WooCommerce - A freely available eCommerce plugin that enables shop facilities on your WordPress website. Functionality enabling extensions & beautiful themes available.
Shoppy - Automatically get order notifications & summaries in Slack
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.
Sell.app - Sell.app is the easiest way to sell digital products online. Spin up your own storefront in just a few minutes and start selling instantly.
OpenCart - A free shopping cart system. OpenCart is an open source PHP-based online e-commerce solution.s
Thirty Bees - Open e-commerce platform designed to work out of the box.