A DONE file is a marker file that indicates to a user that the file is complete and ready. It is commonly used in shared repositories to differentiate between files that should or should not be accessed by another user.

The ".done" file extension may be appended onto any type of file, such as a .TXT or .LOG file, and may be found on an FTP server where multiple have access to the file. The DONE file helps prevents a user from accessing a file that is not meant to be accessed. The ".done" extension should be removed in order to open the actual file.