WADL is an XML description of HTTP-based web applications such as RESTful web services. WADL was submitted to the World Wide Web Consortium (W3C) by Sun in 2009 but has not been standardized yet.

Similar to WSDL used for describing SOAP web services, WADL models the resources provided by a RESTful web service with relationships between the resources. It also allows you to clearly represent the media types used for the request and response contents.