If you use an ad blocker, you’ve probably come across sites which ask you to switch it off. Doing so exposes you to not only ads and spying, but often malware too—as many Forbes readers discovered when they did just that at the behest of the site.

Many ad-dependent sites are now so desperate for ad money that they’ll give you a stern telling off if they find you’re using an ad blocker, or prevent you from seeing their content until you turn it off.

In Why It’s Okay to Block Ads, James Williams writes that in much of the debate around ad-blocking, there’s a surprising assumption, from both sides, that “the large-scale capture and exploitation of human attention [is] ethical and/or inevitable in the first place”. He continues

…the question should not be whether ad blocking is ethical, but whether it is a moral obligation. The burden of proof falls squarely on advertising to justify its intrusions into users’ attentional spaces—not on users to justify exercising their freedom of attention.

Today on fivefilters.org we’re displaying a corner ribbon for our visitors who don’t have an ad blocker installed1. Rather than warning against ad blocking, we want to actively encourage it.

Detecting absence of ad blocker

While our little corner ribbon is not very intrusive, we won’t show it to visitors already using an ad blocker. How do we detect if someone isn’t running an ad blocker? We make a request for a file that most ad blockers will block2. In this case, we’re calling our file ads.css.

Our little ribbon promoting ad blocking is hidden on our site. But it’s made visible if our ads.css file loads (indicating an absence of an ad blocker)—the file contains one line:

#use-adblock { display: block; }

If the file fails to load, because it’s prevented by your ad blocker, the ribbon remains invisible.

Test site for ad blocking

We’ve also set up a site—blockads.fivefilters.org—anyone can visit to see if their browser is blocking ads or not. It not only tests for ad blocking, but also checks to see if the browser is letting through ‘acceptable’ ads—if it is, you get warned about it. Many users of Adblock Plus are unaware that the company makes money from whitelisting advertisers.

Why do we recommend uBlock Origin?

Because of its uncompromising stance towards 'acceptable’ ads:

The uBlock project does not support Adblock Plus’ “Acceptable Ads Manifesto”, because the “Acceptable Ads” marketing campaign is really the business plan of a for-profit entity.

Users are best placed to know what is or is not acceptable to them. uBlock’s sole purpose is to give users the means to enforce their own choices.

Technically, it also performs better than Adblock Plus and other ad blockers.


Let us know what you think. This is really an experiment at this stage. The code for the test site (it’s quite simple) is available on Github. Feel free to copy, improve, share your changes.

  1. Thanks to Miro Karilahti ↩︎

  2. At least the ones relying on EasyList ↩︎