zenmix.io - Ambient background sound generator
Defonic - Create a unique sound environment at home or in the office
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.
SoundDrown - Ambient sounds to help you focus, relax, and escape
Focus Noise - Productivity sounds and color noises to stay focused at work
Silenz - Mix ambient noise in with the music you're listening to