Application program caching and execution is disclosed. An application program component, which may constitute the only component of an application program, is cached by a computing device from an original computing device. The computing device executes the cached component in lieu of its execution by the original computing device. The computing device may be a client computing device, where the client device executes the cached component for itself. The computing device may also be a caching computing device, where the caching device executes the cached component for the client computing device.