FreeNAS is a free and open-source network-attached storage (NAS) software based on FreeBSD and the OpenZFS file system.

NAS4Free is a network-attached storage (NAS) server software with a dedicated management web interface (written in PHP).

unRAID Server is a partition management software.

OpenMediaVault (OMV) is a free Linux distribution designed for network-attached storage (NAS).

Amahi Home Server is a free and open-source home server software that's based on Fedora Linux.