A mobile device for populating application-specific information using overlay applications through transmissions of application programming interface, API, requests to remote sources across a computer network, the mobile device comprising: memory configured to store a first application and a second application; control circuitry configured to: generate for display, on the mobile device, an application overlay, corresponding to the first application, wherein the application overlay overlays a user interface generated by the second application; receive a user input selecting the application overlay while the user interface is displayed; in response to the user input: identify the second application; and determine whether a field currently displayed in the user interface corresponds to a predetermined field that is automatically populated by the first application by: determining a conceptual data model for the second application, wherein the conceptual data model includes semantic information; and determining the field based on the conceptual data model; transmit, to a remote source, an API for supplemental content for populating the field, wherein the supplemental content is selected from available supplemental content based on the second application and the field in response to determining that the field corresponds to a predetermined field; receive, from the remote source, the supplemental content, wherein the supplemental content is virtual account number for a service provider; and input/output circuitry configured to populate, on a display screen, the field in the second application with the supplemental content. memory configured to store a first application and a second application; control circuitry configured to: generate for display, on the mobile device, an application overlay, corresponding to the first application, wherein the application overlay overlays a user interface generated by the second application; receive a user input selecting the application overlay while the user interface is displayed; in response to the user input: identify the second application; and determine whether a field currently displayed in the user interface corresponds to a predetermined field that is automatically populated by the first application by: determining a conceptual data model for the second application, wherein the conceptual data model includes semantic information; and determining the field based on the conceptual data model; transmit, to a remote source, an API for supplemental content for populating the field, wherein the supplemental content is selected from available supplemental content based on the second application and the field in response to determining that the field corresponds to a predetermined field; receive, from the remote source, the supplemental content, wherein the supplemental content is virtual account number for a service provider; and generate for display, on the mobile device, an application overlay, corresponding to the first application, wherein the application overlay overlays a user interface generated by the second application; receive a user input selecting the application overlay while the user interface is displayed; in response to the user input: identify the second application; and determine whether a field currently displayed in the user interface corresponds to a predetermined field that is automatically populated by the first application by: determining a conceptual data model for the second application, wherein the conceptual data model includes semantic information; and determining the field based on the conceptual data model; identify the second application; and determine whether a field currently displayed in the user interface corresponds to a predetermined field that is automatically populated by the first application by: determining a conceptual data model for the second application, wherein the conceptual data model includes semantic information; and determining the field based on the conceptual data model; determining a conceptual data model for the second application, wherein the conceptual data model includes semantic information; and determining the field based on the conceptual data model; transmit, to a remote source, an API for supplemental content for populating the field, wherein the supplemental content is selected from available supplemental content based on the second application and the field in response to determining that the field corresponds to a predetermined field; receive, from the remote source, the supplemental content, wherein the supplemental content is virtual account number for a service provider; and input/output circuitry configured to populate, on a display screen, the field in the second application with the supplemental content.