Most songs are built from a small number of chord progressions. This library has 307 of them, named and explained: the four-chord loop I–V–vi–IV, the ’50s progression I–vi–IV–V, the 12-bar blues and its variations, jazz’s ii–V–I, the Andalusian cadence, Bollywood and devotional favourites, modal vamps and cinematic minor progressions.
Every progression is written in Roman numerals, so it plays in any key: tap a key and the chords change. Each one has a note on how it sounds and where it is used, its styles, and what every chord does: tonic (home), predominant (moving away) or dominant (pulling back).
Play guitar with a capo? Pick a capo position and every chord shows the shape you play and the chord it sounds. A star marks the easiest position, so a progression in E♭ can be played with C shapes and the capo on the 3rd fret.
Search by name, by numerals (“vi IV”) or by the chords of your song (“Am F C G”): the library finds every progression that has them, in any key. Press Play to hear it with strumming, bass and drums in a groove that suits its style, then send it to the backing track player or the chord transposer.