Show HN: Lunar 2.0 – Adapt monitor brightness using built-in light sensor

You can download the (free) macOS app here:
You can also install it using cask: brew cask install lunar

The source code is hosted on Github:

A few weeks ago I launched Lunar, a macOS app that gives you adaptive brightness for external displays.
The first adaptive brightness implementation worked by calculating the sunrise and sunset times for your location, and then adapting the brightness/contrast throughout the day based on those times.

But then, a Reddit user ( came up with a brilliant idea. Sync the built-in display’s brightness with the external displays.
So I implemented just that and /u/jimmyco2008 helped me test the idea. It turned out to be much more useful and precise than the location mode.

There are a few notable advantages now:
– the brightness/contrast responds to the built-in light sensor readings
– you can use the brightness keys (or TouchBar slider) to adjust external monitor’s brightness
– the behaviour of the algorithm is now adjustable through global brightness/contrast offsets on the settings page

To get access to all the features above, make sure to put Lunar in Sync mode like in this picture:

I’m keeping the app free as it was from the start.
If you have some spare change, you can buy me a coffee here: ^_^