> You'd have to install the TestPilot extension first, and then the Containers addon.

No you wouldn't …? Firefox has had support for profiles as long as I've been using it, which goes back to the Phoenix days. It tries to pretend that you can't run it with multiple profiles simultaneously, but you can (`firefox-bin -profilemanager`).

Thanks for the reminder. I remember checking that out when it first launched and then I drifted away from using it for reasons that I no longer recall. I'll check it out again.