A GMake Developer primarily works on GNU Make, a powerful tool used in software development for managing and automating workflows. They write makefiles, which are special format files that help build and manage projects automatically. These developers identify dependencies between project components and ensure efficient building and re-building processes. They debug makefiles, enhance the functionality of existing ones, and develop new features. They also collaborate with other software developers to understand their needs and ensure GMake serves those needs effectively. Additionally, they may be involved in troubleshooting, resolving issues, and maintaining the GNU Make documentation.