macFuse
FUSE extends macOS by adding support for user space file systems
...As a user, installing the macFUSE software package will let you use any third-party FUSE file system. Legacy MacFUSE file systems are supported through the optional MacFUSE compatibility layer. As a developer, you can use the FUSE SDK to write numerous types of new file systems as regular user space programs. The content of these file systems can come from anywhere: from the local disk, from 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. ...