What are some alternatives?
When comparing GetHarmony.net and ChordU, you can also consider the following products
yalp.io - Automatic chords extraction from mp3 and YouTube
Chordify - Chordify turns any music or song (YouTube, Deezer, SoundCloud, MP3) into chords.
Riffstation - The web version is Free and you can learn how to play Chords with Youtube Songs.
GUITAA - Turn ANY song into chords, play along with interactive chords and diagram, transpose, loop, tempo control.
MusicTrans - MusicTrans is a powerful learning tool for playing any song.
Amazing Slow Downer - !A slow down music software for Mac and Windows computers - Amazing Slow Downer