An IBM WebSphere MQ developer is responsible for designing, developing, and maintaining message-oriented middleware applications using IBM's WebSphere MQ. They configure MQ objects like Queue Managers, Queues, and Channels, and handle error logs and dead letter queues. The developer ensures seamless data communication across multiple platforms, integrates applications and services with MQ, and troubleshoots any issues in the messaging system. They also optimize system performance, ensure system security, and may provide technical support. Proficiency in JMS API, MQ scripting, and understanding of network protocols and database connectivity are crucial for this role.