview process began with a phone screen where an engineer asked typical questions. This was followed by a full day on-site, which involved pair coding problems and some design questions. Most of the people I interacted with were quite friendly, and I enjoyed the pair coding format. The company allowed me to use the programming language I was most comfortable with.

In the interest of professionalism and confidentiality, I refuse to provide hints as to what they ask in their interviews.

One thing that I would mention is that the interview was difficult and included somewhat typical CS-related questions.

Some of the questions were somewhat pointless and would be poor predictors of success at the company.

Being completely devoted to Ruby on Rails is probably a better predictor of success at Square.