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Vivaldi's tab tilling add-on in Firefox
(lemmy.dbzer0.com)
A place to discuss the news and latest developments on the open-source browser Firefox
I haven't tried them out, but a quick Google search gave me 2 extensions
https://addons.mozilla.org/en-US/firefox/addon/tile-tabs-we/
https://addons.mozilla.org/en-US/firefox/addon/tiled-tab-groups/