uBO-Scope by Raymond Hill

A simple extension which primary purpose is to reveal all the connections -- attempted or successful -- to remote servers.

Important: The badge count on the toolbar icon reports the number of distinct third-party remote servers for which there was a connection. Therefore a lower count is more desirable than a higher one.

Keep in mind that not all third party remote servers are necessarily to be avoided, though the number of legitimate third parties are usually low count, typically CDNs.

The extension uses webRequest listeners to report what exactly happened to network requests made by webpages.

This extension is able to report the outcome of network requests regardless of which content blocker is in effect, including content blocking through DNS servers, as long as the browser reports network requests through its webRequest API. Network requests made outside the reach of the webRequest API cannot be reported by this extension.