A Jenkins developer is responsible for setting up, configuring, and managing continuous integration (CI) and continuous delivery (CD) pipelines using Jenkins software. They automate the software development process by integrating code changes, validating those changes, and building project artifacts. They also maintain the Jenkins system, manage plugins, troubleshoot build failures, and ensure system reliability. Additionally, they collaborate with other developers to implement testing strategies, improve code quality, and optimize deployment processes. Their work facilitates a more efficient and error-free development lifecycle, leading to faster, more reliable software releases.