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Third-party trackers explained: who is watching you across the web

Third-party trackers are scripts and cookies from domains other than the one you are visiting. They build profiles of your browsing across multiple sites. Here is how they work and how to spot them.

Published: 2 min read

How third-party trackers work

When you visit a website, it often loads resources from other domains — analytics scripts, advertising pixels, social media buttons. These third-party resources can set cookies and collect data about your visit.

Over time, these trackers build a profile of your browsing habits across all the sites that include them. This profile is used for targeted advertising, analytics, and sometimes sold to data brokers.

The most common trackers

Google Analytics, Facebook Pixel, and Google Ads are among the most widely deployed trackers. They appear on a significant percentage of the top websites on the internet.

Other common trackers include advertising networks, social media widgets, and analytics platforms. Many sites load dozens of third-party resources without the visitor realizing it.

  • Google Analytics: site analytics used by millions of websites
  • Facebook Pixel: advertising and conversion tracking
  • Google Ads: retargeting and ad measurement
  • Hotjar: session recording and heatmaps

How to see and block trackers

This site's tracker detection tool shows you which third-party services are loaded on the current page. It categorizes them by type — analytics, advertising, social — so you can see who is watching.

To block trackers, use a content blocker like uBlock Origin, enable your browser's built-in tracking protection, or use a privacy-focused browser like Brave or Firefox with strict protection enabled.