there is an app i want to share is
Twilight
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.
another one is
TrueCaller
See names and photos of people who call, even if they aren’t saved in your phonebook.