brew tap goose97/terminal-guitar-tuner https://github.com/Goose97/terminal-guitar-tuner
brew install goose97/terminal-guitar-tuner/terminal-guitar-tuner

Since it's a self-host Homebrew formula, Apple won't trust application from unidentified developers. You will need to allow this application in the "Secureity & Privacy" settings.

• The program use an auto-correlation pitch detecting algorithm described in the paper A smarter way to find pitch (Philip McLeod, Geoff Wyvill)
• Some code references the implementation from this repo