Abstract: Described herein are systems and methods for redirecting to track user identifiers across web sessions and websites. A web browser may receive a first webpage requested by a user of the client. The first webpage may be referenced by a first address including a domain name of the website host and may include a linkage script. The linkage script may be provided by a tracking service and may specify retrieval of a second webpage of the website host. The web browser may determine whether a user identifier of the tracking service is associated with a cookie of the website host. The web browser may identify a second address including at least a portion of the domain name. The web browser may transmit a request for the second webpage of the website host including the second address. The web browser may receive the second webpage for display.