Palemoon has the Tab Groups feature as a separate addon: <a href="http:&#x2F;&#x2F;www.palemoon.org&#x2F;tabgroups.shtml" rel="nofollow">http:&#x2F;&#x2F;www.palemoon.org&#x2F;tabgroups.shtml</a><p>Source code is here: <a href="https:&#x2F;&#x2F;github.com&#x2F;wolfbeast&#x2F;palemoon-tabgroups" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;wolfbeast&#x2F;palemoon-tabgroups</a><p>&quot;This is the repository for the Tabgroups add-on source code for Pale Moon, based on Tim Taubert&#x27;s work as part of the proposal to remove Tab groups from Firefox and moving the removed code to an extension.&quot;<p>Installs fine in Firefox 45a too, but it&#x27;s not signed (obviously).