B♭maj7 (also written A♯maj7) is a major seventh chord made of 4 notes: B♭, D, F, A. It sounds dreamy, warm and a little wistful, and you hear it in ballads, bossa nova, neo-soul and lo-fi. It is the I chord of B♭ major and turns up in 3 other keys.
The library above opens on B♭maj7 with 14 shapes up and down the neck, starting with hand-checked ones. Tap a shape to hear it, or play it one string at a time.