The App Store keyword field: how the 100 characters actually work

If you build iPhone apps alone, the keyword field is the cheapest growth lever you have. It costs nothing, it doesn't need review copy that users see, and a bad one can quietly cap your app at a few hundred impressions a day. It is also the part of App Store optimization (ASO) with the most folklore around it. This guide sticks to what Apple documents, what we have measured ourselves, and what is still uncertain.

#What the App Store actually searches

Apple's own summary is short: "Search results are based on a number of factors, including text relevance (matches for your app's title, subtitle, keywords, and primary category), as well as user behavior (downloads, ratings and reviews, and more)."

So there are two halves. Text relevance decides which searches you can appear for at all. User behavior decides how high you appear among the apps that match. You fully control the first half, and the keyword field is the biggest part of it. Everything else you write on the product page (description, promotional text, What's New) affects whether people install after they find you, but not whether they find you.

Two notes on that table:

• Description and promotional text. Apple's documentation says the description "will be used for web engine search results", meaning Google and Bing, not the App Store, and that "promotional text doesn't affect your app's search ranking". Write both for humans who are deciding whether to install, not for keyword density.
• Screenshot captions. In June 2025 Appfigures reported that ranking changes suggested Apple had started reading caption text in screenshots. The author was clear that this was observational and that it "doesn't seem to be as strong of a signal alone". We haven't been able to confirm it either way. Putting your main keyword in your first screenshot caption helps conversion anyway, so it is a free bet.

#100 characters or 100 bytes?

Apple isn't consistent about this. The App Store Connect reference describes the keyword field as "up to 100 bytes of content", made of keywords "each greater than two characters". Apple's App Store search page says "Keywords are limited to 100 characters total". For plain English letters, digits and commas, the two are the same. For accented letters and non-Latin scripts they aren't: in UTF-8, ä is 2 bytes and most Japanese or Chinese characters are 3.

We tested it while maintaining a Finnish keyword field in October 2026: App Store Connect accepted a field that was 98 characters but 105 bytes long, because it contained ä and ö. So today the form counts characters, which matches the search page. If your language has many multi-byte characters, it's still safest to stay under 100 bytes. Nothing tells you what the indexer does with text past the documented limit, and a rule that changes quietly is worse than a few lost characters.

#How to write the field

#Commas, no spaces

Apple's instruction is "terms separated by commas and no spaces". A space after a comma costs a character and adds nothing: workout,lifting,tracker and workout, lifting, tracker are indexed the same way. You can use spaces inside a phrase (Apple's example is Property,House,Real Estate), but you rarely need to (see the next section).

#Single words beat phrases

The App Store builds search matches from the individual words in your title, subtitle and keyword field, and combines words across those fields. If your subtitle says Workout Tracker and your keyword field contains gym,log, you can rank for gym log, gym tracker, workout log and gym workout tracker without ever writing those phrases.

That is why the most efficient field is a list of single, distinct words. Write a multi-word phrase only when the exact order matters and the words are useless on their own.

#Never repeat a word

A word in your title is already indexed, and so is a word in your subtitle and your category name. Apple says it directly: "Don't repeat any words included in your app name, subtitle, or category." Repeating a word doesn't make it count twice. It just takes space from a word you could have added. The same goes for your developer name.

#Plurals and close variants

Apple lists "plurals of words you've already included, such as 'climbs' and 'climb'" among the things to leave out, because they "are considered duplicates". Pick one form. In our tracking, ranks for singular and plural searches are usually close but not identical, and the gap varies by language. If you care about one specific form, track both and decide from the numbers rather than adding both by default.

#What to leave out

• Your app name and company name. Already indexed. Apple says so in its documentation.
• Names of other apps or companies. Apple's rules say "Names of other apps or companies aren't allowed." Competitor names in the keyword field are a common reason for rejection, and the rankings rarely stick anyway.
• Generic words like "app", "iphone", "free". Apple calls out "generic terms that are too broad for your app or category, such as 'app' or 'game'". Practically every result is a free iPhone app anyway.
• Your category name. Apple indexes your primary and secondary category already.
• Filler words such as "the" and "to", and special characters like # or @ unless they are part of your brand.
• Words of two characters or fewer. The App Store Connect reference says each keyword must be longer than two characters.

#Choosing the words

A good keyword field is a short list of words that are popular, winnable and true to what your app does. In that order of difficulty:

1. Relevance first. If people who search a word don't want your app, you might rank, but nobody installs. A poor install rate also seems to push the ranking back down.
2. Popularity. Apple Ads shows a search popularity score for terms that have enough volume. Long-tail searches often have no score at all. That doesn't mean nobody searches them; it means volume is below Apple's threshold.
3. Difficulty. Look at the apps already in the top 10 for a search. If every one has hundreds of thousands of ratings and the search term in its title, a new app can't win that search with the keyword field alone. If some of the top 10 are small, old or off-topic, that is an opening.

The useful middle is usually two-word searches with real popularity where the top results are weak. Your title and subtitle should hold the one or two searches you most want to win. The keyword field holds the supporting words that turn those into dozens of combinations.

One more lever that few indie developers use: custom product pages. Apple lets you assign keywords to a custom product page so that it, rather than your default page, appears in search for those keywords. If your app serves two different audiences (say, lifters and runners), each search can land on screenshots made for that audience.

#Get more space: every localization has its own field

Each App Store country indexes one or more localizations of your app, and each localization has its own title, subtitle and 100-byte keyword field. The US store, for example, also indexes Spanish (Mexico) and several other localizations, while the UK localization is indexed across much of Europe. Filling those extra keyword fields with words in the country's main language gives you another 100 bytes per localization without touching your visible English listing.

We wrote a separate guide with the country table, the risks and a worked example: App Store cross-localization.

#Measure the change

Keyword changes go live with a new app version. Ranking movement starts within a day or two but can take a couple of weeks to settle, because the user-behavior half of the ranking (downloads, ratings) needs time to catch up with the new text. To know whether a change worked:

1. Record the baseline. Track your rank for every search you care about, daily, for at least a week before the change.
2. Change one field at a time. If you change the title, subtitle and keyword field together, you won't know which one did it.
3. Write down the date. Mark the day the version went live so you can see it on your rank chart.
4. Compare two weeks later. Look at ranks and impressions from App Store Connect analytics. Judge the change by the searches that moved, not by the total.

This loop is the reason Fledly tracks your ranks every day: a change is only as measurable as the baseline before it.

#Frequently asked questions

#How many characters is the App Store keyword field?

100 per localization. Apple's App Store search page says 100 characters and the App Store Connect reference says 100 bytes. For plain English text those are the same. In October 2026 App Store Connect accepted a 98-character field that was 105 bytes long, so the form counts characters, but staying under 100 bytes is the safe choice for languages with accented or non-Latin characters.

#Should I put spaces after commas in App Store keywords?

No. Separate keywords with commas only. Spaces after commas use up bytes and don't change how the words are indexed.

#Does the App Store description affect search ranking?

Not on the App Store. Apple's documentation says the description is used for web search engine results. App Store search matches the app name, subtitle, keyword field and primary category, and then weighs user behavior such as downloads, ratings and reviews.

#Can I use competitor names in my keyword field?

No. Apple's documentation says names of other apps or companies aren't allowed in keywords, and apps are rejected for it.

#Should I repeat words from my title in the keyword field?

No. Apple says not to repeat words from your app name, subtitle or category, and to leave out plurals of words you already have. They are already indexed, and the App Store combines them with your keyword field words.

#How long does it take for keyword changes to affect rankings?

Ranks usually start moving within one to three days after the new version is live and settle within about two weeks. Track daily before and after the change so you can compare.

#Sources

• Apple Developer: App Store search (ranking factors and keyword tips).
• Apple, App Store Connect Help: Platform version information (keyword, description and promotional text limits) and App information (name and subtitle limits). Checked October 27, 2026.
• Appfigures: The Biggest App Store Algorithm Change is Here, June 16, 2025.
• Fledly's own keyword tracking for indie apps in the US and Finnish stores, October 2026.