In-App Billing Plugin for .NET MAUI and Windows

Important Note: I do not plan on continuing support for this library. As noted in April of 2025: In App Purchase APIs have always been extremely complex, hard to manage, hard to update, and hard to streamline into a single API. I have enjoyed working and evolving this project over the years, but with StoreKit being deprecated for StoreKit2 and the ever-evolving Android Billing Library that always has massive changes, I simply do not have the time and energy to keep the library up to date. I appreciate everyone that has contributed over and used the library over the years. I encourage forking and evolving the library and of course you can just pull the source code into your project directly.

A simple In-App Purchase plugin for .NET MAUI and Windows to query item information, purchase items, restore items, and more.

Subscriptions are supported on iOS, Android, and Mac. Windows/UWP/WinUI 3 - does not support subscriptions at this time.

Important Version Information

• v10 now supports .NET 10+ and Android Billing v8
• v9 now supports .NET 9+ and Android Billing v7
• v8 now supports .NET 8+ .NET MAUI and Windows Apps.
• v7 now supports .NET 6+, .NET MAUI, UWP, and Xamarin/Xamarin.Forms projects
• v7 is built against Android Billing Library 6.0
• See migration guides below

Documentation

Get started by reading through the In-App Billing Plugin documentation.

NuGet

• NuGet: Plugin.InAppBilling

Platform Support

Platform	Version
iOS for .NET	10+
macCatlyst for .NET	All
Android for .NET	21+
Windows App SDK (WinUI 3)	10+
.NET MAUI	All

Created By: @JamesMontemagno

• Twitter: @JamesMontemagno
• Blog: Montemagno.com
• Podcast: Merge Conflict
• Videos: James's YouTube Channel

Version 8 Major Updates

• Nice new re-write and re-implementation of APIs!
• Built against .NET 8
• Now using latest Android Billing v6.2.1

Version 7 Major Updates

• Android: You must compile and target against Android 12 or higher (or Android 13 if v7.1)
• Android: Now using Android Billing v6
• Android: Major changes to Android product details, subscriptions, and more
• Android: Please read through: https://developer.android.com/google/play/billing/migrate-gpblv6
• Android: AcknowledgePurchaseAsync is now FinalizePurchaseAsync
• All: There are now "Extras" for all products that give you back tons of info for each platform

If you receive an error in Google Play you may need to add this to your AndroidManifest.xml inside the application node:

<meta-data
  android:name="com.google.android.play.billingclient.version"
  android:value="X.X.X" />

Update X.X.X with the version of the Billing Library that is a dependency on the NuGet package.

Pending Transactions:

• If the result of PurchaseAsync is PurchaseState.PaymentPending, store the order details locally and inform the user that they will have access to the product when the payment completes
• When the user starts the app (and/or visits a particular page), if the stored PurchaseState is PaymentPending, call GetPurchasesAsync and query the result for a purchase that matches the stored purchase.
• If the PurchaseState for this purchase is still PaymentPending, show the same no-access message
• If the PurchaseState is Purchased, call ConsumePurchaseAsync or AcknowledgePurchaseAsync, depending on the product type

To respond to pending transactions you can subscribe to a listener in your Android project startup:

// Connect to the service here
await CrossInAppBilling.Current.ConnectAsync();

// Check if there are pending orders, if so then subscribe
var purchases = await CrossInAppBilling.Current.GetPurchasesAsync(ItemType.InAppPurchase);

if (purchases?.Any(p => p.State == PurchaseState.PaymentPending) ?? false)
{
  Plugin.InAppBilling.InAppBillingImplementation.OnAndroidPurchasesUpdated = (billingResult, purchases) =>
  {
       // decide what you are going to do here with purchases
       // probably acknowledge
       // probably disconnect
  };
}
else
{
  await CrossInAppBilling.Current.DisconnectAsync();
}

If you do connect the IsConnected propety will be true and when you make purchases or check purchases again you should check ahead of time and not re-connect or disconnect if there are pending purchases

I highly recommend reading the entire Google Play Billing System docs.

Consumable vs Non-consumables on Android

On Android if you purchase anything you must first Acknowledge a purchase else it will be refunded. See the android documentation.

https://developer.android.com/google/play/billing/integrate#process https://developer.android.com/google/play/billing/integrate#pending

For consumables, the consumeAsync() method fulfills the acknowledgement requirement and indicates that your app has granted entitlement to the user. This method also enables your app to make the one-time product available for purchase again.

So, if you have a consumable... ConsumePurchaseAsync will also acknowledge it, if you have a non-consumable you will need to call AcknowledgePurchaseAsync.

Version 4+ Linker Settings

For linking if you are setting Link All you may need to add:

Android:

Plugin.InAppBilling;Xamarin.Android.Google.BillingClient

Android Progaurd Rules

-keep class com.android.billingclient.api.** { *; }
-keep class com.android.vending.billing.** { *; }

iOS:

--linkskip=Plugin.InAppBilling

License

The MIT License (MIT), see LICENSE file.

Want To Support This Project?

All I have ever asked is to be active by submitting bugs, features, and sending those pull requests down! Want to go further? Make sure to subscribe to my weekly development podcast Merge Conflict, where I talk all about awesome Xamarin goodies and you can optionally support the show by becoming a supporter on Patreon.