A Merise developer designs, develops, and maintains databases and applications using the Merise methodology. This French approach to systems analysis and design involves detailing the functional and physical aspects of a system. The developer starts by understanding the system's processes, then represents them using Merise models. They then translate these models into code, often using SQL. They also ensure data integrity and security, manage updates and backups, and troubleshoot any issues that arise. Merise developers often work closely with other IT professionals, like systems analysts and database administrators, to create efficient, effective systems.