Bluelight Filter is a free Android app which aims to reduce the harmful effects of the blue light emitted by smartphones and tablets.
This could reduce eye strain, help you sleep better, and generally make the screen easier to read.
The app is a tiny 83KB, ad-free and doesn’t ask for any special permissions, which makes for a quick and easy installation.
There are various bundled filters, each with their own custom tint. You can select whatever you want or add a new filter of your own.
Full control of opacity levels means the program also doubles as a screen dimmer, perhaps improving battery life.
An optional scheduler can turn the effect on and off at set times, perhaps dimming and softening the screen in the evening.
Generally this works well and it shouldn’t get in your way, but if you do have any issues then the filter can easily be toggled on and off from the status bar.
Bluelight Filter is a free app for Android.