The open IAP standardopeniap-apple 4.1.0 · openiap-google 4.1.0

OpenIAPOne API for every store

Name: OpenIAP
Author: OpenIAP

One type-safe purchase contract across Apple, Google, Amazon, Meta, and 6 app frameworks.

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4K+ combined GitHub stars6 framework libraries

OpenIAP governs two protocols

Client Protocolv1.4.0The purchase API every SDK implements.Commerce Protocolv0.3.4The server-side contract backends implement.

StoreKit 2Play BillingAmazonHorizonVega OS

One open contract OpenIAP mascot

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Native core

AppleStoreKit 2 Google PlayBilling 9.1

Frameworks

Expo React Native Flutter KMP .NET MAUI Godot

Backed by

The problem

Different stores, one contract

Every store ships its own API, types, and events. Your product logic should not have to be rewritten for each one.

Without a shared contractRepeat the same work

StoreKit 2 API Types Events

Play Billing API Types Events

Amazon API Types Events

Horizon API Types Events

Vega OS API Types Events

One shared contractrequestPurchase()Same method · generated types · predictable eventsSee the API

One implementation

Build purchase logic once across 6 framework libraries.

Types that agree

Generated models catch mismatches before they reach production.

Native when needed

Keep access to platform-specific capabilities without forking the whole flow.

How OpenIAP works

One contract, three surfaces

01 / Methods

Unified APIs

Standard methods across all platforms

initConnection()Initialize IAP service fetchProducts()Fetch product details requestPurchase()Initiate purchase flow finishTransaction()Complete purchase getAvailablePurchases()Restore entitlements getActiveSubscriptions()Query active subscriptions

02 / Signals

Standard Events

Consistent event handling patterns

purchaseUpdatedListenerPurchase state changes purchaseErrorListenerError handling promotedProductListenerIOSApp Store promoted products userChoiceBillingListenerAndroidUser Choice Billing selection developerProvidedBillingListenerAndroidExternal billing choice subscriptionBillingIssueListenerSuspended / retry subscriptions

03 / Data

Unified Types

Common data structures for all platforms

ProductProduct information PurchaseTransaction details PurchaseErrorError definitions SubscriptionPeriodBilling cycles ProductSubscriptionSubscription product shape ActiveSubscriptionEntitlement status payload

Hosted infrastructure

A hosted backend for your purchases

IAPKit verifies purchases with each store, keeps entitlements current from store notifications, syncs products through MCP, and reports revenue. It is one open-source implementation of the Commerce Protocol, so your backend can call it, another provider, or your own server through the same protocol.

Open IAPKit MCP workflow

Your appIAPKitStore ecosystemsApple · Google · Amazon · Meta · Vega

Store operations with MCP
Ask your coding agent to create and manage products, then sync them to App Store Connect and Google Play.
Purchase verification
Validate Apple, Google Play, Amazon Appstore, Meta Horizon, and Vega OS purchases server-side.
Subscription state
Track subscription status and user entitlements from store lifecycle events.
Revenue visibility
With store notifications connected, monitor revenue, MRR, churn, and refunds.