The Firefox web browser saves session information automatically in intervals. The default interval is set to 15 seconds, with options to change it in the about:config configuration window (See: Change the Session Store Interval in Firefox).
Firefox does however save only one session, and while that should not be a problem for most users of the browser, it could be a issue for some. At its core, Session Manager offers better session management including options to save multiple sessions on user request or automatically. This alone can be very helpful for users who are experiencing occasional crashes or other issues that may prevent the saving of recently opened tabs.
Saving sessions can also be beneficial for users who use the browser for different purposes, say work and after-work. Instead of having to juggle around with multiple profiles, they could simply save and load sessions instead whenever they switch between different purposes.
Session Manager, the successor of Session Saver, is a Firefox add-on that can save and restore sessions either on user request or automatically. The Firefox add-on will automatically backup the session when the browser shuts down. This option, and many more, can be changed in the program settings.
Session Manager adds an entry to the browser's Firefox menu that links to the most important extension options.
Backup Sessions list sessions that have been automatically saved by the extension, Session Manager options to save and load sessions, group them or open the extension settings to configure its behavior. You can load user saved sessions under Session Manager.
To save a session, simply select Session Manager > Save Session to do so. The extension displays a list of all windows and tabs that are currently open. You can save all windows and tabs, or only selected windows and tabs here.
It is furthermore possible to change the name to a descriptive one, and put the saved session into a specific group.
You can configure the extension's behavior in the options. Here it is possible to define if and when sessions are saved automatically (on browser start, on shutdown), how sessions are restored (replace existing windows, bypass cache when restoring sessions, open as tabs in current window), and to configure keyboard shortcuts for fast access to program features.
The extension settings are extensive and leave little to be desired. Sessions are stored in the Firefox profile folder under sessions. They may take up considerable space, depending on the number of tabs and windows that are open at the time of saving.
Firefox users can download and install the Session Manager extension from the official Mozilla Firefox add-ons repository.