What is a UTOC file? A UTOC file stores the table of contents for an Unreal Engine IO Store container, a packaged, optimized storage system that bundles cooked game assets for faster loading and efficient runtime streaming. It contains metadata that the engine uses to locate and identify assets inside a paired .UCAS container, such as asset paths or IDs, byte offsets, compressed sizes, and compression or encryption flags. UTOC files are saved in a compact, binary format optimized for fast lookups at runtime .

More Information Unreal Engine creates UTOC files when developers cook and package a project using the IO Store system. The engine reads the UTOC first to find out where each asset is stored in the paired UCAS file. By using the UTOC and UCAS together, the engine can load game assets quickly during gameplay without needing to unpack many separate files.