App Store keyword difficulty, in practice
Difficulty on the App Store is not something Apple publishes, and it is not the same everywhere. The same phrase can have a first page of giants in the United States and a first page of small apps in Brazil. So difficulty has to be measured per storefront, from the apps that actually rank there today. aso.best searches the phrase in the store you pick, records the top 50 with their rating counts, and scores the first ten.
Rating count is used because it is the one strength signal Apple hands out for every app in search results, and because it correlates with the thing you are actually fighting: an install base that keeps an app ranking. The scale is logarithmic, so a page of ten apps with a few hundred ratings scores low even if one has a few thousand, and a page with three apps above a million scores high however weak the other seven are. Those top three are shown as their own number, because they decide whether page one is reachable at all.
Two more things sit beside the score. The average days since the first-page apps last shipped an update, because a stale first page is softer than its ratings suggest. And the words the first-page listings share, because they tell you what Apple currently rewards for the phrase. Together with popularity, that is enough to decide whether a phrase is worth a slot in your 100 characters.
Written by Primo, who builds aso.best. We ship iOS apps ourselves; every method on this page is one we use on our own listings, and the hidden-field inference is tested against our own keyword field. Not affiliated with Apple.