Building a real-time bidirectional chat and live device tracking application using Socket.io WebSocket protocol and HTML5 Geolocation API with Leaflet.js live map visualization. - Architecture designed to handle 10+ concurrent WebSocket connections via event-driven, non-blocking Node.js backend optimized for high-concurrency scenarios - Implementing JWT refresh-token rotation for secure session management. - Integrating HTML5 Geolocation API with Leaflet.js interactive maps for live multi-user device tracking with real-time position updates - Mobile-first React.js frontend with lazy loading and Core Web Vitals optimization for fast, smooth user experience across devices Tech: React.js · Node.js · Express.js · MongoDB · Socket.io · WebSocket · Leaflet.js · JWT · HTML5 Geolocation API