webext-firstpartyisolation

Toggling it manually requires going to about:config, and searching for it. On startup it's enabled (i.e. do isolate) via a config file, so I could change it there with a shell script. I think though that I'd have to restart Firefox for it to take effect. The extension gives me a handy button in the toolbar that's red (danger) when it's off (i.e. not isolating) that I can just click to toggle. Yes it's a tiny job for an extension, but do one thing well right? Also, to be honest, it's easier that it's there than switching to or pulling up a new shell. Afk to confirm, but pretty sure this is the one I use: https://github.com/mozfreddyb/webext-firstpartyisolation

That's an existing Firefox feature called First Party Isolation. Here's a plugin that toggles it: https://github.com/mozfreddyb/webext-firstpartyisolation It sometimes (rarely) breaks payment processors but otherwise works fine

Firefox's first-party isolation (brought across from Tor Browser) will foil cross-site tracking. Combined with Privacy Badger and Cookie Autodelete, your browser won't make the requests and even if they did, they wouldn't have any cookies attached. https://github.com/mozfreddyb/webext-firstpartyisolation https://www.eff.org/privacybadger https://github.com/Cookie-AutoDelete/Cookie-AutoDelete

You can also run multiple Firefox profiles at the same time, each with different extensions. Something like: $ firefox -ProfileManager -no-remote & Also interesting: https://github.com/mozfreddyb/webext-firstpartyisolation https://github.com/stoically/temporary-containers