The latest Firefox Nightly builds have now enabled the Split View mode by default to easily view two web pages at once within a single window.

Firefox Split View is now on by default in the latest Firefox 149 Nightly builds so you can add an existing tab to a split view or multi-select two tabs for the split viewing mode.

[1]

I tried out the latest Firefox Nightly Linux build and indeed the split-view mode is working as advertised.

[2]

The Firefox Nightly builds now having split view mode enabled by default was mentioned in today's [3]Firefox Nightly News .

[4]

That Mozilla blog post also noted the addition of the new browser.aiwindow.enabled configuration option to open a new AI Window. That Firefox AI Window is still in its "extremely early days". The AI chat functionality also requires being signed into a Mozilla Account.



[1] https://www.phoronix.com/image-viewer.php?id=2026&image=firefox_split_1_lrg

[2] https://www.phoronix.com/image-viewer.php?id=2026&image=firefox_split_2_lrg

[3] https://blog.nightly.mozilla.org/2026/01/26/take-note-split-view-is-ready-for-testing-these-weeks-in-firefox-issue-194/

[4] https://www.phoronix.com/image-viewer.php?id=2026&image=firefox_split_3_lrg