I've tried all sorts of session and tab management plugins in several browsers. This plugin is a real gem. I develop websites for many clients, and I often need to keep a record of several urls for each one - the abiility to save groups of tabs grouped under my client name is a huge benefit. I can simply re-open a group of pages when I need to. I've found that other tab/session managers tend to have little control over whether they restore tabs to the same window, or even replace the current session completely - not so with Session Sync - you can open the tabs in the same window, or a new one. Or even open tabs individually if you prefer. One other nice touch, is that the saved 'sessions' are actually saved as bookmark groups, so even if the addon stops working, I still have all of them saved. Massively useful, and I'm not sure I could manage without it. Many thanks to Gabriel for an essential addon.