Firefox 153 Brings Native Containers, Weeks Behind Brave’s Launch

Firefox 153 reached Mozilla’s Release channel on July 21, 2026, folding Containers, the color-coded account isolation tool Mozilla has sold as an add-on since 2017, directly into the browser itself. The update also patches dozens of security flaws and adds HDR video playback on Windows. Brave got there first.

Brave built a native version of the same idea into its own browser nearly three weeks earlier. Mozilla’s own blog still labels its version a preview, and the isolation stops at cookies: IP address and operating system data still travel between every color coded tab, no matter which container it sits in.

Containers Move Inside the Browser Itself

Containers let a user keep Work, Personal, Shopping and Banking browsing in separate color-coded tabs inside one window. Each container carries its own cookies and site storage, so a person can stay logged into a personal Reddit account in one tab and a work account in another without signing out and back in.

Mozilla describes the feature as a way to keep separate parts of your online life logged in at once while ad tracking stays boxed inside each container. A search for a hat before a party, in Mozilla’s own framing, no longer means hat ads chasing the user around the web for weeks afterward.

That framing has a real limit. Device characteristics such as IP address and operating system are still shared across every container on the same machine, a caveat Mozilla does not hide but also does not headline.

A Decade-Old Idea Mozilla Left on the Shelf

Mozilla previewed the underlying concept as Container Tabs back in June 2016, then ran it as a Firefox Test Pilot experiment before publishing it as the standalone Multi-Account Containers extension in September 2017. The wider Test Pilot program shut down in January 2019, but the extension kept going on its own.

Mozilla’s own announcement puts the extension’s run at nearly a decade, and the math checks out: from a 2017 launch to a 2026 native rollout is close enough to call it a lost decade for a feature Mozilla invented and then left bolted on as an optional download.

Firefox took a different approach with Profiles, redesigned last year into the main interface. Profiles create fully separate environments, with their own bookmarks, extensions, history and logins, a heavier tool for splitting entire identities rather than a quick way to juggle two logins on one site.

Brave Beat Firefox to the Native Version by Weeks

Brave shipped its own built-in Containers with version 1.92 starting July 2, 2026, rolling out in phases across Windows, macOS and Linux with four default categories: Personal, Work, Social and School. No extension required, a detail Brave’s own release post makes a point of noting.

Brave frames the feature as a workflow convenience rather than a new privacy layer, since its storage partitioning already limits cross-site tracking by default for every user. Firefox, by contrast, still markets Containers as both a productivity shortcut and an added layer of isolation.

Reaction from privacy watchers leaned less on gratitude than on timing.

It’s bizarre that Firefox requires an extension to use this feature, even though it came out years ago.

Fria, a contributor at the privacy advocacy site Privacy Guides, wrote that after testing Brave’s rollout, adding that Firefox, Brave and Safari (through its own Profiles feature) are the only three browsers with anything like it today.

Does Firefox Containers Hide Your IP Address?

No. Firefox Containers separate cookies and site storage between tabs, but device-level signals such as IP address and operating system still pass through every container on the same computer. A tracker that fingerprints hardware rather than cookies can still connect a user’s Work and Personal tabs even with Containers switched on.

Mozilla’s own support pages describe how the underlying color-coded container system separates cookies and site data without touching what a website’s server sees about the connection itself. Masking IP address per container still requires pairing the Multi-Account Containers extension with Mozilla VPN or a custom proxy, a combination the native preview does not replace.

Mozilla Still Calls This a Preview

Mozilla’s own blog post announcing the feature is titled, plainly, Containers Preview. Its companion post on the Mozilla Connect community platform tells developers that Containers are now built into the browser, then describes what testers can do inside what it calls this preview release.

That word choice matters more than the wider coverage of Firefox 153 let on. This is a staged rollout, not a single switch flipped for every installed copy of Firefox at once.

The old extension is not going anywhere either. It remains available through Mozilla’s own add-ons listing, now on its 25th published version, and it keeps the features the native preview does not ship: automatic site assignment rules, cross-device sync, and that VPN and proxy pairing. The free native layer handles the basics; the deeper toolkit still lives behind an install.

The Last Release Before Everything Speeds Up

Firefox 153 lands just before Mozilla rewrites its own release calendar. Sylvestre Ledru, Mozilla’s director of engineering, told developers on the dev-platform mailing list on July 9, 2026, that the company plans to move Firefox Desktop and Android from a four-week release cadence to a two-week one starting in September.

Ledru called it an experiment, writing that the goal is to give finished work more frequent opportunities to reach users rather than to force every team to ship twice as fast.

Firefox 154, due August 18, 2026, will be the last release on the old four-week schedule. Firefox 155 then arrives September 1, 2026, moved up from an original date of September 15, kicking off the new two-week cycle. Chrome and Edge are making nearly identical moves within weeks of Firefox: Edge switches on August 27, and Chrome, which announced its own two-week plan back in March 2026, follows on September 8.

• What we know: Firefox 154 ships August 18 as the last four-week release; Firefox 155 starts the two-week cycle on September 1; Edge and Chrome shift to the same cadence within the same six-week window.

• What’s unconfirmed: whether the faster pace survives past Mozilla’s stated experiment, how extension developers adjust testing cycles to half the runway, and how IT departments standardized on the Firefox 153 Extended Support Release manage a consumer channel now moving twice as fast beside it.

Firefox 153 also becomes Mozilla’s new Extended Support Release, the long-term build enterprises deploy for stability rather than new features, arriving on the same version number that finally shipped native Containers and just weeks before the channel it feeds from starts moving at double speed.

Dozens of Security Holes Close Quietly

Underneath the headline features, Firefox 153 fixes dozens of vulnerabilities, including multiple high-severity flaws in the browser’s DOM, WebAssembly, WebRTC, JavaScript engine, graphics and networking components. Several of the memory safety issues patched could reportedly have been abused to achieve arbitrary code execution if exploited successfully.

The release also closes a permissions gap: extensions can no longer read local files by default unless a user explicitly grants a new local file access permission. Local Network Access restrictions now apply to every user, requiring a website to ask before it can reach devices or services on a home or office network. Mozilla stripped out legacy cookie settings entirely, pushing everyone toward its default cross-site cookie isolation model instead of the old opt-in controls.

A smaller batch of upgrades rides along with the same release:

• HDR video playback on Windows, for displays with HDR mode enabled in Windows Settings (some laptop panels limited to HDR video streaming only are not yet supported)
• QR code generation for sharing any open webpage straight from the address bar
• Image insertion and drag-to-merge PDFs inside the built-in PDF editor
• A new color picker launched from address bar quick actions
• A red-highlighted location icon whenever a site is actively reading a user’s location
• Support for Apple’s Globe+F fullscreen keyboard shortcut
• Experimental JPEG XL image support, opt-in through Firefox Labs

Users get the update by opening Menu, then Help, then About Firefox, where the browser downloads and applies it automatically.

Frequently Asked Questions

Is the Multi-Account Containers extension still necessary after Firefox 153?

Yes, for anyone who relies on its advanced tools. The extension has reached 25 published versions on Mozilla’s own add-ons store and still holds features the native preview skips entirely, including automatic site-to-container assignment, syncing containers across devices, and pairing individual containers with Mozilla VPN or a custom proxy.

Do Chrome or Edge have anything similar to Firefox Containers?

Not natively. Safari offers a comparable Profiles feature, and Brave shipped its own native Containers in version 1.92 in early July 2026. Privacy-focused reviewers count Firefox, Brave and Safari as the only three mainstream browsers with this kind of tool right now.

Does turning on Containers hide my IP address from websites?

No, not by itself. Containers isolate cookies and site storage, but a device’s IP address and operating system details still reach every website regardless of which container a tab belongs to. Masking IP per container still requires combining the Multi-Account Containers extension with Mozilla VPN or a separate proxy service.

How long will Firefox keep its new two-week release schedule?

Mozilla has not committed to it long term. One published rollout plan lists major releases every two weeks through Firefox 164 on January 26, 2027, but Mozilla’s engineering leadership has described the entire stretch as an experiment it will evaluate before deciding whether to keep the faster pace.