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 and Arc import. It is an early preview for Apple Silicon Macs on macOS 26 or later, on Chromium 151 with manual updates, and its release notes say that build is not a current Chromium security release.
67% Arc feature parity (yes = 1, partial = ½).
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.comNot counted in Arc parity: some people want AI, some avoid it.
Bloat 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 |
|---|---|---|---|
| Vertical 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 hold their own Pins and folders; switch from the sidebar Space bar or Dock menu.github.com |
| 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. | ✓ | ✓ | Create a Space on the current or a new profile; several Spaces can share one profile.github.com |
| Global 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 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 |
| Auto-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 |
| Space 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; experimental split Pins keep two pages together.github.com |
| Link 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 |
| Mini 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 and ChatGPT scopes.github.com |
| Link 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 |
| Site 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 picture-in-picturePlaying video pops out into picture-in-picture automatically when you switch tabs. | ◐ | ✓ | Experimental setting, on by default but unavailable unless Blink's auto-PiP feature flag is enabled.github.com |
Compatibility & migration
| Feature | Arcium | Arc | Note |
|---|---|---|---|
| Arc importImports Arc spaces, pinned tabs and folders. | ✓ | – | Imports Spaces, Pins, folders, Favorites and history; split views flatten; passwords via 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 (Widevine)Netflix, Disney+, Spotify web and other DRM video/audio play. Chromium forks need a Google Widevine licence. | ✓ | ✓ | Widevine is enabled in the build and its CDM arrives through the component updater.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 |
Extension support
Which extension formats and stores run, beyond the Chrome Web Store row above. Not counted in Arc parity.
| 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 151 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 |