The essential tool for song-writers and musicians in general assists with all chord spelling tasks. Features a built-in Circle of Fifths and chord finder for when you know the pitches, but not the chord. Many times chord spelling becomes an essential task, be it to communicate what you are playing to others or simply when writing it down. To complicate matters music theory is often complex and correctly spelling a chord that may have sharps AND flats, double flats or double sharps is not always easy. That is where ChordLab can be of great assistance as a sort of chord calculator.
In addition ChordLab can also show you how to finger given chords on the piano or guitar. It features all the standard voicings commonly used in Jazz, Rock, Pop, and elsewhere. This helps to write fitting music for an instrument one might not be too familiar with.
Another essential tool found in ChordLab is the Circle of Fifths which is implemented interactively and can be used to show parallel minor/major key signatures.
The most important tool for many, however, will probably be the Chord Finder. This tool allows one to just enter a bunch of notes and find out what chord exactly these might represent. Many guitar players often play fingering combinations without being aware of the kind of chord these notes might represent. Notes can be entered just by pitch and without having to have the correct name.