Systems and methods for authenticating applications that access web services. In one embodiment, a web service gateway intercepts a request for a web service from an application, and determines if the application is authorized by a service provider based on information provided in the web service request. If the application is authorized, then the web service gateway identifies a profile for an end user that initiated the web service using the application, and determines if the web service is allowed for the end user based on the profile. If the web service is allowed for the end user, then the web service gateway determines that the application is authenticated, converts the web service request to a protocol used by a server that provides the web service, and transmits the web service request to the server.