I completed the first round engineering interview, which was an over the phone interview with a programming question/challenge on a shared screen. The interview was 1 hour long, with 45 minutes for a coding and then 15 minutes for conversation and questions - I was the one asking questions. I spent almost a full hour on the programming question, but we went a little overtime with the conversation. For the programming question, I was allowed to use whatever language I wanted. In fact, I was advised to choose the language I was most comfortable with, rather than one that I would be using if I were working at Square. You are also allowed to use online resources like Stack Overflow or Google search at any time throughout the assignment. It was a very relaxed environment, and an overall enjoyable experience.