Wunderflats allows you to book for 1+ month at a time, and they have a different/mostly nicer selection than Airbnb.
They are mostly geared towards people relocating (I think).
I like the idea of using them for a longer term stay, but the lack of reviews makes me nervous. I see Airbnb options that look great, but the reviews are crappy. A bummer for a few days, but a disaster if you are trying to live there for a month. With Airbnb, as long as there are a good number of reviews, you are warned.
Wunderflats has no reviews at all. Can I trust the company? Many of these places seem not to be booked at all for 2026, so I don't know what to think...