I happened to try dozens of Firefox addons that copy/export tabs URLs lately.
Searching on Mozilla Firefox extensions catalog, at the moment I write, one of the most popular addon is
Export Tabs URLs and in fact it is not bad but, yet, digging a little bit more I think there are better alternatives, so now I'll suggest the ones I prefer.
First of all, a due premise: this makes sense only if you're dealing with lots of tabs, indeed, the addons I'm going to suggest do not distinguish current selected tab, they always take into account ALL the tabs you have opened in that moment in a Firefox window.
That said, here comes my favorite: Save Tab URLs.
This addon adds a new "Copy URLs (all tabs)" command into tab context menu and a tool button that makes a popup show up when clicked, the latter being the truly interesting stuff; indeed, once the popup is opened, you'll see a text-area, listing title and URLs of all the currently opened tabs, and commands that will let you filter listed entries, even using regex for it. Besides letting you copy to clipboard the text-area content (btw, you can also edit that if you want), you can as well save/export as a text file or it is possible for you to paste http(s) links in the text area and click on the provided command button to open them up back in new tabs (kinda as when you open all entries in a bookmarked folder). All of this is presented in pretty clean GUI.
Both the tabs context menu and the popup commands always take into account all the tabs opened on the actual Firefox window (so no option for the single tab, as I said in the premise) and also keep in mind, btw, that this will be limited to current window only opened tabs (always including pinned ones) and if you have more than one Firefox windows opened, the tabs in others windows won't be taken into account.
(I wish this one had some little more of improvements, like for example the option to copy only current tab URL/title via context menu, an option to copy only URLs without titles and adding at least Markdown -and maybe Json- format; with those features added this extension would be simply perfect for me!)
Save Tab URLs seems having a very similar alter ego (a kind of clone tbh) the only difference with it seems it lists tabs URLs only and no titles: URLs List.
And, in case you're looking for an even minimalistic equivalent (just copy or open tab URLs): tabs2txt
- Copy/Paste and Save tabs list
It provide more or less the same features of the previous one thus it has a little messy GUI compared to it and it lacks text-area contents filtering and exporting to text file capabilities but kinda provide themes (lets you change color combination choosing beetween 2 dark ones and a light one) the option to add line-breaks between entries or not and to include or not titles with URLs. It also provide a kind of internal bookmarks system called "Saved lists".
- Bulk URL Opener
It has a nice GUI with dark/light theme, lets you save URLs lists in a similar fashion of the previous addon I talked about (I think the previous one has a better approach with that imho) but does not include tab titles in any way, just URLs.
Just like in the case of Save Tab URLs, both of them let you export the tabs list to a text file with few mouse clicks on some buttons but lack to provide other than titles+URLs and support no custom formats, if you need that you must use other Firefox addons such as Copy URL To Clipboard, CopyTabTitleUrl or Copy Selected Tabs to Clipboard (which imho are all better alternatives to the more popular Copy All Tab Urls) but they only let you copy to clipboard, so if you need to export the list to a file you'll have to create it by yourself and then paste the list in it and save it.