That is not misleading at all. Many add-ons require such companion apps. Any add-on that wants to access the filesystem in a more broad way or needs to use raw

That is not misleading at all. Many add-ons require such companion apps. Any add-on that wants to access the filesystem in a more broad way or needs to use raw sockets will need this type of native app to be present. There is a protocol for talking between the native app and the WebExtension called "Native Messaging": https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Native_messaging https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/Web... Native Messaging allow an Add-on to launch a native application that follows its rules. Basically, the add-on needs to ask for nativeMessaging permission, as this one does in: https://github.com/hensm/fx_cast/blob/master/ext/src/manifest.json#L31 https://github.com/hensm/fx_cast/blob/master/ext/src/manifes... And the native application needs to whitelist the add-on as someone who can call them, as seen in: https://github.com/hensm/fx_cast/blob/master/app/bin/build.js#L53-L63 https://github.com/hensm/fx_cast/blob/master/app/bin/build.j... You can see similar setups in many of the WebExtensions that are exploring the p2p/dweb/decentralization space. PS: I am not the author, I checked the source and knew what to look for.