OpenCart - A free shopping cart system. OpenCart is an open source PHP-based online e-commerce solution.s
1ShoppingCart - 1ShoppingCart is an online store software to build a secure eCommerce storefront.
Shopaccino - Best Ecommerce Platform to Create an Online Store
WooCommerce - A freely available eCommerce plugin that enables shop facilities on your WordPress website. Functionality enabling extensions & beautiful themes available.
3dcart - We provide ecommerce software, web design and inbound marketing services to help online businesses be more successful.
AbanteCart - Free, open source, shopping cart/ e-commerce platform.