The library gathers 563 hand-written diagrams across six instruments. Each instrument covers the same harmonic families on all twelve roots, so that no common chord is missing.

Families covered: major, minor, 7, maj7, min7, diminished, augmented, sus2 and sus4. Piano adds sus and add9 chords. Bass shows the root only: on four low strings a full chord sounds muddy, and bass players work the foundation note.

These positions are deliberately limited to the main fingerings, not every possible variation. A chord missing, or a mistake? Write to us and we will fix it.

Beyond the catalogue, 33 extended chord formulas are computed on the fly across the twelve roots: ninths, elevenths, thirteenths, m7b5, dim7, mMaj7 and altered chords. That is why a chord absent from the diagrams still appears when it turns up in a chart.

The number of positions actually produced varies by instrument: some combinations have no playable fingering on four strings while they do on six. The table above gives the exact count, instrument by instrument.

On a string instrument the diagram shows the neck head-on: strings as columns, frets as rows. Dots mark where the fingers go. A cross above a string means it must not ring, a circle means it is played open. When the chord does not start at the nut, the starting fret is shown at the side.

On piano the diagram shows a fragment of keyboard with the keys to press. Notes run from lowest to highest, in the most natural position for the right hand.

Two systems name the same notes. The American system uses letters, inherited from Anglo-Saxon notation; the Latin system uses the syllables of Guido of Arezzo, in use across France, Italy and Spain. They refer to exactly the same pitches.

For minor chords, French adds “m” just as American does: A minor is written “Lam” or “Am”.

Alviena accepts both when you type: enter “Lam” or “Am” and you get the same chord. Display follows the preference set in your profile and switches everywhere at once. Charts, however, are always stored in American notation — which is what lets you change the display without ever losing anything.

C sharp and D flat name the same pitch and use the same fingering. This is called enharmonic equivalence. The choice between the two spellings still matters: it depends on the key of the piece, and a well-written score stays consistent.

When you transpose a chart, Alviena applies a simple rule: the keys of F, B flat, E flat, A flat, D flat and G flat are written with flats; the others with sharps. A chord originally written with a flat keeps that spelling. This is what stops you reading “A sharp” where every musician expects “B flat”.

A chord written G/B reads “G over B”: the G chord, played with a B in the bass. This notation writes a bass line that walks down or up underneath chords that do not themselves move — common in songwriting and pop alike.

Transposition handles both halves of the chord. A G/B moved up a tone becomes A/C#, not A/B. Many transposition tools miss this detail, and the bass line breaks when they do.

Every chord in the library has its own page: the diagram, the notes it is built from, the shape string by string, neighbouring chords, and the charts on the site that use it. Banjo and bass are not covered yet.

• Guitar — 108 chords
• Ukulele — 108 chords
• Mandolin — 108 chords
• Piano — 119 chords

There are two routes. You can select the notes you hear, or see under your fingers, and let the library suggest matching chords. Or play the chord into your microphone and let recognition do the work.

If a position is missing you can draw it yourself while editing a chart: place your fingers on the neck, name the chord, and it will be saved with the chart and shown in its place wherever it appears.