•Architected and developed a real-time customer transaction monitoring system that processed over 10 million transactions daily, leveraging advanced algorithms to detect fraudulent activities and prevent financial losses, thereby improving security for Capital One’s customers.•Built robust backend services using Java 8 and Spring Boot, following microservices architecture principles. Designed and implemented RESTful APIs for seamless integration with front-end systems, third-party services, and databases, ensuring modularity, scalability, and ease of maintenance.•Developed a user-friendly fraud detection dashboard using Angular, enabling fraud analysts to view real-time alerts and insights into suspicious transactions which included advanced filtering, data visualization, and decision-making tools, optimizing the response time for manual investigations.•Utilized MongoDB for storing unstructured and semi-structured data (such as transaction metadata and logs), and Oracle DB for structured transactional records, providing efficient data storage and fast retrieval capabilities to support real-time fraud analysis, made database indexing, and optimized query performance for rapid data access.•Created multithreading and asynchronous processing techniques in Java to enhance application performance and reduce response times by 25% under high transaction volumes which improved system throughput and responsiveness, especially during peak periods.•Connected Spring Security for authentication and authorization, using JWT (JSON Web Tokens) for token-based user authentication, ensuring secure access to backend services and protecting sensitive data in the fraud detection system.•Leveraged AWS Lambda for serverless computing to execute code in response to events or API calls, optimizing cost efficiency and scaling based on demand without managing server infrastructure and reducing infrastructure costs by 35%.

•Developed scalable backend solutions using Java to manage core functionalities such as user authentication, product catalog management, and order processing, enhancing system modularity and maintainability.•Made responsive and interactive user interfaces for the e-commerce platform using React.js, allowing real-time updates of product availability, customer reviews, and order status, improving user engagement and reducing page load times by 30%.•Created a microservices-based e-commerce platform, breaking down core functionalities such as user authentication, product catalog management, and order processing into independently deployable services, ensuring scalability and flexibility.•Improved page load times by 20% by implementing asynchronous data fetching, lazy loading, and optimizing React components for better client-side performance.•Integrated PostgreSQL with Spring Data JPA for seamless interaction between the application’s backend services and the database, ensuring smooth data persistence and retrieval for user and order-related information.•Created a JMS Queue to handle high-volume order processing requests, allowing the system to process orders asynchronously, thus decoupling order creation from payment verification and speeding up overall order flow.•Integrated Azure Key Vault to securely manage sensitive credentials, API keys, & connection strings, enhancing the security of the application and reducing the risk of data breaches by enforcing encryption & secure access policies.•Designed a scalable caching layer using Redis to store frequently accessed data such as product details, user sessions, and shopping carts, reducing database load and improving response times by up to 40%.•Wrote unit tests using JUnit and Mockito, achieving 90%+ test coverage, ensuring robust and error-free code before production deployment.