A GEB Framework developer is responsible for automating browser interactions using the Groovy language. They utilize GEB, a powerful library for handling such tasks, to create comprehensive, readable, and maintainable test scripts. Their tasks involve integrating the framework with testing tools like Spock or JUnit, managing page objects, handling different browser setups, and dealing with asynchronous content. They also ensure that the web application's interface functions as expected across various platforms and browsers. Solving complex technical issues, enhancing the test automation framework, and collaborating with the software development team is also a part of their role.