ChordIQ - Learn notes, chords, sight reading, perfect pitch and more.
Typatone - Make music while you write
muted.io - A magical collection of interactive music theory tools & visual reference pages for musicians and music producers
Frettable - Play your instrument and AI will write the sheet music
7Pad Scales and chords - Music instrument and assistant for playing scales and chords.
Tab Lab - Read and write music notation and tablature, together.