Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for requesting handling web applications provided from a server. A bootstrap object is received from the server. The bootstrap object is independent of the requested web application and includes default settings for a plurality of different web applications. An application configuration object is also received from the server. The application configuration object is specific to the requested web application and includes a plurality of plugin handles. The bootstrap object loads the application configuration object, and identifies, based on the plugin handles, a first plugin for the requested web application. The first plugin is requested, and upon receipt the from the server the first plugin is loaded in a user interface. The first plugin exposes an application programming interface (API) of the first plugin to the bootstrap object.