flutter_crosspay

Cross-platform in-app purchase plugin for Flutter. Supports Android, iOS, macOS, Web, Windows, and Linux by Maxint Inc.

Features

• Unified API - one interface for all platforms, regardless of the underlying store
• Entitlement-based model - define products once on the Crosspay backend, map them to App Store, Google Play, Stripe, and GoCardless or Create from the Crosspay dashboard across all platforms
• Consumables, non-consumables, and subscriptions - full support for all product types
• Upgrade/downgrade (proration) - change subscriptions with prorated billing
• Real-time purchase events - listen to a stream of purchase successes, cancellations, and failures
• Active entitlement tracking - query the user's current subscriptions and owned products

Platform Support

Platform	Store	Mechanism
Android	Google Play	in_app_purchase_android (BillingClient)
iOS	App Store	in_app_purchase_storekit (StoreKit)
macOS	App Store	in_app_purchase_storekit (StoreKit)
Web	Stripe / GoCardless	Browser redirect to checkout
Windows	Stripe / GoCardless	Browser redirect to checkout
Linux	Stripe / GoCardless	Browser redirect to checkout

Installation

Run following in your terminal to add the package to your Flutter project:

$ flutter pub add flutter_crosspay

Setup

Follow our docs to setup your Crosspay account and configure your products and entitlements: https://crosspay.dev/docs/

Usage

Initialize

Create a FlutterCrosspay instance with your Crosspay API key and environment:

import 'package:flutter_crosspay/flutter_crosspay.dart';

final crosspay = FlutterCrosspay(
  publicKey: 'YOUR_CROSSPAY_PUBLIC_KEY',
  environment: CrosspayEnvironment.sandbox, // or .production
);

// Identify the customer (required before making purchases)
await crosspay.identify('user@example.com');

List available entitlements

Fetch all products/entitlements configured in your Crosspay dashboard:

final entitlements = await crosspay.listEntitlements();

for (final entitlement in entitlements) {
  print('${entitlement.name} - ${entitlement.entitlementType.name}');
}

Each CrosspayEntitlement contains store-specific product references (.products.playStore, .products.appStore, .products.stripe, .products.gocardless).

Query store products

Get normalized product details (price, currency, recurrence) for a specific external store:

// On web/desktop, specify the store:
final products = await crosspay.queryProducts(ExternalStore.stripe);

// On mobile/macOS, the externalStore is ignored (IAP is used):
final iapProducts = await crosspay.queryProducts(ExternalStore.stripe);

for (final product in products) {
  print('${product.name}: ${product.formattedPrice}');
}

Make a purchase

await crosspay.purchase(
  entitlement,
  externalStore: ExternalStore.stripe,    // stripe or gocardless for web/desktop
  redirectUrl: 'https://yourapp.com/success',
  failureRedirectUrl: 'https://yourapp.com/failure',
);

On mobile/macOS, the externalStore parameter is ignored - the native IAP flow is used automatically.

Upgrade / downgrade a subscription

PlayStore and App Store support this automatically. But for Stripe/GoCardless, we need the hierarchy of products to be defined in the Crosspay dashboard. So make sure to create Offerings in the Crosspay dashboard for the entitlements you want to allow upgrades/downgrades for.

Otherwise, it needs to be done manually like below. Pass the current product and proration mode when changing subscriptions:

await crosspay.purchase(
  newEntitlement,
  externalStore: ExternalStore.stripe,
  redirectUrl: 'https://yourapp.com/success',
  failureRedirectUrl: 'https://yourapp.com/failure',
  proratedProduct: currentEntitlement.products.stripe,
  prorationMode: ProrationMode.upgrade,   // or ProrationMode.downgrade
);

Listen to purchase events

crosspay.purchaseEvents.listen((event) {
  switch (event.event) {
    case PurchaseEventType.success:
      print('Purchase completed!');
    case PurchaseEventType.canceled:
      print('User cancelled the purchase.');
    case PurchaseEventType.failed:
      print('Receipt verification failed.');
    case PurchaseEventType.error:
      print('An error occurred during purchase.');
  }
});

Get active entitlements

Check what the user currently owns:

final activeEntitlements = await crosspay.getActiveEntitlements();

for (final e in activeEntitlements) {
  print('${e.entitlementId} - status: ${e.status.name}, expires: ${e.expiresAt}');
}

Manage subscriptions

// Android: open Google Play subscription management
launchUrl(Uri.parse(crosspay.playStoreManagementUrl));

// iOS / macOS: open App Store subscription management
launchUrl(Uri.parse(crosspay.appStoreManagementUrl));

Clean up

crosspay.logout();  // Clears customer identity, stops SSE stream

Configuration

The Crosspay backend must be configured with your products and store mappings. See the Crosspay documentation for details on setting up entitlements, products, and store integrations.

License

MIT - see the LICENSE file for details.