The App Store keyword field: how to fill its 100 characters

The keyword field is a hidden list of search terms that Apple indexes for your app: one list per localization, separated by commas with no spaces, never shown to customers, and changed only with a new version. Apple’s search page limits it to 100 characters; App Store Connect Help says 100 bytes, and the counter in App Store Connect counted characters when we checked. Fill it with words that are not already in your app name, your subtitle or your category, one form of each word, and nothing that names another app.

What Apple documents

Apple describes the field in two places. The search page gives the format:

Keywords are limited to 100 characters total, with terms separated by commas and no spaces. You can use spaces to separate words within keyword phrases. For example: Property,House,Real Estate.

App Store Connect Help gives the rules of the field itself:

One or more keywords (each greater than two characters) describing your app. You can provide up to 100 bytes of content. Your app is searchable by app name and company name, so you shouldn’t duplicate these values in the keyword list. Names of other apps or companies aren’t allowed.

Put together, Apple’s pages say this:

• Format. Terms separated by commas, no space after a comma. A space inside a term is allowed: Real Estate is one term.
• Length. 100 characters on one page, 100 bytes on the other (see the next section).
• Each keyword longer than two characters. A two-letter term breaks that rule.
• Not your app name or company name. The app is already searchable by both.
• No other app or company names.
• One field per localization. The field “can be localized”, so each language you add has its own 100.

The search page also lists what to avoid, to make room:

• plurals of words you already included, “as these are considered duplicates”;
• generic terms “too broad for your app or category, such as ‘app’ or ‘game’”;
• filler words “like ‘the’ and ‘to’”;
• special characters such as # or @, unless they are part of your brand.

And what not to include at all, because “improper use of keywords is a common reason for App Store rejections”: trademarked terms and celebrity names used without authorization, terms not relevant to the app, competing app names, and offensive terms. Guideline 2.3.7 adds that “Apple may modify inappropriate keywords at any time or take other appropriate steps to prevent abuse.”

Characters or bytes?

The difference matters for every language that is not written in Latin letters. In UTF-8, a Chinese or Japanese character takes 3 bytes and a Cyrillic letter takes 2. If the limit were 100 bytes, a Chinese keyword field would hold about 33 characters. If it is 100 characters, it holds 100.

Apple’s two pages disagree. The only way to know what App Store Connect accepts is to look at App Store Connect.

So, as of that day, App Store Connect counts characters, for every script. Two consequences:

• Count characters, not bytes. In code, that is the length of the string in characters (len() in Python, .count in Swift), not the size of its UTF-8 encoding. Some ASO tools and guides still count bytes, and leave two thirds of a Chinese or Japanese field empty.
• Trust the counter. Apple can change how the field is counted. Before you submit, look at what App Store Connect says is left.

How the field is matched

Apple documents a few things about matching, and leaves the rest unsaid.

Documented. A term can be a phrase with spaces (Real Estate). Plurals of words you already included “are considered duplicates”, which means one form of a word is enough. Words in your app name and company name are already searchable, and Apple asks you not to repeat words from your name, subtitle or category in this field.

Not documented. Apple does not say whether separate keywords are combined into longer searches, for example whether habit and tracker in the field make your app match a search for “habit tracker”. It does not say whether a word in the keyword field counts as much as the same word in the subtitle. Guides that state these as rules are reporting their own observations, at best. If it matters to you, measure it: change one thing, wait for the version to go live, and compare the ranks for the phrase before and after, over several days.

Observed. Apple’s duplicate rule is about what you write, not about what people search. Two forms of one search can return two different lists:

So keep one form of a word in the keyword field, as Apple asks: the rule saves characters. It does not promise the same rank for both searches. If people type both forms, measure both.

How to choose the words

A keyword is worth its characters when people search for it and your app is a good answer to that search.

1. Start from what people type. The App Store’s search hints, which appear as someone types, show real searches. Apple Ads shows a search popularity for each keyword, from 1 to 5. The keyword research guide explains both.
2. Be specific. Apple’s advice: “Be specific when describing your app’s features and functionality to help the search algorithm surface your app in relevant searches.”
3. Weigh popular against reachable. Apple writes that popular, functional terms “may drive a lot of traffic, but are highly competitive – especially if you are a newer or smaller app. Less common terms drive lower traffic, but are less competitive.”
4. Measure where you are before you choose. A keyword where your app is already 8th is not the same bet as one where it is not in the first 250. Measure each candidate in each country you sell in.

A worked example, line by line

Here is a made-up app, so you can see every step. Its listing:

• Name (21 characters): Daybit: Habit Tracker
• Subtitle (30 characters): Daily routine and goal planner
• Primary category: Productivity

A first draft of its keyword field might look like this:

habit tracker, habits, daily routine, planner, productivity, app, the best habit app, morning

Almost everything in it is wasted:

Draft term	Problem
habit tracker	Both words are already in the name
habits	Plural of a word already in the name
daily routine	Both words are already in the subtitle
planner	Already in the subtitle
productivity	The primary category is already indexed
app	Apple names it as too generic
the best habit app	Filler words, a repeated word, and a claim
spaces after commas	Spaces take room; Apple asks for none

After removing everything Apple calls a duplicate, too generic or filler, and adding words people search that describe the app, the field becomes:

streak,reminder,morning,checklist,journal,focus,self care,mood,todo,schedule,wellness,discipline

That is 96 characters, twelve terms, no repeated word, every term longer than two characters, and no other app’s name. The draft added one useful word to the listing, morning; this field adds thirteen.

When a change takes effect

The keyword field belongs to a version in App Store Connect, under the version’s information. You change it when you submit a new version, and App Review sees it with that version. Once the version is live, give the search a few days before you judge: ranks move a little every day on their own, and a new word can take time to settle. The guide to judging a listing change explains how to read the before and after.

Common mistakes

• Spaces after commas. Apple asks for “no spaces”. Each one costs a character.
• Repeating the app name or company name. Both are already searchable.
• Keeping both singular and plural. Apple counts them as duplicates.
• Competitor names. App Store Connect Help says they “aren’t allowed”, and they are a common reason for rejection.
• Counting bytes in a non-Latin script. You lose most of the field.
• Moving keywords into the promotional text. Apple says promotional text “doesn’t affect your app’s search ranking”.
• Never measuring. A field you never measure is a field you cannot improve.

Sources

• Apple, App Store search: keyword format, what to avoid and not to include, popular versus less common terms.
• Apple, App Store Connect Help, Platform version information: the field’s rules and its 100 bytes.
• Apple, App Review Guidelines, 2.3.7: keywords and metadata.
• Apple, Creating your product page: promotional text and search.
• Observation: App Store Connect’s keyword counter, on an app’s version page, 20 October 2026.
• Measurement: the App Store app’s iPhone search in the United States, one search per form, at 23:23 Paris time on 25 October 2026.

Checked on 25 October 2026.