Thanks for the addon, I confirm it works on Firefox Quantom (specifically dev edition v. 65).
But I rate it only 3 stars because there is absolutely no feedback.
I expect to see a list of tabs when I enter the domain name, or at minimum the number of tabs closed.

I always have been using this Power Close Firefox Add-on. It's very effective and extremely useful for me. Sadly, lately it's no longer compatible for my Firefox version, Firefox Quantum. I really hope that the developer would update it to support the new version of Firefox! Greatly appreciate!! Thank you very much!

UPDATE - 03/29/2019: So glad to see this helpful little add-on working again!
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This is a great, simple add-on that aids with saving system resources and clearing tabs quickly. Please update for Firefox 57!

can it close tabs i open with "content keyword" ? if not, an update would be great

I would like two things: a keyboard shortcut to pull it up (possibly configurable), and a right click option on tabs that would close any tabs from the same domain.

Oh, and if you could allow regex in the box, that would be AMAZING. You could identify regex by the use of //.

EDIT: I see you've said you plan on adding the right click tab option. Thanks. (right clicking in the content area means I have to actually load the tab, which I don't want.)

On my new Firefox 42 64bit windows it does not work, maybe because of other extensions, maybe not.
there is a symbol and when i click on it a menu opens and it said enter a domain or press enter to close all tabs or esc. i did try with * or space or just empty and it did not close all tabs, but tabmix+ can do it.
The idea is good but i think it should also provide a menu with all open domains to select them while browsing just with the mouse without typing. If it works it could be a nice tool for people who can use it ;)

Only issue for me is that the text area doesn't have focus after clicking the icon, so I have to click the icon and then the text area, or click the icon and hit tab twice to give the text area focus before being able to enter domain text.

please add menu to tab context menu.
It is useful addon, but I don't use it frequently.
so, I want to hide icon.

I Love this Add-on "Firefox Power Close"
I really needed it some times. it created by you and I'm so happy found it finally here.
Thank you so much dear developer "Mosab Ahmad"
continue to developing this nice Add-on hope it Firefox's Featured add-on.
Thank you.