The Zen Browser team released version 1.19.9b on April 24, 2026, bringing a focused round of security patches, long-standing bug fixes, and a handful of quality-of-life improvements.
The update upgrades the underlying engine to Firefox 150.0 and resolves several stability issues that have been affecting users across sessions. Security is the headline reason to update promptly.
Zen Browser inherits its rendering engine directly from Mozilla Firefox, which means every upstream security advisory applies to Zen as well. Version 1.19.9b pulls in all patches from Mozilla’s MFSA 2026-30 advisory alongside additional fixes tracked through Zen’s own security advisory channel on GitHub.
Users running older builds are exposed to the vulnerabilities addressed in this release until they update.
One of the most welcome fixes in this release tackles issue #10649, a bug that caused the browser to halt and become temporarily unresponsive at irregular intervals. For users who keep many tabs open during long work sessions, this freeze was genuinely disruptive.
The fix stabilizes the internal process handling responsible for the halts, restoring the smooth, continuous experience that Zen users expect.
Duplicate bookmarks appearing on startup also get resolved here. The bug, tracked as issue #9540, caused Zen to create redundant bookmark entries each time the browser launched. Users who had been manually cleaning up their bookmarks folder after every session will find this fixed without any additional intervention needed.
Live folders, one of Zen’s more distinctive features, also receive a correction in this build. GitHub recently updated its pull request interface, and the change broke live folder synchronization for users tracking repositories or code reviews directly in the sidebar.
Version 1.19.9b restores correct behavior, so pull request data populates again without requiring a manual page refresh.
On the feature side, this update introduces a few practical additions. Holding Alt or Option and clicking a tab now splits it alongside the currently selected tab, offering a fast shortcut for developers and power users who rely on split-tab workflows.
A new Move to Folder context menu item has been added to the tab right-click menu, giving users a quicker way to organize tabs into their existing folder structure without dragging. A loading progress animation has also been added, giving visible feedback while pages are fetching.
Safebrowsing and geolocation APIs now behave more consistently across varied network configurations. This is particularly relevant for users who route traffic through local proxies or work inside containerized development environments.
Earlier builds occasionally threw false positives under these conditions, blocking legitimate requests. That behavior should no longer occur.
There is also a platform-specific fix for macOS users running Lockdown Mode. A regression in that environment caused emoji characters to fail rendering inside web content. This build corrects it, though it is worth noting for Linux users that no equivalent issue was reported on that platform.
Zen Browser is a free and open-source Firefox-based browser built around a vertical sidebar-first interface and a clean, focused design philosophy. It has grown a substantial community since its initial release, largely because it combines the full power of Firefox’s engine and extension ecosystem with a more modern, opinionated layout suited to keyboard-driven and developer workflows.
The update is available now through Zen’s official release channel, Flatpak, and the GitHub releases page. Users on distribution packages should check their package manager for availability. Full details on the changes in this build are documented in the Zen Browser 1.19.9b release notes.
