Magento

Magento is an open source ecommerce web application. It was created by Varien, building on components of the Zend Framework.

License: OSL
Written in: PHP
Operating system: Cross-platform

Website: http://www.magentocommerce.com/product/community-edition
Download: http://www.magentocommerce.com/download
Documents: http://www.magentocommerce.com/knowledge-base