There are more guitarists in the world than ukulele, mandolin, and banjo players (combined). As such, the vast majority of songs indexed by the Chord Genome Project are pulled from guitar websites. This approach maximizes the number of tunes you can search for and play.
What if you’re learning the ukulele, mandolin, or banjo?
What if you use non-standard tuning for whatever instrument you’re on?
It doesn’t matter.
When it comes to chords, music notation is 100% interchangeable.
If you look at both versions of Twist & Shout below, you'll see exactly what I mean.
Twist & Shout - Version 1
Twist & Shout - Version 2
One version was pulled from a ukulele site. The other came from a guitar site.
But it’s impossible to tell which is which.
And that’s the whole point.
No matter what instrument you’re on, you can use “guitar” notation just as easily as you can use songs written for the ukulele, banjo, or mandolin.