The Firefox web browser displays extra permissions that an extension requests during installation and won't proceed with the installation until you activate the add button.
Extra permissions may request access to specific domains or all sites on the Internet, to display notifications, or to access the browser tabs.
You may notice sometimes that Firefox lists only some of the domains an extension requests access. Firefox displays a number, e.g. 13 other domains, in that case.
The prompt offers no option to display the entire list of domains an extension requests access to. You see such a prompt on the screenshot below.
The page of the extension on the Mozilla website lists the very same permissions so that it is not possible to verify all domains an extension requests access to using it or the installation prompt.
While it is certainly better if extensions requests access to as few domains as possible to provide its functionality, it is a usability issue that you cannot look the information up prior to the installation.
Here is a quick guide on how to display all domains without installing the extension.
First the manual way:
Now with the help of the Firefox add-on Extension Source Viewer. We reviewed the extension back in 2016, check out the review for additional details. Chrome users can install this extension to verify Chrome extensions. You may also want to check out our precautions to take before installing Chrome extensions guide.
Tip: You may use a web version of Extension Source Viewer if you prefer not to install an extension to check other extensions.
Mozilla should consider adding an option to the extension page on the Firefox website and the installation prompt to list all domains an extension requests access to. (via Reddit)
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Ghacks is a technology news blog that was founded in 2005 by Martin Brinkmann. It has since then become one of the most popular tech news sites on the Internet with five authors and regular contributions from freelance writers.