ChordU - Extracts chords from any song, integrated YouTube.
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.
UkeLib - Ukulele Chords - A comprehensive library of ukulele chords with suggested finger positions for every chord.
Chordify - Chordify turns any music or song (YouTube, Deezer, SoundCloud, MP3) into chords.
MusicTrans - MusicTrans is a powerful learning tool for playing any song.