PaymentGateway-LLD

# Payment Gateway System - Low Level Design A **sophisticated C++ payment gateway system** that demonstrates enterprise-level design patterns and architecture for secure, scalable payment processing infrastructure. ## Design Pattern Implementation - **Template Method Pattern**: Standardized payment flow with validation, initiation, and confirmation steps - **Strategy Pattern**: Multiple banking system integrations with interchangeable payment processors - **Proxy Pattern**: Intelligent retry mechanisms and transaction monitoring - **Factory Pattern**: Dynamic payment gateway creation (Paytm, Razorpay, Stripe) - **Singleton Pattern**: Centralized service management for security and configuration ## Payment Processing Features - **Multi-Gateway Support**: Integration with multiple payment providers (Paytm, Razorpay, and extensible for others) - **Transaction Security**: Secure payment processing with encryption and fraud detection - **Retry Logic**: Intelligent retry mechanisms for failed transactions with exponential backoff - **Transaction Validation**: Comprehensive validation for payment amounts, user credentials, and merchant details - **Status Tracking**: Real-time transaction status monitoring and reporting ## Security Implementation - **Data Encryption**: End-to-end encryption for sensitive payment information - **PCI Compliance**: Architecture designed for PCI DSS compliance requirements - **Fraud Detection**: Built-in fraud detection algorithms and risk assessment - **Audit Trail**: Comprehensive logging and audit trail for all transactions - **Token Management**: Secure token generation and management for recurring payments ## Advanced Features - **Payment Analytics**: Transaction analytics and reporting dashboard - **Webhook Integration**: Real-time payment status updates via webhooks - **Currency Support**: Multi-currency support with real-time exchange rates - **Refund Management**: Automated refund processing and reconciliation - **Merchant Management**: Multi-merchant support with individual configurations ## Technical Excellence - **SOLID Principles**: Clean architecture with dependency injection and interface segregation - **Error Handling**: Comprehensive error handling with custom exception hierarchy - **Performance Optimization**: Optimized algorithms for high-volume transaction processing - **Memory Management**: Efficient resource utilization with smart pointer usage - **Scalability**: Architecture designed for horizontal scaling and high availability The system demonstrates production-ready payment processing architecture with emphasis on security, reliability, and regulatory compliance, suitable for enterprise-level financial applications.

A C++ payment gateway system with multiple design patterns