The number of keywords that an app should target for app store optimization (ASO) will depend on the specific needs and goals of the app and its target audience. However, it’s generally recommended to target a relatively small number of high-quality keywords rather than a large number of low-quality keywords.

In the Apple App Store, the app’s title is limited to 30 characters, and the keyword field is limited to 100 characters. In the Google Play Store, the app’s title is limited to 50 characters, and the keyword field is not visible to users.

When selecting keywords for ASO, it’s important to choose keywords that are relevant to the app and are likely to be used by users when searching for apps within the app store. It’s also important to consider the competitiveness of the keywords and the likelihood that the app will rank well for those keywords.

It can be helpful to use tools such as the App Store Connect Keyword Tool or the Google Play Console to research and identify relevant and high-quality keywords for the app. It’s also a good idea to regularly review and update the app’s keywords in order to ensure that they are still relevant and effective for driving visibility and downloads.