Multibox Privacy Policy

Multibox · Last updated: July 30, 2026

Short version: Multibox does not collect, store, transmit, or sell any personal data. Your sessions and their logins stay on your own device, and the developer has no servers and receives nothing from your use of the extension.

What we collect

Nothing. Multibox does not collect or transmit any personal information, browsing history, or usage analytics. The developer has no servers and receives no data from your use of the extension. Nothing about your sessions, the sites you use them on, or your logins is ever sent to the developer or any third party.

How Multibox works

Multibox lets you be signed in to the same website with several accounts at once. It does this by keeping each session's cookies in a separate, private jar and sending only that session's cookies on that session's own tabs. Each session lives in its own colored tab group. Your normal (non-session) browsing is untouched: Multibox never reads or writes your regular cookie store, and it does not request the browser's cookies permission at all.

What is stored, and where

Everything Multibox keeps is stored locally, in this browser on your device (chrome.storage.local):

Your sessions (their names, the site they belong to, and their color) and your layouts (named snapshots of open sessions and their tabs).
Each session's cookies, kept in that session's own local jar so the account stays signed in when you reopen it. These are treated as private and are never exported or synced.
Your settings and your theme choice.

Nothing here leaves your device on its own, there is no account to create, and there is no developer server involved.

Optional cross-device backup

If you turn on "Sync my setup across devices," Multibox uses Chrome's own built-in sync (chrome.storage.sync, tied to your Google account) to back up your setup only: your session list, your layouts, and your settings. Your logins are never synced, and saved web addresses are reduced to the site and page path (no query strings or tokens). This is off by default, it is handled entirely by Chrome, and nothing is sent to the developer. Turning it off stops future backups.

Exporting a backup

The Data settings let you export a backup file of your sessions (their names, sites, and colors) and layouts. For your security this file never contains any logins, so after importing it you sign in to each session again. The file is created on your device and saved only where you choose to put it.

Permissions and why they are needed

declarativeNetRequest (with host access): to rewrite the cookie headers on a session's own tabs so each session sends and receives only its own cookies. This is what keeps sessions separate.
webRequest: to read the Set-Cookie headers a site returns to a session's tabs, so that session's private jar stays current. It is read-only and nothing is sent anywhere.
storage: to keep your sessions, layouts, settings, and each session's cookie jar on your device.
tabGroups: to place each session's tabs in their own colored tab group and keep its name and color in sync.
contextMenus: to add an optional right-click "Multibox" item for opening a link, or the current page, in a session. It can be turned off.
Host access (all sites): because you can start a session on any website, Multibox needs to rewrite cookie headers on the sites you use it on. It never reads page content, and it never touches your normal cookies.

Multibox does not request the cookies permission and never accesses your real cookie store. None of these permissions is used to read, collect, or send your data anywhere.

Third parties

Multibox does not share data with any third party, because it does not collect any. The optional "Donate" link opens an external page (Ko-fi) only if you click it; any payment there is handled by that service under its own privacy policy.

Children

Multibox is a general-purpose utility and does not knowingly collect information from anyone, including children.

Changes

If this policy changes, the updated version will be posted on this page with a new "last updated" date.

Contact

Questions? Contact the developer at contact@mcguigansoftware.com.