An IIB Developer is responsible for designing, developing, and maintaining integration solutions using IBM Integration Bus (IIB), now known as IBM App Connect Enterprise (ACE). They work with enterprise systems to facilitate seamless data flow between applications through message transformation, routing, and protocol mediation. Their role involves developing message flows, configuring message queues, troubleshooting integration issues, and ensuring data consistency across systems. IIB Developers typically work in middleware environments, collaborating with business analysts, architects, and other developers to create efficient integration solutions. Strong knowledge of IBM MQ, ESQL, Java, and XML is essential for success in this role.