To make a trusted web service call, a client application sends a series of messages to obtain tokens that allow service requests to pass through a service relay. The user obtains a first security token by providing the user's credentials. A second token is obtained from a trust broker that validates the first token. Both tokens are then sent with a service request to a service relay. The service relay validates the second token and then passes the first token and the service request to a connector service. The connector service validates the first token and passes the service request to a target back end service. The connector service acts as the user when communicating with the back end service. Service responses are routed back to the user through the connector service and the service relay.