Meludia - Listening exercises and to sharpen your ear and music theory skills
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.
GNU Solfege - GNU Solfege is free music education software.
Noizio - Feeling that the noise of the big city is too much for you to bear?
Perfect Ear - A simple yet advanced application for improving your solfege skills.
zenmix.io - Ambient background sound generator