A Data Flow Diagrams (DFD) developer designs and implements visual representations of data flow within a system. They outline how information moves and how it is processed, focusing on where it originates and where it goes. The DFD developer's role includes analyzing and understanding business requirements, designing DFDs to represent the flow of data accurately, and validating these diagrams against user requirements. They also work closely with various stakeholders such as system developers, project managers, and end users to ensure the DFDs accurately represent the system and its processes. Additionally, DFD developers play a critical role in system development lifecycle.