Noisli - Noisli is a fantastic background noise and color generator for working and relaxing. Online soothing ambient sounds like White noise, Rain and Coffee Shop.
Noiseblend - One-tap music for every occasion, with Spotify Premium
Noizio - Feeling that the noise of the big city is too much for you to bear?
Spotify - Map shows when two people play same song at same time
A Soft Murmur - Ambient sounds to wash away distraction.
22tracks - DJ curated Spotify playlists on iOS