macFuse
FUSE extends macOS by adding support for user space file systems
... across the network, from memory, or any other combination of sources. Writing a file system using FUSE is orders of magnitude easier and quicker than the traditional approach of writing in-kernel file systems. Since FUSE file systems are regular applications (as opposed to kernel extensions), you have just as much flexibility and choice in programming tools, debuggers, and libraries as you have if you were developing standard macOS applications.