Please don't let an app tell you how long you will live; It's probably not good for your mental health.
There is a website that I know since the 90's called The Death Clock (http://deathclock.com). It's pretty much the same website since then.
The problem here is give your actual personal data to people you don't know how they will use it. So don't.
Btw, I'll die in:
- The Death Clock: April 2051;
- Population.io: July 2059
¯\_(ツ)_/¯