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.
Sitecake - Drag and drop CMS for HTML websites. It's flat file CMS so it's pretty fast.
Eventzilla - Eventzilla lets you sell tickets online and manage attendees from one integrated application.
ClassicPress - The WordPress fork. No Gutenberg. Great future!
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
TYPO3 - TYPO3.com - Infos, SLAs, Extended Support Versions and more
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.