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.
Codefield - Tools for developers, designers and photographers
Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform
LaunchKit - Open Source - A popular suite of developer tools, now 100% open source.
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
GitHub - Originally founded as a project to simplify sharing code, GitHub has grown into an application used by over a million people to store over two million code repositories, making GitHub the largest code host in the world.