Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform
Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Iventlist - Create an app for your event in minutes 🎟️
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
sched - Event management software
Bigtent - BigTent is a web-based organization and communication portal for groups.