WhoTracks.me: Find out who’s spying on you on the web

In a two-part blog series, we introduce the website WhoTracks.me – the first transparency tool for online-tracking on the web. It profiles trackers and popular domains and sheds light on the market structure of data-sharing on the web.

Björn GreifEditor

Which websites spy on you the most? Which trackers are the most common? And which companies are behind them? Answers to these questions can be found on the new website WhoTracks.me, which builds upon the anti-tracking technology that powers Cliqz and Ghostery. The online tool provides structured information on tracking technologies, market structure and data-sharing on the web.

WhoTracks.me starts in a pilot phase with German data. In the coming months, tracking data on many more countries will be added.

What is a Tracker?

Whether you’re shopping, doing online banking, reading the news, spending time on social networks or watching porn (which no one does, of course), you’re almost always being watched by third parties. Because on almost every website there are trackers that record virtually everything you do online, usually without you knowing anything about it. In order to make trackers visible on websites and to prevent private data transfer to third parties, the use of an anti-tracking tool like Ghostery is recommended.

WhoTracks.me defines a tracker as a third-party domain which

  • is present on more than 10 different websites with a significant combined traffic.
  • uses cookies or fingerprinting methods in order to transmit user identifiers (UIDs).

Tracker operators use UIDs to link the information about users that is collected across websites. Based on the browsing history, they then create a detailed profile, which is usually used for analysis or advertising purposes.

The problem is that even the most confidential information ends up in the trackers’ databases and no one can say for sure what it is or will be used for. This data does not only allow them to draw conclusions about your interests and buying intentions, but also about your state of health, your sexual orientation or your political and religious attitudes. Just a few URLs from your browsing history are enough to uniquely identify you. An alleged anonymization is easy to circumvent, so that deeply private information from your previous website visits can be allocated to you.

Google and Facebook are watching you almost everywhere

WhoTracks.me sheds light on an extremely complex and hidden part of the web: tracking. This way you can quickly get an overview of the most popular trackers or the websites with most trackers on them. For example, did you know that Google’s tracking scripts together monitor 79 percent of the total web traffic and that 29 percent of all websites have a Facebook tracker? Even if you deliberately choose to opt out of all services and products from Google and Facebook, they still see a large part of what you do on the web through their third-party tracking scripts placed on websites.

Top 500 of the most common trackers

The trackers page lists the 500 most prevalent trackers on the web. You can sort the list by popularity or tracking company (alphabetically). You will also learn more about the share of different tracking methods (cookies, fingerprinting) and the average data usage of trackers.

For each tracker there is a detail page with in-depth statistics. It informs about:

  • the company behind the tracker
  • tracker rank
  • domains which the tracker operates under
  • reach by web traffic
  • reach by websites
  • distribution by types of websites (e.g. Adult, E-Commerce, Entertainment, News and Portals)
  • tracking type (Cookies, Fingerprinting)
  • tracker category (e.g. Advertising, Site Analytics, Social Media)
  • similar trackers

On which specific websites the respective tracker appears most frequently is visualized by a word cloud that can be filtered by website type.

For example, the number one in the tracker ranking, Google Analytics, tracks 44.2 percent of the total web traffic. In total, 61.3 percent of all websites use the Google Analytics tracker. These figures indicate that Google Analytics is present on an extremely large number of pages, but less often on popular sites.

WhoTracks.me also lets you search for specific websites to find out how many and which trackers are active on them. You can learn more about this in the second part of our blog series, in which we will also explain where the data for WhoTracks.me comes from.