I applied on their website, followed by a phone screen from an HR person.

You can find a list of such questions on this website.

After that, I had a Skype interview with an engineer. He asked several basic questions about data structures, algorithms, and networking, then a coding question using a linked list.

A week later, I had an onsite interview in San Francisco, which consisted of several 1:1 interviews with managers and senior engineers. Most of the questions were whiteboard coding questions and behavioral questions.

How can you improve the service of Yelp?