Firefox 153 Bakes Multi-Account Containers Into the Browser as a Native Feature

Mozilla is previewing native Containers in Firefox 153, promoting a capability that has lived in the Multi-Account Containers extension for nearly a decade into a built-in, first-party feature. Containers let a single browser window hold separate logged-in identities—work, personal, banking, shopping—while isolating cookies and tracking data so activity in one context can’t follow you into another. The practical payoff is both organizational (juggling multiple accounts without separate profiles or browsers) and privacy-oriented (a product you browse in one container won’t trigger retargeting ads everywhere else).

The preview supports opening tabs in specific containers, creating and customizing them with names, colors, and icons, and managing them from Firefox settings. Users can spin up a container tab by right-clicking a tab or long-pressing the new-tab button. Existing extension users don’t need to change anything; the native version doesn’t yet match the add-on’s full feature set, so Mozilla says the two can run side by side during the transition.

The significance is less about new functionality than about commitment: by making container-based isolation visible by default and a maintained first-party citizen, Mozilla is signaling continued investment in context separation as a core browser primitive rather than a power-user add-on. Mozilla frames this as a foundation for future work and is soliciting feedback through a Mozilla Connect thread.