Where the session actually lives

Storage is not one thing. Cookies, local storage, databases, service workers and the cache share one jar, and a page can write to any of them.

So a tool either gives an account a jar of its own or it does not. Emptying a jar afterwards is a different job from keeping two jars apart.

• One jar for everything

  Every tab of the browser reads and writes the same set.

• A jar for the window

  A set that exists while a window is open and goes with it.

• A jar per account

  A set that stays on disk between launches and belongs to one login.

• A jar on other hardware

  A set kept apart because the machine under it is a different machine.

Rows are the approaches and columns are the questions this axis asks. An empty cell means the question does not apply rather than that the answer is bad.

The last row is ours, and you can check every cell in it yourself: each one comes from code you can open, not from a brochure.

Every profile gets a data directory of its own, so its cookies and logins never meet another profile's. Nothing else stands between them: the separate directory is the whole of it.

• Cookies and logins

  Written into that directory by the browser and read back only from it.

• Storage and databases

  Local storage, databases and service workers sit beside them.

• The cache

  Kept there too, and left behind when the session travels.

• Browser preferences

  The profile keeps its own settings file in that directory too.

Profiles are processes on your own system and they share it with each other and with you. Anything running under your user account can read those directories.

Your profile opens on any machine you move it to, because it is not tied to one computer's system keychain.

You move a session either as one encrypted file or through a folder you already sync. Both carry the settings along with the browser data, so the account stays signed in on the second machine.

What keeps the account signed in travels: cookies, saved logins and local storage. The caches stay behind on purpose, and so do the service worker and a few site stores beside them.

• Sealed with a password

  A wrong password gives a plain refusal instead of damaged data.

• The profile identity travels

  The same profile describes the same machine on the second computer.

• An open profile will not travel

  Close it before you move it: copying live databases would deliver a session that does not open.

• You settle a two machine clash

  If both machines worked since the last sync, the app asks you instead of overwriting one quietly.

A deleted profile waits in the recycle bin with all of its browser data. Emptying the bin removes the directory holding the cookies, not just the row in the list.