App Store Keyword Rules: Apple's 100-Character Field Explained

Apple's App Store keyword field holds exactly 100 characters. Terms are separated by commas with no spaces, though you can use spaces inside a multi-word phrase. Anything over 100 characters is rejected at save. The field is private — users never see it — but it directly controls which searches your app can appear in.

That single field is the most misunderstood part of App Store Optimization. Most rejections and most wasted characters come from developers who never read the App Store keywords rules. This guide covers what Apple actually enforces, what it silently ignores, and how to spend all 100 characters without wasting one.

The App Store keywords rules split into three groups: format rules App Store Connect enforces at save, content rules App Review enforces at submission, and efficiency rules nobody enforces but that decide how much search surface you actually get. All three are below.

If you want the wider strategy first, start with the App Store keyword optimization guide. This page is the rulebook.

The Format Rules Apple Enforces

Apple limits keywords to 100 characters total, separated by commas with no spaces after the commas. Spaces are allowed within a phrase. A valid entry looks like run,tracker,jogging,marathon,heart rate. Every space after a comma costs you one character you could have spent on a term.

Three format rules matter:

1. 100 characters, hard cap. App Store Connect will not save a longer string. Punctuation and spaces count.
2. Commas separate terms, no space after the comma. run,tracker is correct. run, tracker wastes a character.
3. Spaces inside a phrase are allowed. heart rate is one term worth two words. Apple's guidance explicitly permits this.

The field is set per localization, not per app. A single app with English (U.S.), Spanish (Mexico), and German localizations gets three separate 100-character fields, and each one is indexed independently.

What Apple Rejects Outright

Improper keyword use is one of the most common causes of App Store rejection. Apple's App Review Guidelines require keywords that accurately describe your app, and reviewers reject listings that use protected terms.

Do not put any of these in the field:

• Trademarked terms you do not own. Competitor brand names are the most frequent offender.
• Celebrity names and other protected words or phrases.
• Irrelevant terms that do not describe what the app actually does.
• Pricing or promotional claims — the keyword field is not ad copy.

A rejection here costs you a full review cycle. Because the field is invisible to users, developers assume nobody checks it. Reviewers do.

What Apple Indexes For Free

Some things are already indexed, so spending characters on them is pure waste. Apple automatically indexes:

• Your app name and subtitle. Every word in both fields is already searchable. Repeating them in the keyword field buys nothing.
• Your category name. If you are in Health & Fitness, you are already indexed for the category term.
• Your developer/company name.

Apple's matching also handles singular and plural variants, so covering both habit and habits usually costs eight characters for a marginal gain. Apple's own best-practice guidance is to avoid plurals of words already included in singular form, and to avoid special characters such as # or @ unless they are part of your brand.

The word "app" is another classic waste. Nearly every search containing "app" still matches without it. Those four characters are better spent on a real modifier.

How Keywords Combine Into Phrases

Apple builds searchable phrases by combining terms across your name, subtitle, and keyword field. You do not need to enter full phrases — you need the component words.

If your name contains "Runly" and your subtitle contains "Marathon Training," adding plan,pace,split to the keyword field lets you surface for combinations such as "marathon training plan" and "marathon pace" without ever typing those phrases. This is why duplication is so expensive: a word already in your title is already in every combination Apple can build.

The practical rule: the keyword field is for net-new terms only. Use the name and subtitle for readable, high-value phrases a human will actually read. Use the keyword field for the synonyms, long-tail modifiers, and validated competitor-adjacent terms that are left over.

A Character Budget That Works

With 100 characters and no wasted space, most apps fit 10 to 14 terms. A workable budget:

Allocation	Characters	Purpose
Core synonyms	~35	Words users search instead of your category term
Long-tail modifiers	~35	"free," "offline," "beginner," "tracker"
Use-case terms	~30	The job the user is hiring your app to do

Write the list in a plain text editor first, count it, then paste. App Store Connect's counter includes commas, so a list that looks like 96 characters in your head is often 103 in the field.

Once the field is set, the rest of your listing has to carry the same terms in readable form. The App Store description guide covers how the visible copy should support the hidden field, and IconikAI's Store Description Generator writes ASO-optimized listing copy for Google Play and the App Store from the terms you have chosen.

A Worked Example: Trimming a Real Field

Here is a first draft from a habit-tracking app called Streakly, subtitle "Daily Habit Tracker":

habit, habits, tracker, tracking, daily habits, streakly, routine app, goal app, productivity

That string is 94 characters and roughly half of it is dead weight. Working through the checks:

• streakly — already in the app name. Cut.
• habit and daily habits — both duplicate the subtitle. Cut.
• habits, tracking — plural and inflected forms of terms already covered. Cut.
• tracker — in the subtitle. Cut.
• productivity — the app's category name, indexed automatically. Cut.
• routine app, goal app — the word "app" adds nothing. Trim to routine, goal.
• Spaces after commas — nine wasted characters.

What remains is routine,goal at 12 characters, which frees 88 for net-new terms:

routine,goal,streak,accountability,self care,morning ritual,water,journal,reminder,checklist

Same field, same 100-character ceiling, roughly four times the search surface. The original draft was competing only for terms the app already ranked for.

Localization Multiplies the Field

Each localization gets its own 100-character field, indexed independently. An app localized into five languages has 500 characters of keyword space, not 100 — and this is the single largest under-used lever in iOS ASO.

Two details make it more valuable than it first looks:

• English (U.S.) and English (U.K.) are separate fields on the U.S. storefront for many configurations, and terms from both can contribute. Check your own App Store Connect setup before assuming.
• Users searching in one language often surface apps indexed in another. Adding a localization for a market you already sell in costs nothing but the translation.

Do not paste the English list into every locale. Search behaviour differs by market — the literal translation of your best English term is frequently not what local users type. Re-run term selection per locale, even if the app's UI copy is a straight translation.

iOS vs Google Play: Different Rules Entirely

The 100-character keyword field is an Apple-only mechanism. Google Play has no equivalent field. Google indexes your full store listing text — title, short description, and long description — so keyword placement on Android is a copywriting problem, not a budgeting problem.

Rule	Apple App Store	Google Play
Dedicated keyword field	Yes, 100 characters, private	No
Where terms are indexed	Name, subtitle, keyword field	Title, short + long description
Repetition helps ranking	No	Modest effect, 3-5 mentions
Category auto-indexed	Yes	Yes

Running the same keyword list on both stores is a mistake. Android needs the terms woven into readable sentences; iOS needs them compressed into a comma-separated string.

App Store Keywords Best Practices: The Short List

If you only remember ten App Store keywords best practices, make them these:

1. Use all 100 characters. An unused character is a term you did not compete for.
2. No spaces after commas. Spaces inside a phrase are fine.
3. Never repeat a word from your app name, subtitle, or category.
4. Skip plurals when the singular is already there.
5. Skip "app," "the," "for," and other stop words.
6. No trademarks, competitor names, or celebrity names — this is a rejection trigger.
7. No special characters like # or @ unless they are part of your brand.
8. Prefer specific over broad: "sleep meditation" beats "wellness."
9. Localize each field separately — every locale gets its own 100 characters.
10. Log every version of the field with its release date so you can tell what worked.

Apple's own guidance on keyword best practices is short and worth reading directly. Everything above is downstream of two ideas: do not spend characters on terms you already have, and do not spend characters on terms you cannot win.

Checking Your Field Before You Ship

Run this pass before every submission:

1. Count the characters, including commas. Must be 100 or fewer.
2. Remove any word already in your app name, subtitle, or category.
3. Remove plurals where the singular is present.
4. Remove trademarks, competitor names, and celebrity names.
5. Remove "app," "the," and other stop words.
6. Confirm every remaining term describes something the app actually does.

Steps 2 and 3 alone typically free 15 to 25 characters on a first-time listing — enough for two or three additional terms.

When You Can Change Keywords

The keyword field is version-locked. You can edit it while a version is in "Prepare for Submission," but once a version is live the field is frozen until you submit a new one. There is no way to hot-swap keywords on a shipped release.

This has two practical consequences:

• Ship keyword changes with real releases. Submitting a build purely to change keywords burns a review cycle and resets nothing else in your favour.
• Give changes time. Ranking re-indexes over days, not hours, and install data needs a few weeks to separate a keyword effect from seasonality. Most teams hold a change for at least four weeks before judging it.

Change one variable at a time where you can. If you rewrite the subtitle, the icon, and the keyword field in the same release, you will not know which one moved the number. The organic downloads guide covers isolating ASO changes from the rest of your growth work.

FAQ

How many characters is the App Store keyword field? 100 characters, including commas. Terms are separated by commas with no spaces after the comma, though spaces are allowed inside a multi-word phrase.

Should I repeat my app name in the keyword field? No. Apple already indexes every word in your app name and subtitle. Repeating them wastes characters that could hold new terms.

Can I use competitor brand names as keywords? No. Unauthorized trademarked terms are a documented cause of App Store rejection. Use category and use-case terms your competitors also rank for instead of their brand name.

Do I need both singular and plural forms? Usually not. Apple's matching handles variants, and its own guidance is to avoid plurals of words already included in singular form.

Does the keyword field exist on Google Play? No. Google Play indexes your title, short description, and long description instead. Android keyword placement is a copywriting task, not a 100-character budget.

How often should I change my keywords? The field can only be updated with a new app version submission. Most teams revisit it every release and hold changes for at least four weeks before judging the result.

Do keywords need to be in the same language as my app? Each localization has its own 100-character field, indexed independently. Localize the terms — do not paste the English list into every locale.

What are "personal keywords" on the App Store? "Personal keywords" is an informal name developers use for the private 100-character keyword field, because unlike the app name and subtitle it is personal to you and never shown to users. Apple's own label in App Store Connect is simply "Keywords."

Where do I edit iOS App Store keywords? In App Store Connect, open your app, select the version you are preparing, and scroll to the "Keywords" field under App Information for that localization. The field is editable only while the version is in "Prepare for Submission."

Are iPhone app keywords different from iPad keywords? No. The keyword field is set per app and per localization, not per device. One field covers iPhone, iPad, and any other Apple platform the app ships on.

Is this the same as iTunes keywords optimization? Yes. "iTunes keywords" is a legacy name from before App Store Connect replaced iTunes Connect in 2018. The field, the 100-character limit, and the rules are the same thing under a newer name.

Next Steps

The keyword field is a budget problem with a fixed ceiling. The harder question is which terms deserve the space, and that comes from research: what your competitors rank for, and which of those terms you can realistically win. The App Store optimization guide covers the full ASO picture across both stores.

If you would rather not run keyword cycles yourself, IconikAI's ASO Growth Agent handles keyword research, metadata optimization, screenshot experiments, and competitor tracking at $50 per app per month, with a 30-day money-back guarantee.