this is PUSHKA

I like it a lot better than Tree Style Tabs. Sidebery is the superior add-on.

It's under very active development and receives regular updates.

It's a real must-have in Firefox, and I think Mozilla should implement it as an official functionality.

This extension has matured a LOT! Extremely configurable. I've used Firefox with Tree style tab a lot in the past, then switched to edge for some time (once they added native side-tabs) and now floating between the 2 browsers. Been using visual tabs more recently to keep things simpler. Now trying Sidebery again & it's been a very nice UX, better then TST. Search tab feature is in v5 beta and that will probably round out what I need from this side tab type of extension :)

Extremely good work to update and maintain this actively for firefox which is right now an extremely good browser (even though missing side-tabs natively and we have to resort to custom overrides etc), thank you sir!

I have to use it longer but this may be even better than Tree-Style Tabs (which is very good, to be clear)