Monitorian

Monitorian is a free Windows desktop application that lets you control the brightness of multiple monitors from a single place. Without it, adjusting the brightness of external monitors typically requires pressing physical buttons on the monitor itself, which can be awkward. Monitorian puts that control into a small system tray app so you can change brightness using your mouse or keyboard instead.

The app supports adjusting monitors individually or all at once in unison, which is handy when you want everything to match. You can also adjust contrast and change the adjustable range for each monitor. If your computer has an ambient light sensor, the app can display both the system-configured brightness and the adjusted one side by side. Up to four monitors can be shown at one time.

For an external monitor to work with Monitorian, it needs to have DDC/CI enabled, which is a standard that allows software to communicate with monitors over the cable connection. Most modern monitors support this, but it may need to be turned on in the monitor's own settings menu. The app works on Windows 7 and newer and can be installed from the Microsoft Store or via the Windows Package Manager.

Some features are available only through a paid add-on subscription in the Microsoft Store version. These include keyboard hot keys for changing brightness and contrast on the fly, and command-line options that let you get or set brightness levels from scripts, scheduled tasks, or desktop shortcuts. The command-line interface lets you target a single monitor, all monitors at once, or specific ones by ID, and you can set an absolute value or increment and decrement from the current level.

The app has been translated into more than 20 languages by community contributors, covering Arabic, German, French, Japanese, Chinese, Russian, and many others. The README is longer than what was shown here.