Dimmerly
Guides
How hardware and software brightness differ on a Mac, how to set up a desk with several monitors, what to check when a monitor stops responding, and how Dimmerly compares with other display apps.
Control external monitor brightness on macOS
Understand hardware control, software fallback, and the connection issues that can block DDC/CI.
Read the guideControl multiple monitors from one Mac menu bar panel
Set up independent display controls, presets, schedules, and shortcuts for a multi-monitor desk.
Read the guideExternal monitor brightness not working on your Mac?
Find where DDC/CI stops: the monitor setting, a dock or adapter, the HDMI port, or a locked-up controller.
Read the guideDDC/CI on a Mac mini M4: HDMI, adapters, and a silent monitor
Notes from one debugging session: what the HDMI port forwards, a cable that drops DDC/CI, and the power cycle that fixed the monitor.
Read the notesDimmerly, MonitorControl, Lunar, or BetterDisplay?
What each app does, what it costs, and when another app is the better fit.
Compare the apps