Worked on an enterprise application built with Spring Boot microservices and React.js, supporting secure, role-based workflows in a production environment. • Collaborated closely with backend teams to understand service boundaries, authentication flows, and transactional behavior across microservices. • Gained hands-on experience with OAuth2-based authentication using AWS Cognito, including token-based authorization and RBAC. • Integrated and consumed secure REST APIs, handling backend-driven validation, authorization, and error scenarios. • Implemented and maintained complex GST calculation logic aligned with backend business rules for commercial and industrial property transactions. • Refactored high-complexity logic to improve maintainability and resolve production and UAT issues safely.