Identifiers

Every store-published app needs a unique Android applicationId and iOS bundle identifier. These are the strings the stores treat as your app's identity — you cannot change them after your first submission, so decide now.

Use reverse-DNS with your own domain, for example com.yourcompany.yourapp.

Change them via setup.html

Open setup.html → Customizations → Identifiers. Enter your new Android package name and iOS bundle ID. Save.

The GUI runs the underlying rename across every place they appear:

• android/app/build.gradle — applicationId, namespace
• android/app/src/main/AndroidManifest.xml — package (if present)
• android/app/src/main/kotlin/**/MainActivity.kt — the Kotlin package declaration and its folder path
• ios/Runner.xcodeproj/project.pbxproj — PRODUCT_BUNDLE_IDENTIFIER for the app target and its extensions

Verify

After the rename, open the Android manifest and confirm:

And the Kotlin MainActivity.kt:

And Xcode's target settings:

After changing identifiers

If you had already run flutterfire configure for the old identifiers, run it again — Firebase binds its config files to the exact bundle ID / applicationId, and the old files won't match anymore. See Firebase.