Architecting an enterprise-grade full-stack banking web application covering account management, fund transfers, transaction history, and Razorpay Payment Gateway integration. - Designing atomic MongoDB schemas for accounts and audit logs to prevent race conditions and double-spend vulnerabilities in concurrent financial operations - Implementing Razorpay webhook listeners for real-time payment - Building Jest unit and integration test suites for end-to-end data integrity verification across all critical financial workflows - Secured with JWT refresh-token rotation + bcrypt password hashing + RBAC multi-tier access control for role-based permissions Tech: MongoDB · Express.js · React.js · Node.js · JWT · bcrypt · Razorpay API · Jest · Webhook Integration