It was a 3-step interview process via Skype.
The first interview was with the HR representative and was pretty standard and boring.
The second one was a Q&A session on different programming subjects, ranging from networking, hardware, database, big data processing techniques, binary logic, arithmetic.. all of these ranging from what they considered easier to harder. Once you miss one or two questions in a subject, they change subjects. I recommend being honest about this. I guessed several of the answers, out of hearasay and common sense rather than actual familiarity with the terms I was asked about, and did well, but I do recommend spicing it with things like "I'm not familiar with the term, but it sounds like it must be...". I think they seem like the kind of company that values common sense and capacity rather than sheer brute knowledge.
the third one was a live coding test in the language of my choice that included some simple but pretty core Computer Science stuff, such as trees and graphs, and the chosen language's mastery. I finally failed this test because I became quite nervous, and was tested on graphs which I hadn't worked with since forever, while I had focused my preparation in trees specifically. Finally I couldn't produce a BFS algorithm, and in retrospect I really should have googled for some pseudocode instead of trying to pull it out of thin air.
After that there would've been a fourth interview on-site which apparently includes designing solution to some real-world problems the team you're interviewing for is facing. They would've payed for the tickets and the stay for a night in Stockholm.