TinyCat - The online catalog and integrated library system for tiny libraries, powered by LibraryThing.
Get Shit Done - Free Bootstrap 3 UI kit
DSpace - DSpace open source software enables open sharing of content that spans organizations, continents...
NOW UI kit by InVision - A beautiful cross-platform UI kit (PSD & Sketch)
Invenio - Invenio is a free, open-source software to run a digital library or document repository on the web.
Spaces by proto.io - A community to showcase your interactive prototypes