Extra Localizations for More Keywords: What Apple Documents and How to Test It

• The keyword field accepts up to 100 bytes, and keywords are a required property that can be localized.
• Apple's example: if you localize into French, the French localization is shown to users whose language is French and to users in countries where the App Store supports French but not English. Users can search for your app using localized keywords in all countries or regions where the App Store supports French.
• If no localization matches a user's language, the next most relevant localization is used. In other countries the primary language is shown.
• Apple lists name, subtitle, keywords and company name as the searchable fields.

Apple's localizations table lists additional languages per country. For the United States it lists Arabic, Chinese (Simplified), Chinese (Traditional), French, Korean, Portuguese (Brazil), Russian, Spanish (Mexico) and Vietnamese next to the default English (US). Switzerland lists German by default plus English (U.K.), French and Italian. Mexico has Spanish (Mexico) by default plus English (U.K.).

Apple does not state that a keyword in a secondary localization competes in the same way as a keyword in the storefront's default language. Many ASO blogs call this "cross-localization" and describe how it behaves. None of that is on Apple's pages, so do not plan a launch around it. The honest approach is to run your own experiment.

1. Pick a storefront and a second localization from Apple's table, for example the United States and Spanish (Mexico).
2. Choose a test keyword that appears only in the second localization's keyword field: not in your name, subtitle or any other field. Use a term with a few ranking competitors so a change is visible.
3. Record the baseline. Rank for that term in the storefront, from a device with the matching language and, separately, from an English device. Note the date.
4. Ship the localization and wait. Apple says changes may take up to 24 hours to appear, so check daily for a week.
5. Compare. Rank appears only for the matching-language searches, for both, or not at all. Each outcome tells you something different.
6. Keep only what works. If the keyword never ranks, give the 100 bytes back to a term that does.

Change one thing at a time. If you also edit the title that week, you cannot say which change moved the rank.

A hypothetical habit tracker, Streakly, sells in the United States. The US row of Apple's table has 9 additional languages. If Streakly localized the default English plus all 9, it would own 10 keyword fields. That is 10 x 100 = 1,000 bytes of keyword space in total.

But a field only helps when it holds terms people search. Spanish (Mexico) is the natural first test: the US lists it, and Mexico uses it as the default. Streakly writes a Spanish keyword field of its own research, such as "hábitos,rutina,metas diarias", which is 29 bytes because the "á" takes two. It keeps the English field untouched and runs the experiment above for one term.

Remember that a new localization copies the primary language's screenshots and properties, except description and keywords. You must write both.

• The more localizations you add, the more text you maintain. A language you cannot review is a risk to the page conversion.
• Spreading identical words across fields wastes bytes. Apple advises not repeating words that already appear in the name, subtitle or category.
• Rankings differ per storefront; test in each country that matters. The ranking by country guide shows how to check.

Use the keyword field guide to pack each field, and check lengths with the keyword field checker. LocalASO checks a keyword in 52 storefronts with local phrases, which gives you a first look before the experiment; see how it handles localization.