A Mapper Developer is responsible for creating and maintaining software applications that convert data from one format to another, typically in a data integration context. They design mapping specifications to transform raw data into meaningful information. This involves understanding source and target data structures, creating transformation rules, and implementing these rules in a mapping tool or programming language. Additionally, they debug and test their maps to ensure accuracy and efficiency. They often work closely with data analysts and other stakeholders to understand business requirements and ensure the transformed data meets these needs. Their role is crucial in data-driven decision making.