Firn
Calm native Mac browser on WebKit: vertical tabs, per-space sign-ins, Lookout previews, split view.
Firn is a free, open-source Mac browser written in Swift, SwiftUI and WebKit by David Wurgler. It borrows ideas from Arc, Dia and Zen but keeps things simple: a vertical sidebar, Spaces that are each their own browser (separate tabs, cookies, sign-ins and history unless you choose to share), Basecamp tiles, flat tab groups, Lookout link previews, two-pane split view and a command bar. Idle tabs are tidied away, ads and trackers are blocked by default, and it can import Arc spaces, favorites and pinned tabs. There are no accounts, no telemetry and no extensions. An earlier Electron/Chromium Firn was retired in October 2026 and its data does not carry over. An iPhone and iPad app is being built in the repo but has no release yet.
Built-in AI
No AI
No AI features; an on-device Apple-model helper is only an undecided idea in the design notes.
github.comBloat check
None found
No accounts, analytics or crash reports; ads and trackers are blocked. Update checks stay off until you say yes on the second launch.
github.comAds, crypto, paid upsells, news feeds, default-on telemetry, required accounts.
Organization
| Feature | Firn | Arc | Note |
|---|---|---|---|
| SidebarVertical sidebarTabs live in a vertical sidebar that is the main tab UI and can be hidden. | ✓ | ✓ | Vertical tab list is the only tab UI; sidebar collapses and peeks at the left edge.github.com |
| SpacesSeveral workspaces per window, each with its own pinned and open tabs, switched by swipe or shortcut. | ✓ | ✓ | Each space has its own Basecamp tiles, groups, tabs and colour; ⌃1–9 switches.github.com |
| ProfilesProfiles 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 gets its own WebKit data store; a new space can instead share another space's sign-ins.github.com |
| FavoritesGlobal favoritesPinned icons at the top of the sidebar shared by every Space (Zen calls them Essentials). | ◐ | ✓ | Basecamp tile grid (max 12) at the top of the sidebar, but different in every space.github.com |
| Pinned TabsPinned tabs & foldersPer-space pinned tabs that act like bookmarks, with nested folders. | ◐ | ✓ | Per-space Basecamp tiles and flat groups that never auto-tidy; no nested folders.github.com |
| Live foldersSidebar folders that fill and refresh themselves from an outside source, such as GitHub pull requests or an RSS feed. | ✕ | ✓ | No live-folder code; groups are flat and filled by hand.github.com |
| ArchiveAuto-archive tabsUnpinned tabs close automatically after a set time and stay recoverable in an archive. | ✓ | ✓ | Idle loose tabs move to Tidied away after 1, 7 (default) or 30 days of use, or never; kept 30 days.github.com |
| Theme pickerSpace themesPer-space colour or gradient themes. | ✓ | ✓ | Each space has one of 8 colours that tints the frame and welcome; no gradients or custom colours.github.com |
Browsing
| Feature | Firn | Arc | Note |
|---|---|---|---|
| Split ViewTwo or more tabs side by side in one window. | ◐ | ✓ | Two pages side by side only, with a draggable divider (30–70%).github.com |
| PeekLink previewOpen a link in an overlay without leaving the current page (Zen calls it Glance). | ✓ | ✓ | Lookout: Shift-click a link opens a floating preview that can be kept as a tab.github.com |
| Little ArcMini windowA small, chrome-less window for links opened from other apps or a quick search. | ✕ | ✓ | Listed under "Deliberately not doing"; links from other apps open as a tab in the main window.github.com |
| Command barA ⌘T palette that searches tabs, history, bookmarks and browser commands. | ✓ | ✓ | ⌘T bar searches open tabs, tidied and closed tabs, history and actions by name.github.com |
| Air Traffic ControlLink routingRules that send links from other apps to a chosen space or profile. | ◐ | ✓ | External links open in the space last used; no per-site rules.github.com |
| BoostsSite customizationPer-site custom CSS/JS, or zapping elements off a page. | ✕ | ✓ | Boosts are listed under "Deliberately not doing".github.com |
| Auto PiPAuto picture-in-picturePlaying video pops out into picture-in-picture automatically when you switch tabs. | ✕ | ✓ | No picture-in-picture code; the mini player only plays or pauses a tab's audio.github.com |
| Mini playerMedia still playing in a tab you left keeps play/pause controls in the sidebar. | ✓ | ✓ | Card above the spaces row for a tab playing out of sight: one play/pause button, no skip or volume.github.com |
| Tab SwitcherRecent-tab switcherCtrl+Tab jumps back to the tab you used last and cycles in recently used order. | ✓ | ✓ | ⌃Tab opens a recent-tabs panel, newest first, and releasing ⌃ switches; ⇧⌃Tab goes backward. Max five tabs.github.com |
| Super CopyClean link copyA shortcut (⌘⇧C) copies the page URL with tracking parameters removed. | ◐ | ✓ | ⇧⌘C Copy Link puts the page address on the clipboard unchanged; no tracking-parameter stripping or toast.github.com |
| CaptureScreenshotsBuilt-in capture of a chosen area or element, and of the full page. | ✕ | ✓ | Only Print… (⌘P) and tab-thumbnail snapshots exist; no screenshot or capture feature.github.com |
Compatibility & migration
| Feature | Firn | Arc | Note |
|---|---|---|---|
| Arc importImports Arc spaces, pinned tabs and folders. | ✓ | – | Reads StorableSidebar.json: spaces, favorites and pinned tabs; nested folders flatten to groups.github.com |
| Chrome extensionsInstalls extensions from the Chrome Web Store. | ✕ | ✓ | WebKit app with no extension support; extensions are only a research item.github.com |
| DRM streamingNetflix, Disney+, Spotify web and other DRM video/audio play, through Widevine or, on WebKit, FairPlay. Chromium forks need a Google Widevine licence; FairPlay counts once a major service is confirmed playing in the app. | ? | ✓ | |
| PasskeysWebAuthn passkeys, Touch ID and the system/iCloud keychain. | ? | ✓ | |
| SyncSpaces, pinned tabs and settings sync across devices. | ✕ | ✓ | No sync; the data model is sync-ready but sync is an open question.github.com |
| Mobile appiPhone, iPad or Android app that shares spaces with desktop. | ✕ | ◐ | Mac only; an iPhone/iPad app is half-built in the repo (phase 2 of 10), with no release and no sync.github.com |
Extras
| Feature | Firn | Arc | Note |
|---|---|---|---|
| Built-in ad blockerAd and tracker blocking without installing an extension. | ✓ | ✓ | Built-in EasyList and EasyPrivacy blocking, on by default, switchable per site.github.com |
| Custom ShortcutsShortcut editorMost browser keyboard shortcuts can be remapped in Settings. | ✕ | ✓ | Settings tabs are General, Tabs, Spaces, Privacy and Passwords; shortcuts are set in menu code.github.com |
More Arc features
Arc features shown but not counted in the score, because almost no replacement has them or only a few people need them.
| Feature | Firn | Arc | Note |
|---|---|---|---|
| EaselsA shareable canvas of live page captures, notes and drawings. | ✕ | ◐ | Easels are listed under "Deliberately not doing".github.com |
| Shared CollectionsShared spaces & foldersShare a Space, folder or set of tabs as a link anyone can open, or another user can add to their sidebar. | ✕ | ✓ | Sidebar and Basecamp menus only copy one tab's link; no way to share a space or group.github.com |
| PreviewsWeb app previewsHover a pinned Gmail, Calendar or other web app to glance at it; a pinned calendar shows the next meeting with Join. | ✕ | ✓ | Lookout previews a clicked link in a floating panel, a generic page glance; no pinned web-app content or badges.github.com |
| Developer modeA developer view that turns on by itself for localhost: full URL, quick DevTools and dev tools in reach. | ✕ | ✓ | Comment in code says the Web Inspector is Firn's only developer tool; no developer mode.github.com |
Extension support
Which extension formats and stores run, beyond the Chrome Web Store row above.
| Feature | Firn | Arc | Note |
|---|---|---|---|
| Manifest V2 extensionsThe older extension format Chrome removed in 2025. Needed for full uBlock Origin and other extensions that block requests. | – | ✕ | WebKit app with no extension support; extensions are only a research item.github.com |
| Manifest V3 extensionsThe current extension format used by the Chrome Web Store (and supported by Firefox and Safari). | – | ✓ | WebKit app with no extension support; extensions are only a research item.github.com |
| Firefox add-onsAdd-ons from addons.mozilla.org or .xpi files install and run. | – | ✕ | WebKit app with no extension support; extensions are only a research item.github.com |
| Safari extensionsSafari web extensions (the App Store extension apps Safari uses) install and run. | – | ✕ | WebKit app with no extension support; extensions are only a research item.github.com |