Blacklight - Blacklight is a free and open source ruby-on-rails based discovery interface (a.k.a.
DSpace - DSpace open source software enables open sharing of content that spans organizations, continents...
OpenBiblio - It is an easy to use, automated library system written in PHP containing OPAC, circulation...
Invenio - Invenio is a free, open-source software to run a digital library or document repository on the web.
Primo - Like Amazon's 1-click shopping--but for everything
Koha - Koha is the first free and open source software library automation package (ILS).