Dark Sky meter App (iPhones)
The Award-winning Dark Sky Meter by DDQ helps you measure the night sky brightness with the press of a button. Get instant information about the night sky quality and contribute to creating a global map of sky darkness. See our Measuring Light Pollution page for more information.
F.lux (available for Mac OS/X, Windows, Linx, iPhones and iPads)
f.lux is a colour temperature app that makes the colour of your computer’s display adapt to the time of day, warm at night and like sunlight during the day. It makes your computer screen look like the room you’re in, all the time. When the sun sets, it makes your computer look like your indoor lights. In the morning, it makes things look like sunlight again.
Lux (Android phones free or paid versions)
Lux intelligently adjusts the brightness of your display based on the environment you’re in. It’s also able to adjust the screen temperature of your display automatically to make it appropriate for night usage. At sunset, you can have Lux automatically warm your display and switch to your Night profile. If you’re an astronomer, you can enable astronomer mode to cut out harsh white light.
Twilight (for smartphones or tablets)
The Twilight app makes your device screen adapt to the time of the day. It filters the flux of blue light emitted by your phone or tablet after sunset and protects your eyes with a soft and pleasant red filter. The filter intensity is smoothly adjusted to the sun cycle based on your local sunset and sunrise times.