Guitaa is a free online music platform for musicians, that lets them find chords of any song of their choice on Guitar, Piano and Ukulele.
Chordify - Chordify turns any music or song (YouTube, Deezer, SoundCloud, MP3) into chords.
ChordU - Extracts chords from any song, integrated YouTube.
Sonic Visualiser - Sonic Visualiser is a program for viewing and analysing the contents of music audio files.
yalp.io - Automatic chords extraction from mp3 and YouTube
Amazing Slow Downer - !A slow down music software for Mac and Windows computers - Amazing Slow Downer
Riffstation - The web version is Free and you can learn how to play Chords with Youtube Songs.