Here are a list o 9 Open Source Tools for Building E-Commerce Sites:
Zen Cart E-Commerce Shopping Cart: This is a PHP based e-commerce shopping cart built on OScommerce’s GPL code. It’s easy to setup, highly customizable, and can be run from your own webserver, thereby giving you full in control over its features and capabilities.
Symphero: This one runs on Linux and other Unixlike OSs, supports multiple databases (MySQL and PostgreSQL), distributed object storage (in beta), marketing and affiliate tracking capabilities.
XOS-Shop E-Commerce Shopping Cart: This is an open source shopping cart software, written in PHP/MySQL, and originally based on osCommerce.
PrestaShop: A robust, professional-grade e-Commerce solution with a full-featured back-office application to manage your online business, which includes inventory, orders, shipping, and customers--all in real-time.
VirtueMart: An Open Source E-Commerce solution to be used along with the famous CMS Joomla.
Axis 0.8.7.2: A popular e-commerce tool based on PHP, MySQL, ExtJS, jQuery and the Zend PHP framework. It has features like a product catalog manager, products organizer, order management, customer mgmt, discounts mgmt, store statistics, and much more.
CF Shopkart 5.5 build 006: Here’s a shopping cart utility for the ColdFusion development stack, which is currently inactive, but mature enough to be used for online stores today. A few key features of the software include mgmt. modules for products, categories, customers, orders, wishlists, support tickets, taxes, and payment gateways. Plus, there are modules for blogging, statistics, comment moderation, product reviews, and much more.
Magento Community Edition 18.104.22.168 / 22.214.171.124 Alpha 1: Create advanced stores in just a few clicks. Spend more time entering product information instead of customizing HTML code. There’s an easy to use Permissions Editor so that you can create users for all your employees and then assign them to groups like “Full Admin”, “Customer Service”, “Warehouse”, etc.
VamCart 0.9: This software allows users to easily install and run an online shop, without any technical knowledge. Built on CakePHP framework, the software provides SEO, unlimited categories and products, Multilingual and Multi currency support, automatic image resizing, coupons, product reviews, and much more.