A CSE developer is primarily involved in developing, implementing, and maintaining databases and web applications. This involves designing and implementing database schemas, writing SQL queries, and developing functional and interactive web applications. They often work with languages like Python, Java, and JavaScript, and use tools like SQL, HTML, CSS, and jQuery. They also ensure data integrity, performance, and security in databases. Furthermore, they may also be responsible for server-side web application logic and integration of the front-end part. Their work requires a strong understanding of relational databases and web technologies.