CrossDeviceTracking

Cross-device tracking is a set of methods and technologies that link user activity across multiple devices to form a single, coherent view of an individual’s interactions with apps, websites, and services. Its goal is to enable attribution, targeting, and measurement that span smartphones, tablets, desktops, and other connected devices.

There are two main approaches. Deterministic tracking uses user-provided identifiers that persist across devices, such as accounts or sign-ins, to directly couple devices to one user. Probabilistic tracking relies on signals like device IDs, cookies or app IDs, IP address, device characteristics, timing, location, and behavioral patterns to infer that two devices belong to the same person. An identity graph or resolution system combines these signals to maintain a cross-device user profile, often in near real time.

Data sources for cross-device tracking include login data from apps and services, customer relationship management systems, website analytics, advertising IDs (on mobile), cookies, IP geolocation, and offline data. Accuracy can vary due to device churn, shared devices, and privacy restrictions. Privacy-preserving techniques, such as on-device processing and aggregated or de-identified data, are increasingly used to mitigate risks while preserving useful insights.

Applications span advertising attribution across devices, cross-device conversion measurement, frequency capping, audience deduplication, and omnichannel analytics that inform marketing and product decisions. Challenges include fragmentation of identifiers, evolving consent regimes, and tighter restrictions on third-party data. Regulatory frameworks in regions like the EU and California, along with industry standards and privacy-by-design practices, influence how cross-device tracking is implemented and governed.