Referer Control app (or website) is a tool designed to help users protect their privacy while browsing the web. It is used to control the data sent to websites in HTTP referer headers. A referer is a field in an HTTP request that identifies the URL the user was on before the request was made. By controlling the referer, users can prevent third-party websites from tracking their browsing activities. Referer Control can also be used to block certain websites from getting information about visits to the user’s website. This can be used to avoid malicious tracking or to protect user data.
RefControl
Smart Referer
Mason
Discontinued No longer updated. The last version, 0.3.7.9.18, released on January 31, 2013, was compatible with Firefox 18.