My favourite vertical tab extension is Vertical Tab Reloaded, but their scrollbar cover half of the close button. Then I tried Tree Style Tab, which fixed my issue with VTR but it has a tree which I don't like.

I have searched for nice middle ground but Sidebery is more than just middle ground. Super easy to customize. I can have usable vertical tab that don't use tree system.

If there is one thing I missed from other extension is, TST's ability to search and filter tabs. Which is an additional addon that you have to install in TST.

Also color customization is kinda confusing. I can't figure out how to change certain part by matching what it's said on the settings. The color of suspended tab are too dark, trying out to change settings one by one doesn't seem to fix it.

This add on to firefox works great. It gets my bookmarks where they're easy to access

Beautifull UI, easy to use, powerfull...

Really excellent, the way this product should be done!

Smoother than Tree Syle Tab, but lacks many of it's additional plugins that expand it's functionality, also i'm surprised i found no option to restore Tree order when i restore parent Tab, i TST restored parent tab get placed above it's children like nothing has happened, in Sidebery i need to reorder them again. Is that a bug?

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.