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In development

Tarn for Windows

Tarn for Windows is in development and has no release yet. It is the same GPUI app as on macOS, built from the same crates, with Chromium (through CEF) rendering every page. Shield's request filter, navigation policy, prompts and Lockdown run the macOS Chromium code. CI builds and tests it on every push; a release waits on the Chromium sandbox and an updater.
Shell
Rust, drawn with GPUI (same app as macOS)
Engine
Chromium through CEF
Checked on
Windows 10, x86_64
Data
%LOCALAPPDATA%\Tarn
Install
None yet; build from source

What works on Windows today?

Checked by hand: pages load and render, typing in pages and the address field with suggestions, Shield's per-profile request filter, tabs, back, settings, window move, maximize and close, session restore, a private space in memory, PDF, downloads and importing history from Edge.

  • Rebindable shortcuts, read in Ctrl, Alt and Shift instead of ⌘
  • Downloads saved to ~\Downloads with a Zone.Identifier stream, so SmartScreen treats them as downloaded
  • Import from Chrome, Edge, Brave and Firefox: history and bookmarks from all, cookies from Firefox
  • Lockdown sites get a Chromium view of their own, made without JavaScript

How is it built?

The Windows client lives in the same crates as macOS, behind cfg(windows). It uses Chromium through CEF for every page instead of WebView2, so it reuses the macOS Chromium engine code. Each Tarn profile gets its own Chromium profile; private and Lockdown stores stay in memory.

How does it differ from macOS?

macOS renders pages in WebKit and offers Chromium per tab; Windows renders every page in Chromium. A few things Chromium does differently show through.

  • Element hiding from the filter lists is a style sheet in the top frame only, and a page can briefly show its ads while it loads
  • Pop-ups and pages are clipped to rounded corners; pop-up shadows are not drawn
  • Touchpad swipes use Chrome's own back and forward arrow
  • Translation stays macOS-only: Windows has no on-device translation

Can I build it myself?

Yes, with access to the repository, the MSVC tools and Git Bash. Fetch CEF first, then build with CEF_PATH pointing at it.

scripts/fetch-cef.sh   # Git Bash: unpacks windows64 from packaging/cef.lock
CEF_PATH=<repo>/target/cef/windows64 cargo build -p app --release

What it does not do yet

  • No release for users yet. A v* tag adds an unsigned zip to a draft release only.
  • Chromium's child processes run without their sandbox until CEF's bootstrap launcher is in place; this blocks a release.
  • No updater yet, so release builds keep Chromium closed.
  • No installer, no Authenticode signing and no ARM64 build yet.
  • Extensions are not available: CEF cannot limit them to one profile or ask per site.
  • The memory panel lists no tabs, because CEF does not say which renderer shows a page.

Questions

Can I download Tarn for Windows?

Not yet. Windows builds are made and tested in CI, but a tag only adds an unsigned zip to a draft release. It is not meant for users until the Chromium sandbox and the updater are done.

Which engine does Tarn use on Windows?

Chromium, through CEF, for every page. The original plan used WebView2; the build switched to CEF so it could reuse the macOS Chromium engine code.

Is it the same app as on the Mac?

Yes. The interface is the same GPUI app from the same crates; only the engine and platform pieces differ, behind cfg(windows).

Which Windows versions are supported?

No version is supported yet, because nothing is released. The build and tests pass on Windows 10, x86_64; ARM64 is still open.

Do extensions work on Windows?

No. CEF loads extensions for every profile at once and cannot ask per site, which would break Tarn's rules for extensions, so Settings › Extensions says they are not available on Windows.

Last reviewed

Try Tarn on your Mac

No account to make and nothing sent home. macOS 14 or later; other platforms are in development.

Download for macOSAll platforms