The structural advantage most apps are leaving on the table
Every iOS App Store territory indexes keywords from more than one language locale. Each territory has a primary locale — the default language for that market — and most have one or more secondary locales that Apple's search algorithm also crawls and ranks. Keywords entered in secondary locale metadata contribute directly to search rankings in the primary territory, even when users never see that secondary locale.
This means a US-targeting app can rank for English keywords placed in Spanish (Mexico) metadata, Russian metadata, or Korean metadata, because all of those are secondary locales indexed by the US App Store. The user never sees the keyword field. The metadata space is already there. It just requires a deliberate strategy to fill it correctly.
For the majority of global App Store territories, English (UK) is indexed as a secondary locale. An English (UK) metadata set quietly contributes to keyword reach in dozens of markets, regardless of whether those territories are primary targets. The real keyword math for a US app: English (US) provides 160 characters (30-character title, 30-character subtitle, 100-character keyword field). Adding French, Arabic, Korean, Portuguese (BR), Chinese, Vietnamese, Russian, Spanish (MX), and Traditional Chinese locales adds 160 characters each — nine locales, 1,440 additional indexed characters.
An app with all nine US secondary locales filled can access up to 1,440 characters of keyword metadata that feeds directly into US App Store rankings, compared to 160 for an app using only English (US). Not every team will activate all nine. But even two or three secondary locales with targeted keywords can yield a material increase in wiki:keyword-indexing-ios coverage.
How cross-localization actually works
App Store Connect allows independent metadata entry for every supported language. Each locale gets its own title (30 characters), subtitle (30 characters), keyword field (100 characters), description, and promotional text. Localization decisions are made at the version level, inside the App Store Information section.
The primary language set in App Store Connect serves as the fallback if a specific localization is not available. This is a platform-level setting, not version-specific. Industry observation has noted a fallback behavior: if a specific locale is not active, a related locale may serve instead. For example, if French (Canada) is not enabled but French (France) is, French (France) metadata may appear to French-speaking users in Canada until French (Canada) is explicitly activated.
Keywords must not be duplicated across locales. Duplicating a primary locale's metadata into a secondary locale wastes available character space. Each locale should contribute unique content. Phrase combinations only form within a single locale, not across them — the algorithm does not concatenate keywords from English (US) with keywords from Spanish (MX) to form new search terms.
Visible metadata fields (title, subtitle) should be wiki:localization-strategy for the audience that will see them. Mixing languages in the keyword field is not visible to users; they never see that field. Mixing languages in the title is visible and can affect user trust. Localize visible fields for your audience. Use the keyword field more flexibly.
The operational workflow
Start by mapping priority territories. Open Apple's territory table and note the default language and additional supported languages for each territory where the app has installs or potential. Audit current locale coverage in App Store Connect. Compare active locales against supported languages for key territories. Supported languages that have not yet been activated represent available metadata space.
Plan keyword allocation per locale. Each locale provides up to 160 indexed characters. To avoid waste, do not repeat the same keyword across primary and secondary locale fields unless specifically needed to form keyword combinations within a single locale. Use each locale's fields for distinct terms. This expands total keyword reach rather than duplicating it.
Every localization decision should be grounded in wiki:keyword-research. A direct translation of an English keyword often has low search volume in the target market. Research what users in each market actually search for. The term that ranks in English (US) may not be the term users type in Portuguese (BR) or Korean. AI-powered localization tools can translate and culturally adapt metadata for 40+ languages, handling keyword research, cultural adaptation, and character-limit compliance automatically.
Setting a non-standard locale as the primary locale can add global keyword coverage. For example, setting English (UK) as primary while also maintaining English (US) as a secondary locale allows both to be indexed independently. This is an advanced tactic that requires careful testing to ensure user-facing metadata remains appropriate for the app's core market.
Common mistakes and how to avoid them
Activating a locale but leaving fields empty does not help. An empty locale contributes nothing. If a language is added, fill the fields with intention. Duplicating the primary locale into every secondary locale wastes available space. Repeating every keyword across all locales reduces the total number of unique keywords the app can potentially reach. Use each locale to expand coverage, not duplicate it.
Ignoring visible metadata fields is a conversion risk. Titles and subtitles are seen by users. Even if the primary goal is keyword coverage, do not neglect how these fields appear to real people. A title that reads naturally in the user's language builds trust. A title that mixes languages or includes awkward phrasing for the sake of keyword insertion can reduce tap-through and install rates.
Timing the rollout of new locales matters. Each metadata update triggers re-indexing. Adding multiple locales simultaneously makes it difficult to isolate the ranking impact of any single locale. A staggered approach — one or two locales per update cycle — allows clearer measurement of the effect on search visibility and download velocity.
Cross-localization is now table stakes
The character space is already there. It just requires a deliberate strategy to fill it correctly. Cross-localization is one of the highest-leverage, lowest-cost techniques in App Store optimization. The principles to carry forward: the App Store indexes keywords from both primary and secondary locales for each territory; the US App Store has nine secondary locales, giving well-optimized apps access to 10x the baseline keyword space; keywords must not be duplicated across locales; phrase combinations only form within a single locale, not across them; visible metadata fields should be localized; keyword fields can be used for additional target-language keywords; setting a non-standard locale as primary can add global keyword coverage; every localization decision should be grounded in keyword research.
For apps managing multiple markets simultaneously, the scale of available keyword data makes it possible to build localization strategies grounded in real search behavior rather than assumptions. The execution of a strong cross-localization strategy depends on the quality of the keyword data it is built on. Guessing which terms to place in secondary locale fields is not a strategy. Start with a data-backed foundation and see the keyword opportunities current metadata is leaving on the table.