App Store Keyword Optimizer
Optimize ASO keywords across every locale Apple indexes for your target App Store territory. 50 locales, 182 territories, cross-localization aware.
United States indexes 10 locales
The US App Store indexes keywords from 10 locales totaling 1,000 characters of keyword budget.
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How App Store Cross-Localization Works
Apple gives each locale a separate 100-character keyword field in App Store Connect. Most ASO tutorials stop there. What they miss is that Apple indexes keywords from multiple locales at the same time for a given territory, not just the primary locale. This means a fully-localized app in the US App Store can have 1,000 characters of indexed keyword budget across 10 locales, compared to 100 characters for English-only metadata.
The mechanism is territory-based, not device-language-based. If you are on an iPhone in Brazil, the App Store decides which locales to index based on the territory (Brazil), not your device language. Apple then scores app results using keywords from the primary locale (Portuguese BR) plus the indexed secondary locale (English UK). The keywords you place in both fields compete for the same 100-char budget in each locale.
That is where the tool above comes in. It shows you exactly which locales Apple indexes for your target territory, gives you a 100-char counter per field, and flags duplicate keywords across locales in red so you can reclaim the wasted characters.
Why Duplicate Keywords Waste Your Budget
Imagine you target the US App Store and put the keyword "free" in both your English (U.S.) field and your Spanish (Mexico) field. Apple already indexes "free" from the English field - it does not get a second boost from the Spanish field. But that second "free" still costs you 5 characters (4 for the word plus 1 for the comma separator) in your 100-char Spanish budget. Over 10 locales, duplicates compound fast and can cost you 100+ characters of useful keyword space.
The right move is to fill each secondary locale with translations or with English keywords Apple will still index but that do not repeat the primary field. For example: put "free" in English (U.S.), put "gratis" in Spanish (Mexico), and use the reclaimed characters in both fields for long-tail keywords that are unique to each locale.
Territory Reference Table
Here are the primary + secondary locale mappings and total keyword budgets for the 15 most common App Store territories. The full 182 territories are available in the tool above.
| Territory | Primary | Secondaries | Budget |
|---|---|---|---|
| United States | English (U.S.) | 9 locales (Spanish MX, Russian, Chinese Simp., Arabic, French, Portuguese BR, Chinese Trad., Vietnamese, Korean) | 1,000 |
| Canada | English (Canada) | French (Canada) | 200 |
| United Kingdom | English (U.K.) | English (Australia) | 200 |
| Australia | English (Australia) | English (U.K.) | 200 |
| Germany | German | English (U.K.) | 200 |
| Switzerland | German | English (U.K.), French, Italian | 400 |
| France | French | English (U.K.) | 200 |
| Spain | Spanish (Spain) | English (U.K.), Catalan | 300 |
| Italy | Italian | English (U.K.) | 200 |
| Japan | Japanese | English (U.S.) | 200 |
| South Korea | Korean | English (U.K.) | 200 |
| China | Chinese (Simplified) | None | 100 |
| Brazil | Portuguese (Brazil) | English (U.K.) | 200 |
| Mexico | Spanish (Mexico) | English (U.K.) | 200 |
| India | English (U.K.) | Hindi, Bengali, Gujarati, Kannada, Malayalam, Marathi, Odia, Punjabi, Tamil, Telugu, Urdu | 1,200 |
Recommended ASO Keyword Workflow
- Research primary market keywords. Use App Store Connect search analytics or a paid ASO platform to list 20-30 keyword candidates with volume data for your primary territory.
- List synonyms and long-tail variants. For each core keyword, write 3-5 synonyms. These go into secondary locales later.
- Fill the primary locale field first. Pack the 100 chars with your highest-intent, highest-volume keywords.
- Fill secondary locales with translations or long-tail keywords that do not repeat. If your primary has "photo editor", do not put "photo editor" in Spanish (MX) - use "editor de fotos" or a long-tail English variant Apple will still index.
- Validate with the tool above. Switch to your target territory, paste each locale field, and make sure the Wasted Chars stat stays near zero. If duplicates creep in, trim them.
Want the deep dive? Our App Store Cross-Localization Guide covers every territory quirk, the 210-character hook for the app subtitle, the US 1,000-char ceiling, and a worked example with real keyword math.
Apple caps the keyword field at 100 characters per locale. This is separate from the app title, subtitle, and description. The cap is confirmed in Apple Developer documentation and has been 100 characters since App Store Connect added localized keyword support.
Apple's App Store indexes keywords from BOTH the primary and secondary locales of a given territory at the same time. For example, the US App Store indexes English (U.S.) plus 9 secondary locales (Spanish MX, Russian, Chinese Simplified, Arabic, French, Portuguese BR, Chinese Traditional, Vietnamese, Korean). Each locale has its own 100-char field, so a fully-localized app has up to 1,000 characters of indexed keyword space in the US market. This is not a fallback system - it is simultaneous dual or multi-index.
The US App Store indexes 10 locales: English (U.S.) as primary, plus Spanish (Mexico), Russian, Chinese (Simplified), Arabic, French, Portuguese (Brazil), Chinese (Traditional), Vietnamese, and Korean as secondaries. Filling all 10 locale fields gives you 1,000 characters of keyword budget in the US market versus 100 for English-only metadata.
English (U.K.) serves as the indexed secondary locale for roughly 140-180 territories worldwide. If you only ever localize one secondary locale, make it English (U.K.) - it quietly expands your keyword reach across Europe, Africa, the Middle East, Asia-Pacific, and Latin America with one metadata file.
No. Apple counts spaces toward the 100-character limit. A field with 'word1, word2, word3' wastes 2 characters on spaces that do not help indexing. Write 'word1,word2,word3' instead. The tool above highlights this pattern in the parsed preview.
No. The title, subtitle, and description are separate metadata fields. This tool is for the dedicated keyword field only (called 'Keywords' in App Store Connect). Your title and subtitle are indexed by Apple separately and should use your strongest primary keyword naturally within the title copy.
Yes. Chinese (Simplified) is the primary locale for China and Singapore. Chinese (Traditional) is the primary for Hong Kong, Macau, and Taiwan. Keywords do not spill over between the two variants, and indexing is territory-based (not device-language-based). A user in Hong Kong with a Simplified Chinese device will still see Traditional results.
No. Apple tokenizes the keyword field and scores each keyword independently. Position within the field does not affect ranking. What matters is keyword relevance, uniqueness across locales, and total coverage within your character budget.
Generally no. Apple matches partial strings and handles simple plurals automatically. Including both 'photo' and 'photos' wastes characters that could go toward unique keywords. Focus on root forms and distinct synonyms instead.
Review quarterly or after major app updates. Apple allows you to update the keyword metadata with every new build submission, so you can iterate freely. Track which keywords convert via App Store Connect analytics and rotate underperformers out.
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