Abstract: An online marketplace for commerce between multiple buyers and multiple suppliers. The marketplace includes hosted supplier stores opened, managed and maintained by individual registered suppliers. The suppliers upload supplier catalog information to the hosted supplier stores. The marketplace also includes a supplier hub, or general open market, where registered buyers can browse an aggregated catalog made up from an aggregation of the supplier catalogs from the hosted supplier stores. The marketplace administrator may define a catalog topology based upon which the suppliers may structure their own supplier catalogs, thereby easing aggregation of the supplier catalogs into the aggregated catalog. The marketplace also includes trading mechanisms for conducting online ordering, purchasing, requests for quotations, and negotiations.