Zen Browser
Free Firefox-based browser with vertical tabs, Spaces, Essentials, Glance and split view. Imports Arc.
Zen is a free, open-source fork of Firefox with a vertical sidebar, workspaces (Spaces), pinned tabs and folders, Essentials, Glance link previews and split view. Version 1.24b (October 2026) added an Arc importer for Spaces, pinned tabs, folders and profiles, and a Dia importer for browser data (not Dia pinned tabs). It installs Firefox add-ons rather than Chrome extensions, and it has no Google Widevine licence, so Netflix and Spotify do not play on Windows and macOS. The project calls itself beta and is built by a small volunteer team funded by donations.
74% Arc feature parity (yes = 1, partial = ½).
Built-in AI
No AI
No Zen-built AI. Firefox chat sidebar, shortcuts, link previews and ML are pinned off in Zen default prefs.
github.comNot counted in Arc parity: some people want AI, some avoid it.
Bloat check
None found
No ads, wallet, feed or upsells; sponsored suggestions are locked off, and telemetry and the crash reporter are compiled out.
github.comAds, crypto, paid upsells, news feeds, default-on telemetry, required accounts.
Organization
| Feature | Zen Browser | Arc | Note |
|---|---|---|---|
| Vertical sidebarTabs live in a vertical sidebar that is the main tab UI and can be hidden. | ✓ | ✓ | Vertical tabs are the core design; horizontal tabs are not planned.docs.zen-browser.app |
| SpacesSeveral workspaces per window, each with its own pinned and open tabs, switched by swipe or shortcut. | ✓ | ✓ | Workspaces with their own tabs and pinned tabs, switched by shortcut or swipe.docs.zen-browser.app |
| Profiles per Space (shareable)Each Space can use its own browser profile (separate cookies, logins, history), and one profile can be shared by several Spaces. | ◐ | ✓ | Each Space can use a Firefox container (cookies/logins only; history and extensions shared); Spaces can share one.github.com |
| Global favoritesPinned icons at the top of the sidebar shared by every Space (Zen calls them Essentials). | ✓ | ✓ | Called Essentials; shared across Spaces, but split per container by default (separate-essentials pref).github.com |
| Pinned tabs & foldersPer-space pinned tabs that act like bookmarks, with nested folders. | ✓ | ✓ | Per-space pinned tabs; nestable folders added in 1.15b.zen-browser.app |
| Auto-archive tabsUnpinned tabs close automatically after a set time and stay recoverable in an archive. | ◐ | ✓ | Firefox tab unloader frees idle tabs (time/memory); Clear Tabs button; no archive or timed close in code.github.com |
| Space themesPer-space colour or gradient themes. | ✓ | ✓ | Per-workspace gradient themes with a colour picker and grain options.zen-browser.app |
Browsing
| Feature | Zen Browser | Arc | Note |
|---|---|---|---|
| Split ViewTwo or more tabs side by side in one window. | ✓ | ✓ | Up to 4 tabs side by side in horizontal, vertical or grid layouts.docs.zen-browser.app |
| Link previewOpen a link in an overlay without leaving the current page (Zen calls it Glance). | ✓ | ✓ | Called Glance; Alt+Click by default, expandable into a tab or split view.docs.zen-browser.app |
| Mini windowA small, chrome-less window for links opened from other apps or a quick search. | ✕ | ✓ | Open feature request; external links open as normal tabs, Glance is an in-window overlay.github.com |
| Command barA ⌘T palette that searches tabs, history, bookmarks and browser commands. | ✓ | ✓ | New Tab opens a floating URL bar that searches tabs, folders, history and bookmarks and runs commands.zen-browser.app |
| Link routingRules that send links from other apps to a chosen space or profile. | ✓ | ✓ | Space Routing: URL rules (incl. regex) send links to a Space, plus a default route for external links.github.com |
| Site customizationPer-site custom CSS/JS, or zapping elements off a page. | ✓ | ✓ | Boosts (since 1.20b): per-site colours, fonts, styles, zap and dark mode; shareable since 1.24b.linuxiac.com |
| Auto picture-in-picturePlaying video pops out into picture-in-picture automatically when you switch tabs. | ◐ | ✓ | Auto-PiP on tab switch exists but Zen ships its pref off (about:config flag); no settings UI yet.github.com |
Compatibility & migration
| Feature | Zen Browser | Arc | Note |
|---|---|---|---|
| Arc importImports Arc spaces, pinned tabs and folders. | ✓ | – | Since 1.24b: Spaces, pinned tabs, folders and Favorites as Essentials; extra Arc profiles become containers.github.com |
| Chrome extensionsInstalls extensions from the Chrome Web Store. | ◐ | ✓ | Firefox add-ons only (addons.mozilla.org); the Chrome Web Store is not supported.docs.zen-browser.app |
| DRM (Widevine)Netflix, Disney+, Spotify web and other DRM video/audio play. Chromium forks need a Google Widevine licence. | ✕ | ✓ | Widevine CDM is built in but unlicensed (FAQ): DRM sites fail on Windows/macOS; Linux streams per HowToGeek.docs.zen-browser.app |
| PasskeysWebAuthn passkeys, Touch ID and the system/iCloud keychain. | ✓ | ✓ | Passkeys on macOS since 1.10b; release builds carry Apple's passkey entitlement and a provisioning profile.github.com |
| SyncSpaces, pinned tabs and settings sync across devices. | ✓ | ✓ | Mozilla account sync; Spaces/folders since 1.22b via a Settings > Sync toggle (off by default), tabs optional.github.com |
| Mobile appiPhone, iPad or Android app that shares spaces with desktop. | ✕ | ◐ | No Android or iOS app and none planned.docs.zen-browser.app |
Extras
| Feature | Zen Browser | Arc | Note |
|---|---|---|---|
| Built-in ad blockerAd and tracker blocking without installing an extension. | ◐ | ✓ | Onboarding pre-selects installing uBlock Origin (1.22.1b+); no built-in blocker beyond Firefox tracker blocking.github.com |
Extension support
Which extension formats and stores run, beyond the Chrome Web Store row above. Not counted in Arc parity.
| Feature | Zen Browser | Arc | Note |
|---|---|---|---|
| Manifest V2 extensionsThe older extension format Chrome removed in 2025. Needed for full uBlock Origin and other extensions that block requests. | ✓ | ✕ | Firefox 159 keeps MV2 and blocking webRequest; Zen patches neither, so full uBlock Origin works.blog.mozilla.org |
| Manifest V3 extensionsThe current extension format used by the Chrome Web Store (and supported by Firefox and Safari). | ✓ | ✓ | Firefox 159's manifest schema accepts MV3 (event pages, no service workers); Zen does not patch it.github.com |
| Firefox add-onsAdd-ons from addons.mozilla.org or .xpi files install and run. | ✓ | ✕ | Installs add-ons from addons.mozilla.org per the docs; Firefox themes are not supported.docs.zen-browser.app |
| Safari extensionsSafari web extensions (the App Store extension apps Safari uses) install and run. | ✕ | ✕ | Gecko-based: runs only add-ons from addons.mozilla.org; no Safari web extension support.docs.zen-browser.app |