Developed a full-stack real-time chat application with intelligent AI-powered auto-response functionality, enabling seamless communication between users with automated message handling during offline periods. Key Features & Contributions: - Built robust user authentication system with JWT-based authorization, including secure registration, login, and logout functionality using Bcrypt password hashing. - Implemented real-time bidirectional messaging using Socket.IO, enabling instant message delivery and live online/offline user status tracking. - Integrated AI-powered automated response system using LLM API that intelligently replies to incoming messages when users set themselves to offline mode, maintaining conversation continuity Designed RESTful APIs with Express.js for user management, message handling, and real-time data synchronization between frontend and backend. - Implemented comprehensive security measures including rate limiting with Express-rate-limit, MongoDB query sanitization, XSS attack prevention, and CORS configuration. - Developed responsive and intuitive user interface using React.js with Redux Toolkit for global state management and Redux-persist for session persistence across browser refreshes. - Built user search functionality and real-time notification system using React-hot-toast for enhanced user experience. - Optimized backend performance with compression middleware for gzip compression and efficient MongoDB data modeling using Mongoose.