Regpack is an online payment software that allows businesses to collect and manage client data and payments from a secure back end dashboard. Email communication, integrated payments, recurring billing, reporting, and analytics are built-in. Regpack makes it easy to manage and charge clients securely with your team and embeds on your website for a seamless process.
Eventzilla - Eventzilla lets you sell tickets online and manage attendees from one integrated application.
4D - 4D is a relational database management system and IDE.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
LiveCode Platform - It is Both Under the GPL and it is also Proprietary if using the GPL version the software you make...
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.
ESM Tools - ESM Tools is a powerful and widely known software development platform that comes with a centralized model infrastructure, providing the common frame for compiling, running, downloading, and organizing models (ones or multiple).