Irish bouzouki A chord (ADAD)A major: 0 2 4 2, and 2 more shapes

Frets, low course to high: 0 2 4 2 (open position)

Sounds: A E C♯ E · A is A, C♯, E (1 · 3 · 5)

Found in: D major (V), A major (I), E major (IV), A mixolydian (I), E mixolydian (IV), B mixolydian (♭VII)

Open courses that ring: A is a note of A, so it can drone under it.

No 3rd: A5 (0 2 0 2) leaves the 3rd out, so it backs A major, mixolydian, dorian and minor tunes alike.

Tuning ADAD: A D A D, low to high.

The link can’t set the tuning: the app starts on the Irish bouzouki in GDAD. Choose ADAD once in its Settings and it remembers.

More A shapes

D major (V, a main chord): D – G – D – A (a plain backing for many reels and jigs)
A major (I, a main chord): A – D – A – E (a plain backing for many reels and jigs)
E major (IV, a main chord): E – A – E – B (a plain backing for many reels and jigs)
A mixolydian (I, a main chord): A – G – A
E mixolydian (IV, a main chord): E – A – E – D (reels in D or A mix)
B mixolydian (♭VII, a main chord): B – A – B