AlegroCart is an opensource e-commerce solution based on the final version of Opencart with many modifications and enhancements. (GPL)

dashCommerce is an ASP.NET Open Source e-Commerce Application. (MIT)

Freeway is an advanced Open Source eCommerce platform which can sell using methods only previously available in enterprise class or niche bespoke systems. (GPL)

Magento is a feature-rich, professional open-source eCommerce solution offering merchants complete flexibility and control over the look, content, and functionality of their online store. (GPL)

OpenCart is a robust e-commerce solution for Internet merchants with the ability to create their own online business and participate in e-commerce at a minimal cost. (LGPL)

osCommerce is an online shop e-commerce solution that offers a wide range of out-of-the-box features. (GPL)

Ubercart is an exciting open source e-commerce package that fully integrates your online store with Drupal. (GPL)

VirtueMart is an Open Source eCommerce solution to be used together with Joomla! or Mambo. (GPL)

xt:Commerce is developed as a powerful ecommerce webcart shop system for small, medium and full-sized merchants as well as wholesalers. (GPL)

Zen Cart is a PHP e-commerce shopping program. Built on a foundation of OScommerce GPL code, it provides an easy-to-setup and run online store. (GPL)