Extremely happy with this addon, and have used it successfully for many years in Firefox 😊 Apparently though, in modern Firefox, privacy.firstparty.isolate = false is the default because it is all handled automatically by other processes. However, in Mullvad browser, privacy.firstparty.isolate = true - is the default because they have a stricter configuration. So there is a distinction between these two Firefox-based browsers and how they deal with the privacy.firstparty.isolate issue.

Very nice add-on, works like expected, only Apple iCloud in the browser doesn't load, have to deactivate the add-on it prior, after loading one of the "apps" I can activate it again. But I rarely need this, only sometimes when I'm at work. Indeed a whitelist would be nice, but not possible like you statet below.

Does one thing. Does it well.

Simple and clean add-on, does what it needs to do with just a click (activate or de-activate).

Complete perfectly my other privacy add-ons and it has NO conflict with them (u-block origin, editThisCookie, bloody viking!, Grammarly, User Agent switcher, and few others).

Strongly recommended!

Works as expected, easy to use: install and forget. Been using it for months, don't plan to stop using it.

Simple
Easy to use
First party isolation is the simpliest way to avoid tracking !