Safeguard Scientifics, Inc. (NYSE:SFE) led a $3.35 million Series C financing round for Swaptree.com, an internet-based service that leverages a proprietary trading technology to enable users to swap books, CDs, DVDs and video games for free.

Based in Boston, MA, Swaptree.com will use the proceeds of the financing round for continued technological and operational development, marketing support and senior management recruitment.

With over 100,000 trades completed since its public launch in July 2007, the Swaptree.com website allows consumers to obtain items in a way that is cost-effective, friendly to the environment, and rooted in the basic notion of sharing. Unlike auction sites, classified ad services, or other e-commerce sites which sell used items, Swaptree.com is completely free, and doesn’t involve buying or selling.

After signing up for the service, consumers simply add items they would like to trade to their “have list”, and put items they would like to receive on their “want list.” Swaptree’s trading engine then instantly shows the user all the items they can receive in return for the items they are trading. The only expense members incur is the cost of shipping, for which labels can be purchased and printed directly from the Swaptree website.

“Swaptree has built a defensible technology platform that enables multi-way trading, and is well positioned to tap into the millions of users who purchase items such as books, CDs, DVDs and video games online,” said Peter J. Boni, President and CEO of Safeguard.

By the end of the year, Swaptree will have a million items listed for trade, making it easy for users to use the website to discover new authors, musicians, films, and games for free.