ThemeEngine

ThemeEngine is a macOS application designed for editing compiled .car files, the resource bundles used by the operating system to store image and UI assets. It provides a graphical interface that lets users open, modify, and save these files, enabling the creation or alteration of visual themes for OS X Yosemite and later versions. The tool targets developers, designers, and power users who need to customize the appearance of macOS applications or the system itself by working directly with the compiled asset containers.

The software runs natively on macOS, with its stable release supporting OS X Yosemite and the V.2 branch extending compatibility to macOS 10.11 and newer. It focuses on the specific task of .car file manipulation, offering a straightforward workflow for inspecting the contents of a compiled asset catalog, making changes, and exporting the updated file for use in the operating system or applications.

Because it operates on the compiled form of asset catalogs, ThemeEngine bypasses the need to rebuild source asset files for visual tweaks, making it a practical utility for those who need to experiment with or apply custom themes without deep integration into the original development pipeline.