What is priv8? This is a Firefox addon that uses part of the security model of Firefox OS to create sandboxed tabs. Each sandbox is a completely separated world: it doesn t share COOKIEs, storage, and a lots of other stuff with the rest of Firefox, but just with other tabs from the same sandbox. Each sandbox has a NAME and a color, therefore it will be always easy to identify which tab is sandboxed. Also, these sandboxes are permanent! So, when you OPEN one of them the second time, maybe after a restart, that sandbox will still have the same COOKIEs, same storage, etc – as you left the previous time. You can also switch between sandboxes using the cONTEXT menu for the tab. Here an example: with priv8 you can read your gmail webmail in a tab, and another gmail webmail in another tab at the same time. Still, you can be logged in on Facebook in a tab and not in the others. This is nice! Moreover, if you are a web developer and you want to test a website using multiple accounts, priv8 gives you the opportunity to have each account in a sandboxed tab. Much easier then have multiple profiles or login and logout manung>ally every time! Is it stable? I don t know : It works but more test must be done. Help needed! Known issues: window.OPEN doesn t work from a sandbox and e10s is not supported yet. Priv8 is released under Mozilla Public License.