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https://github.com/aliumairdev/flutter_pay_kit

A unified API for integrating multiple payment processors in Flutter apps.
https://github.com/aliumairdev/flutter_pay_kit

braintree flutter paddle paymetgateway stripe-payments

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A unified API for integrating multiple payment processors in Flutter apps.

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README 

          
# Flutter Universal Payments



[![pub package](https://img.shields.io/pub/v/flutter_universal_payments.svg)](https://pub.dev/packages/flutter_universal_payments)

[![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](https://opensource.org/licenses/MIT)



A unified, production-ready payment API for Flutter that supports multiple payment processors with a single, consistent interface. Switch between payment providers without rewriting your code.



## ✨ Features



- 🔌 **Unified API** - One consistent interface for all payment processors

- 💳 **6 Payment Processors** - Stripe, Paddle, Braintree, Lemon Squeezy, Totalpay, and Fake (for testing)

- 🔄 **Hot-Swappable** - Switch processors at runtime without code changes

- 📱 **Ready-to-Use Widgets** - Pre-built payment UI components

- 🎨 **Highly Customizable** - Customize every aspect to match your brand

- 🔒 **Secure by Design** - PCI-compliant patterns, no card data storage

- 🧪 **Testing Support** - Built-in fake processor for development

- 📊 **Analytics Ready** - Firebase, Sentry, and custom analytics integrations

- 🔐 **Smart Caching** - Automatic data caching with secure storage

- 🚀 **Production Ready** - Comprehensive error handling and retry logic

- 🎯 **Type Safe** - Full Dart type safety with Freezed models

- ⚡ **State Management** - Built-in Riverpod integration



## 📦 Supported Payment Processors



| Processor | Subscriptions | One-time Payments | Plan Swapping | Webhooks | Testing |

|-----------|:-------------:|:-----------------:|:-------------:|:--------:|:-------:|

| **Stripe** | ✅ | ✅ | ✅ | ✅ | Sandbox |

| **Paddle** | ✅ | ✅ | ✅ | ✅ | Sandbox |

| **Braintree** | ✅ | ✅ | ✅ | ✅ | Sandbox |

| **Lemon Squeezy** | ✅ | ✅ | ✅ | ✅ | Test Mode |

| **Totalpay** | ✅ | ✅ | ✅ | ✅ | Sandbox |

| **Fake** | ✅ | ✅ | ✅ | ❌ | Built-in |



## 🚀 Quick Start

- Unified API across all payment processors

- **Native Google Pay integration for Android**

- **Native Apple Pay integration for iOS** (iOS 13.0+)

- Type-safe payment models using Freezed

- State management with Riverpod

- Comprehensive error handling

- Easy switching between processors

- Built-in retry logic

- Local payment method storage

- Support for one-time and recurring payments

- Production-ready architecture



### Installation



Add to your `pubspec.yaml`:



```yaml

dependencies:

  flutter_universal_payments: ^0.1.0

```



Then run:



```bash

flutter pub get

```



### Basic Usage



### Apple Pay Integration (iOS)



```dart

import 'package:flutter_universal_payments/flutter_universal_payments.dart';



// 1. Configure your payment processor

final config = PaymentConfigurationBuilder()

  .useStripe(

    publishableKey: 'pk_test_...',

    secretKey: 'sk_test_...',

    webhookSecret: 'whsec_...',

  )

  .enableLogging()

  .build();



// 2. Initialize the payment service

await FlutterUniversalPayments.initialize(

  config: config,

  storage: storage, // Your Storage implementation

);



// 3. Get the service instance

final paymentService = FlutterUniversalPayments.instance;



// 4. Initialize customer

await paymentService.initialize(

  email: 'customer@example.com',

  name: 'John Doe',

);



// 5. Create a subscription

final subscription = await paymentService.subscribe(

  priceId: 'price_monthly_999',

  trialDays: 14,

);



print('Subscription created: ${subscription.id}');

```



### UI Widgets



The package includes ready-to-use payment widgets:



```dart

// Display pricing plans

PricingTable(

  plans: [

    SubscriptionPlanData(

      id: 'basic',

      name: 'Basic',

      price: Price(

        id: 'price_basic',

        amount: 999,

        currency: 'USD',

        interval: BillingInterval.month,

      ),

      features: ['Feature 1', 'Feature 2'],

    ),

  ],

  onPlanSelected: (plan) async {

    await paymentService.subscribe(priceId: plan.price.id);

  },

)



// Payment card input

PaymentCardInput(

  onCardChanged: (cardData) {

    // Handle card data

  },

)



// Subscription status display

SubscriptionStatusWidget(

  subscription: subscription,

)

```



## 📖 Documentation



- **[Getting Started Guide](doc/getting_started.md)** - Detailed setup for each processor

- **[Widgets Documentation](doc/widgets.md)** - UI components and customization

- **[Advanced Usage](doc/advanced.md)** - Webhooks, custom processors, best practices

- **[API Reference](https://pub.dev/documentation/flutter_universal_payments/latest/)** - Complete API docs



### Processor-Specific Guides



- [Stripe Integration](doc/processors/stripe.md)

- [Paddle Integration](doc/processors/paddle.md)

- [Braintree Integration](doc/processors/braintree.md)

- [Lemon Squeezy Integration](doc/processors/lemon_squeezy.md)

- [Totalpay Integration](doc/processors/totalpay.md)



## 🎯 Core Concepts



### Customer Management



```dart

// Initialize a customer

await paymentService.initialize(

  email: 'customer@example.com',

  name: 'John Doe',

  phone: '+1234567890',

);



// Get current customer

final customer = await paymentService.getCurrentCustomer();



// Refresh customer data

await paymentService.refreshCustomer();

```



### Subscriptions



```dart

// Create subscription with trial

final subscription = await paymentService.subscribe(

  priceId: 'price_monthly',

  trialDays: 14,

);



// Check subscription status

final hasActive = await paymentService.hasActiveSubscription('product_id');

final isOnTrial = await paymentService.isOnTrial('product_id');



// Change subscription plan

await paymentService.changePlan(

  subscriptionId: subscription.id,

  newPriceId: 'price_annual',

);



// Cancel subscription

await paymentService.cancelSubscription(

  id: subscription.id,

  immediate: false, // Grace period until end of billing cycle

);



// Resume canceled subscription

await paymentService.resumeSubscription(id: subscription.id);

```



### Payment Methods



```dart

// Add payment method

await paymentService.setDefaultPaymentMethod(paymentMethodToken);



// Get all payment methods

final methods = await paymentService.getPaymentMethods();



// Remove payment method

await paymentService.removePaymentMethod(methodId);

```



### One-Time Payments



```dart

// Create a one-time charge

final charge = await paymentService.makePayment(

  amount: 2999, // $29.99

  currency: 'USD',

  description: 'Premium upgrade',

  paymentMethodToken: token,

// Configure Google Pay

final googlePayConfig = GooglePayConfig(

  merchantId: 'your-merchant-id',

  merchantName: 'Your Store',

  environment: GooglePayEnvironment.production,

);

```



## 🔄 Switching Processors



One of the most powerful features is the ability to switch payment processors without changing your code:



```dart

// Start with Stripe

final stripeConfig = PaymentConfigurationBuilder()

  .useStripe(publishableKey: '...', secretKey: '...')

  .build();



await FlutterUniversalPayments.initialize(config: stripeConfig);



// Later, switch to Paddle

final paddleConfig = PaymentConfigurationBuilder()

  .usePaddle(

    vendorId: '...',

    authCode: '...',

    publicKey: '...',

  )

  .build();



await FlutterUniversalPayments.reinitialize(config: paddleConfig);



// Your app code remains the same!

```



## 🎨 Customization



All widgets are highly customizable:



```dart

PricingTable(

  plans: plans,

  layout: PricingLayout.grid(crossAxisCount: 3),

  cardDecoration: BoxDecoration(

    gradient: LinearGradient(

      colors: [Colors.blue, Colors.purple],

    ),

    borderRadius: BorderRadius.circular(20),

  ),

  selectedPlanColor: Colors.green,

  onPlanSelected: (plan) => handlePlanSelection(plan),

  headerBuilder: (context) => CustomHeader(),

)

```



## 📊 Analytics & Logging



Built-in support for analytics and logging:



```dart

// Enable logging

PaymentLogger.enable();

PaymentLogger.setLogLevel(LogLevel.debug);



// Add analytics providers

PaymentLogger.registerAnalyticsProvider(

  FirebaseAnalyticsProvider(analytics),

);



// Automatic event logging

// - Payment success/failure

// - Subscription created/canceled

// - Plan changes

// - Checkout events

```



## 🧪 Testing



Use the built-in fake processor for testing:



```dart

final testConfig = PaymentConfigurationBuilder()

  .useFake(

    simulateDelays: true,

    delayDuration: Duration(seconds: 1),

    failureRate: 0.1, // 10% failure rate

  )

  .build();



await FlutterUniversalPayments.initialize(config: testConfig);

```



## 🏗️ Architecture



The package follows clean architecture principles:



```

lib/

├── src/

│   ├── models/          # Data models (Customer, Subscription, Charge, etc.)

│   ├── processors/      # Payment processor implementations

│   ├── services/        # Business logic (PaymentService)

│   ├── widgets/         # UI components

│   ├── utils/           # Logging, analytics

│   └── exceptions/      # Custom exceptions

└── flutter_universal_payments.dart  # Public API

```



## 🔒 Security Best Practices



- Never store sensitive card data locally

- Use tokenization for payment methods

- Implement webhook signature verification

- Enable logging with sensitive data masking

- Use secure storage for customer IDs and tokens

- Always use HTTPS endpoints

- Validate all user inputs



See [Advanced Usage](doc/advanced.md#security-best-practices) for detailed security guidelines.



## 🤝 Contributing



We welcome contributions! Please see our [Contributing Guide](CONTRIBUTING.md) for details.



### Development Setup



```bash

# Clone the repository

git clone https://github.com/aliumairdev/flutter_pay_kit.git

cd flutter_pay_kit



# Install dependencies

flutter pub get



# Run code generation

flutter pub run build_runner build



# Run tests

flutter test



# Run example app

cd example

flutter run

```



## 📝 License



This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.



## 🆘 Support

// Check availability

final isAvailable = await googlePayConfig.isAvailable();



if (isAvailable) {

  // Request payment

  final token = await googlePayConfig.requestPayment(amount: 2500);



  if (token != null) {

    // Process the token with your payment processor

    print('Payment token: $token');

  }

}

```



For detailed Google Pay integration instructions, see [GOOGLE_PAY_INTEGRATION.md](GOOGLE_PAY_INTEGRATION.md).

// Check if Apple Pay is available

final isAvailable = await ApplePayHandler.isAvailable();

if (isAvailable) {

  // Request payment

  final result = await ApplePayHandler.requestPayment(

    amount: 1999, // $19.99 in cents

    currency: 'USD',

    merchantId: 'merchant.com.yourcompany.yourapp',

    countryCode: 'US',

    label: 'Premium Subscription',

  );



  // Process the payment token with your backend

  final paymentData = result['paymentData'];

  // Send to your payment processor

}

```



For complete Apple Pay setup instructions, see [APPLE_PAY_SETUP.md](APPLE_PAY_SETUP.md).



## Architecture



- **Documentation**: [doc/getting_started.md](doc/getting_started.md)

- **Issues**: [GitHub Issues](https://github.com/aliumairdev/flutter_pay_kit/issues)

- **Discussions**: [GitHub Discussions](https://github.com/aliumairdev/flutter_pay_kit/discussions)



## 🗺️ Roadmap



- [ ] Apple Pay support

- [ ] Google Pay support

- [ ] PayPal direct integration

- [ ] Cryptocurrency payments

- [ ] Invoice generation

- [ ] Receipt management

- [ ] Multi-currency support

- [ ] Tax calculation integration

- [ ] Fraud detection hooks



## 📦 Requirements



- **Dart SDK**: `>=3.0.0 <4.0.0`

- **Flutter SDK**: `>=3.10.0`



## 🌟 Examples



Check out the [example](example/) directory for a complete Flutter app demonstrating all features:



- Customer initialization

- Subscription management

- Payment method handling

- One-time payments

- UI widgets showcase

- Analytics integration



## 📚 Additional Resources



- [Flutter Documentation](https://flutter.dev/docs)

- [Dart Documentation](https://dart.dev/guides)

- [Riverpod Documentation](https://riverpod.dev)

- [Stripe API Documentation](https://stripe.com/docs/api)

- [Paddle API Documentation](https://developer.paddle.com/)

- [Braintree API Documentation](https://developer.paypal.com/braintree/docs)



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