The subject matter of this specification can be embodied in, among other things, a method that includes receiving an indication that a first activity has occurred. The first activity is associated with a uniform resource identifier (URI) that specifies at least one web page. The method also includes identifying an application that is associated with the URI using a registry that associates particular URIs with particular applications, retrieving, using the identified application, content associated with the URI, displaying the content or information derived from the content in a first format that is not controlled by a second format specified by a markup language of the at least one web page.