Gumroad - An all-in-one solution to sell your work and grow your audience.
OpenCart - A free shopping cart system. OpenCart is an open source PHP-based online e-commerce solution.s
Payhip - Sell digital downloads, courses, coaching, and more from one simple platform.
PayKickstart - PayKickstart is the ultimate shopping cart and affiliate management platform, empowering online Entrepreneurs and digital publishers with the tools to sell their products online.
robora - Robora is a service which aims to help you sell anything, anyway you like.
WooCommerce - A freely available eCommerce plugin that enables shop facilities on your WordPress website. Functionality enabling extensions & beautiful themes available.