# WinDiskWriter: Windows installers on a USB stick, built from a Mac > WinDiskWriter is a GPL-3.0 C application for macOS that creates bootable universal Windows installer USB drives supporting both UEFI and Legacy BIOS modes, usable on PCs, Intel Macs and certain virtual machines. It patches Windows 11 installers to bypass TPM, RAM, Secure Boot and other requirements, adds EFI boot support to Windows Vista and 7, and automatically splits oversized install.wim files for FAT32. **TechUnRestricted/WinDiskWriter** — 🖥 Windows Bootable USB creator for macOS. 🛠 Patches Windows 11 to bypass TPM and Secure Boot requirements. 👾 UEFI & Legacy Support - Repository: https://github.com/TechUnRestricted/WinDiskWriter - Stars: 4,791 · Forks: 140 - Language: C - License: GPL-3.0 - Published: 2026-09-23 · Updated: 2026-09-23 · Language: en - Canonical page: https://hysenlabs.com/projects/techunrestricted-windiskwriter ## The job: a universal installer from a Mac WinDiskWriter creates bootable universal USB Windows installers that support both UEFI and Legacy BIOS modes, and the stated destinations are a PC, an Intel Mac, or certain virtual machines, the three places a Windows installation from removable media actually happens. The tool exists because the Mac side of this task is underserved, mainstream imaging tools either run on Windows or handle macOS images, and the Windows ISO's internal layout needs specific treatment for each boot mode. The project is written in C for macOS, GPL-3.0 licensed, with an Xcode project at the repository root and the latest tagged release at v1.3 from January 2024, with the repository pushed 2026-09-06. Writing an installer drive is destructive by nature, the target USB is reformatted and repartitioned, so the tool's value concentrates in getting the layout right the first time, the boot partitions, the file system choices and the patched or split images all decided before bytes hit the disk. ## The Windows 11 patch, as a checkbox The patch feature addresses Microsoft's hardware requirements directly, you can bypass TPM, Minimum RAM, Secure Boot and some other System Requirements set by Microsoft for Windows 11, and the mechanism is deliberately simple, just click Patch Installer Requirements before writing. The patch modifies the installer media rather than the target machine, so the resulting USB installs on hardware that the stock installer would refuse, and the choice remains per-drive rather than global. For context this is a compatibility patch, the Windows 11 requirements exclude otherwise-capable older machines, and several mainstream tools offer similar patches, but WinDiskWriter's version matters specifically for Mac users preparing drives for old PCs. The requirement bypasses also have a practical scope, they change what the installer will accept as target hardware, not what Windows itself needs after installation, so a machine that scrapes past the installer check still runs the installed system under the same constraints it always had, minus the artificial gates. ## Legacy BIOS, and EFI backports for Vista and 7 Two features address old hardware in opposite directions. Legacy BIOS support creates an all-in-one USB drive that supports both UEFI and Legacy boot modes, required for installing Windows on computers with old firmwares that do not support EFI booting. And the EFI feature works backwards, adding EFI support to Windows Vista and 7, versions that do not support EFI booting out of the box, with the description explaining the manual alternative, additional steps such as extracting an EFI-capable bootloader from the installer, which WinDiskWriter does for you. The pair covers the full firmware history a technician encounters, modern UEFI machines, legacy BIOS boxes, and the transitional era where Vista and 7 installations meet UEFI firmware. ## The 4GB problem, solved automatically The splitting feature exists because of a file system collision, newer Windows ISOs contain a large install.wim file over 4GB, and since FAT32 only supports file sizes up to 4GB, WinDiskWriter automatically splits it. FAT32 is the partition format UEFI firmware reliably boots from, so the naive path, format FAT32 and copy the ISO contents, fails exactly on the newest installers, and the split, with the matching .swm references the Windows installer understands, is the standard workaround implemented so the user never sees it. Planned work extends the same idea to install.esd, the compressed system image format some Windows ISOs, usually repacks, use, where sometimes even a .esd file is too large to fit into FAT32. The split behavior being automatic rather than an option reflects the failure mode it prevents, a user who formatted FAT32 and hit the file size wall would otherwise need to understand the swm mechanism themselves, and the tool simply removes the decision. ## Compatibility tables, verified honestly Two tables state support with a verified column rather than promises. The Windows images table covers Windows 11 through Vista, x64 and x32 architectures, all verified for both UEFI and Legacy boot. The macOS table is the longer story, covering Tahoe 26.0 through Lion 10.7 and Snow Leopard 10.6, with architectures splitting at Catalina, x86_64 and ARM64 for the six newest releases and x86_64 only below, and the verification markers showing Tahoe verified with a separate build, the middle range verified, and Lion and Snow Leopard marked not yet, but it should work. The should-work honesty in a compatibility table is characteristic, distinguishing untested from unsupported, which is what a user choosing which Mac to run the tool on needs to know. The separate-build note for Tahoe also signals how the tool interacts with macOS changes, system API shifts between releases can force dedicated builds, and the verified column being per-version rather than per-family tells users which macOS they run the tool on matters as much as the Windows ISO they feed it. ## The fake-sites warning The README's most unusual element is a preformatted warning block at the top, this project only has a GitHub page, all other websites are fake, and this GitHub page is the only official place where you can download the software. The warning exists because download aggregator sites clone popular utilities, repackaging them with installers or adware, and a tool whose users are exactly the people searching for bootable USB creators on Mac is a prime target. The same section carries the financial support request through Buy Me a Coffee beside the download badges, and the project structure is minimal, the WinDiskWriter source directory, the Xcode project, the license and a single readme, a shape that makes the official repository the whole product. ## Planned changes, and what the tool is not The planned changes list names the roadmap, selecting individual partitions as destinations, choosing not only from whole disks but individual partitions of a USB drive or internal disk, and the install.esd splitting described above. What the tool does not attempt is equally clear from the feature set, it writes installer media rather than imaging arbitrary disks, it targets Windows ISOs specifically rather than general ISO burning, and it runs on macOS only, with no Windows or Linux version in the plans. The releases tell a slow and steady story, v1.1 in September 2023, v1.2 in December 2023 and v1.3 on 2024-01-07, each landing months apart, matching a utility whose feature set is small and whose failure modes, a bad USB write, are expensive enough to justify the measured pace. For evaluation, the source being C with an Xcode project means the tool is a native macOS application rather than a script around command line utilities, and the compiled artifact downloads directly from the repository releases without an installer or package manager step. ## Conclusion Use WinDiskWriter when the only machine available for preparing a Windows installer is a Mac, and when the target hardware needs the compatibility features, Legacy BIOS booting, EFI backports for Vista and 7, or Windows 11 requirement patches. It is not a Windows-side tool and does not run there. Before using, download only from the official GitHub repository, the project warns all other websites are fake, verify your macOS version against the compatibility table, noting Tahoe needs a separate build and Lion and Snow Leopard are not yet verified, and check the target machine's firmware mode to decide whether the Legacy support option matters. ## FAQ ### What does WinDiskWriter do? WinDiskWriter is a macOS application that creates bootable universal Windows installer USB drives supporting both UEFI and Legacy BIOS modes. It can patch Windows 11 installers to bypass TPM, RAM and Secure Boot requirements, add EFI boot support to Windows Vista and 7, and automatically split install.wim files larger than 4GB for FAT32. ### how to use windiskwriter? Download the app from the official GitHub releases page, open it on your Mac, select your Windows ISO and target USB drive, and choose options like Patch Installer Requirements for Windows 11 or Legacy BIOS support before writing. The resulting drive installs Windows on PCs, Intel Macs and certain virtual machines. ### is windiskwriter free? Yes, WinDiskWriter is free, open-source software licensed under GPL-3.0, with source code available in the repository and releases published on GitHub. The developer accepts voluntary donations through Buy Me a Coffee. ## Sources - [Issues](https://github.com/TechUnRestricted/WinDiskWriter/issues) - [License: GPL-3.0](https://github.com/TechUnRestricted/WinDiskWriter/blob/main/LICENSE) - [README](https://github.com/TechUnRestricted/WinDiskWriter/blob/main/README.md) - [Releases](https://github.com/TechUnRestricted/WinDiskWriter/releases) - [TechUnRestricted/WinDiskWriter on GitHub](https://github.com/TechUnRestricted/WinDiskWriter) --- Hysen Labs editorial analysis, written from the project's own repository and release notes. Cite the canonical page: https://hysenlabs.com/projects/techunrestricted-windiskwriter