A Mingle developer works with ThoughtWorks' Mingle, a project management and collaboration software. Their role involves creating, customizing, and managing agile project workflows, enabling teams to collaborate and track their work effectively. They use Mingle's flexible templates to adapt to unique project needs, integrate with other tools for a seamless workflow, and ensure data security. They also troubleshoot technical issues and provide user support. Additionally, the developer uses analytics features in Mingle to generate insightful reports, aiding strategic decision-making. Hence, a Mingle developer plays a crucial role in enhancing project management and team productivity.