> Deprecated:
> Product subscription app extensions won't be supported as of December 3, 2025. You should migrate existing product subscription app extensions to [purchase options extensions](/docs/apps/build/purchase-options/purchase-options-extensions).
Learn about the APIs provided to extension points:
- LayoutApi: Adjust your content based on the user's screen size.
- LocaleApi: Access a merchant’s current locale to internationalize your extension content.
- SessionTokenApi: Get a fresh session token for communication with your app's backend service.
- ToastApi: Provide quick, at-a-glance feedback on the outcome of an action.