Privacy Possum is a new open source browser extension for the Mozilla Firefox and Google Chrome web browser by a former developer of the EFF's Privacy Badger extension.

The extension focuses on blocking data that companies may use to track you across the Internet. Tracking has gotten way out of hand on today's Internet thanks to a growing list of technologies that companies may use to track users and the financial incentives.

Tracking happens in the background most of the time; while you may notice that some company must have been tracking you if all sites start to display product ads after you looked at the product on a single site, it is often the case that there is no indicator that you are being tracked by companies.

Internet users may install browser extensions that improve privacy, and Privacy Possum looks to be a good choice in that regard.

Privacy Possum

Privacy Possum is available for Google Chrome and Mozilla Firefox. Like most privacy extensions, it adds an icon to the main toolbar that acts as an indicator of blocking activity and control panel when clicked on.

The current version of the extension blocks four different tracking methods:

• blocks referer headers that may reveal the browsing location.
• blocks etag headers to block browser caching tracking. Privacy Possum strips and stores etag header data and compares it with third-party requests to the URL to determine whether the header is used for tracking or not.
• blocks (all third-party) cookies that are used to track users.
• blocks some browser features that may be used to fingerprint users. If a site mixes first-party fingerprinting code with code necessary to run the site, Privacy Possum won't block but will dilute the data by injecting random data to "spoil the fingerprint".

Privacy Possum runs automatically; it blocks elements automatically and there is nothing that you need to do.

The extension indicates blocking activity by adding a number to its icon. A click on the icon reveals how many tracking related elements it blocked and the type of the blocked elements.

The interface has an on-off switch that you may use to deactivate the extension. Privacy Possum supports whitelist functionality. It lists blocked elements, e.g. tracking headers or JavaScript files that get loaded in the interface; just click on a checkbox in front of a blocked element to disable the blocking for that particular site.

Closing Words

Privacy Possum is a promising new browser extension for Chrome and Firefox that improves your privacy while you browse the Internet. It offers more protective features than Privacy Badger and is certainly an extension that privacy-conscious users may want to try out or at least keep an eye on to see how it evolves over time.