Methods, systems, and apparatus, including computer program products, for storing an application fragment. In one aspect, a method includes presenting a component in a donor application window corresponding to a donor application, wherein the donor application is executing in a computing system; receiving input selecting the component in the donor application window for insertion into a file system associated with the computing system; generating an application fragment corresponding to the component; and storing the application fragment in the file system. Further, the method can include inserting the application fragment into a recipient application window associated with a recipient application and activating functionality of the recipient application based on the application fragment. Additionally, the application fragment can be activated in the file system and an application including at least a component based on the application fragment can be generated in response to the activating.