The key of A♭ major
A♭ B♭ C D♭ E♭ F G
4 flats: B♭ E♭ A♭ D♭. Relative minor: The key of F minor.
The triads of the key
I
A♭ | ii
B♭m | iii
Cm | IV
D♭ | V
E♭ | vi
Fm | vii°
G° |
The seventh chords
Imaj7
A♭maj7 | ii7
B♭m7 | iii7
Cm7 | IVmaj7
D♭maj7 | V7
E♭7 | vi7
Fm7 | viiø7
Gm7♭5 |
A♭ major scale
Open it in the app: 6. Harmony, in A♭