How to disable Firefox's Adult Filter on the New Tab Page

Martin Brinkmann
Jan 8, 2019
Updated • Jan 8, 2019

Did you know that Firefox filters certain sites so that they don't appear in the Top Sites and Highlights listing on the New Tab Page?

Firefox's Top Sites listing on the New Tab Page displays popular sites visited by the user and sites and search shortcuts that Mozilla added to the listing by default.

Mozilla implemented a filter for the top sites listing in 2014 to prevent certain sites from appearing on the New Tab Page.

The reason for the filter? conflicts with commercial partners. Kevin Ghim opened the issue on Bugzilla in 2014 using the following description:

Problem: commercial partners do not want their content to be negatively associated with adult content. In the context of Suggested Tiles, this means no sponsored or affiliate tiles should appear within same browser viewport. As an example, MGM would not want a 007 DVD release to be appearing within the same page (in particular, directly next to) where PirateBay tile appears.

In other words, commercial partners who are interested in placing sponsored tiles on the New Tab Page might not wand their content displayed next to sites opened by the user that may affect the sponsored content negatively.

Mozilla launched sponsored tiles, a new revenue option embedded in Firefox, in 2014. Back then, I suggested that sponsored tiles might not be worth it as revenue would be comparatively low and might affect user perception of Firefox negatively. Mozilla dropped sponsored tiles one year later in Firefox but did not remove the content filter.

Certain sites won't be listed on Firefox's New Tab Page even if you visit them regularly or if they are the most visited sites in the browser.

firefox adult filter
Firefox's New Tab Page with disabled content filter

A quick check in Firefox Stable on Windows confirmed this. Visits of popular adult sites -- for research -- did not result in these sites being added to the Top Sites or Highlights listing on the New Tab Page.

Disabling the filter in Firefox would make these visited sites appear eventually (I had to dismiss one item to get these to display, probably because of caching).

Catalin Cimpanu, who discovered the filter, notes that the filter prevents [certain] adult sites from appearing in the Top sites and Highlights section of Firefox's New Tab Page.

He notes that Firefox users may disable the filter; this is done in the following way:

  1. Load about:config?filter=browser.newtabpage.activity-stream.filterAdult in the Firefox address bar.
  2. Confirm that you will be careful if the warning prompt is displayed.
  3. Set the preference browser.newtabpage.activity-stream.filterAdult to false by double-clicking on it.

A value of false disables the adult filter, a value of true is the default filter and means that it is enabled.

A list of domain hashes that Firefox uses for the filter is listed here. The list contains a total of 2919 encoded URLs.

Closing Words

The filter was introduced at a time when Mozilla tried various monetization options to diversify revenue. Mozilla's decision was based on commercial interests only and not Firefox user interest. The organization could have used a different implementation: maintain a list of sites that advertisers object to and if found on the New Tab Page in Firefox, omit the advertisement.

Limiting Firefox's Top Sites and Highlights functionality in favor of commercial interests is not something that one would expect from an organization that states on its start page "Your life is your business. Not ours".

Mozilla should consider removing the filter from the New Tab Page.

How to disable Firefox's Adult Filter on the New Tab Page
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How to disable Firefox's Adult Filter on the New Tab Page
Did you know that Firefox filters certain sites so that they don't appear in the Top Sites and Highlights listing on the New Tab Page?
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  1. KCP said on July 3, 2021 at 2:40 am

    I changed the setting and it did not work for me.

  2. John_3_16 said on March 19, 2019 at 3:01 pm

    I agree. The only thing I want on a new tab/page at FF startup is my DuckDuckGo search bar with my presets active. I blanked all of the FF options for showing their garbage & made DDG search my default for the URL window & after copying the URL for DDG with my settings active I transferred it to show on any new tab/window. The filter discussed here is of no consequence to me beyond demonstrating that even those claiming user interests above all else can be corrupted by the trust we place & the power they have. All sheep need a dogs & a shepherd to care for them. If you don’t want the life they design for you, then educate yourself to become a dog &/or shepherd. God bless.

  3. Tom Hawack said on January 9, 2019 at 7:44 pm

    Why not just forget Firefox’s default NewTab? :

    Firefox Options > Home
    > Homepage and new Windows
    > New tabs

    Further elaborated :
    New Tab Override (WebExtension)

    I avoid, always have, Firefox’s Homepage (startup page) and its highly problematic Newtab page, I’ve set one page of my own worth Home and Newtab pages. No fuss.

  4. Yuliya said on January 8, 2019 at 10:20 pm

    I never liked this “top sites” feature in any browser. Not only I find it useless, but it never works properly. I just tried to see if Chromium has the same problem, but I can’t even get ghacks to show up, let alone a pornographic site.

  5. jan said on January 8, 2019 at 5:52 pm

    Catalin Cimpanu, who discovered the filter, notes that the filter prevents [certain] adult sites from appearing in the Top sites and Highlights section of Firefox’s New Tab Page.

    1,) WHY is that filter DISCOVERED and not part of the FF documentation??
    2.) Whatelse is there to be DISCOVERED in FF??
    3.) By an update of FF will the filter be affected or reset???

    Thanks for your comments on this

  6. Anonymous said on January 8, 2019 at 3:25 pm
    1. Anonymous said on January 8, 2019 at 5:17 pm

      Gotcha! So your id is 3n.0038.2256.gf0ao06f39.2crr!

      1. Tom Hawack said on January 8, 2019 at 6:08 pm

        3n.0038.2256.gf0ao06f39.2crr and I never met, she couldn’t make it to my place :

      2. ShintoPlasm said on January 8, 2019 at 7:26 pm

        @Tom: lol. Also, nice skin :)

      3. Tom Hawack said on January 8, 2019 at 9:23 pm

        @ShintoPlasm, well I had to show show the skin to display the soul, I mean the address in the urlbar :=)

        The Big Eyes (as well as any perspicacity) will wonder why different users on different sites, when they happen to show their Firefox skin, show the very same, ultimately specific. Gosh, damned, I’m done!

        Of course this skin is a deep modification of the original, toolbar buttons’ icons included. Well, I have this browser opened all day long so I like to feel at home with it. I can tell you, FF out-of-the-box (as I happened to rediscover it when creating a new profile for testing purposes) seem to me abominable. You are facing a designer, an artist, an exceptional talent, of course!

        There I went again off-topic (I knew it in advance but considered that the mea culpa would get me away with it, as usual!).

    2. Tom Hawack said on January 8, 2019 at 4:30 pm

      I guess this is managed by WordPress, not sure though.

      Good to know : I couldn’t reach such newsletters’ links’ destinations given I’ve added to my Acrylic DNS Proxy application the four following marketing trackers : > > > >

      Marketing trackers, indeed, among millions …

  7. Mayday said on January 8, 2019 at 3:17 pm

    “Visits of popular adult sites — for research” You don’t have to be so coy, we all know you yanked your crank while conducting your investigation, meanwhile an upwards of 2,000+ websites have been bookmarked for further research. [Herp derp derp, you knew it was coming]

    On a serious note; Mozillas decision to make the new tab unchangeable for the user in is ironically sinister as they’ve become gatekeepers while simultaneously doing what the bad guys were doing. On one hand Anonymous is correct, users should be more aware of clearing out history and private browsing and on another hand most users are complete imbeciles and really do need companies like Mozilla to babysit and direct their behavior. But the fact is, advertisers should clearly not even be in this discussion at all, especially coming from a company like Mozilla, but alas here are. Welcome to the modern web where advertisers and huge mega companies bend our perception at will.

  8. Anonymous said on January 8, 2019 at 2:14 pm

    Yes, advertising will make our planet great again.

  9. ULBoom said on January 8, 2019 at 1:26 pm

    “Mozilla’s decision was based on commercial interests only and not Firefox user interest.”

    The customer is always right, especially when Mozilla is their own customer. Nothing new from an industry that can’t see anything wrong with letting users do QA for them.

  10. ShintoPlasm said on January 8, 2019 at 1:06 pm

    At least it saves you from annoying questions by your boss… :P

  11. TelV said on January 8, 2019 at 12:03 pm

    They got the slogan the wrong way round then. Should be: “Your life is our business. Not yours”.

    Out of pure curiousity, how does one use one of those hash tags to identify the site it’s linked to?

    Fortunately, the filter isn’t present on Waterfox. I didn’t expect it to be, but I just checked anyway.

  12. Anonymous said on January 8, 2019 at 11:50 am

    I appreciate to see you leave your usual neutral tone to justly criticize Mozilla for working for advertisers more than for users.

    Some people say that this is also useful to save users from possible embarrassment. My view on this is that if users had seen their porn history displayed all over their home page, maybe they would have started thinking about clearing history automatically when exiting the browser, making it harder for Firefox to data mine their history for advertisers.

    1. user17843 said on January 8, 2019 at 12:53 pm

      This is symptomatic for Mozilla. It’s not a big deal in itself, but things add up over time. And everytime their response to the community is “well, it’s irrelevant anyway, and you can just disable it”.

      If it’s so irrelevant, why does Mozilla pay their employees to do all the extra unnecessary work?

      Because, like the bug reveals, in the end it’s always about money. But that means your browser is not yours.

      Fascinatingly Chrome is the only browser nowadays that treats it’s users like grown ups.

      1. ShintoPlasm said on January 8, 2019 at 3:41 pm

        @user17843: Agreed about Chrome. At least with Google you know where you stand – they’re a commercial enterprise, they want to use your data when you allow them (in the EULAs) under some limitations, but they still give you enough options, configs and extensions to control your internet presence. No wonder that large companies only ever use Chrome in their laptop fleet.

      2. Mikhoul said on January 8, 2019 at 7:02 pm

        Don’t forget you can also use Chromium forks or Chromium plain with lot more options than Firefox:

        But my personal favorite fork is CentBrowser which target power users and customisation:

      3. ShintoPlasm said on January 9, 2019 at 3:17 pm

        The Chromium builds on Woolyss (even the Marmaduke/Sync one) give me ‘Google API’ errors and I can’t use the sync functionality. Bit of a pain in the arse… Am I doing something wrong? I find the instructions on how to install the APIs very confusing.

      4. Mikhoul said on January 10, 2019 at 3:11 am

        I don’t use the sync with the Woolyss builds but I use the sync with CentBrowser and it work fine, CentBrowser have more features/customisations than plain Chromium if you are a power user you should like it.:

      5. user17843 said on January 8, 2019 at 9:38 pm

        Personally I like the free market and capitalism to an extent, I am perfectly fine with using a google product.

        Google makes money with ads, so what. There is always a dark side in every industry, that’s true. But Google is the most transparent when it comes to what they collect from all companies I know.

        The biggest threats are companies that tell you they don’t have any self-interest. Because that means they have some other interest, which they hide. And then one has to ask, what are they hiding. With those companies, you never know what you are up to. They might secretly sell out when they think the end justifies the means.

      6. Tom Hawack said on January 9, 2019 at 2:47 pm

        That’s what one could call a self-confident capitalism, at ease with itself. Another approach is to consider that an admitted sin is half forgiven. Self-confidence and lack of hypocrisy may be a lure, hiding vice of facts behind virtue of honesty.

        Personally I take into consideration only the facts : Google brings near excellency products and services but the price, that of its intrusion in our lives, is excessively high. I’d say the deal is not balanced. Therfor as many others I search — and find — alternatives.

      7. Anonymous said on January 9, 2019 at 10:59 am

        “At least with Google you know where you stand”
        “But Google is the most transparent when it comes to what they collect from all companies I know.”

        Your remember that Chromium build that listened to discussions in the room with the microphone ? That’s one counterexample among a million. Spyware companies always rely on deception at many levels to make their business model look acceptable to the masses and sometimes to the more technically literate. Since when have the most evil spyware companies become “transparent” just because they don’t hide that their only motivation is making money ?

        Using a Google browser is not only using an unpredictable proprietary spyware made by an evil company, it’s also giving Google more monopolistic power over the web standards.

        The solution to the current Mozilla plague is not to use the worse Google products, it’s Firefox forks.

      8. user17843 said on January 9, 2019 at 12:40 pm

        @ Anonymous: There is no collective solution. If you look beyond your narrow view you see that there are always downsides to everything. Everything has a price. But sometimes the price is worth it, which differs for everyone.

        The company is bound to GDPR and public scrutiny.

        I avoid most Google products, because they are everywhere, but I would do that with every company that has so much control.

      9. Anonymous said on January 10, 2019 at 12:08 am

        “The company is bound to GDPR and public scrutiny.”

        I don’t think Google and the other big players of privacy violation have changed significantly since GDPR. It’s sad to hear that law considered like a magic talisman that would finally save us.

        As for public scrutiny… people publicly uncover Google privacy horrors all the time, but they can’t help you if you chose to downplay everything they warn you about. And then there’s what we don’t know yet.

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