ChordU - Extracts chords from any song, integrated YouTube.
UltimateGuitar.com - Learn how to play your favourite songs on guitar or ukulele
yalp.io - Automatic chords extraction from mp3 and YouTube
Guitaa.com - Turn ANY song into chords, play along with interactive chords and diagram, transpose, loop, tempo control.
Chord AI - Chord AI is one of the advanced applications based upon artificial intelligence that provides you a cord of ant songs automatically and reliably.
Guitar Dashboard - Open-source interactive music theory for guitarists.