I've been using Tree Style Tab for years. Occasionally it reloads (as in seems to close itself and reopen), but otherwise has performed flawlessly. It's a staple add-on for me, and is a big reason I use FireFox.

SUPER

I expect that tabs are grouped automatically by root domain search on top in text box by words.

I really like what this add-on does. The problem is that it never stops doing it. I have tabs that need to be in a tree structure. That part is great. But I don't want new trees created every time I run a Google search or open a new tab from an existing page. Sadly, there seems to be no way to control that. So if I want to use this add-on at all, I have to manually flatten every newly created tree. It is a chore, and it seems unnecessary.

how about a version for vivaldi? it have sibebar panel too

Just found this, love it! :D

Pretty simple, works great, excellent for organisation and power users with MANY tabs :D

długo używam ten styl i dobrze się sprawuje

I cannot imagine using a browser without it. It's a pity that Firefox breaks compatibility and right now my main issue is that I cannot share tabs between devices.

Extremely nice

1) wish the "header" in the tree pane could be much more minimal.
2) wish there was a GUI control or d&d operation to create new tab-group elements vs bookmarking `about:treestyletab-group?title=New Tab Group`

Overall great, but it becomes too laggy when many tabs are opened.