The Java API's for WSDL are a standard set of APIs for representing and manipulating services described by WSDL (Web Services Description Language) documents. A client can treat the service descriptions in a uniform manner, regardless of the origin of the descriptions. That is, the descriptions can be built as a result of parsing a WSDL document, constructed programmatically by direct invocation of the APIs, built using information provided by a user via a command-line or graphical interface, or built using information retrieved from a network source.

WSDL4J is a reference implementation of the API.