Tracking survey
What 11,596 Websites Load Behind the Content
We crawled the web's most-linked sites and recorded every advertising, analytics and fingerprinting service each one loads. Search for any site below, or read the findings.
The most widespread trackers
Tracking is far more concentrated than the number of vendors suggests. A handful of services appear on a large share of the web, which is what makes cross-site profiling possible in the first place: a company present on a thousand sites sees a thousand fragments of the same person's activity.
Concentration by company
Grouping by the company behind each service shows the picture more clearly than domain counts do, because one company operating several trackers can join what they each observe.
| Company | Sites present on | Share |
|---|---|---|
| 8,703 | 75% | |
| OneTrust | 1,231 | 11% |
| Meta | 1,101 | 9% |
| Microsoft | 449 | 4% |
| Amazon | 421 | 4% |
| Usercentrics | 403 | 3% |
| Comscore | 401 | 3% |
| Automattic | 294 | 3% |
| Yandex | 284 | 2% |
| Chartbeat | 230 | 2% |
The most heavily tracked sites we found
How this was measured
Each site's homepage was requested once, the way an ordinary browser would, and the returned HTML was matched against our public signature database. No logins, no form submissions, and no crawling beyond the homepage.
Every figure here is a floor. Because the method reads HTML as delivered rather than executing JavaScript, trackers injected at runtime appear as the tag manager that loads them rather than individually. The real averages are higher than the ones above, and we would rather publish a number we can defend than a larger one we cannot.
Frequently asked questions
How many trackers does the average website use?
Across the 11,596 sites in this survey, the average page loads 1.9 known advertising or tracking services and sets 1.2 cookies before you interact with anything. 1,679 of them loaded no recognised tracker at all. These are floors rather than totals, because the method reads HTML as delivered and does not execute JavaScript.
Which tracker is the most widespread on the web?
Google Tag Manager (googletagmanager.com) appears on 69% of the sites surveyed, making it the most widely deployed tracking service in this dataset.
Which company tracks the most of the web?
Google is present on 75% of the sites surveyed, through 8,703 of them. Grouping by parent company matters because one company running several services can join what each of them observes into a single profile.
How was this tracking survey conducted?
Each site's homepage was requested once, exactly as an ordinary browser would, and the returned HTML was matched against our public tracker signature database. No logins, no form submissions, and no crawling beyond the homepage. The signature database is published under CC0.
Using this data
The signature database is released under CC0. Use it, correct it, or build on it without asking. If you are researching this area we would rather you started from our data than rebuilt a worse copy of it.