The Priv3 Firefox Extension
Practical Third-Party Privacy for the Social Web
Install Priv3

About Priv3

Did you know that social networking sites like Facebook, Google+, and Twitter can track your visits to any web page that uses the familiar "Like", "Follow", or "+1" buttons, even if you do not actually click these buttons?

The Priv3 Firefox extension lets you remain logged in to the social networking sites you use and still browse the web, knowing that those third-party sites only learn where you go on the web when you want them to. All this happens transparently, without the need to maintain any filters. Priv3 is free to use for anyone.

How Social Networking Sites Can Track You

In order to integrate interactive features—such as buttons, comment forums, activity feeds, or recommendations—from social networking sites, authors of web content integrate HTML snippets or JavaScript code provided by the social networks into their pages.

For example, when you are logged into your Google or Facebook account and visit a movie review page on rottentomatoes.com, your browser automatically pulls in the "+1" button from Google's servers and the "Like" button from Facebook. These downloads include the session cookies your browser uses to inform Google and Facebook that you have previously logged in, and so Google and Facebook automatically learn about your personal interest in the movie page you're looking at, even if you never actually click on either of their buttons.

How Priv3 Works

Blocking simple "web bugs" or "trackers" is fairly straightforward, because doing so does not harm your web surfing experience. By contrast, completely blocking social networking features is counterproductive, because doing prevents you from actually using these features—say to leave a comment, or to "like" something—when you would like to do so.

Therefore, Priv3 does not block third-party interactions completely. Instead, it selectively suppresses the inclusion of third-party web cookies when your browser pulls in content from the social networks, but does provide them if you decide to interact with the social networking features. You still see the number of "likes" the page has accumulated on Facebook or the comments other people left using Facebook's discussion mechanism. Facebook however only learns the IP address of the computer you are using.

Should you decide to interact with the social feature, Priv3 detects any mouseclick or keystroke directed at the feature. It then reloads it with your session cookies and passes on the click or keystroke, thus revealing your identity to the social network and informing it of your desired action.

Priv3's Currently Supported Social Networking Sites

Priv3 currently understands the interactive features of the following social networks:

  • Facebook
  • Twitter
  • Google +1
  • LinkedIn

We will expand the list in the future, as needed.

Who We Are

We are researchers interested in all aspects of Internet privacy. Our team:

Mohan Dhawan is a graduate student at Rutgers University. His advisors are Professor Vinod Ganapathy and Professor Liviu Iftode.

Christian Kreibich and Nicholas Weaver are staff research scientists at the International Computer Science Institute in Berkeley.

Contact Us

We'd love to hear your feedback. Feel free to send email to priv3@icsi.berkeley.edu.

Other Resources

The Wall Street Journal's What They Know articles provide an excellent introduction to the implications of third-party interactions in web surfing.

Ghostery and Adblock Plus are excellent Firefox extensions that provide complete blocking of third-party trackers and advertising. The privacy section of Mozilla's add-on database lists quite a few more.

Priv3 Version History

7/18/11: Initial Public Beta Release

7/8/11: Initial Internal Beta Release


NSF Logo Priv3 is funded by the
National Science Foundation.