Referer Modifier is a Firefox extension designed to enhance user privacy by controlling the HTTP Referer header sent to websites. This free tool allows users to set specific rules for different domains, offering five customizable actions: Keep, Prune, Target, Remove, and Replace. Each action determines how the Referer header is managed, giving users the flexibility to maintain their privacy while browsing.

With features like domain-specific default actions and the ability to export and import configurations using JSON files, Referer Modifier makes it easier to tailor privacy settings. The extension also ensures that the document.referrer property aligns with the configured rules, providing a seamless browsing experience while safeguarding personal information from unwanted tracking.