The best open source alternative to Undo Close Tab is Tab Mix Plus. If that doesn't work for you, our users have ranked six alternatives to Undo Close Tab, but unfortunately only two of them is open source. If you can't find an alternative you can try to remove all filters.
Tab Mix Plus enhances Firefox's tab browsing capabilities. It includes such features as duplicating tabs, controlling tab focus, tab clicking options, undo closed tabs and windows, plus much more. It also includes a full-featured session manager with crash recovery that can...
Open Bookmarks/History/Homepage/URL/Search in new tabs, and more utilities for tabbed browsing, including open tab next, focus related/last visited tab, protect/lock/faviconize/pin tab, multiple tab handler, tab clicking options, etc.
