Link to QR - Free beautiful QR codes
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Selfie Ticket - Replacing QR codes with selfies for events
Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform
Tickey - Buy tickets for public transport with your smartphone
Ticket Tribe - Sell tickets online with no fees per ticket