Credential and authentication management in scalable data networks is described, including detecting a request from an extension installed on a browser to access a data network, initiating another request from the extension to a server to retrieve authentication data to access the data network, transferring from the server to the extension the authentication data and an instruction to the extension to generate a further request, transmitting the further request to the data network from the browser, the request comprising the authentication data from the server without manual input of the authentication data, presenting an overlay on the browser, the overlay being configured to indicate a login status associated with the data network, and monitoring a cookie and data transferred between the data network and the browser at an application layer or data layer after access to the data network has been provided to the browser in response to the request.