Sval
Free Firefox browser with Workspaces, Peeks and Arc import. No account, no telemetry, sync via your own folder
Sval is a free Firefox ESR browser (0.1.0-rc.9 on ESR 153.7.0) by Ellm Tree, Inc. of Seattle. Tabs live in a Workspace panel with nested groups, pins and up to four-pane Splits; each Workspace has its own colour and emoji and can be isolated with its own sign-ins. Alt-click opens a Quick Peek, links from other apps open in Peek windows or dock into a Workspace by rule, and the Launcher searches tabs across Workspaces, commands and history. It imports Arc Spaces, Favorites, folders and splits. It blocks ads and trackers out of the box, sets JavaScript and media per site, runs Firefox add-ons including MV2 uBlock Origin, and syncs through any folder you choose, end-to-end encrypted, with no account. Protected video (Netflix, Disney+) does not play on macOS and Windows yet, and iCloud passkeys with Touch ID do not work yet. Source is not fully public: only the MPL files are published as a tarball.
Built-in AI
AI optional
No built-in model or chat; Firefox AI is locked off. A built-in MCP server for your own AI apps is off by default.
sval.appBloat check
None found
No ads, feed, upsells or account. Telemetry, studies and sponsored tiles are locked off; crash reports leave only when you press Send.
sval.appAds, crypto, paid upsells, news feeds, default-on telemetry, required accounts.
Organization
| Feature | Sval | Arc | Note |
|---|---|---|---|
| SidebarVertical sidebarTabs live in a vertical sidebar that is the main tab UI and can be hidden. | ✓ | ✓ | Tabs live only in the Workspace panel, on either side; ⌃Z hides it and holding the pointer at the edge slides it back.sval.app |
| SpacesSeveral workspaces per window, each with its own pinned and open tabs, switched by swipe or shortcut. | ✓ | ✓ | Workspaces with their own tabs, groups and pins, switched by swipe, list or a strip; each window shows one.sval.app |
| 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. | ◐ | ✓ | A Workspace can be isolated (own cookies, sign-ins), but all other Workspaces share one store; no reusable named profiles.sval.app |
| FavoritesGlobal favoritesPinned icons at the top of the sidebar shared by every Space (Zen calls them Essentials). | ✓ | ✓ | Pins show in every Workspace unless limited with Show in; each Workspace keeps its own page and sign-in for a pin.sval.app |
| Pinned TabsPinned tabs & foldersPer-space pinned tabs that act like bookmarks, with nested folders. | ✓ | ✓ | Pins can sit in folders (one tile) and be limited to one Workspace; open tabs also nest in groups inside groups.sval.app |
| Live foldersSidebar folders that fill and refresh themselves from an outside source, such as GitHub pull requests or an RSS feed. | ✕ | ✓ | Groups and Favorites folders are manual; no feed, RSS or pull-request source in the docs or the app's code.sval.app |
| ArchiveAuto-archive tabsUnpinned tabs close automatically after a set time and stay recoverable in an archive. | ✓ | ✓ | Idle tabs move to History › Archived tabs after 12 h to 30 d, per Workspace or globally. Off by default (pref "never").sval.app |
| Theme pickerSpace themesPer-space colour or gradient themes. | ✓ | ✓ | Each Workspace has its own colour and emoji that tint the window; a fixed palette of ten colours, no gradient picker.sval.app |
Browsing
| Feature | Sval | Arc | Note |
|---|---|---|---|
| Split ViewTwo or more tabs side by side in one window. | ✓ | ✓ | Up to 4 panes; drag onto a tab, Alt-click a second tab or ⌃+. Splits keep their sizes and sync.sval.app |
| PeekLink previewOpen a link in an overlay without leaving the current page (Zen calls it Glance). | ✓ | ✓ | Option/Alt-click opens a link in a Quick Peek over the page; keep it as a tab or Split. Not triggered by hover.sval.app |
| Little ArcMini windowA small, chrome-less window for links opened from other apps or a quick search. | ✓ | ✓ | Links from other apps open in a Peek, a small window outside any Workspace; on by default, closes after 6 h idle.sval.app |
| Command barA ⌘T palette that searches tabs, history, bookmarks and browser commands. | ✓ | ✓ | The Launcher (⌘L) lists open tabs from every Workspace, Favorites, commands, history and suggestions. ⌘T opens a plain tab.sval.app |
| Air Traffic ControlLink routingRules that send links from other apps to a chosen space or profile. | ✓ | ✓ | Link Docking rules (site or address contains) send links from other apps to a Workspace; links clicked in Sval are unchanged.sval.app |
| BoostsSite customizationPer-site custom CSS/JS, or zapping elements off a page. | ✓ | ✓ | Colorshift (tint, contrast, theme, font) and a persistent Remove from this site per site; no CSS/JS editor, only filter rules.sval.app |
| Auto PiPAuto picture-in-picturePlaying video pops out into picture-in-picture automatically when you switch tabs. | ✓ | ✓ | Playing video moves to Picture-in-Picture when you switch tab or Workspace. On by default; Settings › General turns it off.sval.app |
| Mini playerMedia still playing in a tab you left keeps play/pause controls in the sidebar. | ✓ | ✓ | Panel-bottom controls for what played last: play/pause, ±10 s, previous/next track; pause buttons on tabs, groups, Workspaces.sval.app |
| Tab SwitcherRecent-tab switcherCtrl+Tab jumps back to the tab you used last and cycles in recently used order. | ✓ | ✓ | Ctrl+Tab goes to the last used tab in the Workspace; holding Ctrl opens a recent-tabs grid. Can be turned off.sval.app |
| Super CopyClean link copyA shortcut (⌘⇧C) copies the page URL with tracking parameters removed. | ◐ | ✓ | ⇧⌘C copies the page address unchanged; tracking parameters are stripped only on load at Strict blocking.sval.app |
| CaptureScreenshotsBuilt-in capture of a chosen area or element, and of the full page. | ✓ | ✓ | Firefox Screenshots kept (Tab menu, Launcher command): drag a region, or save visible or full page.github.com |
Compatibility & migration
| Feature | Sval | Arc | Note |
|---|---|---|---|
| Arc importImports Arc spaces, pinned tabs and folders. | ✓ | – | Imports Arc Spaces (colour, emoji), Favorites as pins, folders as groups, splits, Arc card and archive timing.sval.app |
| Chrome extensionsInstalls extensions from the Chrome Web Store. | ◐ | ✓ | Firefox add-ons from addons.mozilla.org only; the Chrome Web Store is not supported.sval.app |
| 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. | ✕ | ✓ | Netflix and Disney+ do not play on macOS and Windows (Google certification pending); Linux plays. EME is off until allowed.sval.app |
| PasskeysWebAuthn passkeys, Touch ID and the system/iCloud keychain. | ◐ | ✓ | Touch ID and iCloud passkeys do not work yet (Apple approval pending); USB and NFC keys do. No passkey entitlement in the app.sval.app |
| SyncSpaces, pinned tabs and settings sync across devices. | ✓ | ✓ | Syncs tabs, Workspaces, history and settings through any folder (iCloud Drive, Dropbox…), end-to-end encrypted; no account.sval.app |
| Mobile appiPhone, iPad or Android app that shares spaces with desktop. | ✕ | ◐ | iOS and Android are listed as coming soon.sval.app |
Extras
| Feature | Sval | Arc | Note |
|---|---|---|---|
| Built-in ad blockerAd and tracker blocking without installing an extension. | ✓ | ✓ | Built-in blocker using open filter lists; Balanced on a new install, Strict or Custom lists available.sval.app |
| Custom ShortcutsShortcut editorMost browser keyboard shortcuts can be remapped in Settings. | ✓ | ✓ | Settings › Keyboard shortcuts lists every shortcut, and most can be changed or cleared.sval.app |
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 | Sval | Arc | Note |
|---|---|---|---|
| EaselsA shareable canvas of live page captures, notes and drawings. | ✕ | ◐ | No board or canvas feature in the docs or the app's code.sval.app |
| 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. | ✕ | ✓ | No share links. Export only writes Workspaces and Favorites to a bookmarks file for another browser.sval.app |
| PreviewsWeb app previewsHover a pinned Gmail, Calendar or other web app to glance at it; a pinned calendar shows the next meeting with Join. | ✕ | ✓ | Hovering a tab shows its title, site and a static page picture; no web app previews, unread badges or calendar.sval.app |
| Developer modeA developer view that turns on by itself for localhost: full URL, quick DevTools and dev tools in reach. | ✕ | ✓ | Only Firefox DevTools (profiler removed); nothing that turns on by itself for localhost.sval.app |
Extension support
Which extension formats and stores run, beyond the Chrome Web Store row above.
| Feature | Sval | Arc | Note |
|---|---|---|---|
| Manifest V2 extensionsThe older extension format Chrome removed in 2025. Needed for full uBlock Origin and other extensions that block requests. | ✓ | ✕ | Firefox ESR keeps MV2 including blocking ad blockers like uBlock Origin; the maker plans to keep it that way.sval.app |
| Manifest V3 extensionsThe current extension format used by the Chrome Web Store (and supported by Firefox and Safari). | ✓ | ✓ | Firefox ESR runs MV3 add-ons too.sval.app |
| Firefox add-onsAdd-ons from addons.mozilla.org or .xpi files install and run. | ✓ | ✕ | Installs add-ons from addons.mozilla.org; each extension has a per-site on/off switch.sval.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.sval.app |