Privately owned and funded TradeComet, formed by former executives from B2B search directory ThomasB2B.com, have launched a new supplier directory at SourceTool.com, which contains 12.5 million unique business terms related to products and services from approximately half a million companies, writes ClickZ. Businesses are listed for free in the online directory, which is supported with contextual ads.

The decision to display contextual ads on Sourcetool is a shift from the model that other online B2B directories use. TradeComet is also promoting SourceTool with a CPC campaign on major search engines.

SourceTool uses the United Nations Standard Products and Services Code (UNSPSC) global classification system and asks marketers who want to be listed to list their products by UNSPSC but will nevertheless index companies that don't, though they'll receive lower rankings.