A Full Stack Developer specializing in the MERN stack is proficient in MongoDB, Express.js, React, and Node.js. They design, build, and maintain web applications, handling both front-end and back-end development. Their responsibilities include creating dynamic user interfaces with React, building scalable server-side applications with Node.js and Express, and managing databases with MongoDB. They are skilled in JavaScript, understand RESTful APIs, and follow best practices for code optimization and security. Their expertise allows them to take projects from concept to deployment, ensuring efficient, high-performing, and user-friendly applications.