Firefox To Block Third-Party Cookies

Mozilla's Firefox browser will soon block some third-party cookies by default, privacy advocate Jonathan Mayer announced on Friday.

The upcoming Firefox 22, set for release in June, will include a patch that blocks some third-party cookies -- like those set by ad networks. Firefox's default settings will still allow first-party cookies, as well as cookies from third parties that users have a relationship with. "Only websites that you actually visit can use cookies to track you across the web," Mayer writes in a blog post explaining the patch, which he developed.

Those settings are similar to the defaults in Safari, although Mayer characterized the Firefox cookie defaults as a "slightly relaxed version" of Safari's settings. Firefox currently commands around 20% of the desktop browser market -- four times as much as Safari.

Online ad companies will almost certainly try to rally opposition to the move. Mike Zaneis, general counsel at the Interactive Advertising Bureau, tweeted on Saturday that the setting "would be a nuclear first strike" against the ad industry.

The move comes around 18 months after the World Wide Web Consortium -- a group of computer scientists, industry representatives and privacy advocates (including Mayer) -- began trying to develop standards for responding to do-not-track headers. Those headers, now offered by all the major browsers, are aimed at letting people permanently opt out of online behavioral advertising. But the headers don't actually prevent tracking. Instead, they send signals to publishers and ad networks, which those companies decide how to interpret.

So far, the W3C hasn't been able to agree on how to interpret the signals. Some privacy advocates previously warned that if W3C fails to reach a consensus, browser manufacturers might follow Safari's lead and simply block third-party cookies.

12 comments about "Firefox To Block Third-Party Cookies".
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  1. Michael Keuntje from Sternzeit Media GmbH, February 25, 2013 at 8:27 a.m.

    With Google and Facebook elements integrated on most websites not only does this strike the ad industry - it most likely comes with a great bias in favour of these two behemoths. This accelerating a trend towards oligopolistic market structures vastly to the disadvantage of those who invest in content. But who knows? - There would always be a chance of blocking blocked browsers to ad financed pages in a joint effort. However relation towards Google under these circumstances - questionable.

  2. Matt Prohaska from Prohaska Consulting, February 25, 2013 at 9:06 a.m.

    Agree with Michael. Plus, someone wanna please catch that baby before it hits the ground with the bath water?

    I've talked with several privacy groups/private companies focused on privacy and found their methodology and understanding of how/why cookies are used are lagging. I'm sure not the case here, and happy to help bring mutual understanding, but hopefully Reid Hoffman can also chat with his Mozilla friends while the IAB maybe discusses this today at their Leadership Summit.

  3. Joe Chiffriller from, February 25, 2013 at 9:35 a.m.

    People don't like being stalked. When I looked at hotels online, it was a bit creepy that ads for hotels in the area followed in my browser for days. Then I shopped for a few days and bought luggage for the trip so the ads for hotels have been replaced with ads for luggage.

    Niche targeting based on page content make a much better basis for presenting ads and don't make people feel that they are being spied on.

    Unsolicited cookies is one baby that deserves to be thrown out with the bath water.

  4. Luke McMullan from Grapeshot, February 25, 2013 at 10:27 a.m.

    Could be brinkmanship. Backlash over disrespect for Do Not Track requests.

    In any case, it's probably time to push more spend into contextual.

  5. James Curran from, February 25, 2013 at 11:25 a.m.

    @Joe Chiffriller - Third party cookies do a lot more for the ad industry than allow ads to follow people.

    For one, it keeps us from showing the user the same ad over and over again. Which no one wants.

    If the "following" piece is what concerns everyone, than attack that specific thing. It is definitely throwing the baby out with the bath water.

  6. Matt Paladino from Acquia, February 25, 2013 at 11:35 a.m.

    @Wendy Davis - Great article. Just a quick note for future reference... The W3C is the World Wide Web Consortium, not Coalition.

  7. Luke McMullan from Grapeshot, February 25, 2013 at 11:56 a.m.

    There's some analysis of this measure here:

  8. Pete Austin from Fresh Relevance, February 28, 2013 at 5:18 a.m.

    @Joe Chiffriller If you click on very few adverts and visit few commercial pages, the ad networks have relatively little information on you and thus will over-target you. This does indeed feel like stalking. Fortunately the solution is very simple: click on one advert every day, at random if you like, and the networks will soon have more data about you and their behavior will become more natural.

  9. Tom Doyle from Aqua Media Direct, Inc., March 1, 2013 at 3:16 p.m.

    Aqua Media Direct has PRE-TARGETING using 3rd party research lifestyle affinities that surpass behavioral and retargeting in performance without using cookies... Our ads are aimed at active interest and appear on any browser.

  10. Adam Berke from AdRoll, March 2, 2013 at 11:44 a.m.

    @Michael Keuntje. Google's pixels, beacons, and ad tags are actually located at and So there would be no bias towards Google at all since the general internet user doesn't navigate to those domains. It would hurt them as much as anyone. Given 80% of Mozilla's revenue comes from Google, there's a good chance that there will be conversations between the two parties before this takes effect.

  11. Brad Flora from Perfect Audience, March 2, 2013 at 6:28 p.m.

    @Adam Berke - Wouldn't it be fairly straightforward for Google to serve those assets from the domain for FireFox users? This is how they've made Google Analytics work for Safarai users.

  12. Michael Keuntje from Sternzeit Media GmbH, March 3, 2013 at 8:25 a.m.

    @Michael Keuntje, @Adam Berke, @Adam Berke
    I think this is of greatest importance for all business models based on content investment on the web:

    I have simplified the tech referring to Google being implemented in almost all web content be it through Doubleclick or Google Analytics and other. So yes Adam - these would also not be able to place Cookies anymore. But for a Google targeting advantage they don't need to: The information coming with the requests they receive can be consolidated with the profile Google (or Facebook) has already aggregated behind the Cookie put on the browser when visiting Google (or Facebook). Neither one can be blamed that almost everybody on the planet alive and on the internet does both no less than once a month. Thus Google and Facebook CAN do it and I don't see why they would not (or should not). However the influence of Google transfers to Firefox in this light - grossly unfair ('purely evil' to put it in their words).

    I am afraid I am stating the same thing as you Brad - however they will probably get away with it as people feel that Targeting=Stalking and Google&Facebook are great and for free thus may have another big bite of Idunnowhat.

    No matter where you look - broadcasting or publishing or advertisement business the greatest participants tend think they can face the structural conflict with Google on eye level and will profit as survivors from the downfall of the competitors in their fields (Hello Andreas Gräther). If you will call prolonged agony just that ... My belief: Only concerted efforts can stop this development.

    From my area of experience I saw Google eliminate Route Planning, than Location&Mapping as businesses. Now they are going after Classifieds&Travel - and in the process Google advances in taking commission-like margins out of businesses of all kinds while disaggregating the traditional link between advertisement and content in a brand/product manner. Google does this while exploiting this content with their search results than replacing it by own information/content.

    While you might find pros and cons from the customer value perspective I do see a right of all owners / investors of content to hold against this when unfairness comes to size advantage. Microsoft was ruled to detach IE from its Office Suite on just that reason (admittedly not entirely comparable). When Google influences Mozilla in a more subtle way that it gains an unfair advantage we see what to expect once Google has nearly monopolized one of the two or three most important and widespread starting points on Internet access paths.

    Or am I freewheeling into a conspiracy theory here? :-)

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