ARX is a archiving file format with advanced features especially designed to meet the requirements of game designers. These features include external data referencing, data synchronization with remote data storages, in-memory merging of multiple archives and arbitrary data items structuring.

Arxx is the application programmer interface (API) definition for using ARX archives in C++ and extends ARX' feature set with Templates, a method of applying semantic meaning to arbitrary binary data by means of an XML data description template.