For hosting common files it's ok. Also it is on Android too do, great to transfer files between your Windows and your phone. But if you want better security you have to subscribe a monthly offer.
Dropbox - Online Sync and File Sharing
Invenio - Invenio is a free, open-source software to run a digital library or document repository on the web.
Google Drive - Access and sync your files anywhere
Greenstone Digital Library - Greenstone is a suite of software tools for building and distributing digital library collections...
Mega - Secure File Storage and collaboration
Koha - Koha is the first free and open source software library automation package (ILS).