A Google DFA Reporting API developer creates, manages, and automizes reports within Google's DoubleClick Campaign Manager (DCM). They utilize Google's DFA Reporting API to extract data from DCM and integrate it with other applications. They also handle the API's interactive features, like filtering and sorting data. Furthermore, they ensure seamless data flow, troubleshoot potential issues, and improve the efficiency of data management. Their work aids in the analysis of advertising campaign performance, thus enabling strategic decision-making. The developer should understand the API's functionalities and stay updated with Google's API changes.