pretix - Ticketing software that cares about your event—all the way

nebulon

Apparently, the only open-source self-hosted software of its type!

Focus on privacy and security
Full multi-language capabilities
Highly adaptable to your event
Extensible with plug-ins and through a REST API
Successfully used for conferences, festivals, concerts, shows, exhibitions, workshops, barcamps, and more

pretix – Reinventing ticket sales for conferences, festivals, exhibitions, ...
https://pretix.eu/