The ChordSpell tool I have developed tells you the name of a chord after you enter the chord's notes. For chords that traditionally contain 6-7 notes, ChordSpell will produce a correct match if you leave out some notes, such as the 5th, 9th, and 11th tones of a 13th chord.
ChordSpell comes in two versions, one where you type in note names and another with a fretboard diagram where you can enter the note positions directly. The fretboard defaults to standard guitar tuning, but the tuning is completely user-selectable. For example, you can set the top 4 strings to a standard mando tuning (G D A E) and use the tool to name standard mandolin chords.
For both versions of ChordSpell, the tool correctly identifies a variety of rootless chord forms. You'll find that entering the notes E G B D, for example, will yield Em7, CM9 (no root), and G6. The "no root" designation on the CM9 means that if you are playing a chord with the notes E G B D, then a bass or keyboard player can strike a C note to give an overall C major 9 sound.
A chord name in the Results table is shown as a button. Click the button and ChordSpell will tell you common functions of the chord in the major scale. For example, F major (F-A-C) can function as the I chord of F major, the IV chord of C major, and the V chord of Bb major.
If you find a mistaken or omitted identification, please send me email with suggestions or corrections.
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