Our Block Ads! site is a simple way for people to check whether their browser is blocking advertising or not, and to get a recommendation for an ad blocker if it isn’t. It’s also intended to be a website you can send to friends and family so they can quickly test their own browsers and install an appropriate ad blocker.

We’ve updated it with the following changes.

Opera, Safari and iOS recommendations

If you’re using the Opera browser, we’ll now point you to the uBlock Origin extension for Opera.

uBlock Origin is, unfortunately, not available for the popular Safari browser or for iOS devices. As such, if we detect that you’re on iOS (accessing the site from your iPhone, iPad or iPod), we will now suggest you install Focus.

If we detect that you’re using the (non-mobile) Safari browser, we will suggest you install Wipr.

For Chrome or Firefox (non-mobile versions), we will, as before, recommend uBlock Origin.

Ad blocker criteria

There are many ad blocking solutions available. In general, here’s what we’re looking for:

  1. No acceptable ads
  2. Preferably free (as in freedom)
  3. Preferably free (as in no payment required)

All the blockers we recommend meet the last criteria. Although we’d love to see people donating and supporting ad blocking projects, we also want it to be as quick and as easy as possible for people to get ad blocking set up. Requiring payment is an obstacle.

uBlock Origin and Focus meet the second criteria. uBlock Origin is GPLv3 licensed and Focus is licensed under the Mozilla Public License. Source code here and here. Wipr does not meet this criteria.

As for ‘acceptable’ ads, uBlock Origin and Wipr both state openly that they are against it. uBlock Origin:

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.


No one can pay to unblock ads. There are no “acceptable ads”.

Focus is a little different here in that it does not claim to be an ad blocker at all. It bills itself as primarily a privacy tool for blocking trackers (blocking ads simply becomes a byproduct of stopping trackers, which is what most ad networks are too). Because it appears to have no position on advertising, it might at some point allow advertising from networks that claim to do no tracking.

No caching

To test whether you have ad blocking enabled, we try to load images from known advertisers. If these images successfully load (you won’t see them, but we’ll try to load them in the background), it’s an indication that your browser is not set up to block advertising.

Once you install an ad blocker and try again, requests for those images will be blocked by your ad blocker. If, however, your browser loaded them successfully before, it might have saved a copy in your cache. If that happens, the ad blocker will not get a chance to intervene and block the requests the second time, resulting in the same diagnosis as before (“no ad blocking detected”), despite the fact that the ad blocker is in fact active.

To avoid this situation, we now ensure the URLs we test for blocking are unique each time, to ensure that your browser does not load a cached copy.

What’s missing?

We are currently not recommending anything for Internet Explorer users. uBlock Origin is being developed for Microsoft Edge (Microsoft’s replacement for Internet Explorer). Once it’s available, we’ll start pointing people to that.

As for Android, one downside of being owned by an advertising company (96% of Google’s revenue was from advertising in 2011), is that it is notoriously hostile to ad blockers. To enable ad blocking for Android, we will have to suggest users install and start using a new browser (with built-in ad blocking). We’re looking into that. If you have recommendations, please let us know.

And if you have any other feedback, we’d love to hear it.