First of all, I would say I always wanted to get hands-on experience in payment systems and Backbase was my target since they had good rating and interesting ideas behind.
There were 3 rounds. First round - the interview with HR manager. Salary expectations, goals and targets for future and why Backbase? question. Sent to me coding task for 5 days. Not so complicated task.
Second round - interview with two technical guys. Since I have security background, I answered to mostly security questions, also design, architecture and Spring ecosystem questions. Not so complicated. Guys were really cool in discussion (like chatting with colleagues ). At the same day I got invitation for third round.
Third round - interview with VP Software Delivery. I was asked several really weird questions. Not sure that not technical guy should ask technical questions. First one was: if you app fails to perform 5 transactions, what would you do? Interesting question if you have enough details behind this question. When I started asking about architecture type, frameworks, databases behind this application to figure out what's the problem could be, I was surprised I didn't get meaningful clarifications. So from my standpoint, it happened to be a question like: I cannot and don't want to tell you anything, but my app fails on 5 transactions in a row, so what to do? Nothing to say, just funny. I was looping through traditional high-level solutions for such kind of problems.
And second question, perhaps, was the funniest one - what integration patterns do you know? Knowing there are a lot of them in several categories, I asked what exactly a category do you want to discuss? Answer: integration patterns. :) Funny. Ok, I started counting any integration patterns coming to my mind. Looking at his face, I was sure he didn't know any of them. Oh...why to give non-technical guy to ask technical questions?
I was asked questions about Backbase project and I assume I failed to tell subtle details. :) This guy started asking details how I think this project works. After thinking-out-loud considerations from me, he interrupted and said "hold on, I can tell you it works".
Several days after last interview I received a letter with official purpose "I'm not interested in Backbase". After clarifications why they decided I am not interested, they said.....because.....VP decided you are not interested.
To be honest, good company with good process, cool technical guys, but there are some not qualified guys who can just reject without reason.
Be careful while applying!