1. A computer-implemented method comprising: receiving, by a content management system from a web server, an indication of receipt of a request received by the web server from a user device, the request being to navigate to a first web based resource, wherein the request includes an appended cookie when the appended cookie is available on the user device, the appended cookie having been loaded onto the user device based on a prior navigation request by the user device to the first web based resource; identifying, by the content management system, one or more partner web based resources that are in a co-operative that (i) includes the first web based resource, and (ii) specifies that the one or more partner web based resources have one or more data-sharing agreements with the first web based resource; responsive to the request for which the indication is received, providing, to the web server by the content management system, a code segment that is configured to send, to one or more respective entities associated with the one or more partner web based resources specified in the co-operative, a second request to share, according to the one or more data-sharing agreements, shared user data with the first web based resource, the shared user data collected by the one or more partner web based resources specified and being associated with the user device; receiving the shared user data directly from the one or more partner web based resources responsive to respective second requests that are generated when the code segment is executed at a time of rendering the first web based resource; and using the shared user data to re-market content to a user.