A device, system, and method are directed towards managing and tracking of cross-domain user activities through use of a beacon. As a user of a client device requests content from different domain services managed by a common entity, they may receive a Uniform Resource Locator (URL) to a beacon in at least one of the different domains. In one embodiment, the beacon is a single pixel image. The client device may also receive a Match-ID. A beacon server in one of the other domains may receive the request for the beacon, and store in a domain log the Match-ID, and other information about the client device, which domain service provided the URL, and/or other related user activities. The different domain logs may then be employed for use in searching for matching Match-IDs, joining common user or client device activities, and for tracking other cross-domain user activities.