When a dashboard reads data from a protected JSON endpoint, authentication headers can be attached in the onBeginProcessData event.

In React.
import { Viewer, Stimulsoft } from "stimulsoft-dashboards-js-react/viewer";

function App() {
    var report = new Stimulsoft.Report.StiReport();
    report.loadFile("Dashboards/OrdersUrl.mrt");

    report.onBeginProcessData = function (args) {
        if (args.database === "JSON" && args.command === "GetData") {
            args.headers.push({ key: "X-Auth-Token", value: "*YOUR TOKEN*" });
        }
    };

    var options = new Stimulsoft.Viewer.StiViewerOptions();
    options.appearance.fullScreenMode = true;

    return <Viewer options={options} report={report} />;
}

How it works. The engine sends the headers with its JSON fetch, so the dashboard can read endpoints behind token protection.