Embodiments extend functionality of a web page using cloud-based page applications. A page application provider, executing as part of a web browser, receives notification of a web page being accessed by a user of a user computing device. One or more page applications associated with the web page are identified. The identified page applications provide functionality related to the web page and, in some embodiments, interact or share data with the web page. The page application provider presents the identified page applications to the user. Based on a selection of at least one of the presented page applications, the selected page application is provided for execution by the user computing device. In some embodiments, the correlations among the user, web pages, and page applications are available from a cloud-based page application service.