ChordIQ - Learn notes, chords, sight reading, perfect pitch and more.
Tonaly - Compose songs and practice scales
muted.io - A magical collection of interactive music theory tools & visual reference pages for musicians and music producers
Sight Reading Machine - Computer generated music for sight reading practice
ChordPic - Create beautiful guitar chord diagrams
Scales-Chords - Free online music tools featuring a searchable chord database and chord charts.