I applied by sending a cover letter and my CV to the email address on their website. They got me back to me quickly and arranged interview. There were three interviews, each an hour long in one afternoon. All the interviews were technical and involved analysing simple problems relating to Semmle's work. Only one personal question was asked, namely "Why do you want to work at Semmle?". I heard back from them two weeks later. I didn't get an offer, but I think I could have if I'd actually prepared/prepared better.