You can now enable Dynamic First Party Isolation in Firefox 77

Mozilla Firefox 77 Nightly version has received a new option in the Custom mode for Enhanced Tracking Protection in Privacy and Security Settings to let users enable the ” Dynamic First party isolation” feature in the Firefox browser, the feature can also be enabled by changing a preference value in about: config.

Beginning with Firefox 53, Mozilla has hidden the first party isolation feature behind a preference called privacy.firstparty.isolate, enabling it may cause certain websites to break. Over the years, Mozilla has integrated stronger privacy protections into Firefox in the form of enhanced tracking Protection or content blocking modes. As of now, Firefox browser with standard ETP blocks tracking cookies, social media trackers, tracking content in private windows, fingerprinters and crypto miners by default. Users who choose custom mode have the luxury to choose which trackers and scripts to block.

Till now custom setting allows blocking these types of cookies in Firefox browser

  • Cross-site and social media trackers
  • Cookies from unvisited websites
  • All third-party cookies
  • All cookies.

In addition to the above, custom setting for Enhanced Tracking Protection in Firefox Nightly offers another new option for cookies in the dropdown:

cross-site and social media trackers, and isolate remaining cookies

block cross site and social cookies and isolate remaining preference
New cross-site and social media trackers, and isolate remaining cookies option

Choosing this option may cause certain websites to break where you may not able to sign into them. The Dynamic FPI can also be enabled by changing the following preference in about:config to 5.

network.cookie.cookieBehavior

Enable Dynamic First Party Isolation in Firefox

To test the feature, launch Firefox Nightly

1. Click on menu, select Options

2. Privacy & Security > Custom,

3. Select “Cross-site and social media trackers, and isolate remaining cookies”

You need to reload all tabs or you can restart the browser for the same.

reload all tabs and isolating cookies warning

When you select the option, Firefox Nightly shows a warning at the bottom alerting you that “blocking trackers and isolating cookies could impact the functionality of some sites”.

Related articles:

UBlock Origin v1.25 introduces First-Party Tracker blocking Exclusively for Firefox [Not available in Chrome]

Firefox 69 release brings Enhanced Tracking Protection and Various Performance Improvements to Windows 10 and macOS

Firefox 70: Mozilla updates Enhanced Tracking Protection Preferences

Firefox updates Protection Report to show Real data about trackers it blocked, adds Monitor and Lockwise sections

Mozilla finds Tracking Protection in Firefox decreases Page Load time for sites by 44%

Venkat Eswarlu

Venkat is an independent technology journalist and the founder of Techdows. He has been covering web browsers, Windows, and software news since 2009. His exclusive scoops on Chrome, Firefox, and Edge features have been cited by Forbes, TechCrunch, Wired, CNET, and other major publications.

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