guitarFineTune in short:
• guitarFineTune is an app. that aids in tuning electric and acoustic guitars.
• It has a very high resolution. Measurements are in 0.1 Hz resolution.
• All strings can be tuned simultaneously. The measured sound for all 6 strings are all shown at the same time, and compared with the sounds for the strings as they must be, when the guitar is in perfect tune.

Features:
▸ Fine tuning of guitars.
▸ Displays the actual tone of the guitar strings compared to their correct tone in
resolution, 0.1 Hz.
▸ Can be used with both acoustic and electric guitars.
▸ Can let the sound pass through so you can hear the electric guitar.

Supported Operation System:
• OS X 10.11 or later
• Apple Silicon or Intel Core processor

Mac App Store : https://apps.apple.com/app/guitarfinetune/id1174405329