A method for single sign-on with established federation includes triggering a single sign-on operation from a first service to a second service, retrieving, by the first service, an associated federation key and pseudo identification for a user agent, generating, by the first service, a token signed with a federation key for the user agent based on the pseudo identification, redirecting, by the first service, the user agent to the second service, wherein the user agent transfers the token to the second service, verifying, by the second service, the token and determining an associated identification in the second service, and returning, by the second service, a resource to the user agent.