Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.

Followup.cc - FollowUp for email is a lightweight productivity suite that keeps your conversations and tasks from slipping through the cracks. Set perfectly timed reminders that arrive at the top of your inbox, right when you need them.

DownToMeet - DownToMeet is a platform to organize, find, and attend group events.

Gmelius - Gmelius is the first collaboration platform designed for G Suite and your company's daily tools.

Mighty Networks - Mighty Networks enables entrepreneurs, organizations, and companies to create and grow a community-powered brand.

Boomerang for Outlook - Boomerang for Outlook offers email productivity tools to track, schedule and send mails at the right time.