A JavaBean developer designs and implements reusable software components in Java, known as JavaBeans. These components are used to encapsulate many objects into a single object (the bean), allowing simplified access and manipulation of data. Responsibilities include defining properties, methods, and events that the bean exposes to other components in an application. JavaBean developers often work with visual programming environments that allow beans to be combined and reused to create complex applications. They must ensure beans are serializable, have a no-argument constructor, and follow specific naming conventions. They may also be involved in debugging and testing.