MusicReasonChords and Harmony
What else could I play here?
Choose a chord and a key. This tool compares bounded substitution options, each with a stated functional or voice-leading reason, never a random reharmonization or a claim that one option is better in every context.
Answer
Want to learn more? Chord Function, Cadence, and Substitution
Understand
A substitution is only defensible when it shares something real with the original, common tones, a shared harmonic function, or a specific interval relationship like a tritone. This tool names that reason for every option rather than presenting a bare list of alternate chords to try.
Worked examples
D minor 7th in the key of C permits F major as an alternative: both share predominant function and lead naturally toward the dominant. G dominant 7th in the same key permits only D-flat 7th, under the tritone-substitution rule: no shared-function swap is offered for a dominant chord in this launch rule set, since a plain diatonic replacement is not a defensible dominant substitution here.
Method and limitations
The tool first classifies the chord's own function (tonic, predominant, or dominant). Tonic and predominant chords receive other diatonic chords sharing that function; dominant chords receive a tritone substitution (a dominant seventh built a tritone away, sharing the same third and seventh). This launch scope covers those bounded families only; it does not generate an open-ended list of "interesting" substitutions.