Puffin for Facebook - Puffin for Facebook is a special edition of https://alternativeto.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Frost for Facebook - Frost is a third party Facebook wrapper geared towards design and functionality
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
Friendly for Facebook - Friendly is the most complete Facebook Lite and FB Messenger alternative.
Ticket Tribe - Sell tickets online with no fees per ticket