Definition & Explanation

A reseller is a third party authorized to sell another publisher’s inventory — too many resellers can lead to transparency issues. In programmatic advertising, resellers are intermediaries that aggregate publisher inventory and submit bids on behalf of buyers to platforms that control the final ad-serving decision. They are typically listed in a publisher’s ads.txt file and may offer specialized ad formats, video content, or unique technology, but excessive reselling can obscure the supply chain and inflate costs.