OpenCart is an open source PHP-based online shopping cart system. 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.
OpenCart is designed feature rich, easy to use, search engine friendly and with a visually appealing interface.
You can download the latest version here.
You can discuss the v0.7 release here.
You can download the older PHP4 version here.