Lunar.fyi - Control monitor brightness, adapt using the ambient light sensor, adjust volume, switch inputs and turn off displays without fiddling with clunky buttons.

f.lux - f. lux is a piece of software for Windows, Mac, Linux, iOS, and Android that provides a blue light filter over your screen. Research suggests limiting our exposure to blue light in the hours before bedtime can help us fall asleep faster.

DisplayBuddy - Control the real brightness of your monitors directly from your Mac - no need to touch the buttons on your Monitor.

Darkness: Beautiful Dark Themes - Chrome extension that provides beautiful dark themes for Facebook, Google and more.

BetterDummy - BetterDummy creates a virtual display which you can utilize as a mirror main for your display on the Mac.

Dark Reader - Reduce eye strain in your browser with this extension that provides a dark theme for browsing.