Maintaining session identifiers across multiple webpages for content selection

Abstract

Systems and methods for maintaining session identifiers across multiple webpages for content selection are described herein. A server can generate a session identifier corresponding to the client device for use in selecting content to be served across the information resources of a content publisher. The server can then receive, from the client device, a request for instructions to insert into a header of an information resource for selecting a content provider. The server can determine that the request includes the session identifier that matches the one generated for a previous request. The server can obtain a parameter value for each content provider with the session identifier. The server can select a content provider using the parameter values. The server can provide a script to the client device for the header. The script can be configured to cause the client device to obtain a content item from the selected content provider to insert into the information resource.