Learn about tracking technologies, market structure and data-sharing on the web

Tracking the trackers 2016

What is a tracker? Where does this data come from?


April Update - Preparing for Internationalisation

A new data format to ease access to tracker data.


Generating Ad-Blocker filters from whotracks.me data

Let's never miss a new tracker again.


The Impact of Tracking on User Experience

Beyond privacy - a survey of hidden and visible effects of tracking on user experience.

Tracker Market Share

Proportion of the web traffic tracked by these companies.


Tracking the Trackers

See Full Chart

Google trackers are present on 81% of the web traffic

That is more than the next 4 biggest trackers combined.

#trackerTopia #growth #topSites

29% of the web has a hidden Facebook tracking pixel

Facebook knows more than what you just do on Facebook

#facebook #trackingPixel #reach

474 companies track more than 0.1% of the web traffic each.

Which of these have you heard of?

#unknown #pervasive #mydata

Websites with the most (and least) tracking



out of 748 top websites have more than 10 trackers per page.


of data per page load on average required by trackers

FINGERPRINTING is a unique digital signature derived from the properties of your device.

COOKIES are files placed by the website, stored in the browser that is used to identify you to the website.

The most common trackers