How App Store keyword rank is actually measured

The only honest way to learn where you rank for a keyword is to actually run that search and find your app in the result list. Rank is not modelled; it is read.

App Store search returns the first 200 results for a query. If your app sits twelfth, your rank is 12. If it is not in the list at all, your rank is not “none” - it is “outside the top 200”, and the difference between those two changes what your monthly report means.

The same word is two different searches in two countries: different result lists, different rivals, a different rank for you. That is why tracked keywords are always counted as phrase × storefront. Tracking 100 words in two countries is 200 measurements.

A small but expensive detail: the same word may not even be spelled the same way in two countries. Turkish and Azerbaijani lowercase a capital “I” to “ı”; apply that rule everywhere and the word “AI” becomes “aı”, and one of the store's most valuable stems quietly disappears. The folding step has to know the storefront.

Apple throttles requests per IP address, and it does it quietly. A throttled request either returns a 503 or a 200 with an empty body - and the second reads exactly like “there is nothing here”.

If a measurement system does not tell those apart, one wave of throttling tells every customer they fell out of the top 200 on the same day. So an empty result set must never be recorded as a measurement. In rankcusp a rank is written only if it was really read; a day that could not be read stays blank.

Rank is not a number, it is a curve. Somebody checking weekly misses both the day a rival shipped and the day their own change took hold. They end up with two points and have to imagine everything in between.

The second benefit of daily measurement gets discussed less: it preserves the difference between “measured for the first time” and “went up”. A keyword measured for the first time has no previous rank - counting that as zero produces a report announcing that hundreds of words “entered the top 200” that day. The correct behaviour is to claim nothing when there is no previous rank.

Play search returns the first 100 results. So “not ranking” on Play says less than the same phrase does on the App Store: you might be 120th and unable to see it.

Likewise, popularity and difficulty scores are not produced for Play; the source those scores rest on has no Play equivalent. Rather than inventing a score where nothing can be measured, the field is left empty - which is the correct answer.