[diroussel]

You can see the tab count without an addon. It's not pretty, but you can do it.

Go to: about:telemetry#scalars-tab

Then look at: browser.engagement.max_concurrent_tab_count

[sfink]

Ah, but if you use https://addons.mozilla.org/en-US/firefox/addon/tab-stats/ then you can not only get the count, but also be able to mass-close large numbers of tabs (eg specific duplicate URLs, or everything for specific domains). A tab hoarder's best friend.

(Pretty clever to use telemetry for this, though.)