App Store subtitle and keyword field: a practical guide

Your App Store name and subtitle can each be up to 30 characters, and the keyword field holds 100 characters of terms separated by commas with no spaces. Those 160 characters do most of the work of deciding which searches your app can appear in. The rules that matter most: don't repeat a word across the name, subtitle and keywords, don't add plurals of words you already have, don't waste space on "app" or category names, and use your other localizations to add room in storefronts that read more than one language. Then change one thing at a time and measure search downloads for two weeks. Below is each rule with Apple's wording, a worked example and a test plan.

The limits, field by field

The 30 character app name limit is written into guideline 2.3.7. Apple's product page guidance gives the 30 character subtitle limit and says you can update the subtitle when you submit a new version. App Store Connect Help lists keywords as version information with a limit of 100 bytes, while Apple's product page guidance says 100 characters. For English these are the same. For languages with accented or non Latin characters, plan on bytes: an accented letter takes two bytes in UTF-8 and most Chinese, Japanese and Korean characters take three.

Promotional text is useful for news and offers, but Apple says it doesn't affect your search ranking, so don't put keywords there.

What each field is for

The name is your brand plus, if it fits naturally, the one phrase that best describes the app. Apple's guidance asks for a name that is simple, memorable and easy to spell, and warns against generic terms.

The subtitle is a short value statement that people read. Apple suggests highlighting features or typical uses rather than generic praise like "world's best app". Apple documents that your app is searchable by its name and company name. It doesn't publish a complete list of the fields it indexes, but practitioners widely treat the subtitle as searchable too, and we write it on that assumption: every word in it should be one someone would type.

The keyword field is invisible and exists only for search. This is where the long tail goes.

Rules for the keyword field

Apple's product page guidance spells out the format: terms separated by commas and no spaces, with spaces allowed inside a phrase. Its own example is Property,House,Real Estate. Apple then lists what to leave out to fit more in:

1. Plurals of words you already have in singular form. If habit is in, habits is a wasted slot.
2. Category names and the word "app". Your category already describes you.
3. Duplicate words. This includes words already in your name or subtitle. App Store Connect Help says plainly that because your app is searchable by name and company name, you shouldn't duplicate those in the keyword list.
4. Special characters such as # or @, unless they are part of your brand. Apple says they carry no extra weight.

And what will get you rejected, from the same guidance, guideline 2.3.7 and App Store Connect Help:

• Trademarked terms, celebrity names and other protected words you are not authorized to use
• Names of other apps or companies, including competitors
• Terms that are not relevant to your app
• Offensive or objectionable terms

Many practitioners write single words rather than phrases, on the observation that the App Store matches combinations of words across your fields. Apple does not document how it combines terms, so treat that as something to test, not a rule. Single words do have a plain advantage: meal,planner costs 12 characters, while meal planner,meal prep costs 22 and repeats meal.

How localizations add room in other storefronts

Each App Store storefront has a default language, and many have additional supported languages. Apple's App Store localizations reference lists them. A few examples from that table:

Apple's page says the language each customer sees depends on the App Store language for their location, their device settings, the languages you have added and your primary language. What Apple does not state on that page is how search treats the additional languages. ASO tools and practitioners widely report that keyword metadata in a storefront's additional languages is also searchable in that storefront, which is why the US store is often described as having ten keyword fields. We have seen behavior consistent with that, but it is observed, not documented, so verify it for your app before you rely on it.

Two cautions if you use it:

• The name and subtitle in a localization are real copy. Customers in Mexico see your Spanish (Mexico) name and subtitle. Never fill a locale with words in the wrong language to gain room elsewhere.
• Use the room for real speakers. Spanish keywords in the Spanish (Mexico) localization help Spanish speaking searchers in the US and are native for Mexico. That is a good use. English filler in the Russian locale is not.

A worked example

Here is a made up habit tracker before and after. This is the kind of metadata we see often.

Before

Name:      Streakly: Habit Tracker               23/30
Subtitle:  Track your habits every day           27/30
Keywords:  habit tracker, habits, daily habits, streak, goals, app, routine tracker, productivity
                                                 86/100

What is wrong:

• The keyword field uses spaces after commas, which costs 7 characters for nothing.
• habit and tracker are already in the name, yet the keyword field repeats them in three phrases.
• habits appears in both the subtitle and the keywords, and it is a plural of a word already present.
• app and productivity (a category name) are words Apple tells you to skip.
• The subtitle says nothing a searcher would add to "habit tracker".

After

Name:      Streakly: Habit Tracker               23/30
Subtitle:  Daily routine & goal planner          28/30
Keywords:  streak,reminder,checklist,morning,journal,mood,water,sleep,workout,quit,smoking,focus,self,care
                                                 95/100

No word appears twice across the three fields. The subtitle adds four searchable words that also read well to a person. The keyword field covers the jobs people hire a habit app for (water, sleep, workout, quit smoking) instead of synonyms of the name.

For the Spanish (Mexico) localization, the same idea in Spanish:

Name:      Streakly: Hábitos diarios             25 characters, 26 bytes
Subtitle:  Rutinas, metas y rachas               23 characters
Keywords:  recordatorio,agua,ejercicio,dormir,meditación,ánimo,enfoque,lista,mañana,fumar
                                                 78 characters, 81 bytes

Note that diario is left out of the keywords because diarios is already in the name, and that the accented letters count as two bytes each.

How to test a change

Because the name, subtitle and keywords only change with a new version, you cannot A/B test them the way you can test screenshots. Apple's product page optimization compares app icons, screenshots and app previews, not text fields. So text changes are tested in sequence, and the discipline is in keeping them clean.

1. Change one field per release, per storefront. If you change the subtitle and the keyword field in the same version, you will not know which one moved the numbers.
2. Write down the date the version went live, not the date you submitted it.
3. Measure downloads from App Store search. App Store Connect Analytics breaks downloads down by source, including App Store search and App Store browse, and lets you filter by territory. Compare the 14 days before the change with the 14 days after. Two full weeks cover each weekday twice, which smooths out weekend swings.
4. Look at impressions as well as downloads. If search impressions rise and conversion falls, you are showing up for searches that don't match the app.
5. Note anything else that happened. A feature, a price change, a press mention, a paid campaign or a holiday will swamp a keyword change. If one landed in the window, extend the test or start again.
6. Low volume apps need longer. If you get a handful of search downloads a day, 14 days may not be enough to tell a real change from noise. Run 28 days, or judge by the rank of specific terms instead.

Keep a simple log for every change: date live, storefront, field, old value, new value, search downloads for 14 days before and after. After a few releases, the log tells you more about your market than any keyword tool.

Checklist

• Name is 30 characters or fewer, brand first, and readable
• Subtitle is 30 characters or fewer and describes a use or feature
• Keywords use commas with no spaces
• No word appears in more than one of name, subtitle and keywords
• No plurals of words you already have
• No "app", no category names, no competitor or trademark terms
• Non Latin and accented locales are checked in bytes
• Each additional language in your top storefronts has real keywords for real speakers
• Only one field changes in this release
• The go live date and a 14 day baseline are recorded

Where asopilot helps

asopilot's free App Store audit checks your name, subtitle and keyword field for repeated words, plural duplicates and unused space in every localization, and Listings drafts keyword sets per storefront for you to approve. Whatever you change, the reviewer reads it too: guideline 2.3.7 covers names, subtitles and keywords, and our guide to Notes for Review that pass covers the rest of a clean submission. If your next release adds iPhone Duo support, read preparing screenshots for iPhone Duo before you upload.