Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
attending.io - Tiny event pages to ask people one question – are you attending? Twitter login.
Cvent - Cvent's event management software provides event planners with a complete solution to increase event attendance and decrease event costs.
Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform
Ticket Tailor - Ticket Tailor is an easy-to-use event ticketing platform that allows event organizers of all shapes and sizes to sell tickets online.
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