I applied online. I interviewed at Vertex (King of Prussia, PA) in May 2017
Interview
1 hour coding exercise. You are given a game with some pre-written code. You have to write the rest of the classes and make the code work. Followed by this there will be 1 hour Q and A interview process with extremely technical questions
Interview questions [1]
Question 1
Explain in detail how to create and consume a REST or SOAP based WS