Sidebery is a Firefox extension designed to enhance tab and bookmark management through a customizable sidebar. It allows users to view tabs in a tree structure, group them into folders, and colorize them based on domain or URL. The extension also offers sorting options by title, URL, or access time, along with features like automatic unloading of tabs in inactive panels and the ability to create and manage bookmarks efficiently. Users can convert between tabs and bookmarks seamlessly, and the tool provides a privacy-focused experience by storing data locally unless synchronization is enabled.

In addition to its core functionalities, Sidebery offers customizable context menus and mouse/keyboard controls, allowing for tailored browsing experiences. Users can apply custom styles via CSS, set up auto snapshots for open windows, and manage tab behavior with drag-and-drop options. With a focus on privacy and local data storage, Sidebery stands out as a powerful tool for users looking to personalize their browsing experience while maintaining control over their data.