Brightness Slider 4+

This is the first app I saw that actually gets it right. Most apps out there are not able to manipulate the backlight, so when you dim the mouse pointer lights up incredibly. This app intelligently combines the two dimming techniques. But the most useful part to me was that it synchronizes the brightness over the internal and all external (Thunderbold) displays. So not only the first external, but also the second external display, and that brightness cannot be reached from the keyboard otherwise (osx <= 10.9). This synchronization also works when the screens are in different ambient lighting, which is a great improvement over the default behaviour.

Tip to make it even better: Make the synchronization of the screens optional (but keep the support for the third screen as is). So, when you decouple you have a slider for each screen, and in the coupled case: one for all. This is particularly handy for watching movies.

Since I wrote the first review (2015), new, brighter macboocs have hit the market. Unfornately, one slider to rule all screens does not work any more, since the macbook always is a lot brighter. So this renders this app a lot less useful. It would be nice if somehow this could be compensated for (percentage settings per screen?), or in case this is difficult, a slider for each screen from the menu bar.

Thanks for this great app.

This is a very handy app to dim the backlight of the iMac screen. Older iMacs cannot dim the brightness enough to a pleasant level for viewing in the evening. One remark is that when the screen has gone to energy save mode, and turned back on again, the brightness is suddenly much higher.
Aside from that, Brightness Slider is an incredibly easy to use application.

It has been a great app for me for years, but I found a better alternative on GitHub called MonitorControl. It uses the standard mac keyboard brightness and volume buttons to control the native brightness and volume of my external LG monitor.