Cloud Firewall is a browser extension/addon that allows users to block connections to sites, pages and web resources (images, videos, etc) hosted in major cloud services if the user wishes to do so.
Example 1: If "Block Amazon" is toggled ON in Popup, all websites hosted on Amazon AWS will be blocked. Future version of addon will have an "allow all clouds in this site" button in UI for excluding some sites from blocking rules. More Info »
Example 2: If "Block Amazon" is toggled ON in Popup, let's say a website is hosted "on-premise (not in cloud)", but has some "resources" like images, video and scripts hosted on Amazon AWS cloud, only those "3rd party" resources are blocked. "3rd party" = these resources. "1st party" = site in address bar + resources delivered from same domain on-premise server.
Regarding Toggle switches in popup menu, the default upon install is "Allow all supported tech companies/clouds". Any allow/block toggling is not persisted across browser restarts i.e. whenever the browser is restarted, all switches are toggled OFF = allow top companies/clouds when browser launches. For advanced users : You have the option to persist the allow/block rules using the switch in Settings page.
The inspiration behind the creation of this addon was the "Life without the tech giants" series by Kashmir Hill and Dhruv Mehrotra.