Header bidding systems and methods increase a number of advertisers that can place bids for an advertising impression while maintaining low latency in loading of the webpage. The systems and methods utilize a specialized control wrapper in the header to manage one or more additional wrappers so as to allow for simultaneous bid collection from multiple groups of advertisers, one group per wrapper, without experiencing the traditional increase in latency of page loading as the number of entities bidding on an impression increases. Each wrapper contains information relating to a separate subset of advertisers from which to receive bids for the advertising impression. The control wrapper, as part of the header of the webpage, controls synchronization and timing of the separate bid processes controlled by the various wrappers to ensure that latency issues are avoided while the number of bids received is increased and revenue maximized.