There is an experimental implementation of that feature, called "First Party Isolation", in Firefox today. You just need to set the `privacy.firstparty.isolate` pref = true in about:config.

With this pref enabled, advertiser X will serve you different cookies on site A and B. They won't be able to track your browsing history from site to site. However, this breaks a lot of sites that depend on third-party services for login authentication or comment systems.

Here is the Firefox bug where you can report broken sites:

https://bugzilla.mozilla.org/show_bug.cgi?id=1299996

This would actually be implementable with the new WebExtensions for containers https://developer.mozilla.org/en-US/Add-ons/WebExtensions/AP...

Essentially building a new container per origin.

We are also hard at work supporting add-on authors porting to WebExtension APIs. I'm especially trying to help Privacy & Security add-on authors.

uBlock, NoScript, Self Destructing Cookies. Also DisableWebRTC. Firefox would be Opera, Chrome or Vivaldi without them. No particular reason to use it or a random one among the others. Stylish and Greasemonkey are useful too, when sites insist doing the wrong things. I hope all of them survive the switch. Will they?

You can keep track at https://arewewebextensionsyet.com/#addons

uBlock Origin started as a Chrome extension.