ASO tools are useful but expensive. Most indie devs do not need to pay for one to get the first round of keyword decisions right. A free three-step workflow gets you 80% of the value, using only the App Store search bar, your competitors' listings, and App Store Connect.
The 100-character keyword field
Apple gives you 100 characters in the keyword field, per locale. That is roughly 12-15 keywords if you separate by commas with no spaces. Words in your title and subtitle are also indexed, so do not duplicate them in the keyword field — burn the space on different terms.
Step 1: brainstorm in the App Store search bar
Type the obvious word for your app on the device. Watch the autocomplete suggestions. Those are real searches, ranked by Apple's own popularity score. Note the top five. Repeat with two or three synonyms.
Step 2: read competitor titles and subtitles
Open the top three apps in your category. The keywords your competitors put in titles and subtitles are signals — those terms rank well enough that paying competitors fight over them. Add the ones that fit your app to your candidate list.
Step 3: cross-check in App Store Connect
App Store Connect's App Analytics has a "Search Popularity" score for keywords. It is rough — a 0-100 score, not precise volume — but it tells you which of your candidates have real traffic. Drop the zeros. Keep the high-popularity, low- competition ones.
Localize per locale
The keyword field is per locale. Translating your English keywords verbatim is wrong; native speakers search differently. The German equivalent of "to-do list" is sometimes "Aufgabenliste", sometimes "Pendenzen", sometimes the loanword "Todo". Ask a native speaker or run step 1 in the German store.
What to leave out
- Brand names that are not yours. "Notion alternative" in the keyword field gets you rejected.
- Plurals if you have the singular. Apple's matcher handles them.
- Common words. "App", "free", "best" rarely move the needle and waste your 100 characters.
When to upgrade
Once you have shipped this list and watched downloads for a month, an ASO tool (AppFollow, Sensor Tower, AppTweak) becomes worth the cost. The spend is justified once you are running multi-market campaigns, not before.