Very informative and Helpful Extension!! It works as described. Thank you!! Thumbs up!

It's changed and not for the better.
I loved that you could tell how many tabs are loaded (not open tabs) from the tool tip, just by hovering.
Now I need to click to find that out. It doesn't sound like much but why change it from the more helpful setup?
Hopefully there is another change to come.

UPDATE: (if I write another review with a new score, the old score I gave doesn't get removed?)
Back to its best. Simple and effective.

Simple, yet doing exactly what it's supposed to, thank you for the great work!

Exactly what I needed since upgrading to the new version of Firefox, although I had to search 5 pages in before I found this. You might want to change the name or add a sub name/metadata to include something like 'Tab Count'.
Every other similar tab counting extension focuses on showing the amount of tabs per window and less so on the total amount of tabs across windows. This is prefect for me as I'd rather see that I currently have 682 tabs open :)

It's about 6.5KB in size (packed), being the smallest contender (the biggest I've tested is 66KB, packed). It uses event triggers to update the badge, which seems to be the best method to do it (most others use timeout counters). It uses WebExtensions technology and is bootstrapped (no restart required).

Good, because uses nearly 0 ressources, (checked on about:addon-memory) Indicates loaded tabs too (it's the only one that shows the number of loaded tabs).