App Store Cross-Localization: The Complete 2026 Guide

What is App Store Cross-Localization?

App Store cross-localization is the mechanism by which Apple indexes keywords from multiple locales simultaneously for search within a single App Store territory. It is not a fallback (where the secondary locale only shows up if the primary is missing). It is a genuine multi-index event: the primary locale and the secondary locales all contribute to search ranking at the same time, each with its own 100-character keyword field.

The practical implication: a fully-localized app can have several hundred to over a thousand characters of indexed keyword space in a single territory - far more than the 100 characters visible in App Store Connect for a single locale.

The 100-Character Keyword Field Rule

Apple caps the keyword field at 100 characters per locale. This cap is confirmed in App Store Connect and has been stable for years. Keywords are separated by commas. Apple recommends not putting spaces after the commas because spaces count toward the 100-char limit and do not help indexing.

The keyword field is one of three primary ASO surfaces, along with the app title and subtitle. Title and subtitle are separately indexed and should use your strongest primary keyword naturally within the copy. The keyword field is where cross-localization multiplies your budget.

Primary vs Secondary Locales

Every App Store territory has one primary locale. Most also have one or more secondary locales that Apple indexes for search. The exact list varies by territory.

The rule of thumb: the primary locale is the dominant spoken language in the territory (Japanese in Japan, French in France). The secondary locale is usually English (U.K.) - Apple's global fallback - but territories with multiple official languages often have more than one secondary locale (Switzerland indexes German, French, Italian, plus English U.K.).

United States: 10 Locales, 1,000 Chars

The US App Store is the exceptional case. It indexes 10 locales: English (U.S.) as primary, plus 9 secondary locales - Spanish (Mexico), Russian, Chinese (Simplified), Arabic, French, Portuguese (Brazil), Chinese (Traditional), Vietnamese, and Korean. Each has its own 100-character field. Total: 1,000 characters of indexed keyword space.

This reflects US demographics - large Spanish-speaking, Chinese-speaking, Russian-speaking, and Vietnamese-speaking populations. If you target the US market, ignoring the 9 secondary locales means leaving 900 characters of keyword real estate on the table.

Territory Quirks: Canada, Switzerland, India, China

Four territories break the simple "primary + English UK" pattern:

• Canada: Independent dual-locale. Primary is English (Canada), secondary is French (Canada). No English (U.K.) spillover. This is the only territory where French (Canada) is indexed as a proper secondary.
• Switzerland: Four-locale territory. Primary is German, secondaries are English (U.K.), French, and Italian. 400 characters of keyword budget in one market.
• India: 12-locale territory. Primary is English (U.K.), secondaries include Hindi, Bengali, Gujarati, Kannada, Malayalam, Marathi, Odia, Punjabi, Tamil, Telugu, and Urdu. 1,200 characters of keyword budget - the largest in the world.
• China: No secondary locale at all. Only Chinese (Simplified) is indexed. 100 characters, no English fallback.

English (U.K.) as the Global Secondary

For roughly 140 to 180 territories - essentially everywhere except the US, Canada, Japan, and the Chinese markets - English (U.K.) is the indexed secondary locale. This is Apple's quiet global fallback system.

Practical advice: if you only ever localize one secondary locale, make it English (U.K.). It extends your keyword reach across Europe, Africa, the Middle East, Asia-Pacific, and Latin America with one metadata file. Do not duplicate it with English (U.S.) - they are treated as separate locales and compete for the same budget.

Duplicate Keyword Math: A Worked Example

Suppose you target the US App Store and you repeat the keyword free in four of the ten indexed locales. How much keyword budget is wasted?

The fix is straightforward: move duplicates out of secondary fields and reclaim the freed characters for long-tail keywords unique to each locale. Use the tool's Parsed Keywords panel to spot duplicates visually - they render in red with occurrence badges.

A Recommended Keyword Research Workflow

1. Research primary-market keywords first. 20-30 candidates with volume data from App Store Connect search analytics or a paid ASO platform.
2. List synonyms and long-tail variants per candidate. Aim for 3-5 variations per core keyword.
3. Pack the primary locale with highest-volume, highest-intent keywords. Target 100 chars exactly. Apple rejects fields over the cap.
4. Fill each secondary locale with translations or long-tail English variants that do not repeat the primary. Use the free Optimizer above to flag any duplicates you introduce.
5. Validate with the tool's stats. Duplicates should stay at zero. Wasted Chars should stay at zero. Total Chars Used should stay close to your Total Budget.
6. Submit, monitor, iterate. Review rankings via App Store Connect analytics quarterly. Rotate underperforming keywords out in the next build submission.

Tracking Rankings Per Locale

App Store Connect analytics show keyword search impressions and conversions. A good iteration loop is: submit new keywords → wait 2-3 weeks for Apple's indexing to stabilize → check Analytics > Search Terms → rotate underperformers.

Paid ASO platforms (AppTweak, Sensor Tower, ASOdesk, Appfollow) add rank tracking per keyword per territory, competitor analysis, and keyword volume estimates. They are optional but helpful when you want to track 10+ keywords across 5+ territories.

Common ASO Mistakes to Avoid

• Putting spaces after commas. Wastes 1 character per separator.
• Repeating keywords across locales. Apple does not double-count; you just lose budget.
• Including plurals of the same root. Apple matches partial strings. "photo" covers "photos".
• Stuffing branded keywords of competitors. Apple may reject. Use your own brand and category terms.
• Ignoring the 9 US secondary locales. Leaving 900 characters on the table for a US-targeted app.
• Forgetting to update keywords across multiple app builds. Old keywords persist unless explicitly edited.

Frequently Asked Questions