Mobilizon - A free and federated tool to get our events off Facebook
Facebook Local - Discover places to go and events happening near you
Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
DownToMeet - DownToMeet is a platform to organize, find, and attend group events.
Openki - Platform where you can search, propose, take part, help organize or publish workshops, lectures...
Get Together - Get Together is an open source event manager for local communities.