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Per site switches

gwarser edited this page Feb 2, 2019 · 56 revisions

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The per-site switches allows you to control uBlock's behavior on a per-site basis.

New in 1.17.0:

Changes to the state of per-site switches will be deemed temporary if and only if the overview panel is visible.

When the overview panel is not visible, toggling a per-site switch will cause the change to be permanent (i.e. same behavior as before).

However, when the overview panel is visible, toggling a per-site switch will cause the change to be temporary. In such case, there will be an eraser and a padlock icon in the overview pane, which can be used to revert or persist the current state of all the per-site switches.

Popup UI

No popups

By default popups are allowed unless there is a filter to block them. When this setting is enabled, all popups will be unconditionally blocked for the current site, regardless of filters:

Popup UI

Blocking popups depends on whether the proper filters are present in the selected filter lists, so this feature is most useful when a site creates popups for which there are no filters to take care of them in 3rd-party filter lists.

Caveat for Chromium-based browsers: Due to Chromium API limitations, it's not always possible for uBlock Origin to determine for sure whether a new tab being opened is that of a popup, or is the result of a legitimate click on a link by the user. So if the no-popups switch is in use, you may not be able to open a link in a new tab through the context menu.

No large media elements

The second icon is to toggle on/off the blocking of large media elements for the current site. The primary purpose of this feature is to save bandwidth. Side effect is to possibly speed up page load.

Popup UI
The badge shows the number of large media elements that have been blocked on the page.

By default, this setting is disabled. The global default can be enabled in the Settings pane in the dashboard.


The threshold size -- a global setting -- to decide when to block or not is also configurable. The threshold size can be set to zero: this will cause all media elements to be blocked. For the sake of documentation, let's refer to media elements (images, videos, audios) which are larger than the set size as "large media elements".

You can enable/disable on a per-site basis, there is a switch in the popup panel to toggle for the current site.

When large media elements have been blocked on a page, you may force a reload of these elements interactively: if you hover over the placeholder of a blocked image and the cursor changes into a magnifier, this means that clicking on a blocked image will force a reload of that image.

If you use this feature and large media elements were blocked on a web page, the context menu will contain a new entry: "Temporarily allow large media elements". When you click this entry, uBO will disable temporarily the blocking of large media element for the site, and attempt to load the blocked media elements without re-loading the page. In some cases you may need to force a reload of the page, for example if large media elements were fetched programmatically by the page. The temporary disabling will be removed for a tab as soon as you travel to a new site, or close the tab.

Blocked large media elements are reported in the logger with the filter no-large-media: [scope] true.

Note that this feature has no privacy value: a connection to the remote server must be performed in order to fetch the size of the resource. This of course applies only to resources which were not otherwise blocked by uBO's filtering engine.

Examples of usefulness (let's say you just stumbled onto these pages not knowing whether the article would really interest you), bandwidth consumed:


If the media elements do not have Content-Length header present, then this switch will fail to block the said media elements by size.

No cosmetic filtering

"Cosmetic filtering" in uBO is what is known as "element hiding" in Adblock Plus.

You can easily toggle on/off cosmetic filtering for a given site:

Popup UI
The badge shows the number of DOM elements that have been hidden on the page.

When present, the badge number indicates the number of elements hidden on the page by uBO as a result of cosmetic filtering. If you disable cosmetic filtering while there are hidden elements on the page, these elements will become visible/hidden as you toggle off/on cosmetic filtering.

A good example of cosmetic filtering in action are the ads showing up with the results of a Google Search page (example).

Cosmetic filtering is always enabled by default.


It is often suggested adding a custom static filter such as @@||^$elemhide or @@||^$generichide to prevent "adblock" detection by specific sites (example, example). You can accomplish the same goal more simply by just toggling off cosmetic filtering using this switch while on the problematic site.

This switch can help uBO to further lower its CPU-cycle footprint, which might be beneficial on devices with limited CPU-cycle resources -- and thus helping extend battery life and speed up page load times. The idea is to disable cosmetic filtering everywhere by default, and to enable it only for those sites which really benefit from it.

To disable cosmetic filtering everywhere by default, go to the Settings pane in the dashboard, and check the option "Disable cosmetic filtering" under the "Default behavior" header:

Disable cosmetic filtering everywhere by default

From then on, cosmetic filtering will be turned off everywhere by default, and to turn it on for a specific site where it is really needed, just enable it using the switch in uBO's popup panel.

No remote fonts

You can prevent web fonts from being downloaded for the current site:

Popup UI
The badge shows the number of font resources that have been seen on the page.

Because of security and privacy concerns, many prefer to block all web fonts by default -- toggle the appropriate default behavior in the Settings pane in the dashboard:

Block remote fonts everywhere by default

This will block all web fonts everywhere by default, and in this case you can toggle off the switch to allow web fonts on a per-site basis.

Keep in mind, though, that this rule blocks all first-party and third-party fonts. As a lighter alternative you can also choose to allow first-party fonts and block only third-party fonts by adding the filter


to the "My filters" pane. If you want to allow third-party fonts for some specific sites you can add them by modifying the above filter:


No scripting

New in 1.17.0

Wholly disable JavaScript for a given site.

Popup UI
The badge shows approximate number of script resources which have been seen on the page (number is limited to 99 because of layout constrains)

This master switch has blocking precedence over dynamic filtering rules and static filters related to script resources.

Furthermore, when JavaScript is disabled through this master switch, noscript tags will be honoured on a page (as opposed to when just using filters/rules to block script resources).

As with some other per-site switches, the default state of per-site JavaScript master switch can be set in the Settings pane, thus allowing to disable JavaScript everywhere by default, and enable on a per-site basis:


JavaScript master switch rules appear as no-scripting: [hostname] true entries in the My rules pane.

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