I applied online. The process took 1+ week. I interviewed at Merchenta (London, England) in Jul 2015
Interview
There were several steps. Most time was spent reviewing my code from previous open source projects - they were interested to learn why I did things the way I did and how I could do things differently again. Had Java and Scala test questions on technical things like frameworks. They were nice team interested in technical design patterns not just "how to do this or that".