Good indicator that helps me save memory ;)

It does what it says it does so 5 stars!

I have a tendency to build up many tabs at once. My max has been roughly around 200 tabs open at once.

I was curious today and found this extension to check my current number.. I have 470 tabs open.......

I think it's time to clean some out.

Since I keep a number of tabs open and can't find a post v57 extension that lets me keep multiple rows of all open tabs, its easy to get lost when tabs are scrolled horizontally off screen. This is a handy little reminder there are out-of-sight tabs.

Note, waterfox (branched from FF v56) supports all legacy functions and extensions, including an extension to use multiple tab rows & also to place tabs below the bookmarks (vastly clearer UI I can't understand why FF v57 dropped). Try Waterfox for support of all modern add-ons and all your favorite legacy ones. It shares the profile with FF and gives you back your old favorite add-ons and more.

I'm all about the simple yet highly effective tools. It tells you how many tabs you have open. That's it. I'm always surprised to see that I keep so many tabs open. Now, when I see a high number, it reminds me to pare down and close a number of tabs.

Like others I tend to accumulate a lot of Tabs as I browse and I find this Add-On to be very useful in helping me know just how many are open.
It's also reassuring to know that it doesn't require any permissions.
I read earlier that the Tab Count font size could not be increased due to Firefox's developer restrictions and so I have chosen to have red text on a white background for increased readability as was suggested by the developer.
I like the fact that the counter updates in real time eg. when I issue a command to Close tabs on the right, I can keep an eye the count as it decreases (my tab count can be quite high).
In these days of increased RAM and increased Tabs, this extension genuinely fills a gap.

Does exactly what it says. 10/10

Really well executed extension. This thing stays out of the way but lets me know how things are going. On browser restart if you have 70 to 700 tabs it takes a while to catch up and there is some update lag when you delete tabs to clean up but that is most likely not a problem with this extension (more like a problem of having too many tabs open :-)).
I have a list of 7 extensions I always install and this is number 3!