Sitecake - Drag and drop CMS for HTML websites. It's flat file CMS so it's pretty fast.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
ClassicPress - The WordPress fork. No Gutenberg. Great future!
Splash - Anyone can create a Splash event, whether you're a company hosting a single event or an individual hosting a personal event like a birthday or wedding. Get Started for Free. Text goes here. X. Full Event Program.
TYPO3 - TYPO3.com - Infos, SLAs, Extended Support Versions and more
Eventzilla - Eventzilla lets you sell tickets online and manage attendees from one integrated application.