Firefox is caching kind of aggressively, too agressive for soundcloud. Soundcloud just doesn't load, except the navigation bar, and it only gives you the respone that your browser might be outdated (which it is not). The reason for that are the locally stored service workers. This addon tries to clear those hen the site is used. No Ctrl + F5 loading needed anymore. It's not quite perfekt, so when it doesn't work just refresh the site (normally).