vBulletin - Build a community website with the leading forum software, vBulletin 5 Connect, or in the cloud on vB Cloud!
Bloomerang - Bloomerang is a simple donor database and fundraising software solution that helps nonprofits decrease donor attrition and increase revenue.
Discourse - Discourse is an open source discussion platform built for the next decade of the Internet.
Kindful - Nonprofit donor database + fundraising tools all in one
XenForo - Intuitive. Social. Engaging. Fast. XenForo brings a fresh outlook to forum software.
Classy - Expressive, flexible, and powerful stylesheets for native iOS apps