OpenCart - A free shopping cart system. OpenCart is an open source PHP-based online e-commerce solution.s
AbanteCart - Free, open source, shopping cart/ e-commerce platform.
Gumroad - An all-in-one solution to sell your work and grow your audience.
Zen Cart - Zen Cart
Sellfy - Sellfy is an easy to use but powerful e-commerce platform where you can sell digital, print on demand or subscription products. Use a Sellfy storefront to create a beautiful online store or embed a Sellfy shopping cart to your own website.
PrestaShop - Create your online store with PrestaShop's free shopping cart software. Build an ecommerce website for free and start selling online with hundreds of powerful features.