Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Iventlist - Create an app for your event in minutes 🎟️
Nvite - The world's first attendee focused events platform.
pretix - pretix helps you to sell tickets for your event in an easy way. It supports multi-lingual events and provides a wide range of features
Meetup for iOS and Android - Discover groups that are all about the things you love