I don't know about an App for minimalistic wallpapers but this site is great for minimalistic wallpapers
Edit : Oh they have a App too
Re:Wallbase: Wallpaper search engine
by coloncapitald on Thursday December 26, 2013 @08:13AM
(#6966148)
The site is beautiful but, unless I am missing something, I can only see a preview of the wallpaper from the browser. I have to have a mac or iphone.
This said, I think there's still a niche for a website or app specialising in new minimalistic wallpapers. Also, I'd pay for a "wallpaper-on-demand" service where one could order custom pics - I think photo websites like 500px are missing a trick there.