A MEANJS developer builds and maintains web applications using the MEAN stack, which includes MongoDB, Express.js, AngularJS, and Node.js. They design and implement APIs, manage data storage, and create dynamic and interactive user interfaces. Their role also involves troubleshooting and resolving application issues. They optimize applications for speed and scalability while ensuring security and data protection. Their work spans the full development cycle, from conceptualization and planning to testing and deployment. They may also collaborate with other team members, like UI/UX designers and project managers, to deliver high-quality software that meets user needs.