Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
QR Code Generator For Developers - A quick API to generate QR codes in your apps
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
Link to QR - Free beautiful QR codes
Ticket Tribe - Sell tickets online with no fees per ticket
VisualCode - QR codes for everything