If you’re just starting off learning guitar then this app isn’t the tool for you. Instead it’s targeted at more accomplished players and aims to provide one of the most comprehensive databases of information on guitar-playing around. It includes pretty much every chord, in every position, that you could think off as well as almost everything you ever wanted to know about guitar scales.
There's plenty of other useful stuff covered too, including alternative tunings, information on chord scale relationships and a tool to allow you to quickly find arpeggios. Be warned, though, the app is quite large when downloaded, weighing in at over 60MB of data.
It takes up a lot of space on your phone, but Guitarist’s Reference is also a goldmine of information for six string players. You’ll be amazed by how much there is on offer here.