Arcium
Helium-based Chromium browser with Arc-style Spaces, Pins, Favorites, Peek and Little Arc for Mac
Arcium is an open-source macOS browser built on Helium, itself a privacy-focused Chromium fork, by dr-baker. It adds a vertical sidebar with Spaces (each tied to a profile), Pins with folders, Favorites, Peek, Little Arc, a glass command bar, automatic Picture-in-Picture and one-click Arc import. The source is on Chromium 156, but the newest download is an early preview for Apple Silicon Macs on macOS 26 or later, built on Chromium 151 with manual updates, and its release notes say that build is not a current Chromium security release.
Built-in AI
No AI
Chromium's Gemini/Glic, ScreenAI and AI omnibox shortcuts are patched out; the command bar's ChatGPT scope only opens a site.
github.comBloat check
None found
No ads, wallet, feed or upsells; Helium states no analytics and no requests without consent. Onboarding asks before services run; crash reports default to ask.
helium.computerAds, crypto, paid upsells, news feeds, default-on telemetry, required accounts.
Organization
| Feature | Arcium | Arc | Note |
|---|---|---|---|
| SidebarVertical sidebarTabs live in a vertical sidebar that is the main tab UI and can be hidden. | ✓ | ✓ | Vertical tabs sidebar with icon-rail or fully hidden collapse; top bar can be hidden.github.com |
| SpacesSeveral workspaces per window, each with its own pinned and open tabs, switched by swipe or shortcut. | ✓ | ✓ | Spaces are created and switched from the sidebar, each with its own icon, theme and Pins.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. | ✓ | ✓ | Create a Space on the current or a new profile; several Spaces can share one profile.github.com |
| FavoritesGlobal favoritesPinned icons at the top of the sidebar shared by every Space (Zen calls them Essentials). | ◐ | ✓ | Favorites are shared per profile; Spaces on other profiles show their own Favorites.github.com |
| Pinned TabsPinned tabs & foldersPer-space pinned tabs that act like bookmarks, with nested folders. | ✓ | ✓ | Per-Space Pins with nested folders; a Pin keeps its home page while the tab navigates.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 in the Arcium patch set or macOS repo at HEAD; folders are plain Pins.github.com |
| ArchiveAuto-archive tabsUnpinned tabs close automatically after a set time and stay recoverable in an archive. | ◐ | ✓ | Chromium Memory Saver is on by default and discards idle tabs; no archive. Shelf-style archive planned.github.com |
| Theme pickerSpace themesPer-space colour or gradient themes. | ✓ | ✓ | Each Space gets its own palette with movable glows, grain and Browser/Pages light or dark.github.com |
Browsing
| Feature | Arcium | Arc | Note |
|---|---|---|---|
| Split ViewTwo or more tabs side by side in one window. | ◐ | ✓ | Chromium two-pane split view; split Pins (experimental) keep two pages together.github.com |
| PeekLink previewOpen a link in an overlay without leaving the current page (Zen calls it Glance). | ✓ | ✓ | Peek previews eligible links over the page and can become a tab or Pin; on by default.github.com |
| Little ArcMini windowA small, chrome-less window for links opened from other apps or a quick search. | ✓ | ✓ | Compact window for one external link; off in core, switched on in the preview's initial prefs.github.com |
| Command barA ⌘T palette that searches tabs, history, bookmarks and browser commands. | ✓ | ✓ | Command-T glass bar searches tabs, Pins, Favorites and the web, with YouTube, X and ChatGPT scopes.github.com |
| Air Traffic ControlLink routingRules that send links from other apps to a chosen space or profile. | ✕ | ✓ | Only a Little Arc toggle and a default Space for new windows; no per-site routing rules.github.com |
| BoostsSite customizationPer-site custom CSS/JS, or zapping elements off a page. | ✕ | ✓ | No per-site CSS/JS or element zapping in the feature docs or patch list.github.com |
| Auto PiPAuto picture-in-picturePlaying video pops out into picture-in-picture automatically when you switch tabs. | ✓ | ✓ | Browser-started auto-PiP is enabled in the build; playing video pops into a native PiP window when you leave the tab.github.com |
| Mini playerMedia still playing in a tab you left keeps play/pause controls in the sidebar. | ◐ | ✓ | Only Chromium's toolbar media button and popover, hidden when Sidebar navigation is on; no sidebar play/pause.github.com |
| Tab SwitcherRecent-tab switcherCtrl+Tab jumps back to the tab you used last and cycles in recently used order. | ✓ | ✓ | Setting "Cycle through tabs in most recently used order with Ctrl+Tab"; Arc shortcut preset also binds Control+Tab to a recent-tabs preview.github.com |
| Super CopyClean link copyA shortcut (⌘⇧C) copies the page URL with tracking parameters removed. | ◐ | ✓ | Ctrl/Cmd+Shift+C copies the page URL (Helium setting, on by default) unchanged; no tracking-parameter stripping found in patches.github.com |
| CaptureScreenshotsBuilt-in capture of a chosen area or element, and of the full page. | ◐ | ✓ | Helium turns on Chromium's Screenshot (Save and share menu): drag a region of the visible page; no full-page capture.github.com |
Compatibility & migration
| Feature | Arcium | Arc | Note |
|---|---|---|---|
| Arc importImports Arc spaces, pinned tabs and folders. | ✓ | – | One-click import of Spaces, icons, Pins, folders, Favorites; history optional; split views flatten; passwords need a script.github.com |
| Chrome extensionsInstalls extensions from the Chrome Web Store. | ✓ | ✓ | Installs Chromium extensions from the Chrome Web Store through Helium's extension proxy.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. | ✓ | ✓ | Widevine is built in; its CDM comes via Helium component updates (services on) or a Settings button that copies Chrome's.github.com |
| PasskeysWebAuthn passkeys, Touch ID and the system/iCloud keychain. | ? | ✓ | Entitlements list no keychain access group; not tested at runtime. |
| SyncSpaces, pinned tabs and settings sync across devices. | ✕ | ✓ | Helium removes the browser's sync account UI; Arcium docs and patches add no sync.github.com |
| Mobile appiPhone, iPad or Android app that shares spaces with desktop. | ✕ | ◐ | Mac-only, Apple Silicon and macOS 26 or later.github.com |
Extras
| Feature | Arcium | Arc | Note |
|---|---|---|---|
| Built-in ad blockerAd and tracker blocking without installing an extension. | ✓ | ✓ | Bundled Helium uBlock Origin component, with assets access enabled by default.github.com |
| Custom ShortcutsShortcut editorMost browser keyboard shortcuts can be remapped in Settings. | ✓ | ✓ | Chromium keyboard-shortcuts settings page (Helium, on by default) rebinds browser commands; Arcium adds an Arc shortcut preset.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 | Arcium | Arc | Note |
|---|---|---|---|
| EaselsA shareable canvas of live page captures, notes and drawings. | ✕ | ◐ | No Easels or canvas code in the patch set or macOS repo; not in the feature-settings audit.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. | ✕ | ✓ | No Space, Pin folder or tab-group sharing or export in the settings audit or patches (searched).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. | ✕ | ✓ | No hover glance, unread badge or calendar widget for Favorites or Pins in the settings audit or patches (searched).github.com |
| Developer modeA developer view that turns on by itself for localhost: full URL, quick DevTools and dev tools in reach. | ✕ | ✓ | Only standard Chromium DevTools; no developer mode, localhost styling or JSON viewer in the settings audit or patches (searched).github.com |
Extension support
Which extension formats and stores run, beyond the Chrome Web Store row above.
| Feature | Arcium | Arc | Note |
|---|---|---|---|
| Manifest V2 extensionsThe older extension format Chrome removed in 2025. Needed for full uBlock Origin and other extensions that block requests. | ✓ | ✕ | Helium patch stops disabling legacy MV2 extensions, so MV2 like uBlock Origin keeps loading.github.com |
| Manifest V3 extensionsThe current extension format used by the Chrome Web Store (and supported by Firefox and Safari). | ✓ | ✓ | Chromium 156 accepts manifest versions 2 and 3; Arcium does not change this.github.com |
| Firefox add-onsAdd-ons from addons.mozilla.org or .xpi files install and run. | ✕ | ✕ | Chromium-based; extensions come from the Chrome Web Store, no Firefox add-on support in the patches.github.com |
| Safari extensionsSafari web extensions (the App Store extension apps Safari uses) install and run. | ✕ | ✕ | Chromium-based; no Safari web extension support in the patches.github.com |