osCommerce Online Merchant System is a free, open source e-commerce software platform that is available for use under the GNU General Public License. It offers a full set of shopping cart functions straight out of the box. Web site merchants can set up and maintain online storefronts with no hidden costs or fees and with very little effort or technical know how.

Over 168,400 online merchants use osCommerce to power their stores. Over 4500 add-ons and extensions increase osCommerce\'s functionality and flexibility. OsCommerce is scripted using PHP and is compatible with all major web browsers including Firefox, Opera, Safari and Internet Explorer.

OsCommerce supports multiple languages as well as multiple currencies. Secure transactions are supported with Secure Socket Layers. There are also a large number of shipping calculation options,including calculations based on product destination, price or weight. Users can also get real time shipping quotes from UPS and USPS.

Design templates do not come as part of the osCommerce package, but there are many third party template solutions available. The lack of a template system means that each web master can develop and implement a custom template to match the rest of an e-commerce web site.