There are provided systems and methods for cross-platform tracking of user generated data for unified data output. A computing device may be utilized to access an online platform and perform one or more processes, including viewing an online marketplace to purchase items in a transaction. The device may be used to browse items and items may be added to a digital shopping cart or other checkout process and interface. However, the device may not finish electronic transaction processing for the items and may abandon the digital cart on a first platform used by the user. When a user uses a second online platform to shop and generate another digital cart, a cross-platform process may retrieve the previously abandoned cart's data, and may generate output for display of the previous cart with the new cart in the second platform's user interface.