Wonderful that this extension is back!
I request for a quick tab search similar to how other sidebar tab extensions are now providing. That will make this a perfect extension.
Also if you could have hiding the close button as an option somewhere that will be nice.

Seems when i restart firefox the connection to the parent tab is dropped, so structure end up flat again. A bit annoying, and looses a big part of its function. Otherwise a nice addon with potential.

must have

It's wonderful to work with tabs in a tree in the sidebar. However, there's a frequent bug appearing: sometimes the last tab or the one before the last one bring you to the incorrect tab (and reloading the extension/sidebar doesn't work). Other times it won't let you change tabs at all (clicking, ctrl+tab works fine), or hang unexpectedly until you reload it. It's not reliable, but when it works is quite useful.

only reason why i am using firefox

Seems to work great and doesnt ask for ridiculous permissions. I appreciate that.

One request i have though. Could it be made into a popout like tabsoutlier on chrome?

I really needed a proper tree-style extension after Tab Tree died, however I can't view any tabs. Something to do with the way it is themed no doubt. I am on 66.0.2

I had to change the theme to dark, and everything else is great! The wiki is very detailed and makes this a great tool in conjunction with tridactyl.

2025-07 更新
Firefox でも標準的に縦タブが可能になったけれども、Tree Style Tab の UX には及ばないので、まだまだ Firefox で必須の拡張機能。と言うか、Tree Style Tab を使うために Firefox を使っている。

THIS IS AN AMAZING ADDON! and its made by an amazing author, no big bugs exist, only small ones, and even they get patched almost immediately by the author, do yourself a favor, and get this extension, with just a little setup, your firefox will be 100 times better than it already is., pair it wih the tab hider extension for the ultimate pairing!

Tips for using this buggy addon:
0. Deal with it.
Ok, 1. Organize with folders or folder trees instead of tab trees when you're working with a big chunk of tabs for maximum safety. Never ever should you make blank tabs (about:blank, new tabs, or blank pages) father of other tabs. Definitely gonna f up your tree after a restart if you spot buggy behaviors with tabs before it. This one is on Firefox.
2. You may often encounter scrambled up tree structures and missing tabs that are actually hidden after a restart, so you might want to have "expand all trees" in your context menu to make them reappear, or enable expanding trees with double click. This alternative doesn't always work though.
3. Use a session restore addon that saves and restores tab metadata 'by nature', just in case everything is beyond redemption. You might already be using one anyway so this tip goes the last.

I only updated past 57 because this add-on got ported. Absolutely essential for anyone using more then a dozen of tabs and integral to my workflow.