Header Bidding: Why can’t header bidding be done server side?
What’s the reason all header bidding implementations are client side, can’t the same be achieved server side? So instead of a waterfall do an auction by getting pre bids from all the demand partners? What would be the down side to that?

This question was asked on Quora, below is my answer.

Header bidding is designed to expose the clearing price of exchange and SSP auctions so that a publisher’s technology can make an informed decision about which ad to serve. These prices are pitted against each other as well as the publisher’s demand from their primary ad server, usually Doubleclick.

In a perfect world all of this would be done on the server side. The primary benefits would be reduced payload size and lower latency in the browser. It’s not likely to happen, however. It would require SSPs, exchanges and ad servers to figure out how to work with each other in a server-to-server relationship. These companies tend to be competitors; count that as a business reason that will prevent a server side solution. Read more