<!--
{
  "availability" : [
    "iOS: 16.0.0 -",
    "iPadOS: 16.0.0 -",
    "macOS: 13.0.0 -",
    "tvOS: 16.0.0 -",
    "visionOS: 1.0.0 -",
    "watchOS: 9.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "StoreKit",
  "identifier" : "/documentation/StoreKit/AppTransaction/appTransactionID",
  "metadataVersion" : "0.1.0",
  "role" : "Instance Property",
  "symbol" : {
    "kind" : "Instance Property",
    "modules" : [
      "StoreKit"
    ],
    "preciseIdentifier" : "s:8StoreKit14AppTransactionV03appD2IDSSvp"
  },
  "title" : "appTransactionID"
}
-->

# appTransactionID

The unique identifier of the app download transaction.

```
@backDeployed(before: iOS 18.4, macOS 15.4, tvOS 18.4, watchOS 11.4, visionOS 2.4)
var appTransactionID: String { get }
```

## Discussion

The App Store generates a single, globally unique `appTransactionID` for each Apple Account that downloads your app and for each family group member for apps that support Family Sharing.

This value remains the same for the same Apple Account and app if the customer redownloads the app on any device, receives a refund, repurchases the app, or changes the storefront. For apps that support Family Sharing, the `appTransactionID` is unique for each family group member.

The `appTransactionID` is available even if a customer makes no in-app purchases.

The App Store server and StoreKit provide the `appTransactionID` in the following APIs:

- This symbol, `appTransactionID`, in the [`AppTransaction`](/documentation/StoreKit/AppTransaction) object
- [`appTransactionID`](/documentation/StoreKit/Product/SubscriptionInfo/RenewalInfo/appTransactionID), in the subscription renewal information [`Product.SubscriptionInfo.RenewalInfo`](/documentation/StoreKit/Product/SubscriptionInfo/RenewalInfo)
- [`appTransactionID`](/documentation/StoreKit/Transaction/appTransactionID), in the transaction information [`Transaction`](/documentation/StoreKit/Transaction)
- In transaction and subscription renewal information you receive from notifications, <doc://com.apple.documentation/documentation/AppStoreServerNotifications/App-Store-Server-Notifications-V2>
- In transaction and subscription renewal information you receive from the <doc://com.apple.documentation/documentation/AppStoreServerAPI>

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)