TL;DR. Apple gives you a hidden 100-character keyword field per locale in App Store Connect. Comma-separated, no spaces around the commas. Apple indexes every token for App Store search. Do not repeat words from your title, subtitle, or other locales. Use singular forms (Apple stems plurals). Skip the word “app” and your brand name. Done well, the field is worth several percentage points of organic growth.

What the keyword field is

In App Store Connect, every app version has a per-locale Keywords field. It accepts up to 100 characters of text that users never see — but Apple indexes every word in it for App Store search.

You find it under App Store → iOS App → the version you are editing → General Information → Keywords.

The field is per-locale, meaning each language you ship gets its own 100-character budget. The English (U.S.) keyword field is separate from the German one, the French one, and so on.

The formatting rules

Apple has three formatting rules. Get them wrong and you waste characters or, worse, accidentally index multi-word phrases:

  1. Comma-separated. Each word or phrase is separated by a comma.
  2. No spaces around the commas. keyword1,keyword2,keyword3 not keyword1, keyword2, keyword3. Spaces around commas count against your 100-character budget and waste roughly 2 characters per keyword.
  3. Spaces inside a phrase are allowed but make the phrase index as a phrase, not as separate words. task manager indexes as the two-word phrase. Apple may rank you for “task manager” but is less likely to rank you for “task” and “manager” as standalone keywords. If you want both, write them as two separate comma-separated entries.

The maximum is exactly 100 characters including commas. Apple counts a character is a character — Unicode characters (like accented letters or non-Latin scripts) each count as one toward the 100-character limit.

What never goes in the keyword field

These are wasted characters every time:

  • Your app name. Already indexed via the title. Putting it in the keyword field gains you nothing.
  • Any word from your subtitle. Same reason.
  • The word “app” or “application”. Nobody searches for “fitness app” with the expectation of finding an iOS app in the App Store search — they search for “fitness” or “workout tracker.” App is implicit.
  • Your developer name. Already indexed.
  • Repeated singular and plural forms. Apple stems most plurals. workout covers workouts in most cases.
  • Words from your category. Apple already ranks you within your category page; the category itself is not a useful keyword.
  • Punctuation other than commas. Apostrophes, hyphens, parentheses — these waste characters and rarely improve ranking.

What goes in well

Use the 100 characters for net-new keywords that:

  • Have measurable search volume (above a popularity score of about 20 in tools like Marteso, Sensor Tower, or AppTweak)
  • Have realistic difficulty for your app’s strength (ratings count, install velocity)
  • Are not already covered by your title or subtitle
  • Are not already covered by other locales’ indexed fields (if you cross-localize)

Practical structure for a fitness app whose title is FitTracker — Workout & Gym Log:

cardio,strength,hiit,yoga,pilates,running,calisthenics,abs,plan,routine,trainer,fitness,exercise

98 characters. Zero overlap with the title. Twelve net-new keyword tokens. That is what a fully-utilized field looks like.

Cross-localization: the 100-character field gets bigger

Apple indexes your app’s keywords from any of its active locales for App Store search in any country. So a German user searching gym will see your app rank if you have gym in your English (U.S.) keyword field — even if your German metadata doesn’t contain that word.

This means: the more locales you have active, the larger your effective keyword pool. Five active locales = 500 effective keyword characters (plus 5 × 30 title + 5 × 30 subtitle).

The trick is to coordinate across locales: each locale’s 100-character field should contain terms that complement, not duplicate, the other locales. Most teams ignore this and translate their keyword field word-for-word, leaving 80% of their effective pool unused.

Read the full cross-localization keyword strategy →

Character-budget math

If your title is 30 characters, your subtitle is 30 characters, and your keyword field is 100 characters, you have 160 total characters of indexed text per locale. With four active locales: 640 characters.

Most indie iOS apps use under half of that effective budget — duplicate words across fields, half-empty keyword field, brand name and “app” wasting space. A two-hour cleanup typically frees up 50–100 characters of net-new keyword space and produces measurable rank lifts within 30 days of the next release.

How to count without losing your mind

Manually counting is tedious and easy to miscount. Tools that count and check for cannibalization in real time:

  • Marteso — the AI Metadata Optimizer shows live character count and flags duplicate words across title, subtitle, and keyword field
  • App Store Connect itself — shows a character counter, but only per-field, no cross-field deduplication
  • AppTweak / Sensor Tower — character counters at the enterprise tier

If you write metadata in a text editor first, set the right margin to column 30 for title/subtitle and column 100 for the keyword field. It catches over-limit drafts before you paste into App Store Connect.

The submission flow

  1. Edit your version in App Store Connect → Keywords
  2. Paste your final, deduplicated, comma-separated keyword string
  3. Submit the version for review (keyword changes go live with the new version, not independently)
  4. Wait for review approval (typically 24–48 hours in 2026)
  5. After release, monitor ranking changes over the next 7–14 days — that is the window where Apple’s index settles on the new metadata

Pro tip: ship keyword-only changes alongside small bug-fix releases. You get to test new metadata without bundling it with risky feature work.

What Marteso does about it

The Metadata Optimizer in Marteso treats title, subtitle, and the 100-character keyword field as one continuous keyword pool. It:

  • Auto-formats keyword1,keyword2,keyword3 with no extra spaces
  • Counts characters in real time, including commas
  • Flags words that already appear in the title or subtitle
  • Suggests net-new replacement keywords from your active research list, ranked by volume and difficulty
  • Supports multi-locale editing with cross-locale deduplication

When the keyword field is filled, Marteso submits the metadata directly to App Store Connect — no copy-paste step.

Try the Metadata Optimizer free →