Zen Cart™ is an open source online store management system. It is PHP-based, using a MySQL database and HTML components. Providing support for many languages and currencies, it is available for free under the GNU General Public License.
Zen Cart™ branched from osCommerce as a separate project. Beyond some aesthetic changes, the major differences between the two systems come from Zen Cart's long list of added features. Among the modules included are a Gift Certificate/Voucher module which allows you to create, send and manage the digital coupons. The Downloads Manager enables you to effectively manage downloadable sales (pdf or other media files). Attribute configuration options in the Download module allows you to configure how many days the download is available for and how many downloads per purchaser.