App Store hidden keyword field, in practice
Apple gives every app 100 characters of keywords that no user ever sees. Developers fill them carefully, because together with the name and subtitle they are the only text the App Store search index reads; the description is not indexed. There is no API that returns another app's keyword field and no tool can show it. What can be shown is its effect: every phrase the app ranks for that is explained by neither the name nor the subtitle.
That is the inference aso.best makes, and it is checked against the one keyword field we do know, our own. FileFast's field is 100 characters we typed ourselves; every phrase the tool marks hidden for FileFast is in it, and that check runs as a test every time the product changes. For a competitor, the hidden pills are the closest anyone gets to reading the field, and they carry the information that matters: not the exact string, but which phrases the string made rank.
The phrases with a hidden pill and real popularity are the shortlist. They are demand the competitor found and you have not used, and unlike name and subtitle words they cost nothing to add. Track them for a few days to see where you stand, then put them in your own field. The App Store Connect editor in the dashboard shows your tracked keywords as one-click chips beside the 100-character counter, so the loop from reading to shipping is one screen.
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.