After a number of interviews, Zalando decided that I was overqualified for the position, and started interviewing me for a more senior position. After over 10 separate interviews, several trips to Berlin, and verbal indications that I would recieve an offer, I was rejected for both the initial and more senior positions.
In one series of interviews that lasted almost an entire day, I had to take taxi's between locations, and amazingly, at least one or two individuals didn't even show up.
Zalando, months later, has yet to reimburse me for my expenses.
Looking back at the process, I gave Zalando a lot of free consulting, at my own expense.
The most memorable quote from all of the interviews was when one of the founders told me, "I could tell everyone here we're going to start selling toilets, and they'd all fall in line..."
If you're interviewing with Zalando, do yourself a favor, and make sure it's not the only opportunity you're pursuing.