Senatus - Upvote for questions around a given topic.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Sli.do - Slido is the ultimate Q&A and polling platform for live and virtual meetings and events. It offers interactive Q&A, live polls and insights about your audience.
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
LiveQ - LiveQ is an interactive presentation software that lets audience can ask & vote questions anonymously. You can collect the best questions that you should answer. Loved by teachers, speakers, event owners.
Ticket Tribe - Sell tickets online with no fees per ticket