MirOS is based on 4.4BSD-Lite (mostly OpenBSD, some NetBSD®). The MirPorts Framework is a portable ports tree to facilitate the installation of additional software. The project also releases some portable software: mksh, a pdksh-based shell; PaxMirabilis, an archiver for various formats; MirMake, a framework for building software; MirNroff, an AT&T nroff based man page (and text document) formatter; MirCksum, a flexible checksumming and hash generation tool; and some more.