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`

Tree Style Tab de Piro (piro_or)

I can't imagine using a browser effectively without this. The non-existence of such addon for Chrome is also the main reason I am not using Chrome.
This performs well, has all features I need, is stable... what more can one want from a plugin.

The only downside is it can't hide the default tab bar, but the author explained that it's because Firefox does not allow that.