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SPECIFICTION
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Sidebery

github.com

Free plan Browser extension
Visit github.com
Spec score 7.8 #9 of 27 in Tab Management Software

What it is

Sidebery is a free Firefox extension for managing tabs and bookmarks in a sidebar. Its panels can display tabs, bookmarks, and browsing history, with tabs shown as a flat list or tree. Users can group tabs under custom names, color and sort them, and automatically unload folded branches or inactive panels. Container features bind containers to panels, reopen URLs in selected containers, and set proxy or User-Agent settings. The extension also supports tab search, session restore, suspension, workspaces, snapshots, and optional cross-device synchronization. Context menus, mouse and keyboard controls, drag-and-drop behavior, and sidebar styles can be customized with variables and CSS. Data is stored locally by default; Firefox Sync or Google Drive can sync selected settings and tab data. The project is MIT-licensed. Firefox does not permit hiding the native horizontal tab bar, and some tab-moving add-ons may conflict.

Spec sheet

Purpose
Sidebery is a Firefox extension for managing tabs and bookmarks in a sidebar.Read 4 Oct 2026 · github.com
Privacy
The privacy policy says Sidebery does not engage in ad targeting or data collection, stores data locally by default, and sends data only when sync is enabled and only to the selected provider.Read 4 Oct 2026 · github.com
Support
The maker invites users to create a GitHub Discussion or email the developer with questions about the privacy policy; the add-on lists [email protected] as its support email.Read 4 Oct 2026 · github.com
License
The repository identifies the project license as MIT.Read 4 Oct 2026 · github.com
Compatibility limit
The project warns Sidebery may conflict with add-ons that position, move, or sort tabs, potentially causing unexpected behavior or broken tab state at initialization.Read 4 Oct 2026 · github.com
Containers
Container features include binding a container to a tabs panel, reopening tabs in a target container by URL, and setting proxy and User-Agent configuration for container tabs.Read 4 Oct 2026 · addons.mozilla.org
Customization
Users can customize the context menu, mouse and keyboard controls, drag-and-drop behavior, and sidebar and group-page styles with variables and custom CSS.Read 4 Oct 2026 · addons.mozilla.org
Native tabs limit
The add-on page says Firefox does not allow extensions to hide the native horizontal tab bar and points users to userChrome.css workarounds.Read 4 Oct 2026 · addons.mozilla.org
Panels
It provides customizable panels for tabs, bookmarks, and browsing history.Read 4 Oct 2026 · addons.mozilla.org
Permissions
Required permissions are access to recently closed tabs and browser tabs; additional permissions are optional and support features such as bookmarks, history, proxy settings, and snapshot export.Read 4 Oct 2026 · addons.mozilla.org
Security reporting
The security policy supports the latest version published on addons.mozilla.org and directs vulnerability reports to [email protected].Read 4 Oct 2026 · github.com
Snapshots
Snapshots can be configured to save information about open windows and tabs.Read 4 Oct 2026 · addons.mozilla.org
Sync data
Users can choose which settings, context-menu configuration, keybindings, custom styles, and selected tab data are synchronized.Read 4 Oct 2026 · github.com
Synchronization
Optional sync providers named in the privacy policy are Firefox Sync and Google Drive.Read 4 Oct 2026 · github.com
Tab layouts
Tabs can be shown as a flat list or a tree, grouped with custom names, colored, sorted, and automatically unloaded in folded branches or inactive panels.Read 4 Oct 2026 · addons.mozilla.org

Plans and prices

Sidebery Free Firefox extension · donations accepted Read 4 Oct 2026 · github.com

Every Sidebery plan and price →

Strong points and limits

Strong points

  • Tree and flat tab layouts
  • Automatic unloading of inactive or folded tabs
  • Container, proxy, and User-Agent controls
  • Custom CSS and interaction settings
  • Optional cross-device synchronization

Limits

  • Firefox cannot hide the native horizontal tab bar
  • Some tab-positioning add-ons may conflict
  • Available only as a Firefox extension

Who it suits

It suits Firefox users who need structured tab, bookmark, history, container, and workspace management. Users wanting local-first storage with optional Firefox Sync or Google Drive synchronization may benefit.

Verdict

Sidebery offers detailed sidebar organization, container controls, snapshots, and customization at no charge. Its Firefox-only scope and documented compatibility limits are important before installation.

Where Specifiction places it

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