A system for detecting user-initiated events within a second mobile application without modifying code of the second mobile application, the system comprising: one or more front-end servers that: receive, from a mobile application management application installed on a client device P of a user, interaction data specifying (i) a user interaction identifier for a user interaction with an interactive item that presents, at a first mobile application, content for said second mobile application installed on the client device and (ii) an interactive item identifier that was submitted to the mobile application management application by the second mobile application in response to the user interaction with the interactive item; store, in a data storage device, a data entry that links the interactive item identifier to the user interaction identifier based on the receipt of the interaction data; and receive, from the mobile application management application, event data specifying (i) an occurrence of specified user action within the second mobile application after the user interaction with the interactive item and (ii) the interactive identifier for the interactive item; and one or more back-end servers that: determine that the specified user action resulted from the user interaction with the interactive item based on a match between the interactive item identifier specified by the event data and the interactive item identifier that links to the user interaction identifier for the user interaction with the interactive item in the data storage device being detected; and provide, to the one or more front-end servers, data indicating that the specified user action resulted from the user interaction with the interactive item, wherein the one or more front-end servers update a user interface to indicate that the specified user action resulted from the user interaction with the interactive item. one or more front-end servers that: receive, from a mobile application management application installed on a client device P of a user, interaction data specifying (i) a user interaction identifier for a user interaction with an interactive item that presents, at a first mobile application, content for said second mobile application installed on the client device and (ii) an interactive item identifier that was submitted to the mobile application management application by the second mobile application in response to the user interaction with the interactive item; store, in a data storage device, a data entry that links the interactive item identifier to the user interaction identifier based on the receipt of the interaction data; and receive, from the mobile application management application, event data specifying (i) an occurrence of specified user action within the second mobile application after the user interaction with the interactive item and (ii) the interactive identifier for the interactive item; and receive, from a mobile application management application installed on a client device P of a user, interaction data specifying (i) a user interaction identifier for a user interaction with an interactive item that presents, at a first mobile application, content for said second mobile application installed on the client device and (ii) an interactive item identifier that was submitted to the mobile application management application by the second mobile application in response to the user interaction with the interactive item; store, in a data storage device, a data entry that links the interactive item identifier to the user interaction identifier based on the receipt of the interaction data; and receive, from the mobile application management application, event data specifying (i) an occurrence of specified user action within the second mobile application after the user interaction with the interactive item and (ii) the interactive identifier for the interactive item; and one or more back-end servers that: determine that the specified user action resulted from the user interaction with the interactive item based on a match between the interactive item identifier specified by the event data and the interactive item identifier that links to the user interaction identifier for the user interaction with the interactive item in the data storage device being detected; and provide, to the one or more front-end servers, data indicating that the specified user action resulted from the user interaction with the interactive item, wherein the one or more front-end servers update a user interface to indicate that the specified user action resulted from the user interaction with the interactive item. determine that the specified user action resulted from the user interaction with the interactive item based on a match between the interactive item identifier specified by the event data and the interactive item identifier that links to the user interaction identifier for the user interaction with the interactive item in the data storage device being detected; and provide, to the one or more front-end servers, data indicating that the specified user action resulted from the user interaction with the interactive item, wherein the one or more front-end servers update a user interface to indicate that the specified user action resulted from the user interaction with the interactive item.