How to save a Firefox session (built-in options and Session Boss)

To save a Firefox session, turn on "Open previous windows and tabs" under Settings > General > Startup so Firefox reopens everything at the next launch. For a copy you control, use Bookmark All Tabs (Ctrl+Shift+D) or a session manager extension such as Session Boss, which saves windows and tabs automatically on a schedule and lets you restore or export them later.

This guide covers the built-in ways to save and restore a Firefox session, where Firefox keeps session data on disk, and how Session Boss works when you need named, restorable snapshots of your tabs.

Save your Firefox session automatically with Session Restore

Firefox Session Restore saves your open windows and tabs continuously and reopens them at startup once you enable it. It is off for many default installs, which open the home page instead.

1. Click the menu button (three horizontal lines) and select Settings.
2. Stay on the General panel and find the Startup section.
3. Check "Open previous windows and tabs".
4. Close the Settings tab. Changes save automatically.

Two habits keep the saved session complete. Quit Firefox from the menu (Exit on Windows, Quit on macOS and Linux) instead of closing windows one by one: Mozilla notes that if you close windows individually, only the tabs of the last window are restored. And remember that private windows are never restored, by design. Pinned tabs come back, and you usually stay signed in to the sites you were using.

If the setting is off, you can still bring back the last session once: open the menu, choose History, then Restore Previous Session. When Session Restore does not work correctly, an independent backup is the safer choice.

Save open tabs as bookmarks or a tab group

Bookmarking all tabs is the quickest built-in way to keep a permanent copy of a Firefox session that survives updates, crashes and profile mistakes. Press Ctrl+Shift+D on Windows and Linux or Command+Shift+D on macOS, name the new folder, and Firefox stores every tab of the current window in it. To reopen the set later, right-click the folder in the bookmarks library or toolbar and open all bookmarks in tabs. The ghacks guide to bookmarking multiple tabs in Firefox covers selecting only some tabs.

Tab groups are the second built-in option. Right-click a group label and choose "Save and close group": the group leaves the tab bar and waits in the List all tabs menu until you reopen it. Mozilla states that tab groups are local only and do not sync with Firefox Sync, so they are a workspace tool, not a backup. If the feature is new to you, see how tab groups work in Firefox.

Where Firefox stores the session file

Firefox stores the current session in a file named sessionstore.jsonlz4 inside your profile folder, which holds the open tabs and windows. Copying this file while Firefox is closed gives you a raw backup of the session.

1. Open the menu, choose Help, then More Troubleshooting Information (about:support).
2. Next to Profile Folder, click Open Folder (Show in Finder on macOS).
3. Close Firefox, then copy sessionstore.jsonlz4 to a safe place.

The file is compressed, so it is not human readable, and restoring it means copying it back into a closed profile. That makes it a last-resort safety net rather than a daily tool. The page on about:profiles in Firefox explains how profiles are organized if you run more than one.

Session Boss: save and restore Firefox tabs with an extension

Session Boss is a free Firefox extension by William Wng that saves windows and tabs as restorable sessions, automatically and on demand. It adds a toolbar icon; the main interface lists user sessions, automatic backups and all sessions, each with search and sorting by time, group or name.

According to its Firefox Add-ons listing, the extension offers:

• Scheduled backups every 15 minutes, hourly, daily, weekly and monthly, keeping three copies per interval.
• Backups on change, saved 30 seconds after a tab URL changes, with eight slots.
• Manual saves of the current window or all windows.
• Restore of a whole session, a single window or single tabs, with container support and lazy loading so large sessions do not freeze the browser.
• Groups, renaming, undo and redo for saved sessions.
• JSON export and import of all or selected sessions.

Restore options let you replace the current windows or open the saved session in new windows next to what is already open. Since version 2.10, private windows are excluded from saves by default; you can include them in Preferences.

Session Boss limits and permissions

Session Boss cannot save per-tab navigation history, so the Back button is empty after a restore. Internal and local pages such as about:addons or file:// addresses are listed in a session but cannot be reopened automatically; copy the address and open it manually.

The extension asks for access to browser tabs and downloads, and its cookies permission triggers the "Access your data for all websites" install notice. The developer states that it collects no data and sends nothing to outside servers. Before you install an older version over a newer one, export your sessions: the listing warns that a downgrade can overwrite saved data. Check the listing for the current version and update date before you rely on it, since session managers depend on Firefox extension APIs that change over time.

Which method should you use?

The right way to save a Firefox session depends on whether you want convenience, a permanent copy or several restorable snapshots.

A practical combination for most people: enable Session Restore for daily use and add Session Boss or a bookmarks folder for the sessions you cannot afford to lose.

FAQ

Related: export Firefox sessions to bookmarks or HTML files, reload previous Firefox sessions