When you install AdBlock for the first time, your browser may show you a notification like this: "AdBlock can read, modify, and transmit content from all web pages. This could include sensitive information like passwords, phone numbers, and credit cards." Although the exact wording depends on which browser you use, the warnings all sound scary for a reason. You should be aware of what the extensions you install can do.


About the permissions AdBlock requests

Lifehacker has a nice article on what browser permissions really mean and how much you should worry about giving them. Here's what they mean when you use AdBlock.


"Read and change all the data on the websites you visit"

Ad blockers work by 1) blocking a web page's requests to download ads from the servers that host them and 2) hiding any ads that can't be blocked. (For details, please see our "Ad Blocking 101" post on AdBlock's Blog.) To do that, the extension needs to:

  1. See every page you open so that AdBlock can work on every page you visit. This also means that AdBlock knows the URL (Internet address) of every page you visit.
  2. See all the data on the page to find any unblocked ads among the other content. This also means that AdBlock can see any forms you submit and your browsing history on that tab.
  3. Change the data on the page by adding some HTML, CSS, and JavaScript code to the page to hide unblocked ads.


It's important to know that just because AdBlock can see everything on a web page, it doesn't mean it actually does read everything or does anything with it. The extension does not record your browsing history, capture your passwords or bank account numbers, or secretly change data you submit on a web form. 


"Display notifications"

This is your browser's way of asking for permission to send data about a page back to our servers, where some of AdBlock's functionality is hosted.


"Manage your apps, extensions, and themes"

This permission is requested later, the first time you report an ad or a bug. It allows your browser to share information with us about other extensions you have installed.


About the information we collect

All that said, we want you to know that we do collect some information about your browser and AdBlock, not about you personally.


Anonymous statistics

We get statistics from Google Analytics and the AdBlock extension that tell us, for example, the language your browser is set to and the country you're in. None of the information that we collect is personally identifiable. If you want to prevent us from seeing this information anyway, you can subscribe to the EasyPrivacy filter list in AdBlock's options.


Troubleshooting information you send us

If you provide debugging information as part of troubleshooting an issue, AdBlock tells us your operating system version, which browser you're using and its version, how long it's been since you installed AdBlock, which version of AdBlock you're using, which options you have set, which filter lists you're subscribed to, any custom filters you've added, and (if you give us permission to collect it) which extensions you have installed and whether they're enabled.


You can read this information yourself to see what you're giving us. Open AdBlock's options and on the SUPPORT tab, click here in the sentence "Have our team requested some debug info? Click here for that!"


Troubleshooting information you can allow the extension to send us

If you have enabled the option to Allow AdBlock to collect anonymous filter list usage and data, we get a subset of the same data that's contained in the debugging information without your having to send it to us.


More information is in our privacy policy

We invite you to read our privacy policy, which goes into great detail about the information we collect and why we collect it.


You're right to be wary, absolutely. You should never install extensions that ask for more permissions than you are comfortable with unless you trust the developer. AdBlock is the most popular extension for Chrome and Safari, in large part because we care about our users. We hope you'll trust us. If you're ever concerned, just ask us! :)


By the way, if we ever release a new feature that requires additional permissions, your browser will alert you to that fact. Some browsers such as Chrome even disable extensions that request additional permissions. In those cases you must specifically grant the new permission by re-enabling the extension.


Note: If your browser keeps showing you the "new permissions" alert, uninstalling and reinstalling the extension should fix it.