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Flutter SDK

Add in-app purchases and paywalls to your Flutter app with a single Dart package.

The CashSDK Flutter SDK is one Dart package that runs on both iOS (StoreKit 2) and Android (Play Billing). Fetch offerings, run purchases, and read entitlements with the same async code on every target.

Install#

bash
flutter pub add cashsdk

This adds the dependency to your pubspec.yaml:

yaml
dependencies:
  cashsdk: ^1.0.0

Configure#

Initialize CashSDK once in main(), before runApp. Use your publishable key.

dart
import 'package:flutter/material.dart';
import 'package:cashsdk/cashsdk.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await CashSDK.configure(apiKey: 'pk_live_...');
  runApp(const MyApp());
}

Ship only publishable keys (pk_live_… / pk_test_…) in your app. Secret keys (csk_sk_…) belong on your backend.

Fetch offerings#

An offering holds the packages you present on a paywall, such as monthly and annual.

dart
final offering = await CashSDK.offerings();

final monthly = offering.monthly;
final annual = offering.annual;

Purchase#

Pass a package to purchase. CashSDK drives the native store flow, validates the receipt, and returns the customer's updated entitlements.

dart
final result = await CashSDK.purchase(offering.monthly);

if (result.entitlements['pro']?.isActive == true) {
  unlockPro();
}

Check entitlements#

Read entitlements from any purchase or restore result to gate features.

dart
if (result.entitlements['pro']?.isActive == true) {
  // Show premium content
} else {
  // Show the paywall
}

Restore purchases#

Let customers recover access on a new device or after a reinstall.

dart
final result = await CashSDK.restorePurchases();

if (result.entitlements['pro']?.isActive == true) {
  unlockPro();
}

Identify the customer#

Link the SDK to your own user ID so entitlements follow the customer across devices and platforms. Call identify once the user has signed in.

dart
CashSDK.identify('u_812');

A paywall widget#

Fetch the offering in initState, present its packages, and unlock on success.

dart
import 'package:flutter/material.dart';
import 'package:cashsdk/cashsdk.dart';

class Paywall extends StatefulWidget {
  const Paywall({super.key, required this.onUnlock});
  final VoidCallback onUnlock;

  @override
  State<Paywall> createState() => _PaywallState();
}

class _PaywallState extends State<Paywall> {
  Offering? _offering;

  @override
  void initState() {
    super.initState();
    CashSDK.offerings().then((o) => setState(() => _offering = o));
  }

  Future<void> _buy(Package package) async {
    final result = await CashSDK.purchase(package);
    if (result.entitlements['pro']?.isActive == true) widget.onUnlock();
  }

  @override
  Widget build(BuildContext context) {
    final offering = _offering;
    if (offering == null) return const CircularProgressIndicator();
    return Column(
      children: [
        const Text('Unlock Pro'),
        FilledButton(
          onPressed: () => _buy(offering.monthly),
          child: Text(offering.monthly.localizedPrice),
        ),
        TextButton(
          onPressed: CashSDK.restorePurchases,
          child: const Text('Restore purchases'),
        ),
      ],
    );
  }
}

Next steps#

Build a paywall

Present offerings and convert.

Entitlements

Model and gate access correctly.

API reference

The REST API behind the SDK.