It's two parts: An App Engine/Python for the UI and user registration, and a Linux server for image capturing (Python, Javascript, RabbitMQ, ...etc.). At first we used popular libraries like Phantomjs, but eventually had to write our own to scale better.
I'm experimenting right now with moving the image capturing code to an App Engine managed VM to simplify things and make it scale easier.
I'm experimenting right now with moving the image capturing code to an App Engine managed VM to simplify things and make it scale easier.