App Store keyword field optimizer.

Apple's keyword field rules — the ones that actually matter

The Keywords field in App Store Connect (under App Information → per-locale metadata) is 100 characters, plain text, comma-separated. It is one of the three inputs Apple indexes for App Store search: the other two are the App name (30 chars) and Subtitle (30 chars). The long Description has not been indexed for search since iOS 14. That single fact reshapes how you should think about the keyword field.

Rule 1: No spaces after commas

Apple counts every character in the keyword field, including whitespace. If you write health, fitness, wellness you have spent 25 characters; written health,fitness,wellness it is 23. Across a 100-character budget that is between two and four extra tokens you could have used. Apple's App Store search treats the two forms identically for indexing purposes.

Rule 2: Never duplicate words from the app name or subtitle

Apple concatenates your app name, subtitle, and keyword field into a single indexed bag of tokens. A word that already appears in the name or subtitle is already indexed. Repeating it in the keyword field earns you nothing — just wasted characters. If your subtitle is "Track blood test results over time", the tokens track, blood, test, results, over, and time are already live. None of them should be in the keyword field.

Rule 3: Singular forms only

Apple stems keywords on both the indexing side and the query side. biomarker indexes for biomarker, biomarkers, and typically for short variations like biomarker tracking. Including both biomarker and biomarkers wastes 11 characters. Stick with singulars.

Rule 4: Partial-match and compound-match work in your favour

The App Store search engine does partial and compound matching across your indexed tokens. If your tokens include blood and test separately, a search for "blood test" will match you — even though you did not write blood test as one phrase. This is the core argument for comma-separated individual tokens over natural-language phrases: six single tokens in 100 characters cover substantially more two- and three-word queries than one long phrase does.

Rule 5: No competitor brand names, no Apple trademarks

Apple's App Review team checks keyword fields against the brand names of other apps, companies, and Apple's own product marks. instagram, facebook, iphone, and apple in a third-party keyword field will trigger a rejection under guideline 2.3.7 (Misleading Metadata) or a trademark claim. If the brand owner has submitted a trademark notice through Apple's form, you will hear about it during review or via a takedown after release.

How to structure 100 characters

With singulars-only and no spaces, a typical well-structured keyword field looks like:

biomarker,cholesterol,lab,vitamin,thyroid,inflammation,glucose,metabolic

That is 71 characters and 8 tokens. Each token is a search term buyers would plausibly type, none duplicate words already in the app name or subtitle, and the compound matching means queries like "vitamin d lab" or "thyroid panel" all surface even though the exact phrases are not in the string.

What to prioritize in the remaining characters

• Intent keywords buyers would type, not internal taxonomy you use in-app.
• Mid-competition terms — the top-1 high-volume term you will not rank for anyway, so spend chars on terms where you can realistically crack top-10.
• Local-language terms per locale. Your French keyword field should be French tokens, not a translation of your English field.
• Spelling variants only when Apple's stemmer does not cover them ("organise" vs "organize", "color" vs "colour").

What to avoid

• Articles and stop words (the, a, for) — Apple ignores them but they still count against your budget.
• Plurals, as above.
• Your category name if you have already selected the primary category — Apple indexes category implicitly.
• Words from your long description — again, not indexed for search.

Frequently asked questions

Why shouldn't I put spaces after commas in the App Store keyword field?

Spaces consume characters without changing how Apple indexes your tokens. A keyword field with 20 tokens separated by , rather than , wastes 19 characters — roughly two extra tokens you could have had.

Does Apple index plurals separately from singulars?

No. Apple's App Store search applies stemming, so biomarker also matches biomarkers and short stem variations. Include the singular only.

Should I repeat keywords that are already in my app name or subtitle?

No. Those fields are already indexed and concatenated with your keyword field at search time. Duplicating wastes characters.

Does Apple do partial or only exact matches on the keyword field?

Partial and compound matching is supported. Single comma-separated tokens usually beat natural-language phrases for that reason.