Barry Eitel

The newest version of the Firefox browser will block third-party cookies by default, a seemingly tiny tweak that signals a major shift in the on-going conflict between online advertisers and Internet users tired of the barrage of marketing blasting through their screens every day.

Firefox 22 is following the lead of Apple’s Safari browser, which edited their programming to also block advertising cookies years ago.

The changes come to the cheers of many users and to the outrage of many marketing insiders.

Mozilla claims the cookie-blocking is in answer to complaints about marauding cookies. Firefox users have even listed “Block cookies from sites I haven't visited” as an official “bug” on Bugzilla, the company’s crowdsourced tech support site.

With a free product and their commitment to an open Internet, the changes are in character for Mozilla (they are technically a nonprofit).

Jonathan Mayer, a Stanford grad student who is responsible for the new piece of programming for the latest Firefox version, discussed the update on his blog (his personal views do not speak for Mozilla).

“The default Firefox cookie policy will, beginning with release 22, more closely reflect user privacy preferences,” Mayer wrote in a post last week.

Mayer detailed how the cookie-blocking will work, both for Firefox users and websites.

“Roughly: Only websites that you actually visit can use cookies to track you across the web,” he continued, “More precisely: If content has a first-party origin, nothing changes. Content from a third-party origin only has cookie permissions if its origin already has at least one cookie set.”

Mayer does not see the new default cookie settings as revolutionary. He believes any worries about the newest Firefox “breaking websites” are unfounded.

“Collateral impact should be limited. Safari’s cookie policy has been in place for over a decade, and it is included in both the desktop and iOS versions of the browser,” he wrote. “A few websites may require a tiny code change to accommodate Firefox in the same way as Safari.”

The advertising industry, not surprisingly, wasn’t comforted by Mayer’s words.

“This default setting would be a nuclear first strike against ad industry,” tweeted Mike Zaneis, the senior vice president and general counsel for the Interactive Advertising Bureau.

Mozilla has not responded to Zaneis’ scathing tweet.

This article is part of Allvoices’ series on ad:tech, the largest, longest-running digital marketing and technology event. Check out for more of Allvoices’ ad:tech coverage. This series is supported by ad:tech.