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Firefox Containers Preview
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Firefox now ships a native Containers preview that isolates cookies and tracking per tab without requiring the Multi-Account Containers add-on.
Engineers no longer need to bundle or maintain a third-party extension to achieve context separation, simplifying deployment and reducing surface-area for bugs. The built-in feature changes how session data is scoped, which may affect automated tests and security policies that previously assumed a single cookie jar per profile. Because the preview lacks some add-on capabilities, teams must decide whether to rely on the native implementation alone or keep the extension for full functionality.
Written by elseif from the cluster below · every claim links back to a sourceThe three things worth knowing
Containers are now a first-party feature in Firefox and appear in the UI by default.
Tabs can be opened, named, colored, and iconified within specific containers via right-click or the settings panel.
The native version does not yet include all Multi-Account Containers add-on features, and the add-on can still be used alongside it.
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The major change is the integration of Containers directly into the browser core, removing the need to install the Multi-Account Containers extension for basic isolation. Users can create distinct workspaces that keep cookies and ad trackers separate, and the UI exposes container controls through right-click on tabs or the new tab button. This shift makes container functionality visible from the first launch of the preview build.
Adopting the native Containers costs nothing in terms of additional downloads, but developers must update any tooling that interacted with the former extension's APIs. Test suites that validated cookie isolation may need to be adjusted to target the built-in implementation, and CI pipelines should verify behavior on the preview channel. Existing automation that relied on extension identifiers will no longer find them unless the add-on remains installed.
The preview does not yet replicate every feature of the long-standing add-on, so power users may continue to install the extension for advanced controls. Consequently, environments that enforce a strict add-on whitelist must allow this specific add-on alongside the native feature. The isolation applies only to cookies and tracking data; other forms of process or memory isolation remain unchanged.
From an operations perspective, the native Containers simplify policy enforcement because administrators can toggle the feature via standard Firefox settings rather than managing separate extensions. However, because the feature is still labeled as a preview, enterprises should monitor its stability and be prepared to revert to the add-on if critical gaps emerge. Documentation and support channels will need to reflect the dual-path option during the transition period.
Mozilla signals ongoing investment in the native Containers, indicating future expansions that may eventually replace the add-on entirely. Until those enhancements arrive, engineers should treat the preview as an optional, incremental improvement rather than a complete replacement. Gathering user feedback through the provided Mozilla Connect thread will influence the roadmap and help prioritize missing capabilities.
Written by elseif from the cluster below · checked for specifics the sources never containedTHE CLUSTER