Files with the .VAULT extension contain data in a format compatible with the Fontcase app and concern fonts in the Mac OS X operating system. The information contained in the file encompass a list of fonts imported by the user, shared fonts, and system fonts, as well as their parameters, such as their activation or deactivation state, rating, and other data.

The files are used by the system via the Fontcase font manager – not directly by the user. The application is currently no longer being developed or supported – the last modifications were made in 2013.