The App Store keyword field is invisible to users. It doesn't appear on your listing, doesn't show up in search results, and Apple never confirmed exactly how it's weighted. So most developers fill it in quickly, never look at it again, and move on.
That's a mistake. The keyword field is 100 characters of direct search signal — indexed by Apple, processed per locale, and consistently one of the highest-ROI fields you can optimize. Done right, it quietly expands your app's search footprint across dozens of additional queries. Done wrong (or left blank), it contributes nothing.
Here's how it actually works.
What the Keyword Field Is
In App Store Connect, every app has a keyword field under each locale's metadata. It accepts up to 100 characters. Apple uses this field — along with your title and subtitle — to determine which search queries your app is eligible to appear in.
It's separate from your description, which Apple does not index for search. It's separate from your app name. It's a dedicated ranking-signal field, and it exists for one purpose: to tell Apple what else your app should rank for beyond what's already in your title and subtitle.
The Rules (Most of Which People Get Wrong)
No commas. Apple uses spaces as delimiters, not commas. If you put commas between your keywords, Apple treats the comma as a character in the keyword — you're wasting characters and potentially creating nonsense terms Apple can't match to anything.
Correct: habit tracker daily routine journal
Wrong: habit tracker, daily routine, journal
No spaces after the last keyword. Every character counts. A trailing space is a wasted character.
Don't repeat words in your title or subtitle. Apple already indexes your title and subtitle. If your title says "FocusFlow — Pomodoro Timer," you don't need "pomodoro" or "timer" in your keyword field. Those characters are wasted. Use the field for terms that aren't already covered.
Don't include your app name. Apple indexes that separately. Putting your app name in the keyword field accomplishes nothing.
Don't include competitor app names. Apple filters these out and it can create policy issues.
Plurals generally aren't necessary. Apple indexes both singular and plural forms of most terms. "habit" and "habits" don't both need to be there.
Filling to exactly 100 characters matters. Every unused character is a missed ranking opportunity. If you're at 87 characters, find a relevant term that fits in the remaining 13.
How Apple Combines Keywords
This is the part most developers don't realize: Apple doesn't just rank you for the exact phrases in your keyword field. It combines individual words across your title, subtitle, and keyword field to create additional ranking matches.
If your title contains "Focus" and your keyword field contains "timer work study," Apple will potentially rank you for searches like "focus timer," "focus work," "focus study," and "work timer" — even if none of those exact phrases appear anywhere in your metadata.
This is why using individual words instead of full phrases in the keyword field is almost always better. Compare:
Full phrases (wasteful):
habit tracker daily routine focus timer pomodoro (48 chars, covers a handful of searches)
Individual words (efficient):
habit tracker daily routine focus timer pomodoro study work productivity (72 chars, combinatorially covers far more search variations)
Apple does the combination work. You give it the raw ingredients.
The Per-Locale Problem
Here's the part that directly costs most apps money: the keyword field is separate for every locale.
Your US English keyword field has no effect on Japanese searches. Your UK English keyword field doesn't affect Germany. Every country in App Store Connect has its own 100-character keyword field, and by default, they're all blank.
When you leave the Japanese keyword field empty:
- Apple has no additional keyword signals to index for Japanese searches
- Your app is available in Japan but essentially invisible to search
- Any Japanese downloads you're getting come from direct brand searches or word-of-mouth — not keyword ranking
This is the single biggest missed opportunity in App Store optimization for indie developers. The US market is relatively competitive; the keyword field has been optimized by hundreds of apps in most categories. But in Japan, Germany, France, Brazil, and South Korea? Most apps have never filled in a single character of localized keywords. The competition for those keyword field rankings is dramatically lower.
Common Keyword Field Mistakes (With Fixes)
Mistake 1: Using it like a sentence
"best app for habits and daily routines and focus"
Fix: Remove articles, prepositions, and connective words. Apple doesn't rank on "and" or "for." Just the meaningful terms.
Mistake 2: Copying your English keywords into international markets Japanese users don't search in English. A Japanese keyword field filled with English terms contributes nothing to your Japanese rankings. Fix: Research keywords in the target language using AppTweak, ASOdesk, or the manual App Store autocomplete method.
Mistake 3: Leaving it mostly empty Some developers fill in 40–50 characters and stop. That's leaving 50+ characters of potential ranking signal unused. Fix: Keep adding relevant terms — related use cases, synonyms, related categories — until you're within 1–2 characters of 100.
Mistake 4: Repeating the title keyword If your title is "Sleep Sounds — White Noise," don't put "sleep sounds" or "white noise" in the keyword field. You're burning 20+ characters on terms Apple already indexes from your title. Fix: Use the keyword field strictly for terms not already in your title or subtitle.
Mistake 5: Never updating it Keyword search behavior shifts. New terms emerge in your category. Competitors update their metadata and your relative position changes. Fix: Check your keyword rankings every 3–6 months and update the field based on what's gaining and losing traction.
A Simple Audit Process
Before you optimize your keyword field, audit what you have:
- Open App Store Connect → your app → App Information (or the specific version metadata)
- Copy your current keyword field into a text editor
- Count the characters — are you close to 100?
- Remove any words already in your title or subtitle
- Remove commas; replace with spaces
- Remove articles and filler words
- Check your locales — which keyword fields are blank?
Then for each locale that's blank or underoptimized, do the research: find what users in that market actually search for, run a competitor keyword gap analysis, and fill the 100 characters with the best terms you've found.
Done properly for a single locale, this process takes 2–4 hours. For 5–10 locales, it's a significant time investment — which is exactly the work LocalizeRank does. Per-market keyword research, competitor analysis, and a ready-to-paste keyword field for every locale you want to target. Starting at $49 for 5 markets.