Cover Your Tracks

When you visit a website, you are allowing that site to access a lot of information about your computer's configuration. Combined, this information can create a kind of fingerprint — a signature that could be used to identify you and your computer. Some companies use this technology to try to identify individual computers.

In 2010, EFF launched Cover Your Tracks, a research project to investigate how unique each browser is. We gathered information about the configuration and version information from your operating system, your browser, and your plug-ins, and compared it to our database of many other Internet users' configurations. Then, we generated a uniqueness score — letting you see how easily identifiable you might be as you surf the web.

In 2015, we upgraded Cover Your Tracks with a new feature: tracker blocker testing. Million of Internet users are using privacy add-ons and other tools to block trackers, including tools like AdBlock, Ghostery and Disconnect. But how well do these add-ons actually protect users from invasive tracking?

Our new version of Cover Your Tracks researches both. We analyze how well you are protected against online tracking by checking the privacy protections you have in place. The test simulates loading of a visible ad that performs tracking, an invisible script that performs tracking, and a site that looks superficially like a tracker but actually has committed to honor Do Not Track.

Even if your privacy add-ons are working well, you may still be vulnerable if your browser fingerprint is unique. So we also analyze the uniqueness of your browser and let you know how it stacks up to other visitors we’ve observed recently.

We generate a report about your tracker protections and browser fingerprint for your own use, and we’ll include anonymous results from your test in our larger research report.