Now UI Kit - A beautiful Bootstrap 4 UI kit. Yours free.
Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.
Bots UI Kit - Fully customizable Sketch UI Kit for Messenger Platform
DownToMeet - DownToMeet is a platform to organize, find, and attend group events.
Landing UI Kit - Handcrafted UI components for landing pages
Mighty Networks - Mighty Networks enables entrepreneurs, organizations, and companies to create and grow a community-powered brand.