FUSE (Filesystem in USErspace) implements a file system that is serviced by a userspace program.

The FUSE module has been worked on by several people:

• CsabaHenk, for Google Summer of Code 2007 (“fuse4bsd”) - start of the port, unstable code
• IlyaPutsikau, for Google Summer of Code 2011 - continued the port by rebasing from macfuse, unfinished project (SOC2011IlyaPutsikau)
• AttilioRao and GeorgeNevilleNeil finished Ilya's GSoC project and imported it into the base system in 2012.
• AlanSomers overhauled the driver and added a test suite in 2019, sponsored by the FreeBSD Foundation.

As of 31-July-2019, the module implements version 7.23 of the FUSE protocol, with a few unimplemented features:

• FUSE_IOCTL
• BATCH_FORGET
• flock(2) (implemented in-kernel, so it doesn't work for networked file systems)
• posix_fallocate(2)
• FUSE_AUTO_INVAL_DATA
• FUSE_READDIRPLUS
• poll(2) (works for pipes and sockets, but not for regular files)
• FUSE_ASYNC_DIO
• FUSE_NO_OPEN_SUPPORT

• libfuse GitHub repository –Library used by many, but not all, FUSE file systems