Design, develop, and maintain responsive, performant mobile applications using ReactJS and TypeScript. Implement scalable, reusable UI components with CSS/SCSS. Build seamless experiences across mobile and desktop devices, iOS and Android. Collaborate with engineers, designers, product managers, and QA to deliver high-impact features. Integrate REST APIs and WebSocket services into the frontend. Optimize for performance, maintainability, and reliability. Review code, share feedback, and mentor junior engineers. Debug and troubleshoot frontend issues using modern developer tools.