When you're working with internal and external displays, the brightness settings do not automatically match. BrightnessSync for Mac links these two settings together, but its operation is more complicated than necessary.
BrightnessSync for Mac is available as freeware, and there are no payments necessary to unlock full functioning. The program's download and installation occurred as quickly as expected. While there were no instructions in the program itself, a Readme file explained the program's operation and how to use it. Technical support was not present and it did not appear there were updates available. Upon starting, the program installs a new menu in the display preferences section of the Mac system menu. A series of sliders controls the picture for both internal and external display. A line indicating the ambient light present did not appear to work. During testing, upon clicking the internal menu, the brightness immediately went to the lowest setting and the computer had to be moved to a brighter room in order to see the screen to reset the settings. The change was also made in the native screen menu rather than the program's own window.
While basically functional, BrightnessSync for Mac would only be a useful option for people who constantly use external displays.