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 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.


Information associated with a unique userID

Most of the data we collect is about your browser and how you use AdBlock, and is tied to a unique userID randomly generated when you installed AdBlock, not to you personally. For instance, we know this userID opened AdBlock's /installed page at this time, or that userID opened the AdBlock menu at that time. We use this information to make AdBlock better.


From our privacy policy:

When you visit the AdBlock website we collect IP address, unique ID, logging of some of the button clicks on our website (clicking download, for example) and user event logging data. When the AdBlock extension communicates with AdBlock servers, we receive the computer’s IP address.


We know more about you personally if you have paid for AdBlock.


From our privacy policy:

When you donate from the AdBlock website, we collect and store all information, excluding the credit card number, given during the payment process. This includes IP address, unique ID, logging some of the button clicks (payment, download buttons) and user event logging. AdBlock does not handle or have access to full credit card numbers, bank account details or payment account login information. Each payment processor stores and uses the data you provide them differently.


We do not target or sell any of the data we collect, personally identifiable or not. Selling user data goes against everything we stand for as a company.


And after a certain length of time, we obfuscate all personally identifiable information in our logs, making all the data we have completely anonymous.


Anonymous statistics

Speaking of anonymous data, we get statistics from Google Analytics and the AdBlock extension, such as the language your browser is set to and the country you're in. None of that information is personally identifiable.


From our privacy policy:

The AdBlock extension captures anonymous usage information including, but not limited to, the version number of the extension, preferred language, Acceptable Ads opt-in, opt-in to advanced features like our local content caching service, number of blocked requests, number of ads blocked, and browser and operating system type. The AdBlock extension also assigns an anonymous, unique ID to each installation. We store this information on AdBlock servers and we utilize this information to help us identify and fix potential issues with AdBlock as well as to determine the performance of AdBlock features.


If you want to prevent us from seeing the data we get from Google Analytics, you can subscribe to the EasyPrivacy filter list in AdBlock's options. We will continue to collect data from the AdBlock extension, but again, none of it can be identified with any individual user.


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, why we collect it, and how we use it.


The bottom line is 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.