Brisync

Brisync runs as a macOS menu‑bar utility that watches the brightness setting of the built‑in display and sends corresponding DDC/CI commands to any connected external monitors. By translating the internal brightness level through a user‑defined curve, it adjusts each external screen in real time, keeping the overall visual experience consistent across devices.

The application lets users create separate brightness curves for each monitor, allowing fine‑grained calibration that accounts for differing panel characteristics. Changes are applied instantly via the hardware‑level DDC/CI protocol, so the external displays follow the Mac’s brightness adjustments without noticeable lag.

Brisync is compatible with macOS 10.11 and newer, supporting both Intel‑based and Apple Silicon Macs. It can be installed via Homebrew or by manually copying the app bundle into the Applications folder, and it requires standard system permissions for accessibility and display control.