Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Higher Logic - Private, secure online communities that stimulate conversation and ignite engagement.
Event Hunt - Startups and Tech Events Curated By Locals
Tribe.so - Tribe is a white-label platform, empowering the new generation of online communities.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Discourse - Discourse is an open source discussion platform built for the next decade of the Internet.