A user of a client computer is authenticated for first and second applications executing in a server. The server authenticates the user for the first application based on a userID and password of the user, and the server returns a token of the authentication to the client computer. The client computer uses the token to request a first function performed by the first application. The user subsequently requests a second function performed by the second application. In response, the client computer determines that the user has not yet been authenticated for the second application and sends a request to the server for an authentication ticket for using the second application. In response to the request for the authentication ticket, the server checks the authentication token. If valid, the server returns an authentication ticket to the client computer. The client computer requests the second function to the server. The client computer request for the second function includes the authentication ticket. The server determines that the authentication ticket supplied with the client request is valid before the second application performs the second function.