Candela – Brightness keys for external displays on macOS

What it does

Candela runs in the background and creates a virtual brightness device for each external display. macOS treats it like a built-in display, so you can use the brightness keys, Control Centre and System Settings › Displays. Candela passes the changes on to the display over DDC/CI and gives macOS an adjusted EDID, so the slider is linked to the right display.

Requirements

A Mac with Apple silicon and macOS 27 or later
A display that supports DDC/CI (most do; some have it turned off in the display's own menu)
Preferably a direct connection, as docks, MST hubs, DisplayLink adapters and TVs often block DDC/CI
Apple and LG UltraFine displays already have built-in brightness and don't need Candela

Getting started

Move Candela to Applications and open it.
Leave Run in background on, and allow Candela Helper to control your Mac when macOS asks.
The display goes black for a moment the first time, while macOS links it up. After that, the brightness keys work.

Uninstalling

Turn off Run in background in Candela's settings before deleting the app. The displays then get their original EDID back.