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.
Monitorian - Monitorian is a Windows desktop tool to adjust the brightness of multiple monitors with ease.
Eye Saver - Free software for eye protection and more!
Twinkle Tray - Easily manage the brightness of your monitors in Windows from the system tray.
CareUEyes - CareUEyes is an eye protection software for windows that comes with blue light filter, screen dimmer, and break reminder
PangoBright - Screen dimming software that allows you to control the brightness of your laptop screens as well as external monitors.