Abstract: A system includes a processor configured to execute a web browser in a first browser execution process initiated by an operating system of the system. The system includes a browser extension installed in the web browser, the browser extension including a markup language file and a file specifying at least one type of action related to a page element on which the browser extension seeks to act. The web browser may be configured to receive a set of rules from a web publisher associated with a first web page prior to rendering the first web page, determine based on the file, without loading the browser extension, that the browser extension is configured to implement a first action prohibited by the set of rules, and restrict the browser extension from implementing the first action on the first web page.