ReactOS isn’t based on disassembly of the original Windows code. It’s based on publicly available documentation of Windows APIs (and reverse engineering those t

ReactOS isn’t based on disassembly of the original Windows code. It’s based on publicly available documentation of Windows APIs (and reverse engineering those that aren’t documented, but that’s a whole different beast from disassembling). In fact, ReactOS maintains a policy to prevent proprietary Windows source code (whether leaked or otherwise) from making its way to the ReactOS codebase [0]. When Windows source code leaked, in 2006, ReactOS did a complete codebase audit to ensure that it was not tainted. [0]: https://reactos.org/intellectual-property-guideline/ https://reactos.org/intellectual-property-guideline/