This document describes techniques that enable an application to operate as if the application were running on its native computing system when it is actually running on another computing system. The techniques may do so by building a portable database having metadata particular to the application, which can be stored in a portable device along with that application. When that portable device is connected to another computing system, the portable database may be used to supplement or supplant the other computing system's database to enable the application to operate with its particular functionality.