Most successful online marketplaces today are owned and operated by firms that are themselves traders in the marketplace. This raises significant concerns about the fairness of the information flow through the marketplace. In this paper, we propose a marketplace design that shifts the locus of control over trader privacy from the marketplace operator to each individual trader. We show how online transactions between trading partners can be conducted in total privacy, so that not even the marketplace owner/operator can exploit transaction information for strategic purposes. At the same time, our approach includes robust methods for transaction integrity and non-repudiation, as well as post-transaction dispute resolution.