Firefox hardening: privacy.firstparty.isolate suggestion?

I was wondering if privacy.firstparty.isolate set to true is still recommended, or if it is outdated with total cookie protection or other changes in firefox cookie protection?

If people have any other recommended settings please feel free to add them and your opinion about them, as well as what they do, if not clear in the name.

Recommended by who?

It seems reputable projects are split:

  • Firefox (Fedora, default): firefox.firstparty.isolate =false
  • Arkenfox: firefox.firstparty.isolate = false
  • Librewolf: firefox.firstparty.isolate = false

  • Tor Browser: firefox.firstparty.isolate = true
  • Mullvad Browser: firefox.firstparty.isolate = true

Arkenfox provides slightly more detail

This feature shortened as FPI, is what makes it that a websites can’t
interact with data from other websites (cache, cookie, etc.) This
shouldn’t be disabled, as you’re breaking the privacy design of Mullvad
Browser. Reply from mullvad support

Should note that according to Arkenfox, FPI is deprecated. Mozilla stopped working on it, in favour of State Partitioning.

The reason Mullvad says to keep it enabled is because the Mullvad browser is a fork of the Tor Browser. The Tor project might be maintaining it (for now). If you’re not using a fork of the Tor Browser, disabling in favour of State Partitioning might be the better move.

Moslty older hardening guides. One example is this Firefox Privacy - The Complete How-To Guide for 2023 | RestorePrivacy.

Also videos by Switched to Linux and Mental Outlaw.

Thank you for the informative information :smile: