HelpScout - Help Scout is a simple, straightforward way to provide excellent support

DSpace - DSpace open source software enables open sharing of content that spans organizations, continents...

Zendesk - Zendesk is a beautiful, lightweight help-desk solution.

Invenio - Invenio is a free, open-source software to run a digital library or document repository on the web.

Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community

Evergreen ILS - Evergreen - Open Source Library Software