monitorcontrol

Install command: 
brew install --cask monitorcontrol

Name: MonitorControl

Tool to control external monitor brightness & volume

https://github.com/MonitorControl/MonitorControl

Cask JSON API: /api/cask/monitorcontrol.json

Cask code: monitorcontrol.rb on GitHub

Current version: 4.3.3

Requirements: macOS >= 10.15

Analytics:

Installs (30 days)
monitorcontrol 2,362
Installs (90 days)
monitorcontrol 6,970
Installs (365 days)
monitorcontrol 30,198