This app notifies you when Pokemon are near without opening Pokemon Go.
Actually it is called “PokeDetector” and it could be game-changer. This works quite simple actually, you just install it. Log in with your email data and this game changer will run on background. It will notify you as soon as he catches a Pokemon for you in a certain radius.
I have caught two Bulbasaurs and a trios of Evees that most likely I would have missed. Just try it out. Actually it costs $2.99 but if you search on android apk file sites you can get it for free most likely, just make sure you search on trusted sites.