Kielbasa is a music theory tool for answering questions such as: what key is this song in?; what are all the chords in that key?; and, what notes are in those chords?

It is used by entering the known notes of the song you wish to find out about. Notes can be added either by clicking on the piano keyboard in the bottom right, or selecting a chord from the list on the bottom left and then clicking Add chord. Adding a chord causes all the notes of the chord to be added to the song.

Once notes have been added to the song they can be removed again by clicking the word Delete below the note. As notes are added and removed from the song Kielbasa will determine which keys contain all the notes in the song. Clicking Display beneath a key will show all the chords in that key. Beneath each chord are the notes that make up that chord.