Features:
- Judge song key.
- Transpose the song.
- Show chord relative degrees in several notetions.
- Input by degrees.
Notation systems:
- Chord names and symbols: C, G, E, Am7
- Roman numerals: I, V, III, VIm7
- Nashville Number System: 1, 5 3M, 6-7
- InstaChord Number: 1,5,3~, 67