Firefox Multi-account Containers
Lightbeam for Firefox
island
Tree Style Tab
App Cloner
AllAccounts
Session Box
Parallel Space
Tab Session Manager
OneTab
Session Buddy
Tabs Outliner
SplitUp!
Workona
Tablerone
Tab Stash
Lightbeam for Firefox - Mozilla is the not-for-profit behind the lightning fast Firefox browser. We put people over profit to give everyone more power online.
OneTab - Whenever you find yourself with too many tabs, click the OneTab icon to convert all of your tabs into a list. When you need to access the tabs again, you can either restore them individually or all at once.
island - a free and opensource alternative to parellel space
Session Buddy - Manage Your Browser Sessions
Tree Style Tab - Tree Style Tab is an all-in-one Firefox extension that provides ability in order to operate tabs as a tree.
Tabs Outliner - Next Generation Session, Windows, Tabs Manager and a TooManyTabs Solution That Really Works.