The ChordSpell tool I have developed tells you the name of a chord after you select 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 click on 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.
The fretboard version of ChordSpell is what I normally use. An "X" at the nut means the string is muted or not played. Click the nut to change to "O" and include the open string note in your chord. Click on the strings between the frets to set a note on each desired string. The Fretboard Notes table shows all the selected notes from left to right (looking at the fretboard). The Unique Notes table displays the names of selected notes in scale order beginning with "E". On this table a note name is listed only once even if it is included multiple times in the fretboard diagram.
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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