Proxied multi-factor authentication using credential and authentication management in scalable data networks is described, including initiating a request by an extension to authenticate a browser to access a data network, the request being associated with an address and transmitted over HTTP, receiving at a proxy browser a first message from the data network in response to the request, the first message comprising authentication data, the authentication data being forwarded to a server in data communication with the proxy browser and the browser, sending a second message from the server to the extension, the second message comprising the authentication data, and transferring authentication data to the data network from the browser and the extension in response to an query from the data network.