The App Store subtitle and keyword field are small, but they are two of the highest-leverage text fields on the product page. Treat them as separate jobs: the subtitle sells the app to humans; the keyword field helps search understand the app.
The limits
- App name: up to 30 characters.
- Subtitle: up to 30 characters.
- Keywords: 100 characters total.
Subtitle rules
Apple recommends using the subtitle to explain value, not to repeat generic claims. Skip phrases like "world's best app" and write the specific use case instead.
Keyword field rules
Separate keywords with commas and no spaces. Do not duplicate words already in the app name or subtitle. Do not use competitor names, trademarked terms, irrelevant terms, categories, or the word "app".
A practical pattern
Put the clearest human phrase in the subtitle. Put shorter search variants in the keyword field. Localize both independently because native users do not search by translating your English keywords word for word.
Source notes
Apple's product page guidance lists the 30-character app name and subtitle limits, the 100-character keyword limit, and the keyword rejection risks.