Note: This document supports a set of APIs for older integrations.
PubMatic's RTB API enables ad networks, demand side platforms, and other inventory buyers (collectively "Demand Partners") to bid dynamically for each advertising impression, as it is served to users in real time. The process by which these advertising impressions are delivered through RTB works as follows:
Ad impression request comes to PubMatic from the user's browser.
PubMatic applies any pre-filters that have been requested by the Demand Partner. More on this can be found in the "Pre-Filtering / Targeted Impressions" section of this document.
PubMatic would make real-time API calls to matching Demand Partners giving all the details about the impression. These details are called "Data Parameters" in this document. You can find out more about them on pages 9-10.
Demand Partner uses the API request Data Parameters to determine the best available advertisement for that inventory and sends back the bid value to PubMatic as an API response.
PubMatic's technology performs an auction among the RTB bids, and other campaigns in the PubMatic platform that are eligible for the advertising impression and determines the winning bid by choosing the bid representing the highest CPM for that impression.
If the RTB Demand Partner wins the impression, PubMatic sends the winning ad URL to the user's browser.
The user's browser then directly draws down the winning Advertiser creative.