users of firefox-based browsers:

what do you use to manage large numbers of tabs? in vivaldi, i use workspaces to keep the tab bar clutter to a minimum, and tab stacks to further sort tabs by function, but i don't see any similar functionality native in firefox 

 @f9acebca nothing available natively I believe, but I use TreeStyle Tabs, and collapse the tab tree that I'm not currently interested in. Other folks use Sidebery for something similar.