Who is paying for online advertising to target you? Who’s showing you ads because you’re married, or you’re a liberal or work in the oil industry or some other category? Are they saying different things to different people? Help hold them accountable by installing our browser plugin, which sends us the ads you see on Facebook and YouTube, without compromising your privacy.

How it works

Ad Observer is a tool you add to your Web browser. It copies the ads you see on Facebook and YouTube, so anyone can see them in our public database. (See documentation here.) If you want, you can enter basic demographic information about yourself in the tool to help improve our understanding of why advertisers targeted you. However, we’ll never ask for information that could identify you.

It doesn’t collect your personal information. We take your privacy very seriously. You can view the extension code on Github.

See Mozilla privacy review.

What we collect

  • The advertiser's name and disclosure string.
  • The ad's text, image, and link.
  • The information Facebook provides about how the ad was targeted.
  • When the ad was shown to you.
  • Your browser language.

What we don't collect

Anything personally identifying, including:

  • Your Facebook ID number.
  • Your name, birthday, friend list, etc.
  • How you interacted with ads or anything else.

Why it matters

Online ads are usually seen only by the audience the advertiser wants to target, and then they disappear. This makes it difficult for the public to monitor them and hold advertisers accountable. While platforms have developed some transparency libraries for political ads, these libraries are missing many ads featuring political content and often don’t include vital information such as ad targeting. This isn’t a partisan issue. We think it’s important to democracy to be able to check who is trying to influence the public and how.

You can learn more about how political campaigns and interest groups are seeking to influence your vote at our Ad Observatory.

How you can help


  1. Go to this link. It will open a new tab that takes you to the Chrome Web Store.
  2. Click the blue button that says + ADD TO CHROME.
  3. A little window will pop up that says “Add ‘Ad Observer?’ It can: Read and change your data on all facebook.com sites, youtube.com sites, and observations.nyuapi.org.” This is the disclaimer Chrome requires us to use, but we promise we aren’t changing your Facebook or YouTube data or collecting anything besides the ads. If you’re OK with that, click the white “Add extension” button.
  4. A new tab will open in your browser which will display Ad Observer’s  “Terms of Use.” Read the terms, and if you’re comfortable with what they say, scroll to the bottom to click the blue button “I accept these terms and conditions.” If you don’t do this, Ad Observer will remain inactive and the Ad Observer icon which appears in the top right corner of the browser will have a red exclamation mark. 


  1. Go to this link. It will open a new tab that takes you to the Firefox Add-ons store.
  2. Click the blue button that says “Add to Firefox”. You may see a small window that says “addons.moziila.org Firefox prevented this site from asking you to install software on your computer.” Please click the blue Allow button. 
  3. You will then see a window that says “Add Ad Observer?” and asks for your permission to access your data for sites facebook.com, youtube.com , and observation.nyuapi.org. This is a disclaimer Firefox requires us to use, but we promise that the only thing we are accessing is the ads you see on Facebook and YouTube. If you’re OK with that, click the blue Add button. 
  4. Another window will tell you Ad Observer has been added to Firefox. Click Okay. 
  5. You’ll see the Ad Observer icon in the top right corner of your browser, with a red exclamation mark. Click on the icon, and a pop-up window will appear with a blue button that says ‘Review Consent”. By clicking on ‘Review Consent’, a new tab will appear with the “Terms of Use”. If you are comfortable with what these terms say, scroll to the bottom and click the blue button “I accept these terms and conditions”. After you do this, the red exclamation point over the Ad Observer icon will disappear.

Who we are

AdObserver is a project of Cybersecurity for Democracy at New York University’s Tandon School of Engineering. This extension was originally developed by researchers from the Algorithmic Transparency Institute, Quartz, New York University, and the University of Grenoble. Technical advice was also provided by ProPublica, WhoTargetsMe, and The Globe And Mail.