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X# (X Sharp)

Build status

Build status

X# is a HLA (High Level Assembler) for X86/X64 assembly. In the future other flavors for ARM and other processors are planned.

X# is integrated into Visual Studio and we are working on support for Visual Studio Code as well. X# can also be used using simple text editors such as notepad.

X# creates NASM style assembly ready to assemble with NASM.

More Info

Please refer to our documentation (


Currently X# is used by the C# Open Source Managed Operating System (COSMOS) and parts of it are bound to Cosmos. We are in the process of and nearly finished separating out X# to allow it to operate as a stand alone project to allow users to make their own custom creations using X#.

We have physicallly separated out X# and checked it in here. However there are still a few hard coded links to Cosmos and there is no independent documentation yet, nor are there standalone samples. We are working all of these issues.