Tab Sessions от Krzysztof Bogdan

Save a window. Close it. Get it back exactly as it was.

Tab Sessions turns the tabs of a window into a named, coloured session: tab order, titles, URLs, pinned tabs and the container each tab was opened in. One click in the toolbar reopens the session as a fresh window.

Reopening is cheap. Tabs come back unloaded, showing their saved title and favicon, and only fetch the page when you click one. A session of thirty tabs opens in about a second and does not hammer thirty sites at once. Pinned tabs are the exception: those load right away, because they are the ones you keep open.

Containers are remembered properly. A session stores the name of each tab's container as well as its id, so a session saved before you rebuilt a container, or on another machine entirely, still puts the tab back where it belongs. If the container is genuinely gone, the tab simply opens without one. This add-on never creates or changes containers behind your back.

What it is good for

• Park a research window, a client project or a bug hunt, close it, and come back to it next week.
• Keep a Morning session of the pages you open every day, and a Deep work session of the ones you do not want to see.
• Split a window that has grown to forty tabs into two sessions, and stop keeping them open just because you might lose them.
• Move a working set to another machine: sessions ride Firefox Sync.

Editing a session

The settings page lists your sessions, reorders them, and opens any of them for editing: rename it, recolour it, reorder its tabs, fix a URL or a title, pin or unpin a tab, change its container, or drop tabs you no longer want. A live size readout tells you how much of Firefox Sync's per-item limit the session uses, before you hit it rather than after.

Sessions are snapshots, on purpose. Opening one and then changing that window never writes back, so a session you saved is still there tomorrow. When you want the new arrangement, save it as a session of its own.

Worth knowing before you install. Pages an extension cannot reopen, such as about:config, view-source: and other add-ons' pages, are left out when you save, and the popup tells you which. Firefox Sync caps a single item at 8 KB, which works out at roughly 55 tabs per session; larger windows are refused with a message rather than saved incomplete. Sessions record the tab list only, not scroll position, form contents or history.

Privacy: nothing leaves your browser. Sessions live in Firefox sync storage, there is no server of ours, no analytics and no telemetry.