Web Services. Web API. Web services are a type of API, which must be accessed through a network connection. APIs are application interfaces, implying that one application can communicate with another application in a standardized manner. Web service is used for REST, SOAP and XML-RPC for communication. Web API is a programming interface/application type that provides communication or interaction between software applications. Web API is often used to provide an interface for web sites and client applications to have data access. Web APIs can be used to access data from a database and save data back to the database.