Pathwright - Teaching platform where educators, trainers and others can easily create online courses.

Eventbrite - Discover Great Events or Create Your Own & Sell Tickets

Guidable - Create and sell guided programs to your followers.

Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform

aria2 - aria2 is a lightweight multi-protocol & multi-source command-line download utility. It supports HTTP/HTTPS, FTP, SFTP, BitTorrent and Metalink.

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