Was great, now constantly flashes "Session did not match and will not save. Click here to reload" and automatically reloads the sidebar every second or so. Completely unusable right now. Seems to be a common theme.

EDIT: I do start with previous session. After ticking that option and restarting FF, the sidebar loaded ok. un-checked it, opened a few tabs, restarted again, and all is still good. Back to 4 *.
Will rate 5 if you give an option to not flash the 'tabs saved' text at the bottom. it is always catching my eye and distracting me.

Doesn't work, the tabs list is reloading every second and it's unusable

Edit: author provided a fix for the bug

Just installed this. looks like it will be super-useful. I did spend time clicking on all the menu buttons, but still unclear on:
1) how to set up groups and folders and how they differ from each other.
2) how to color individual tab rows
Is there any type of User Guide anywhere??
Thank you.

1. sometimes add-on is loosing the sorting of tabs and all tabs appears in "ungrupped" tab
2. two time add-on losed open tabs at all
3. almost always add-on restores the closed tab in the wrong place where the tab was closed. Mostly the tab is restored at the beginning of the next group
4. there is a problems with a focusing on tabs when current tab was closed

so.. it's raw

It's the best addon for tab management, in my opinion. It has groups and folders , autosave(Tools=>Open Window Manager=>Autosave) and import/export sessions feature. If one "loses" its groups folders, it is really easy to get them back by loading and merging a previous (working) session into the current one through the autosave feature mentioned above. Previously i have tried Tab Center Redux then TreeStyleTabs + SimpleTabGroups(my previous setup).

Outstanding plugin over a long period of time. This one plugin continues to keep Firefox a productive personal platform. Respect to the developer kroppy and thank you for your updates and ongoing support. My tips. Use 'groups' for your personal knowledge domains and 'trees' to sub-divide these domains by your interest areas.

Tree Tabs sometimes repeats loading.

Once Turn off "Discard tree structure after browser's restart" option, and turn on to it will be fix.

Very useful; I mainly use it to show my tabs vertically. Lots of options for customization! Also very helpful for restoring a session when Firefox gets shut down unexpectedly (Windows reboots, crashes, etc.)

unfortunately i just lost all ~100 tabs when installing "context seach" addon last (after tree tabs), keeps crashing. all tabs gone. i dont know why.

this addon would be perfect for me if it would not constantly crash the whole system...firefox remains to be unstable
also for wide displays the option to eliminate tabs on top view?

I've switch off automatic tree structure. Nevertheless, sometimes it closes many tabs when I close only one — like they was affilated. It's terrible.

So good ! Thanks ! I am discovering it for now but so much better than competitor. You can configure so many settings ! Try to have a middleclick mouse this is usefull here.
I think im gonna donate cause its realy a productivity enhancer.

I think this extension is the best replacement for Tab Groups.

To make this ideal, I need a keyboard shortcut to cycle groups (Tab Groups had Ctrl + `), and to be able to hide the list of tabs while showing the list of groups, (or have a separate dropdown menu of groups on the toolbar).

But it works well and I've found it more intuitive than alternative extensions. Thanks!

Been using Tree Style Tabs for years but found this and decided to give it a whirl. After three days, decided to clean up a mess of tabs. Selected one tab to keep, clicked "Close other tabs," and sure enough ALL other tabs closed. Unfortunately that included ALL my pinned tabs!! MAJOR oversight!!! Uninstalled. I'll stick with Tree Style Tabs. I find it far better designed and better thought out.

Edit for added detail: A few other reasons I've ditched this in favor of TST:

Messed up the order of pinned tabs
Doesn't have a decent way to organized tab groups automatically with good settings
Appearance settings are way to convoluted. Users shouldn't have to be web designers to understand what to do with appearance settings. There ought to be a few graphical examples of choices. Keep it simple stupid. Simplicity is always better.
Honestly, I find the appearance in terms of usability far to cluttered.

In short, IMHO, Tree Style Tabs is so far ahead of this extension in terms of feel, look and usability right out of the box this one just isn't worth the time. Yet...

Fantastic extension.

Vertical tabs in sidebar is so much better than unreadable horizontal tabs. F1 to open the vertical tabs. Only use Folder feature. You can open and close folders and sub-folders to keep the list manageable.

When you close Firefox and then reopen, your vertical tab list reappears. Perfect. No performance hit.

You can get rid of horizontal tab toolbar using userChrome.css. google it.

Dont know what Groups and Sessions are used for.

This extension makes Quantum worthwhile. But I still need a NoScript replacement.

I GOT SO MUCH MORE THAN I WAS LOOKING FOR with Tree Tabs by Kroppy.

When I first installed Tree Tabs, I just wanted vertical tabs. my favorite super-extension, TabMixPlus, had been obliterated by the Quantum change, but never did i care about trees, levels or groups. yeah, i saw these features touted on Tree Tabs, I DIDN'T CARE. i just knew I had tabs out my ears and couldn't deal with horror of horizontal tab display and navigation.

i tested out a bunch of vertical tab extensions but ultimately dug into Tree Tabs. Why?

THE COMPRESSED FORMAT OF PINNED TABS at the top of the Tree Tabs column. ingenious! once i saw it, I couldn't live without it.

the other bit of perfection was the compact height of the tabs. other extensions waste so much space with big tall tabs and huge fonts. this forces extra scrolling, but the real crime is allowing the user to view only 15 tabs at once! i also quickly embraced the ability to customize all the aesthetics, which only enhanced my joy at being reunited with functional tabs.

after 6 months of use, tabs quickly multiplying like rabbits on coke and viagra, i finally investigated Groups.

HEY, GROUPS ARE A GREAT IDEA! WHY DIDN'T I USE THEM BEFORE?!

while setting up my Groups, i also checked out Folders.

WHOA, GROUPS AND FOLDERS WORK *WONDERS* FOR ORGANIZATION WHEN YOU USE THEM TOGETHER!

what a sap i've been to ignore these useful features! with all this tab management brilliance in play, i hardly notice i have 300 tabs! think that's crazy? think of my tabs like an interactive task and research to-do list. much more productive than preposterous. i'm still not using trees (ironically), but i don't dare say "never!"

i recently trained myself to use the Tree Tab Settings and Re-open Tab buttons instead of right-clicks. also now taking advantage of unloading whole groups at once to save memory... been using these features for about a month and everything's now second nature.

today I re-discovered the Export Session button and contemplating putting it to work. Firefox restores my sessions, but a fail-safe would might be helpful.

guess you could say i've really come around on Tree Tabs, an incredible utility, and I'm super grateful to Kroppy for creating it. come New Year's, when I evaluate my extensions and contribute to my most beloved... Kroppy, you're a sure thing. you're building a productivity powerhouse. thank you for your vision and efforts. hope plenty appreciate your talents.

my only feature suggestions would be

1) some way to backup prefs and color formatting, though i'm assuming it's time consuming, else i would've already found it.

2) the ability to customize the tabs context menu. i could shave off 9 or 10 entries

3) k, just saw my third wish has been pre-granted LOL... F1 to toggle Tree Tabs sidebar. UH-MAZING.

the extension is already 5-stars. these are just first-world whines.

the only bug i've found is that sometimes when trying to drag and drop a tab, no tabs will move. it only happens once in a while, and i haven't yet noticed a pattern or precursor. what happens is, i'll grab a tab as usual, but instead of just dragging normally, where i clearly see both the insertion drop line that appears between other tabs, and the dual lines that designate a drop into a folder, those lines won't appear. the tabs i'm dragging _over_ do change color as the pointer sweeps over them, but nothing happens when i let go (regardless of where i let go). the tab i tried to move remains unmoved, and the tab name oddly remains italicized unless i click on it again to "reset" it.. this lasts several minutes at least. i usually go on with other things and forget it until some time later when it's working again.

wondering if this has to do with uBlock or uMatrix since i see a different script blocker listed as Tree Tabs- incompatible. But since this glitch is intermittent, I can't say, and it's not enough for me to quit on Tree Tabs.

aside from that, it's perfect--a dream extension. BRAVO.