Phone interview: After several phone conversations with a recruiter, I spoke with a lead of an engineering team and talked in detail about my background and qualifications. This led to an on-site interview.

On-site interview: It was a rigorous four-part interview with four different senior engineers. It was similar to what you might expect from a rigorous engineering company: some basic CS theory questions, solve-it-on-the-whiteboard type of questions, plus discussions about my previous work experience and my work in grad school. Because I have a specific background in a research area of computer science, there were many questions about solving the types of problems in this area that may arise either at Groupon or in general.

Culture: I was impressed with all the people I met there, though most had not been there for very long.

There was a difficult CS theory question about data structures and algorithms.