Mozilla will be following in the footsteps of Apple's Safari, which also blocks third-party cookies by default. "The new Firefox policy is a slightly relaxed version of the Safari policy," said Mayer in an FAQ published on his personal blog.
Even so, at least one online ad official slammed Mozilla for making the change. "Firefox to block 3rd party cookies? This default setting would be a nuclear first strike against ad industry," said Mike Zaneis, general counsel for the Interactive Advertising Bureau (IAB), on Twitter Saturday. The IAB is one of several advertising organizations that has been fighting other privacy moves by browser makers, including Microsoft's decision to set "Do Not Track" on by default in Internet Explorer 10 (IE10).
"Second strike, technically (Safari)," retorted Justin Brookman, director of consumer privacy at the Center for Democracy and Technology, also on Twitter.
All browsers, including Firefox, have settings that let users manually switch off all cookies, or refuse those from third-party sites. But only Safari currently blocks all third-party cookies by default. Safari's small share -- in January, Net Applications pegged it as just 5.2 percent -- was likely too low to trigger the online ad industry's concern. Firefox is a different beast: According to Net Applications, Firefox was the second-most-used browser last month, with a 19.9 percent share globally.
But Mozilla didn't view the change as a first strike of any kind, nuclear or otherwise, aimed at online advertising. "We are not trying to stop tracking with this feature," Mozilla's Dotzler said on the discussion thread Sunday. "We are trying to make tracking relationships more obvious to the user."
It would not in Mozilla's self-interest to disrupt the online ad industry, as it generates the bulk of its revenue from a deal with Google, which pays the browser maker a reported $300 million a year for setting Google's search engine as Firefox's default.
The Nightly build of Firefox for Windows, OS X and Linux can be downloaded from Mozilla's website.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, or subscribe to Gregg's RSS feed. His email address is email@example.com.
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