A GoF (Gang of Four) Patterns developer utilizes a set of design patterns to solve common programming challenges. They apply these reusable solutions to enhance modularity and improve code readability. Their responsibilities include, but are not limited to, creating software architecture, identifying and implementing suitable design patterns (like Singleton, Factory, Decorator, and Observer), and ensuring the software can be easily maintained and scaled. They focus on object-oriented design principles, encapsulating changes in software's behavior and making it robust. Their role is crucial in ensuring efficient communication between objects and classes, and enhancing overall software design.