Platform Support

Bunmaska ships on macOS, Linux, and now Windows (in beta, x64) - each driving the operating system’s own WebKit in pure bun:ffi. macOS and Linux use the WebKit that’s already on the machine; Windows has none, so it loads a WinCairo WebKit we build from source and bundle. Support isn’t identical across the three, and we publish exactly where it differs (see the parity matrix). The honest summary:

The support matrix

macOS

• Versions: macOS 13 (Ventura) or later - the oldest macOS a Bun-compiled binary loads on, and what a built .app declares.
• Architectures: both Apple Silicon (arm64) and Intel (x64). Bun runs natively on both; the system WebKit is whatever your Mac ships.
• This is the most complete backend - windows, IPC, menus, tray, dialogs, capturePage/printToPDF, and packaging all work.

Linux

• Requirements: GTK 4.10+ and WebKitGTK 6.0 at 2.42+ must be present (libgtk-4.so.1, libwebkitgtk-6.0.so.4). These ship on most modern desktops; on minimal/server images install your distro’s webkitgtk-6.0 package. The floors are hard: Bun resolves each native symbol table in one go, so an older GTK breaks every dialog and an older WebKitGTK breaks every window, rather than one missing feature.
• Architectures: x64 and ARM64. ARM64 includes Raspberry Pi (Pi 4/5 on a 64-bit OS) wherever WebKitGTK 6 is available - same pure-FFI code path, no special build.
• Display: a desktop session (X11 or Wayland). Headless/CI runs need a virtual display (e.g. Xvfb) and the WebKitGTK sandbox flags.

Windows

A from-scratch Win32 backend on pure bun:ffi - native windows + a cooperative message pump, the WinCairo WebKit view (WebKit’s real Windows port, not WebView2/Chromium), the renderer↔main IPC bridge (no context isolation yet: the preload and window.__bunmaska run in the page world, so load only trusted content), an application menu bar, and the secondary modules: clipboard (text/HTML/images), dialogs, menus, tray, notifications, safeStorage via DPAPI, screen, shell, global shortcuts, power monitor/blocker, native theme, and session.clearStorageData. It validates on a windows-latest CI runner alongside macOS and Linux.

• Architectures: x64 today. Upstream WinCairo is x64-only, so ARM64 is on the roadmap, not shipping. 32-bit (x86) is not supported, on purpose.
• Engine: Windows ships no system WebKit, so an app loads a WinCairo WebKit2.dll - built from WebKit source by us (a clang-cl from-source build, proven end-to-end) and bundled with the app, or resolved from the engine store. The engine directory is placed on the DLL search path so its dependency closure (ICU, libcurl, ANGLE, …) resolves beside it.
• The distribution piece: you can ship a Windows app today by embedding the engine in the build: engine.embed: true for a pinned engine you installed from the feed, or bunmaska build --embed-engine <dir> for your own build. On a dev machine, BUNMASKA_WEBKIT_PATH or a pinned engine in the store also works. With no engine at all, the app refuses to start and tells you which of those to provide. A hosted WinCairo engine is on the feed today; the stable-train build and ARM64 are next.
• Engine-blocked gaps: printToPDF, capturePage, and custom protocol:// schemes can’t be served on Windows - the WinCairo WebKit2 C API simply doesn’t expose those entry points (confirmed against the DLL’s exports). printToPDF and capturePage reject with a clear error, and creating a window while custom schemes are registered logs a warning, rather than anything silently no-opping. DevTools, the tray context menu, and a fully isolated content world are follow-ups. Full picture on the parity matrix.

Requirements (all platforms)

• Bun ≥ 1.3 - Bunmaska runs on Bun, not Node.
• The system WebKit listed above. No Chromium is downloaded or bundled, ever.

Next: Building & Distribution - how to package for each of these.