A Knoppix developer works on the development, maintenance, and improvement of the Knoppix operating system, a Debian-based Linux distribution. Their responsibilities include writing and debugging code, creating innovative features, and ensuring the OS's stability and efficiency. They also troubleshoot and resolve issues reported by users. In addition, they contribute to the design and implementation of user interfaces, ensuring they are user-friendly. They may also collaborate with other developers and professionals, contribute to technical documentation, and stay updated with the latest technological advancements in the field of Linux OS development.