There has been first party isolation from Tor Browser in Firefox for a while. https://addons.mozilla.org/en-US/firefox/addon/first-party-isolation/ https://add

There has been first party isolation from Tor Browser in Firefox for a while. https://addons.mozilla.org/en-US/firefox/addon/first-party-isolation/ https://addons.mozilla.org/en-US/firefox/addon/first-party-i... That addon has links with info and just twiddles an about:config setting. It can break things (for example some ways Paypal is used by websites, although other ways work fine). There has also been the ability to block third party cookies for a very long time, possibly as long as there have been cookies, but it can also break things. As I understand it Total Cookie Protection is similar to these but with some exceptions so that not much breaks that users would notice.