Led the design and development of a scalable, secure, cloud-native referral management SaaS platform connecting job seekers, professional referrers, and recruiters. Architected end-to-end modern authentication flows using OAuth2 SSO (Google/LinkedIn), JWT stateless sessions with secure refresh token rotation, and fine-grained RBAC for API access protection. Designed a fully serverless AWS backend leveraging DynamoDB for scalable NoSQL persistence, S3 for file and resume storage, SES for email delivery, SNS for SMS notifications, and SQS/EventBridge for asynchronous workflows with SLA and expiry automation. Integrated AI-powered fraud detection, multi-factor OTP authentication, rate limiting, and company domain validation to ensure high security and anti-abuse protection. Implemented an event-driven architecture with serverless scheduling, queue-based processing, and automatic scaling for high availability and performance. Delivered advanced marketplace features including batch company/candidate listing, referral assignment automation, and state tracking with expiry management. Built a production-grade React & TypeScript dashboard for job candidates to manage referrals and applications. Delivered a seamless UX with advanced search/filter options, tab-based status views, efficient pagination, and real-time status updates using React Query. Applied modern UI tech including Shadcn/UI and Tailwind CSS for an accessible, mobile-friendly design with robust error handling and toast notifications. Owned the backend microservices development with Spring Boot (Java), implemented all authentication and security layers, AWS integrations, and AI-driven fraud detection flows. Established cloud-first DevOps patterns for seamless scaling, monitoring, and continuous feature delivery.