Amazingly well done. Lives up to all the hype and then some. Makes saving links and organizing them super easy. Love it!

Made my life easier, thanks a lot!

Just like mgkrupa said [(I heard that Mozilla is working on finally giving Firefox its own tab manager, so we'll see if tab manager plugins become unnecessary)].
This is with all my love and I hope the message is understood <3
I hope that all extensions like these are needed again and firefox adopts them natively, I find this extension perfect, it has magnificent synchronization, I can be between my PCs without having to look for another one or search for it in an endless list of pages/History, the I can separate it into different lists and it is simply magnificent, the only pity is that it is not available on the phone through the screen interface, as I see it, the extension does not consume cpu or memory in a strange way, hopefully the rumor that I read is true and firefox take all window managers and unify them, hopefully this extension will work natively :)

Translated from Spanish to English by Google translator, any inconsistency is due to that

I love that it hides but (by default) doesn't automatically unload/close a tab that you stash (it stays loaded in the background) because it allows you to switch back to the hidden tab without having to reload the page (so e.g. you don't lose your place in a video your watching). You can customize this behavior in the options menu or change it so that stashed tabs are automatically unloaded/closed. It might automatically unload running hidden background tabs under certain conditions but this behavior can be disabled in the options.
There's no picture of it, but the "Tab Stash" submenu in the (right-click) context menu has the items:
Show Stashed Tabs in a Tab
Show Stashed Tabs in Sidebar
Stash Tabs
Stash This Tab
Stash This Tab to a New Group
Copy Tabs to Stash
Copy This Tab to Stash
Options

Firefox's sidebar (that I previously hardly ever used) makes using this addon extremely convenient because I don't have to open/switch to an intermediate "tab management/list webpage" (i.e. a webpage that lists all tabs & tab groups, like OneTab's "Display OneTab" page).
[EDIT/UPDATE: Turns out you can using the sidebar] You can stash multiple selected tabs at once but I'm not sure if it's possible to stash them directly/immediately into a preexisting named tab group of your choice like you can do with OneTab (I think that stashed tabs either automatically go to the top-most group or it creates a new unnamed tab group - it seems to only create new unnamed tab groups for me but that may be because I've been fiddling with the options).
It would also be nice if there was a menu item like "Close this tab and remove it from all tab groups" so that I don't have to manually find and remove a tab (from the tab groups) once I'm 100% completely done with it.
Overall, I think this is superior to OneTab, which was my previous tab manager (I hear that Mozilla is working on finally giving Firefox its own tab manager so we'll see if tab manager addons become unnecessary).

ý tưởng thật là tuyệt, tôi đang gặp vấn đề về kho luu trữ của mình, cảm ơn về ý tưởng của bạn

It's what I needed for so long! All the features I actually liked from SimpleTabGroups but as a sidebar and PERFORMANT!
Grouping stuff is super comfortable. And the search with unlimited results is great.

Hi, love this extension. but im currently experiencing alot of ram usage to the point where firefox is useless... i have a AMD Ryzen 9 5900X and 16gb 3000MHz ram.

Firefox slowed down too much to use it after I installed Tab Stash, I did not meticulously troubleshoot the issue, instead I Reset Firefox and today I researched re-installing Tab Stash but after reading reviews with similar reports of Firefox slowing down I decided not to try it again.
I am using an i7-6700K 4 core CPU running windows 10, which is still a decent powered computer so I really do not know if Tab Stash slowed my computer or just Firefox. I gave Tab Stash two stars for a great list of features, maybe I will try it again in a few months.