OpenCart - A free shopping cart system. OpenCart is an open source PHP-based online e-commerce solution.s
Paperform - A digital Swiss Army Knife for Small Businesses
EvenCart - EvenCart is an open source hybrid/headless eCommerce software built on top of ASP.NET Core and Shopify Liquid.
Maian Music - Free Responsive PHP MP3 Music Store
WooCommerce - A freely available eCommerce plugin that enables shop facilities on your WordPress website. Functionality enabling extensions & beautiful themes available.
nopCommerce - nopCommerce is the open-source eCommerce solution. nopCommerce is available for free. It has everything you need to get started in selling physical and digital goods over the internet.