App Store Keyword Field: How to Fill the 100-Byte Field Without Waste

The keyword field is the hidden field that helps decide where your app appears in search. As of November 2026, it holds up to 100 bytes per localization. Separate terms with commas and no spaces, and do not repeat words from your name, subtitle, or category.

This guide is for iOS developers who own their listing. It maps each rule to the Apple page that states it, and shows a counted example you can copy.

What is the keyword field, and where does it sit?

Keywords is the hidden search field in App Store Connect. Users never see it. Apple uses it with your app name, Subtitle, and primary category to decide where your app appears in search results (Apple's search page).

The field is required and localizable: you fill one per localization, and each term must be longer than two characters (Apple's platform version information). Your app is already searchable by app name and company name, so do not duplicate those values in the list.

Apple states that search results rest on text relevance plus user behavior. Text relevance covers matches in app title, Subtitle, Keywords, and primary category. Behavior covers downloads, ratings, reviews, and related signals (Apple's search page). Apple publishes no weighting across the relevancy fields, so no source supports claims such as subtitle counts twice as much as keywords.

What are the limits side by side?

Each text field carries its own limit and its own edit rule. The table below lists the five fields developers confuse most, as of November 2026.

Name and Subtitle limits come from Apple's app information reference. Keywords, Promotional Text, and Description limits come from Apple's platform version information and Apple's product page.

Apple phrases the keyword limit two ways. The help reference says up to 100 bytes. The product and search pages say 100 characters total. For ASCII English the two counts match, so count bytes in practice. Run python3 with len(s.encode('utf-8')) before you save, and keep the result at or under 100.

For the two reader-facing fields in the table, read promotional text vs description. That guide covers where each appears and what to write, so this guide does not repeat it.

How do you format commas, spaces, and repeats?

Follow these steps when you fill Keywords in App Store Connect.

1. Separate terms with commas and no spaces between terms.
2. Keep spaces inside a phrase when the phrase needs one.
3. Remove every word that already appears in your name, Subtitle, or category.
4. Use the singular form and drop the plural of a word you already include.
5. Drop app, category words, filler words, and special characters unless they are part of your brand.
6. Check that each term is longer than two characters, then count bytes with python3.

Apple gives its own example: Property,House,Real Estate (Apple's product page). Note the nuance: no spaces sit between the terms, but a space sits inside the phrase Real Estate. That example defines the rule better than the short phrase no spaces alone.

The following example uses a clearly made-up app. Tempo is a fictional run tracker. Its name is Tempo: Run Tracker and its Subtitle is GPS runs and training plans.

A wasteful first draft looks like this:

run, tracker, running, free, app, Tempo

That line uses 39 of the 100 bytes. The waste matters more than the length. The terms run and tracker repeat the name and Subtitle. Running repeats run in plural form. Free and app add no specific meaning. Tempo repeats the brand. Each space after a comma wastes a byte.

A tighter list keeps only new terms:

gps,marathon,pace,route,interval,splits,heartrate,trail,cadence,coach

That line uses 69 of the 100 bytes and adds ten new terms. Each term is longer than two characters, none repeats the name or Subtitle, none is a plural of another, and no space follows any comma.

What gets a submission rejected?

Choose keywords that describe your own app accurately. Guideline 2.3.7 asks for a unique app name and accurate keywords. It forbids packing metadata with trademarked terms, popular app names, pricing information, or other irrelevant phrases (App Store Review Guidelines).

Apple lists improper keyword use as a common reason for rejection (Apple's product page). Do not include unauthorized trademarked terms, celebrity names, or other protected words. Do not include terms that are not relevant to your app. Do not include competing app names. Do not include inappropriate, offensive, or objectionable terms.

Apple may modify inappropriate keywords at any time or take other steps to prevent abuse (App Store Review Guidelines). When in doubt, leave the term out. A rejected submission costs more time than a missing keyword ever saves.

What this doesn't cover

This guide covers only the App Store. Google Play follows different rules and is out of scope here.

It does not rank keyword weighting. Apple publishes no weights for name, Subtitle, Keywords, or category, so no honest guide can promise that one field counts more than another.

It does not treat Description as a search field. Apple does not state that description text feeds search indexing, so write description for readers, not for ranking.

It does not cover screenshots, ratings and reviews, analytics, custom product pages, or App Review beyond the keyword-misuse note above. Each of those topics needs its own Apple-first guide with its own sources.