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Zen Browser is a free, open-source Firefox fork that rebuilds the desktop browser around vertical tabs, workspaces and split view, now running the Firefox 154.0.1 engine, with every feature free and no paid tier.
Zen is Firefox with the tab strip moved to the side and the clutter taken out.
Instead of fifty shrinking tabs along the top, you get vertical tabs in a sidebar, separate workspaces for work and personal browsing, and a split view that puts two pages side by side in one window.
Version 1.22b, published on 5 September 2026, is a maintenance release that cleans up after a much bigger one.
What Zen Browser Actually Does, in Plain Terms
Zen is Mozilla Firefox underneath. Same rendering engine, same extension support, same privacy foundation, wrapped in a completely rethought interface.
The toolbar and tab list sit on the left of the window, the main area splits into panes so you can compare several pages at once, and workspaces keep separate browsing sessions apart.
A compact mode hides nearly all the controls until you need them, which is why Zen screenshots look more like a reading app than a browser.
Two things you will not find in stock Firefox: Zen Mods, a built-in gallery of community themes and interface tweaks you install with one click, and Boosts, which apply custom styling to individual websites.
Because it inherits the Firefox engine, Zen plays modern web video exactly as Firefox does, including H.264 and VP9 streams on YouTube and similar sites.
AV1, the newer royalty-free codec those sites increasingly default to, decodes the same way, so there is nothing extra to install.
If a file will not play and you want to know whether the browser is the problem, our Web Player and HEVC Player run entirely in your browser and settle it in a few seconds.
What 1.22b Changes
This is a short list of repairs rather than new features, and the headline item is a problem the previous build shipped with and admitted to.
- Saved passwords behave again. A change to password storage had made Zen slow to reach saved logins and had started throwing unexpected Primary Password prompts, and this build ends it.
- Lower CPU and disk use while you browse. Zen writes your open-tab session to disk as you go, and the spikes that caused have been cut down further after a first pass at the same bug two weeks earlier.
- Addresses autofill again. Some sites had stopped accepting the saved address details Zen offered them.
- Picture-in-Picture tucks away properly. Minimising a floating video window was failing to collapse it into the sidebar.
- A duplicate separator is gone from the tab context menu.
- Firefox 155.0.1 underneath. Mozilla lists no security advisory against this engine build, so nothing here is urgent on security grounds.
The release worth paying attention to is 1.22b on 5 September, eight days earlier, which is where the substance landed.
- Security fixes. Mozilla's August advisory covers that build, which is the reason not to sit on anything older than it.
- Video seeking is noticeably faster. Jumping to a point in a video improved on Windows, macOS and Linux alike.
- A different memory allocator. Performance improved across benchmarks generally rather than in one specific place.
- The webrender compositor is on by default on Linux, which improves performance and reduces power draw on hardware that supports it.
- WebRTC memory leaks fixed on macOS, along with general rendering performance - video calls were the worst-affected case.
- Profile backups reach macOS. Local Zen profile backups now cover all three platforms and restore across any of them.
If you are on 1.21.14b or older. Update rather than skipping this one, because the security work in 1.21.15b is carried into every build after it, and 1.21.16b is the first release that has both those fixes and the password repair.
Who Zen Browser Is For
People who keep dozens of tabs open and want structure: researchers, developers, students, anyone juggling several projects at once.
It is also a natural pick if you care about privacy but find stock Firefox visually dated. Our browser privacy roundup covers what each browser sends home.
Pairing it with a private search engine such as Qwant rounds out the setup, and The Open-Source Browser That Wants Your Attention, Not Your Data is a good companion read if the open-source angle is the draw.
Zen is also the closest maintained match for anyone leaving Arc Browser, which stopped active development in 2025. Workspaces, vertical tabs and split view all carry over conceptually.
If you are still deciding whether to move, what happened to the team behind it is the background worth having first.
Who Should Look Elsewhere
Zen does not support Widevine DRM, so protected streaming services including Netflix and HBO Max will not play. The licence carries costs and a corporate structure that are not feasible for an independent open-source project.
If streaming is part of your routine, keep Google Chrome or Microsoft Edge installed alongside Zen for those sites.
Note the "b" in the version number too. Zen still labels its stable channel as beta, and while it is reliable in daily use, the occasional rough edge is part of the deal.
Zen Browser vs Firefox, Brave and the Rest
Against stock Mozilla Firefox, Zen trades familiarity for organisation: same engine, same add-ons, radically different layout.
Against Brave Browser the split is engine philosophy. Brave is Chromium with aggressive built-in ad blocking, while Zen is Firefox with interface innovation and leans on extensions such as uBlock Origin.
If you are weighing Brave specifically, Is Brave Browser Still Worth It? digs into the trade-offs.
Opera Browser and Vivaldi both offer overlapping ideas such as a sidebar and workspaces, but both are Chromium-based and neither is fully open source.
Fellow Firefox forks LibreWolf and Floorp chase privacy and customisation from a different angle if Zen's layout is not for you.
The full lineup is in our web browsers section.
Before You Install
The Windows installer is roughly 92 MB, with separate x64 and ARM64 builds. Pick ARM64 only for Snapdragon-based laptops.
Zen runs on Windows 10 and 11, macOS and Linux. Your Firefox profile does not always migrate on its own, but the import wizard pulls bookmarks, passwords and history from Firefox, Chrome and Edge on first launch.
Expect a short adjustment period. Keyboard-driven features such as Glance, which peeks at a link without leaving the page, and workspace switching pay off after a day or two of muscle memory.
Quick questions
Can Zen play Netflix or other DRM streaming?
No. Zen does not include Widevine DRM, so protected services will not play, which means keeping Chrome or Edge installed for those sites.
What actually changed in 1.22b?
Repairs rather than features: saved passwords are quick to reach again and stop prompting unexpectedly, session saving uses less CPU and disk, addresses autofill again, Picture-in-Picture collapses into the sidebar on minimise, and the engine moves to Firefox 155.0.1.
Is there a security update in this build?
Not in this one specifically, since Mozilla publishes no advisory against Firefox 154.0.1. The security fixes came in 1.21.15b a week earlier, so update if you are on 1.21.14b or older rather than waiting.
Does HDR video work?
Yes, on Windows, and it needs HDR mode switched on for your display in Windows Settings before Zen can use it. It was announced with the Firefox 153 engine but only started working in 1.21.10b, which may need a restart to take effect.
Will my Firefox extensions and bookmarks work?
Extensions install from the same add-ons site, and the import wizard pulls bookmarks, passwords and history from Firefox, Chrome and Edge on first launch.
Why is it still called beta?
Zen has never dropped the "b" from its stable channel, and the team uses it to signal that the interface is still moving. In practice it is stable enough for daily use, but occasional rough edges come with it.
Download Zen Browser 1.22b and see how it handles your tabs, or tell us how you got on if you have used it before.
