Zen Stable Release

Security

• https://www.mozilla.org/en-US/security/advisories/mfsa2026-123/

New Features

• Updated to Firefox 159.0.1
• New grain options have been added to the theme picker. You can cycle through different grain effects by clicking on the circle inside the dial.

Fixes

• Fixed a command prompt window briefly appearing on Windows when Zen restarts to apply an update.
• Fixed passkey sign-in failing on websites that share passkeys across related sites, such as Facebook and Instagram.
• Fixed crashes on Windows that could occur with some antivirus or other security software installed, in some cases also leaving WebGL disabled.
• Fixed red and blue colors appearing swapped on some websites that use WebGL on Linux, including video call background effects.
• More bug fixes and improvements.

Changes

• On macOS, icons on the UI will now start using SF Symbols.
• The 'About Zen' window has been redesigned.
• 'My Review Request' option for Pull Requests live folder now searches for 'user-review-requested:@me' instead of 'review-requested:@me'

Zen Stable Release

Security

• https://www.mozilla.org/en-US/security/advisories/mfsa2026-118/

New Features

• Updated to Firefox 159.0
• You can now import Spaces and Profiles from Arc and Dia.
• Boosts gets a nice upgrade! THey can now be shared with others and they get an overall quality improvement.
• Holding 'ctrl' (or 'cmd' on macOS) while hovering over the new tab button will now give the option to 'Paste & Search'.
• You can now remove/add tabs from the library.
• An indicator will now show when a tab is not visible.

Fixes

• Fixed an issue where expanded glance tabs would not appear on the right Space. (#16080)
• Fixed the file upload dialog opening in the last folder a file was saved to, such as Downloads, instead of the folder last used for uploads.
• Fixed memory usage growing rapidly when sites such as the Zoom web app were left open in a minimized window.
• Fixed some videos displaying incorrectly on Windows when NVIDIA RTX Video HDR is enabled.
• Fixed bookmarks not being imported from Google Chrome profiles that are signed in to a Google account.
• Fixed the Replace button in Apple Writing Tools on macOS inserting the clipboard contents instead of the rewritten text on some sites.
• Fixed long drop-down lists on web pages sometimes showing blank space in place of the last options until the list was scrolled.
• Fixed some sites, such as Slack, failing to load instead of falling back to HTTP/2 when the site rejected an HTTP/3 request.
• Fixed Zen using excessive memory on Linux with AMD graphics when viewing map or place results on sites such as ChatGPT.
• Fixed quick gamepad button presses sometimes being missed in web games on macOS.
• Fixed tabs sometimes detaching into a new window when clicked on Linux with Wayland.
• Fixed menus and panels fading in on Windows and Linux when animation effects are turned off in the operating system.
• More bug fixes and improvements.

Changes

• Zen's keyboard shortcuts have been improved and moved to about:keyboard.
• Space Routing settings have been moved to the Library
• On the site center, the reader mode button has been moved next to the 'Secure' button and shown only if available.
• Web addresses written in the Javanese, Balinese, Canadian Aboriginal Syllabics, and N'Ko scripts are now displayed in their own script instead of as encoded "xn--" text.

Zen Stable Release

Security

• https://www.mozilla.org/en-US/security/advisories/mfsa2026-111/

New Features

• Updated to Firefox 158.0.1
• Boosts now have a 'focus' feature, allowing you to concentrate on a specific part of the website.
• Windows builds now run with CSIR PGO, improving performance and startup times. All other platforms also have performance improvements.

Fixes

• Mozilla blocked compromised eMudhra intermediate certificates via OneCRL on October 17th. The blocks were distributed to clients via Remote Settings the same day. This update contains the updated OneCRL block list, ensuring clients will block the compromised certificates even if RemoteSettings is disabled by policy or otherwise unavailable in the user's network environment. (Learn More)
• Fixed the sidebar hiding when the mouse is still over it. (#15995)
• Fixed devtools not appearing on glance tabs. (#15261)
• Boosts zap bar will now push the web contents up when activated. (#13972)
• Fixed sidebar scroll being reset when entering fullscreen. (#14389)
• Fixed multiple windows launching on startup on Linux and Windows. (#12140)
• Fixed a crash on Windows when printing or saving a page as PDF while a screen reader or other assistive technology was running.
• Fixed an issue where Zen was opening windows on the wrong monitor in multi-monitor setups on Linux.
• Fixed multiple media bars appearing when 2 or more tabs are using WebRTC.
• Fixed an issue where files dragged into Firefox from other applications were not dropped onto the page on macOS.
• External links will now be routed through the Space Routing feature on startup
• More bug fixes and improvements.

Zen Stable Release

Security

• https://www.mozilla.org/security/advisories/mfsa2026-106

New Features

• Updated Firefox to 158.0
• Added a --space <id|name> option to the command line interface.
• Library will now show a 'Open in Folder' option and download speed when hovering over the toolbar icon.
• Zen now creates more accessible PDFs when saving a page as PDF, and when printing on Linux and macOS. This also fixes a variety of PDF rendering issues, such as missing math symbols.

Fixes

• Fixed various animation, urlbar and UI performance issues.
• Fixed Library media tab requesting onedrive to download all files from cloud. (#15888)
• Fixed unwanted label next to the search icon in urlbar. (#14856)
• Fixed Avahi access so CUPS printers are listed in flatpak sandbox. (#9651)
• Fixed various memory leak issues. (#15954)
• Fixed a crash that could occur while Zen loaded website icons (favicons).
• Fixed menus such as List all tabs, Settings, etc being hard to read with a Windows High Contrast theme. Menu background and text colors now follow the Background and Text colors chosen for a custom contrast theme in Windows Settings.
• Other bug fixes and improvements.

Changes

• Space routing regex will now match URLs as case-insensitive.
• Library's widget hover list will now only display recently downloaded files.
• Zen no longer rounds scroll positions to whole screen pixels. Scrolling is now smoother and more precise, especially on high-resolution displays or when a page is zoomed.

Zen Stable Release

New Features

• Added an 'open library' command to the command palette.
• You can now right-click the media tab in the Library to disable it.

Fixes

• Changed session backup file names to use local dates (#15806)
• Fixed the library getting stuck after opening and closing it quickly (#15833)
• Fixed blocked/unsafe downloads not having the choice to be opened or saved. (#15809)
• Fixed moving multiple tabs to new window irrecoverably loses unloaded tabs. (#15810)
• Fixed the sidebar having too much minimum width when they are aligned to the right. (#15794)
• Fixed HEIC media being listed in the media tab but do not render correctly. (#15778)
• Fixed space-assigned bookmarks not being saved anymore. (#12721)
• Fixed a memory leak issue on startup.
• Other bug fixes and improvements.

Zen Stable Release

Security

• https://www.mozilla.org/en-US/security/advisories/mfsa2026-104/

New Features

• Updated to Firefox 157.0.1
• Added an option in the Library to filter closed tabs instead of history entries.
• A keyboard shortcut (opt/alt + shift + L) has been added to quickly open the Library.
• 'Clear all downloads' and 'Clear history' options have been added to the Library by right clicking on the respective section tabs.

Fixes

• Fixed transparent sidebars having low opacity.
• Fixed downloads failing on macOS when Firefox is set to ask where to save files but doesn't have permission to access the Downloads folder.
• Other bug fixes and improvements.

Zen Stable Release

Introducing Library! A better place to organize and access your history, media, downloads, spaces and more.

Security

• https://www.mozilla.org/en-US/security/advisories/mfsa2026-97/

New Features

• Introducing Library! A better place to organize and access your history, media, downloads, spaces and more.
• You can now resize the sidebar even when its hidden. If the sidebar is resized too small, it will automatically hide itself.
• Updated to Firefox 157.0
• WebRTC video calls can now use hardware AV1 decoding on devices that support it, instead of always decoding AV1 video in software.

Fixes

• Significant performance improvements on startups/new windows when there are lots of tabs open.
• Certain icon animations like the boost indicator or musical notes on the sidebar are now more performant. (#15299)
• Fixed status panel and glance controls not using the correct theme colors. (#15280)
• Fixed some HDR videos encoded in 8-bit color formats looking dull and gray on Windows instead of displaying in HDR.
• Improved audio and video synchronization when repeatedly changing the playback speed of videos, for example on YouTube.
• Fixed an issue on Windows where making a video full screen would leave the Windows taskbar showing over the video.

Changes

• When a link gets routed to a specific space, it will prioritize the window that has that space open.
• Some elements like the sidebar and the command bar now appear with blur effects.
• On MacOS, buttons at the bottom of the sidebar now appear larger.
• Swiping to the right on the last space will now try to create a new space.
• When the sidebar is at the right, the buttons at the bottom are now reversed.

Zen Stable Release

New Features

• Updated to Firefox 156.0.1
• The command bar now allows you to search through tabs and folders more efficiently.

Fixes

• Fixed Zen leaking system handles on Windows as content processes were started and stopped.
• Fixed context menu actions on the urlbar not working. (#15437)
• Fixed overflow-extension order in single toolbar mode. (#15419)
• Fixed not being able to install add-ons while in compact mode. (#15445)
• Fixed Zen windows on macOS 27 immediately returning to maximized after being restored by double-clicking the title bar.
• Other bug fixes and improvements.

Zen Stable Release

Security

• https://www.mozilla.org/en-US/security/advisories/mfsa2026-90/

New Features

• Updated to Firefox 156.0
• Zen on macOS can now be set to open automatically when the computer starts up, from the Startup section of Settings.
• Added the following actions to the command bar: 'Expand current view', 'New space', 'Reopen closed tab', 'Duplicate tab', 'Reset pinned tab'.

Fixes

• Fixed high-sample-rate FLAC audio in MP4 failing to play on certain video sites.
• Fixed subtitles not appearing in the Picture-in-Picture window when they are turned on in the video player after the window has already opened.
• Fixed the find bar becoming permanently unavailable in a tab after reversing the panes in Split View.
• Fixed some sites failing to load when DNS over HTTPS is enabled and the site does not support HTTPS.
• Fixed an issue on Windows where Zen could block an auto-hiding taskbar from showing.
• Fixed the sidebar not hiding if the urlbar is open when compact mode is enabled. (#13196)
• Fixed an issue where cross-space tab routing would freeze the browser under certain conditions. (#14171)
• Fixed cross-device sync losing certain tabs if they are created too quickly (#15380)
• Fixed certain issues related to live folders appearing as active even when they are no tabs showing in them.
• Other bug fixes and improvements.

Changes

• Zen's built-in PDF viewer now starts up to 45% faster.
• Improved memory and CPU usage when Zen displays large JPEG images scaled down to fit a page.
• On Windows devices with ARM64 processors, WebRTC video calls may now use hardware H264 decoding instead of falling back to software.
• Live Folders will now ignore archived issues and pull requests.
• Improved the look and feel of drag-and-drop interactions for tabs. Specially on MacOS, where the drag-and-drop behavior is now done natively.
• Folders will now fully-expand if all tabs within them are visible. Folder animations has also been improved for smoother transitions.

Zen Stable Release

New Features

• You now have the option to sync normal tabs across devices along with your Spaces, Folders, and other data. This can be enabled in Settings > Sync > Sync your Spaces across devices.
• You can now share Spaces, folders and split views to other Zen users and non-Zen users via a shareable link. This can be found in the context menu of a Space, folder or split view.

Fixes

• Noticeably improved performance and battery usage while scrolling, and playing videos.
• Other bug fixes and improvements.