James Stringer
910fd5db2b
Port the --headless daemon to macOS so the same loopback HTTP/JSON API the Windows build exposes is available on Apple silicon, driving macOS guests via Virtualization.framework. AppSandbox.app/Contents/MacOS/AppSandbox --headless starts a single-owner daemon (CFRunLoop, no NSApplication/window server) that hosts AppSandboxCore for the process lifetime; a normal GUI launch passes no args and is unaffected. src/app_mac/headless.m/.h: BSD-socket loopback listener, bearer-token auth, a host.json discovery file, an SSE event stream, and the serialized command loop (one request runs to completion before the next). Validation mirrors the GUI; snapshots/templates return 501 (capabilities.snapshots/templates = false) so the HTTP interface matches Windows while gating the unsupported features. Startup fail-fast checks the minimum macOS version (LSMinimumSystemVersion) and VZVirtualMachine.isSupported, requires elevation, and -- because creation stages the guest disk as root -- resolves SUDO_USER so it reads the invoking user's VM registry and restore-image cache and hands created files back to that user. The daemon owns its VMs: exit cleans them up rather than leaving them running. main.m routes --headless to run_headless and otherwise takes the same per-user flock the daemon uses, so GUI and headless are mutually exclusive. The backend gains a g_headless flag (asb_mac_set_headless): the display window, clipboard, and audio (vz_vm_set_no_audio -- host-mic capture would block on a TCC prompt no daemon can show) are gated off headless. vm_dir.m resolves the VM root from SUDO_USER under sudo; iso_patch_mac.m skips the AuthorizationExecuteWithPrivileges prompt when already root. asb_core_mac auto-starts a VM once install completes (polling until the disk image is no longer attached, to avoid the create/boot race) so macOS matches the Windows auto-start behaviour. ui.m reports sshDeployKey/sshKeyDeployed and the GUI SSH terminal logs in with the deployed key. Adds Virtualization.framework to the app target link and headless.m to its sources.
App Sandbox
App Sandbox is a virtual machine app for Windows and macOS that's focused on performance and ease of use.
Windows features:
- Works on Windows 11 Home or Pro, without Hyper-V
- Windows 11 or Ubuntu 26.04 LTS VM Support
- Zero touch install
- Copy and Paste
- 2 Channel Audio
- GPU Acceleration via Paravirtualization (GPU-PV) with support for DirectX 12 (Windows only), OpenGL, Vulkan, CUDA, OpenCL
- GPU Hardware Video Decoder/Encoder support
- SSH via Hyper-V socket proxy (no network required)
- Snapshots
- Fixed 1080P60 display
- Host to client hot-key support
- Provision and boot with / without internet
- Supports running Claude Cowork and Docker inside the VM thanks to Nested Virtualization Support
Mac features:
- macOS VM support
- Skips most of the install setup process
- Copy and Paste
- 2 Channel Audio
- GPU Acceleration via Paravirtualization with support for Metal
- SSH via virtio-vsock (no network required)
- Dynamic display sizing
- Provision and boot with / without internet
Requirements: Windows 11 with an x64 Processor or macOS Tahoe (M Series)
About App Sandbox
App Sandbox creates and runs full desktop virtual machines — Windows 11, Ubuntu, and macOS. It is free, open-source (MIT), and distributed as prebuilt, signed releases on its Releases page. It is operated from a graphical UI: pick an OS, point it at an installer image, and App Sandbox provisions the disk, runs an unattended install, and boots the guest. You supply a Windows or Ubuntu ISO; macOS guests download their restore image automatically. It runs on a Windows 11 (x64) PC or an Apple Silicon Mac, including laptops.
Runs on Windows 11 Home, without Hyper-V. On Windows, App Sandbox does not use Hyper-V or Hyper-V Manager; it creates and runs VMs through the Windows Host Compute System (HCS) and Host Compute Network (HCN) APIs, which require only the Virtual Machine Platform feature. Hyper-V is limited to Windows 11 Pro and Enterprise, while Virtual Machine Platform is available on Windows 11 Home, so a Windows 11 Pro license is not required. Virtual Machine Platform is the same Windows feature WSL2 uses.
What you can use it for:
- A fresh Windows or Ubuntu VM for building and testing your own software on a clean OS install.
- Running a program in a VM, kept separate from your main OS and files.
- Developing and testing Windows drivers: a built-in Test Mode enables test-signing inside the guest, so the host's Secure Boot and boot configuration are left unchanged.
- Running a computer-use AI agent (such as Claude's computer use model) in its own VM, so it has a desktop to work in without taking over your own. Several agents can run at once, each in its own VM, on a single laptop or desktop.
- Creating GPU-accelerated (GPU-PV) VMs from a native-app GUI.
How it works: this repo also aims to be a working example of creating full desktop VMs
programmatically with the Windows HCS/HCN APIs and Apple's Virtualization.framework. On
Windows, App Sandbox submits a hand-built HCS machine document to computecore.dll /
computenetwork.dll — the HCS/HCN layer that also underlies WSL2 and Windows Sandbox —
rather than going through Hyper-V Manager. GPU acceleration uses GPU paravirtualization
(GPU-PV) to share the host GPU with the guest, with DirectX 12, OpenGL, Vulkan, CUDA, and
OpenCL on Windows and Metal on macOS. A custom IddCx indirect display driver and a
virtual audio device carry the screen and sound, and guest↔host clipboard, audio, input,
and SSH run over Hyper-V sockets. Guest disks are built by an in-repo tool with support
for ext4, squashfs, qcow2, and VHDX. On macOS, App Sandbox uses Apple's
Virtualization.framework (VZVirtualMachine, VZMacOSInstaller) over
virtio-vsock. On Windows, Linux (Ubuntu) guests reach the GPU through a custom DRM/KMS
kernel module (asb_drm), Microsoft's WSL2 dxgkrnl, and a custom Mesa build. The apps
are native C / Objective-C with an HTML/JS UI (WebView2 on Windows, WKWebView on macOS).
Tips:
[Windows] Enable hotkeys or mute the VM audio: connect to the VM and right-click the connection title bar
[Windows] Need a high performance remote desktop to remotely access your VM? Phaze works well
[Windows] You can check if the GPU-PV driver setup is working by running gpu-test.exe inside your App Sandbox Windows VM, gpu-test.exe will show a box with 6 rotating cubes, each using a different rendering engine (D3D9, D3D10, D3D11, D3D12, OpenGL and Vulkan). If one or more fail, they will not correctly show a rotating cube for that rendering API. gpu-test.zip. Note: The rendering API succeeding means that the GPU-PV worked, but sometimes games or apps are coded in such a way that they will not detect the GPU-PV system correctly and still show an error.
License
AppSandbox is licensed under the MIT License — Copyright (c) 2026 James Stringer.
It bundles third-party components that are not covered by the MIT license and
retain their own terms — most notably the Microsoft WSL2 dxgkrnl GPU driver
(GPL-2.0) and the embedded XZ decoder (0BSD). See
THIRD-PARTY-NOTICES.md for the full list. AppSandbox's
own Linux DRM kernel module (tools/linux/asb_drm/) is dual-licensed MIT OR
GPL-2.0 so it can resolve the kernel's GPL-only symbols.
Acknowledgements
Beyond my own experience building Easy-GPU-PV, I found NanaBox to be a really helpful resource for understanding HCS.
Author
James Stringer — author of Easy-GPU-PV.