How to Tell Who's Tracking You Online

A new tool reveals your virtual footsteps and who's taking note

Join Our Community of Science Lovers!

Mozilla has introduced Collusion, an add-on for the Firefox browser that shows you how companies are tracking you as you surf the Web. A cool visual demonstration of the software illustrates all the links that form as you crisscross just a few popular sites online, including IMDb, the New York Times and the Huffington Post. The software shows the connections among sites you visit and third-party tracking and advertising networks such as DoubleClick and Scorecard Research. It makes plain the invisible web that has been woven through the Web.

The software was created as a prototype by Atul Varma, who explained in a blog post that he “didn’t know a lot about tracking myself, so I whipped up a Firefox add-on called Collusion to help me visualize it better. The results were a little unsettling.”

Collusion will help you understand how you are being tracked online, but it won’t stop it from happening. For that, you can disable third-party cookies on your browser and install other add-ons such as TrackerBlock. A number of Internet giants have also announced support for a “do not track” button, although that option may not become available until the end of the year.

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

This article was published in print as "How to Tell Who's Tracking You Online."

Subscribe to Support Independent Journalism

Great science journalism requires human expertise, time, effort and creativity. And it costs money. That’s why I and the journalists here at Scientific American hope you’ll join our community.

When you subscribe, you are supporting staff and freelance journalists who are passionate about telling science stories that are true, important and compelling. Our editors and reporters are often experts in their fields, which means they understand the nuances of big discoveries and can untangle the breakthroughs from the hype. With a subscription, you are also supporting rigorous fact-checking to ensure the words we publish are precise and accurate. And you’re supporting original illustrations, graphics and photos that bring you closer to an advanced laboratory, an ice sheet in Antarctica or a space mission in orbit. You’re helping us craft other types of high-quality journalism as well: Our newsletters are carefully written, edited and curated by staffers you have or will come to know and love. Our Science Quickly podcast is based on original reporting, collaboration with editors and scientists and exacting production.

Subscriptions keep this engine running so we can continue to deliver thoughtful, rigorous and independent science journalism to you. In an era of viral misinformation, this work is crucial. If you value what we do, I hope you’ll consider joining us as a subscriber

Thank you,

Jeanna Bryner, Editor in Chief, Scientific American