GmailFS is a virtual file system originally developed by Richard Jones that uses a Gmail e-mail account for storage. GmailFS is written for Linux, but Windows and Mac OS X ports exist too. It originally was based on underlying SMTP and POP3 interation with gmail. Since 2010 a fork exists that uses IMAP.

It works by building a filesystem with the Filesystem in Userspace loadable kernel module, and manages communication with Gmail through a special purpose Python library called libgmail. The actual GmailFS is also implemented in Python.