In-App Purchases SDK

Developers can use Apple's StoreKit framework to incorporate in-app purchases (IAPs) into their apps on iOS, macOS, watchOS, and tvOS. The framework facilitates secure payment processing on behalf of the app, connecting with the AppStore and requesting user authorization for payments.

Google Play Billing is Google's required payment system for in-app purchases and subscriptions distributed through the Google Play Store. It handles transaction processing, receipt verification, subscription lifecycle management (renewals, cancellations, grace periods, holds), and revenue reporting. Google charges a commission of 15% on the first $1 million in annual revenue earned through the Play Store, and 30% on revenue above that threshold. For subscriptions specifically, Google reduced its commission to 15% for all subscription revenue starting in January 2022, recognizing the importance of recurring relationships. The Google Play Billing Library provides APIs for querying available products, launching purchase flows, acknowledging purchases, and handling subscription state changes. Like Apple's StoreKit, Google Play Billing abstracts the complexity of payment processing across regions, currencies, and payment methods. However, regulatory pressure — particularly in the EU, South Korea, and India — has led Google to allow alternative billing options in certain markets, enabling developers to process payments through third-party systems while still distributing their apps on the Play Store, sometimes with a reduced commission.

In iOS, developers can enable users to purchase additional features or content within an app using in-app purchases, providing a way to monetize their apps beyond the initial purchase price or to offer a "freemium" model. Apple manages the payment process and deducts a commission, known as the "Apple tax", from the sales amount.

In-app subscriptions are a payment model in which users are charged on a recurring basis in exchange for access to premium content, exclusive features, or services. They are frequently used by developers as a way to monetize their apps by providing users with ad-free experiences or exclusive content.

Server validation, also known as server-side receipt validation, is a process used to ensure that purchases made within an app are authentic. This is achieved by using an encrypted file, in PKCS#7 format, which contains information about all in-app purchases. To authenticate purchased content, you can include receipt validation code in your app or server. App Store receipt validation involves sending a request to Apple's servers to verify the purchase and determine whether it was valid. This is particularly important for auto-renewable subscriptions as you need to know when they expire in order to provide or block access to your content. Receipt validation is also used when users need to restore a purchase, such as when they reinstall your app.