MacFUSE implements a mechanism that makes it possible to implement a fully functional file system in a user-space program on Mac OS X (10.4 and above). It aims to be API-compliant with the FUSE (File-system in USErspace) mechanism that originated on Linux. Therefore, many existing FUSE file systems become readily usable on Mac OS X. The core of MacFUSE is in a dynamically loadable kernel extension.

Although MacFUSE has a completely different kernel-level implementation from Linux FUSE, it supports the FUSE specification well enough that many popular FUSE file systems can be easily compiled and work on Mac OS X--often out of the box.