osCMax is a powerful and flexible e-commerce shopping cart and inventory tracking system. osCMax is free and 100% customizable to your needs and supports all the major payment gateways: Authorize.net, LinkPoint, Paypal, 2Checkout to name a few. All major shippers are supported: FedX, UPS, USPS, and custom. Also fully supported are virtual products, such as downloads, gift vouchers/coupons. osCMax has all the features you would expect in a commercial shopping cart that would normally cost hundreds or thousands of dollars, but osCMax is absolutely free.
Thousands of sites run osCMax already, from small startup sites, to extremely high volume established companies.