What are some alternatives?
When comparing GUITAA and Amazing Slow Downer, you can also consider the following products
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.
Guitar Dashboard - Open-source interactive music theory for guitarists.
Chord Generator - Used to draw guitar chord images.
Riffstation - The web version is Free and you can learn how to play Chords with Youtube Songs.