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Privacy Badger is a browser extension that automatically learns to block invisible trackers.

Frequently Asked Questions

What is Privacy Badger?

Privacy Badger is a browser extension that stops advertisers and other third-party trackers from secretly tracking where you go and what pages you look at on the web. If an advertiser seems to be tracking you across multiple websites without your permission, Privacy Badger automatically blocks that advertiser from loading any more content in your browser. To the advertiser, it’s like you suddenly disappeared.

How is Privacy Badger different from other blocking extensions?

Privacy Badger was born out of our desire to be able to recommend a single extension that would automatically analyze and block any tracker or ad that violated the principle of user consent; which could function well without any settings, knowledge, or configuration by the user; which is produced by an organization that is unambiguously working for its users rather than for advertisers; and which uses algorithmic methods to decide what is and isn’t tracking.

As a result, Privacy Badger differs from traditional ad-blocking extensions in two key ways. First, while most other blocking extensions prioritize blocking ads, Privacy Badger is purely a tracker-blocker. The extension doesn’t block ads unless they happen to be tracking you; in fact, one of our goals is to incentivize advertisers to adopt better privacy practices. Second, most other blockers rely on a human-curated list of domains or URLs to block. Privacy Badger is an algorithmic tracker blocker – we define what “tracking” looks like, and then Privacy Badger blocks or restricts domains that it observes tracking in the wild. What is and isn’t considered a tracker is entirely based on how a specific domain acts, not on human judgment. (See also.)

How does Privacy Badger work?

When you view a webpage, that page will often be made up of content from many different sources. (For example, a news webpage might load the actual article from the news company, ads from an ad company, and the comments section from a different company that’s been contracted out to provide that service.) Privacy Badger keeps track of all of this. If as you browse the web, the same source seems to be tracking your browser across different websites, then Privacy Badger springs into action, telling your browser not to load any more content from that source. And when your browser stops loading content from a source, that source can no longer track you. Voila!

At a more technical level, Privacy Badger keeps note of the “third party” domains that embed images, scripts and advertising in the pages you visit. Privacy Badger looks for tracking techniques like uniquely identifying cookies, local storage “supercookies,” and canvas fingerprinting. If it observes a single third-party host tracking you on three separate sites, Privacy Badger will automatically disallow content from that third-party tracker.

By default, Privacy Badger receives periodic learning updates from Badger Sett, our Badger training project. This “remote learning” automatically discovers trackers present on thousands of the most popular sites on the Web. Privacy Badger no longer learns from your browsing by default, as “local learning” may make you more identifiable to websites. You may want to opt back in to local learning if you regularly browse less popular websites. To do so, visit your Badger’s options page and mark the checkbox for learning to block new trackers from your browsing.

What is a third party tracker?

When you visit a webpage parts of the page may come from domains and servers other than the one you asked to visit. This is an essential feature of hypertext. On the modern Web, embedded images and code often use cookies and other methods to track your browsing habits — often to display advertisements. The domains that do this are called “third party trackers”, and you can read more about how they work here.

What do the red, yellow and green sliders in the Privacy Badger menu mean?

Red means that content from this third party domain has been completely disallowed.

Yellow means that the third party domain appears to be trying to track you, but it is on Privacy Badger’s cookie-blocking “yellowlist” of third party domains that, when analyzed, seemed to be necessary for Web functionality. In that case, Privacy Badger will load content from the domain but will try to screen out third party cookies and referrers from it.

Green means “no action”; Privacy Badger will leave the domain alone.

Why does Privacy Badger block ads?

Actually, nothing in the Privacy Badger code is specifically written to block ads. Rather, it focuses on disallowing any visible or invisible “third party” scripts or images that appear to be tracking you even though you specifically denied consent by sending Do Not Track and Global Privacy Control signals. It just so happens that most (but not all) of these third party trackers are advertisements. When you see an ad, the ad sees you, and can track you. Privacy Badger is here to stop that.

Why doesn't Privacy Badger block all ads?

Because Privacy Badger is primarily a privacy tool, not an ad blocker. Our aim is not to block ads, but to prevent non-consensual invasions of people’s privacy because we believe they are inherently objectionable. We also want to create incentives for advertising companies to do the right thing. Of course, if you really dislike ads, you can also install a traditional ad blocker.

What is Global Privacy Control (GPC)?

Global Privacy Control (GPC) is a new specification that allows users to tell companies they’d like to opt out of having their data shared or sold. By default, Privacy Badger sends the GPC signal to every company you interact with alongside the Do Not Track (DNT) signal.

What’s the difference? Do Not Track is meant to tell companies that you don’t want to be tracked in any way (learn more about what we mean by “tracking” here). Privacy Badger gives third-party companies a chance to comply with DNT by adopting our DNT policy, and blocks those that look like they’re tracking you anyway.

When DNT was developed, many websites simply ignored users’ requests not to be tracked. That’s why Privacy Badger has to act as an enforcer: trackers that don’t want to comply with your wishes get blocked. Today, users in many jurisdictions have the legal right to opt out of some kinds of tracking. That’s where GPC comes in.

GPC is meant to be a legally-binding request to all companies in places with applicable privacy laws. For example, the California Consumer Privacy Act gives California residents the right to opt out of having their data sold. By sending the GPC signal, Privacy Badger is telling companies that you would like to exercise your rights. And while Privacy Badger only enforces DNT compliance against third-party domains, GPC applies to everyone – the first-party sites you visit, and any third-party trackers they might invite in.

The CCPA and other laws are not perfect, which is why Privacy Badger uses both approaches. It asks websites to respect your privacy, and it blocks known trackers from loading at all.

You can learn more about GPC and your rights here.

What about tracking by the sites I actively visit, like NYTimes.com or Facebook.com?

At present, Privacy Badger primarily protects you against tracking by third party sites. As far as privacy protections for “first party” sites (sites that you visit directly), Privacy Badger removes outgoing link click tracking on Facebook and Google. We plan on adding more first party privacy protections in the future.

We are doing things in this order because the most scandalous, intrusive and objectionable form of online tracking is that conducted by companies you’ve often never heard of and have no relationship with. First and foremost, Privacy Badger is there to enforce Do Not Track against these domains by providing the technical means to restrict access to their tracking scripts and images. The right policy for whether nytimes.com, facebook.com or google.com can track you when you visit that site – and the technical task of preventing it – is more complicated because often (though not always) tracking is interwoven with the features the site offers, and sometimes (though not always) users may understand that the price of an excellent free tool like Google’s search engine is measured in privacy, not money.

Does Privacy Badger contain a list of blocked sites?

Unlike other blocking tools, we have not made decisions about which sites to block, but rather about which behavior is objectionable. Domains will only be blocked if Privacy Badger observes the domain collecting unique identifiers after it was sent Do Not Track and Global Privacy Control signals.

Privacy Badger does contain a “yellowlist” of some sites that are known to provide essential third party resources; those sites show up as yellow and have their cookies blocked rather than being blocked entirely. This is a compromise with practicality, and in the long term we hope to phase out the yellowlist as these third parties begin to explicitly commit to respecting Do Not Track. The criteria for including a domain on the yellowlist can be found here.

The initial list of domains that should be cookie blocked rather than blocked entirely was derived from a research project on classifying third party domains as trackers and non-trackers. We will make occasional adjustments to it as necessary. If you find domains that are under- or over-blocked, please file a bug on Github.

Does Privacy Badger prevent fingerprinting?

Browser fingerprinting is an extremely subtle and problematic method of tracking, which we documented with the Panopticlick project. Privacy Badger can detect canvas-based fingerprinting, and will block third party domains that use it. Detection of other forms of fingerprinting and protections against first-party fingerprinting are ongoing projects. Of course, once a domain is blocked by Privacy Badger, it will no longer be able to fingerprint you. No. Privacy Badger analyzes the cookies from each site; unique cookies that contain tracking IDs are disallowed, while “low entropy” cookies that perform other functions are allowed. For instance a cookie like LANG=fr that encodes the user’s language preference, or a cookie that preserves a very small amount of information about ads the user has been shown, would be allowed provided that individual or small groups of users’ reading habits could not be collected with them. Yes. When learning is enabled, Privacy Badger keeps track of cookies that could be used to track you and where they came from, even if you frequently clear your browser’s cookies.

Does Privacy Badger still learn when I set my browser to block all third-party cookies?

When learning is enabled and you tell your browser to deny third-party cookies, Privacy Badger still gets to learn from third parties trying to set cookies via HTTP headers (as well as from other tracking techniques such as canvas fingerprinting). Privacy Badger no longer gets to learn from cookies or HTML5 local storage being set via JavaScript, however. So, Privacy Badger’s learning still works, it’ll just learn to block fewer trackers.

Will you be supporting any other browsers besides Chrome, Firefox, Edge and Opera?

Safari/iOS: Safari seems to lack certain extension capabilities required by Privacy Badger to function properly.

Chrome on Android does not support extensions. To use Privacy Badger on Android, install Firefox for Android.

Privacy Badger does not work with Microsoft Edge Legacy. Please switch to the new Microsoft Edge browser.

Can I download Privacy Badger directly from eff.org?

If you use Google Chrome, you have to install extensions from Chrome Web Store. To install Privacy Badger in Chrome, visit Privacy Badger’s Chrome Web Store listing and click the “Add to Chrome” button there.

Otherwise, you can use the following links to get the latest version of Privacy Badger directly from eff.org:

I run a domain that uses cookies or other tracking. How do I stop Privacy Badger from blocking me?

One way is to stop tracking users who have turned on the Do Not Track signal (i.e., stop collecting cookies, supercookies or fingerprints from them). That will work for new Privacy Badger installs.

You can also unblock yourself by promising to meaningfully respect the Do Not Track signal. To do so, post a verbatim copy of EFF’s Do Not Track policy to the URL https://example.com/.well-known/dnt-policy.txt, where “example.com” is replaced by your domain. Posting EFF’s DNT policy on a domain is a promise of compliance with EFF’s DNT Policy by that domain.

Note that the domain must support HTTPS, to protect against tampering by network attackers. The path contains “.well-known” per RFC 5785. Also note that you must post a copy of the policy at each compliant subdomain you control. For example, if you wish to declare compliance by both sub1.example.com and sub2.example.com, you must post EFF’s DNT policy on each domain.

Where can I find general information about Privacy Badger that I can use for a piece I'm writing?

Glad you asked! Check out this downloadable press kit that we’ve put together.

As an administrator, how do I configure Privacy Badger on my managed devices?

Please see our enterprise deployment and configuration document.

What is the Privacy Badger license? Where is the Privacy Badger source code?

Privacy Badger’s source code is licensed under GPLv3+. This website’s source code is licensed under AGPLv3+.

How can I support Privacy Badger?

Thanks for asking! Individual donations make up about half of EFF’s support, which gives us the freedom to work on user-focused projects. If you want to support the development of Privacy Badger and other projects like it, helping build a more secure Internet ecosystem, you can throw us a few dollars here. Thank you.

If you want to help directly with the project, we appreciate that as well. Please see Privacy Badger’s CONTRIBUTING document for ways to get started.

How does Privacy Badger handle social media widgets?

Social media widgets (such as the Facebook Like button) often track your reading habits. Even if you don’t click them, the social media companies often see exactly which pages you’re seeing the widget on. When blocking social buttons and other potentially useful (video, audio, comments) widgets, Privacy Badger can replace them with click-to-activate placeholders. You will not be tracked by these replacements unless you explicitly choose to click them.

Note that Privacy Badger will not replace social media widgets unless it has blocked the associated tracker. If you’re seeing real social media widgets, it generally means that Privacy Badger hasn’t detected tracking from that variant of the widget, or that the site you’re looking at has implemented its own version of the widget.

How do I uninstall/remove Privacy Badger?

Firefox: See the Disable or remove Add-ons Mozilla help page.

Chrome: See the Install and manage extensions Chrome Web Store help page.

Edge: See the Add or remove browser add-ons, extensions, and toolbars Microsoft help page.

Opera: Click the menu button in the top left of the window, and then click “Extensions” and then “Manage Extensions.” Scroll until you see Privacy Badger, move your mouse over it, and then click the “X” icon in the upper right. Click “OK” to confirm removal. You can then safely close the Extensions tab.

Is Privacy Badger compatible with other extensions, including adblockers?

Privacy Badger should be compatible with other extensions.

While there is likely to be overlap between the various manually-edited advertising/tracker lists and Privacy Badger, unlike adblockers, Privacy Badger automatically learns to block trackers based on their behavior. This means that Privacy Badger may learn to block trackers your adblocker doesn’t know about.

Besides automatic learning, Privacy Badger comes with other advantages like cookie blocking, click-to-activate placeholders for potentially useful tracker widgets (video players, comments widgets, etc.), and outgoing link click tracking removal on Facebook and Google.

Privacy Badger is also a political tool. Privacy Badger sends the Global Privacy Control signal to opt you out of data sharing and selling, and the Do Not Track signal to tell companies not to track you. If trackers ignore your wishes, Privacy Badger will learn to block them. By using Privacy Badger, you support the Electronic Frontier Foundation and help fight for a better Web for everybody.

Is Privacy Badger compatible with Firefox's built-in content blocking?

It’s fine to use Firefox’s native content blocking and Privacy Badger together.

While there is overlap between Firefox’s tracker lists and Privacy Badger’s protections, unlike list-based blockers, Privacy Badger automatically discovers trackers. This means that Privacy Badger’s automatically-generated and regularly-updated blocklist may learn to block trackers that blockers with human-generated lists don’t know about. And if you enable local learning, your Badger will learn about the trackers you encounter as you browse as well.

See also the following FAQ entries:

Why does my browser connect to fastly.com IP addresses on startup after installing Privacy Badger?

EFF uses Fastly to host EFF’s Web resources: Fastly is EFF’s CDN. Privacy Badger pings the CDN for the following resources to ensure that the information in them is fresh even if there hasn’t been a new Privacy Badger release in a while:

EFF does not set cookies or retain IP addresses for these queries.

Why does Privacy Badger need access to my data for all websites?

When you install Privacy Badger, your browser warns that Privacy Badger can “access your data for all websites” (in Firefox, or “read and change all your data on the websites you visit” in Chrome). You are right to be alarmed. You should only install extensions made by organizations you trust.

Privacy Badger requires these permissions to do its job of automatically detecting and blocking trackers on all websites you visit. We are not ironically (or unironically) spying on you. For more information, see our Privacy Badger extension permissions explainer.

Note that the extension permissions warnings only cover what the extension has access to, not what the extension actually does with what it has access to (such as whether the extension secretly uploads your browsing data to its servers). Privacy Badger will never share data about your browsing unless you choose to share it (by filing a broken site report). For more information, see EFF’s Privacy Policy for Software.

I need help! I found a bug! What do I do now?

  • If a website isn’t working like it should, you can disable Privacy Badger just for that site, leaving Privacy Badger enabled and protecting you everywhere else. To do so, navigate to the site with the problem, click on Privacy Badger’s icon in your browser toolbar, and click the “Disable for this site” button in Privacy Badger’s popup. You can also quickly let us know about broken sites by clicking on the “Report broken site” button.

  • Did you run into “An unexpected error occurred” in Firefox? Your disk is probably low on space. All extensions have this problem; they just don’t all tell you about it. To fix, free up some disk space and then restart Firefox. If that didn’t help, please let us know (see below).

To get help or to report bugs, please email extension-devs@eff.org. If you have a GitHub account, you can use our GitHub issue tracker.