I'm a professional and power user (now 4K+ tabs opened).
I'm using Sidebery since 2020: with lateral tabs, grouping and panels, Sidebery changed my way of using the browser and it's great, organized and efficient.
Thank you so much!
P.s. Probably it's the main reason because I stay with Firefox.

Suggestion: in the years, it happened 2 or 3 times that it has lost the hierarchy of my tabs and flattened the list, so I've set Sidebery appropriate automatic snapshots and to avoid eventual bugs, if a version works without problems, I update Sidebery to a new release only after many weeks since it has been released.

Best tab organizer I've seen (and I've been on the 'Net since Netscape!)

The best sidebar there is.
Thanks a lot!

Fantastic plugin. I eventually used my profile's userChrome.css to hide Firefox's horizontal tab row because I just don't use it anymore, and I much prefer Sidebery's use of tab panels over Floorp's use of workspaces (not to mention Sidebery + Firefox don't crash on me constantly, or ever).

Of note: if/when customizing the size of tabs height in Sidebery's style settings, stick to px and don't use relative units like ems, as this will mess up your drag & drop interactions.

WOW! Very in-depth and extremely customizable tab extension, clearly a lot of effort has gone into it's development. Thanks to the dev(s)!

This add-on is honestly amazing! It takes a bit of work setting everything up but that is only because it is so insanely costumisable.

Awesome add-on! This helps me a lot for managing multiple projects at the same time. I feel it could use a few more colors and icons for distinguishing projects, but since it's free, it's still definitely 5 stars from me.

fantastic...good workflow!

Really good add-on if you want to take control of your browser even more having a sidebar is important. Well done to the maker.

Its very nice if you dont want or can't use the Zen Browser(Firefoxbased) But I use and recoment the Zen Browser! :D

searched among other extensions the copy of Opera features, this one is the best!