A MERN stack developer is responsible for the full lifecycle of web application development, using MongoDB, Express.js, React.js, and Node.js. Key duties include designing and developing applications, writing clean code, collaborating with cross-functional teams, troubleshooting issues, and ensuring application performance, quality, and responsiveness. Core responsibilitiesFull-stack development: Design, develop, and maintain web applications from front-end to back-end using the MERN stack.Code and quality: Write efficient, testable, and reusable code, and ensure the performance, quality, and responsiveness of applications.Collaboration: Work with project managers, designers, and other developers to define, design, and ship new features.Problem-solving: Troubleshoot and debug issues throughout the development lifecycle.Maintenance and deployment: Manage application deployment and ensure security and data protection settings are in place.