About Sidebery
Sidebery is a Firefox sidebar that turns tabs into vertical panels, in a tree or flat layout, alongside bookmarks and history. Its README also lists search, a customisable context menu, custom styles and snapshots of saved windows, panels and tabs. Each panel is set up separately, so one can hold work tabs and another a container.
It is free, MIT licensed and developed in the open by one developer, mbnuqw. The Firefox listing shows about 55,000 users, a 4.7 average from about 1,100 ratings and the Recommended badge. Firefox shipped its own vertical tabs in version 136, and the README explains how to combine the two: turn on the native vertical tabs and shrink that sidebar to its minimum so the native tab strip takes little space.
The README warns that Sidebery may conflict with add-ons that handle where new tabs go or that sort tabs, such as Tree Style Tab, so disable those. The permissions list is long because it manages tabs, containers, cookies, sessions and bookmarks in one place, but it requests no site access. If you want one configurable sidebar for everything, this is the one. If the built-in layout works, or you only want a simple tab tree, skip it.
Pros and cons
- Vertical tab panels in tree or flat layout, with bookmarks and history in the same sidebar
- Snapshots save windows, panels and tabs
- Free and MIT licensed, rated 4.7 from about 1,100 Firefox reviews
- Actively developed: version 5.6.1, with GitHub activity in late October 2026
- Firefox only
- Can conflict with add-ons that move tabs or set where new tabs open, such as Tree Style Tab
- Lots of settings, and hiding the native tab bar takes extra steps
Permissions
On Firefox it asks to read and manage your tabs, container identities, cookies, sessions, the browser theme and search. It does not request access to website content.
