Firefox 91 pushes privacy with stronger new cookie-clearing option

Enhanced cookie clearing is designed to wipe out all tracking traces that websites, advertisers and others leave on your computer.

Stephen Shankland Former Principal Writer
Stephen Shankland worked at CNET from 1998 to 2024 and wrote about processors, digital photography, AI, quantum computing, computer science, materials science, supercomputers, drones, browsers, 3D printing, USB, and new computing technology in general. He has a soft spot in his heart for standards groups and I/O interfaces. His first big scoop was about radioactive cat poop.
Expertise Processors, semiconductors, web browsers, quantum computing, supercomputers, AI, 3D printing, drones, computer science, physics, programming, materials science, USB, UWB, Android, digital photography, science. Credentials
  • Shankland covered the tech industry for more than 25 years and was a science writer for five years before that. He has deep expertise in microprocessors, digital photography, computer hardware and software, internet standards, web technology, and more.
Stephen Shankland
2 min read
Firefox icon

WIth the release of Firefox 91 on Tuesday, Mozilla has introduced a bigger hammer for smashing the cookies that websites, advertisers and tracking companies can use to record your online behavior. The new feature, called enhanced cookie clearing, is designed to block tracking not just from a website, but also from third parties whose code appears on the site.

The technology is designed to let you clear cookies for a particular website but also the more aggressive "supercookies" designed to evade lesser privacy protections. The feature is an option if you enable Firefox's strict mode for cookie handling, which partitions website data into separate storage containers.

"You can easily recognize and remove all data a website has stored on your computer, without having to worry about leftover data from third parties embedded in that website," Mozilla said in a blog post.

Cookies are text files that websites and their partners can store in your browser. That's convenient for tasks like remembering your username, preferred language and the contents of your e-commerce shopping cart. But they also let companies keep track of your online activity. For example, a Facebook "like" button on a bicycle maker's website can tell Facebook you might be a likely prospect for bike ads when using the Facebook app.

Now, with privacy a top priority, the browser industry is trying to find a way to make the web less intrusive. Free websites and online services aren't so great when they're supported by advertising technology that peers too closely into your life.

Firefox, along with other browsers like Apple Safari, Brave Software's Brave and Microsoft's Edge, are investing engineering resources in technology to block cookies and other tracking technology. Google, which has an enormous online advertising business and likes the idea of personalizing ads, is trying -- with some difficulty -- to come up with alternatives that offer both targeted ads and privacy in its Chrome browser.

Firefox helped invigorate browser competition that had stalled after Microsoft's Internet Explorer grew to dominance two decades ago. But Firefox steadily declined in influence after Google introduced Chrome in 2008. Smartphones also have hurt Firefox's share of usage, now down to 3.4%, with Android smartphones using Chrome and iPhones using Safari by default.