A Burp Suite developer utilizes the Burp Suite toolset for web security testing. They identify potential vulnerabilities by intercepting, reviewing, and modifying network requests and responses between a browser and a web application. They perform functions like mapping and analyzing application content, automating customized attacks to exploit vulnerabilities, and checking session tokens or other security-related data. The developer may also use the tool's features to decipher and compare application data, and document key details of their testing process. They play a crucial role in enhancing an organization's web application security and preventing potential cyber threats.