I'm using Firefox 57. I'm looking for software that blocks the 1x1 pixels that cause the HTTP{S} fetches that are used to track users. The product I used in the past is called PixelBlock. I searched Firefox add-ons, but I did not find it.

The add-on search returned about 650+ results. I visited the top hits and the functionality was not described in the add-on's descriptions. For example, the number one hit when searching for "PixelBlock" (with quotes) returned uBlock Origin, and it does not appear to provide the blocking (based on the product details).

A second requirement is, I want something that requires a minimum set of permissions. I don't want software that takes full control of the computer just to block the HTTP request generated by a tracking pixel.

What is the recommendation for software that blocks the small pixels, like 1x1 and 3x3, which advertisers and data harvesters use to track users?

I've been kind of laxed of late, and I have not been using the blocking technology. How Email Open Tracking Quietly Took Over the Web brought back the desire to run the defensive software.

  • uBlock Origin not only blocks those tracking pixels, but a bunch of other trackers as well. But it works rather by URLs than by element sizes :)
    – Izzy
    Dec 17, 2017 at 22:51
  • You can't know picture size until you download it. And if you did, you are already tracked and it's too late to block it. So I don't understand what you are asking about.
    – Qwertiy
    Dec 18, 2017 at 19:41
  • PixelBlock is a Gmail extension not a Firefox Add-on. Dec 26, 2017 at 11:44
  • 1
    To clarify Izzy's comment: Generic content blockers, like the one he mentioned, can block tracking pixels, if and only if those images are somehow specified in a filter list (often by URL). Feb 23, 2019 at 20:28
  • I just tested and uBlock Origin does not block Mixmax tracked emails.
    – Garrett
    Feb 26, 2019 at 2:23

2 Answers 2


Ugly Email is probably what you are looking for




Those 1×1 tracking pixels AKA "web bugs" or "web beacons" are blocked by default by ScriptSafe (among other tracking content). To toggle, click the ScriptSafe toolbar button → Options → Privacy Settings → Remove Webbugs.

Also, note that uBlock Origin (Chrome version / Firefox version) (while not exactly what you described) can block many trackers, including most 1×1 tracking pixels. In uBO settings → Filter Lists, enable all the filters in the Privacy section to block tracking content.

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