Appnexus Seller (Xandr Supply)

AppNexus Seller (the supply-side component of the Xandr/Microsoft stack) is a heavily armored, deeply entrenched veteran titan that mathematically defined modern programmatic advertising infrastructure. It engineered the foundational RTB auction technology that the entire programmatic industry is built upon. It is the absolute weapon of choice for technically sophisticated publisher ad ops teams who mathematically demand granular, API-level control over every single auction parameter in their programmatic waterfall.