An Apache Qpid developer works on the Qpid messaging system that implements the Advanced Message Queuing Protocol (AMQP). They design and develop reliable, distributed, and asynchronous messaging systems to enable communication between applications. They ensure seamless interoperability and compatibility across various languages and platforms. Their tasks involve writing code, debugging issues, optimizing performance, and ensuring system security. They also create and maintain documentation, contribute to open-source community discussions, and stay updated with new developments in messaging protocols and technologies. They work closely with other developers to integrate and utilize Qpid in diverse application scenarios.