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. 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.

Privacy policy

July 2021

This Privacy Policy (“the Policy”) explains how and why New York University (“NYU”) processes personal data when people install Ad Observer (“the Application”).

The Policy does not cover any other personal data processing by NYU, which is covered by other applicable policies and procedures, including NYU’s Digital Privacy Statement

If you have a question regarding the Policy or the use of the Application, please contact developers@adobserver.org.  

Data controller 

NYU is the controller of the data covered by the Policy. You can contact NYU’s Data Protection Officer with any questions about this notice, our data collection practices, or your rights. You can reach NYU’s Data Protection Officer, Peter Christensen, at:

Peter Christensen

c/o Data Protection Officer’s Office

70 Washington Square South

Room 1201

New York, NY 10012

+1 212 992 7256

Guiding principles

NYU is committed to respecting individuals’ right to privacy, protecting personal data and compliance with applicable laws globally. In accordance with these guiding principles, the Application has been designed to process the minimum amount of personal data possible to achieve NYU’s objectives. 

Purposes and means of data processing

The purpose of the Application is to collect information about the political ads directed at and seen by private individuals on Facebook & YouTube. This is done with the objective of facilitating public understanding of how political advertising is deployed. NYU believes that it is in the public interest to understand this phenomenon and its impact on democracy. 

NYU also maintains a public, online repository of aggregate data (“the Database”) collected by the Application in order to render its research findings transparent and facilitate research by others. This information is anonymised so that it is not possible to identify individual users of the Application from within the Database. The Database can be accessed via [link].

Data processed by the Application 

When an individual user installs the Application, they are invited to provide basic demographic information about themselves: their age group, gender and ethnicity. This basic demographic profile (“the Profile”) helps NYU understand which people see which ads. It is not mandatory to provide this information and the Application can still collect data that contributes to the research project without creating a Profile. 

No other personally identifiable information is requested or processed by NYU. The browser language, which is recorded by the Application for the purposes of correctly parsing the ads, is also included in the Profile. The Application does not undertake any “profiling” or “automated decision-making” as defined by the GDPR. 

If the user has decided not to create or share a Profile, only the data related to the ads is transmitted to and included in the Database. All users can view the data related to the ads that has been processed by the Application at any time by clicking on the Ad Observer icon and navigating to ‘My Archive’. 

The Application will collect and transmit to NYU the ad creative data for each ad displayed to the user. If the user has the 'Collect Ad Targeting Data' setting turned on, the Application will also cause the user's browser to request the targeting data (i.e., the data shown to the user when the user clicks on the Why Am I Seeing This? button) associated with each ad shown to the user.

Legal basis for processing

NYU processes data for the above purposes on the basis of consent. By installing the Application, users consent to the processing of their data for the purposes described above. Individuals may withdraw their consent at any time by uninstalling the Application. 

As noted above, data retained in the Database is anonymized, meaning that a user’s withdrawal of consent will not mean the deletion of the data related to the ads that the Application has collected.

“Sensitive data” 

As noted above, individuals may elect to provide information about their ethnicity when they install the Application. This data, which may fall within the definition of “special category data” under the GDPR, is processed with consent. As noted above, this data is not stored by NYU in a format that allows identification of the individual concerned. No other sensitive data is requested or processed by NYU. 

Information security

NYU takes reasonable steps to protect personal data against loss, misuse, and unauthorized access, alteration, disclosure or destruction. This includes the use of technical, organisational and legal measures to ensure the confidentiality, integrity and availability of personal data. 

Information transmitted across the internet remains vulnerable to unauthorised access. The transmission of such data is therefore at the individual’s own risk. See further [link to ToU]

Data retention 

No personal data is retained by NYU. The only data that is retained has been fully and irreversibly anonymised.  

Data Subjects Rights

Individuals whose personal data is processed in accordance with the GDPR have the following rights:

  • The right to be informed as to whether NYU holds data about them;
  • The right of access to that information;
  • The right to have inaccurate data corrected;
  • The right to have their data deleted;
  • The right to opt-out of particular data processing operations;
  • The right to receive their data in a form that makes it “portable”;
  • The right to object to data processing;
  • The right to receive an explanation about any automated decision making and/or profiling, and to challenge those decisions where appropriate.

Individuals wishing to exercise their rights in respect of the Application can do so by contacting NYU’s Data Protection Officer’s Office using the contact details provided above. 

Data subjects covered by EU law may also be entitled to lodge complaints in regard to data processing or the handling of subject access requests with data protection supervisory authority in their country of residence. Relevant supervisory authority names and contact details are listed here

Changes and revisions

Should NYU make changes to this Policy, the date and nature of the change will be indicated below.

July, 2021: Clarified description of ad targeting collection