It works out of the box in Firefox 48.0a2. Navigate to about:debugging, and load the manifest.json as a Temporary Add-on. It will stay installed until you clo

It works out of the box in Firefox 48.0a2. Navigate to about:debugging, and load the manifest.json as a Temporary Add-on. It will stay installed until you close the browser. I don't think permanently loading extensions this way will work in the normal Extensions pane until Firefox 48 is in release. See the "Chrome compatibility" section: https://blog.mozilla.org/addons/2016/04/29/webextensions-in-firefox-48/ https://blog.mozilla.org/addons/2016/04/29/webextensions-in-...