Why do yu need an App? All you need to do is read the list of ingredients on a tin or packet to know whether it is processed it untra processed.
Anyway, there are no such things as healthy/unhealthy foods, only healthy/unhealthy diets.
Some one gave DH a box of choolate caramels last week. Probably defined as an 'unhealthy' food. We scoffed the lot, in one afternoon, BUT they were the first chocs or sweets we had eaten since Christmas, so highly unlikely to damage our health, given that we generally have a healthy diet with very little processed food.