Web Application Description Language (WADL) je strojově čitelný popis XML pro webové aplikace HTTP (typicky webové služby REST ). Analog WSDL pro SOAP.
WADL modeluje zdroje poskytované službou a vztahy mezi nimi. WADL byl navržen jako standard W3C společností Sun Microsystems v srpnu 2009, ale konsorcium s ním nemá žádné plány a WADL dosud nebyl široce přijat.
Příklad popisu služby Yahoo News Search
<application xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation= "http://wadl.dev.java.net/2009/02 wadl.xsd" xmlns:tns = "urn:yahoo:yn" xmlns:xsd= "http://www.w3.org/2001/XMLSchema" xmlns:yn= "urn:yahoo:yn" xmlns:ya= "urn:yahoo:api" xmlns = "http://wadl.dev.java.net/2009/02" > <grammars> <include href= "NewsSearchResponse.xsd" /> <include href= "Error.xsd" /> </grammars> <resources base= "http://api.search.yahoo.com/NewsSearchService/V1/" > <resource path= "newsSearch" > <metoda name= "GET" id= "search" > <request> < název parametru = "appid" type= "xsd:string" style= "query" required= "true" /> <param name= "query" type= "xsd:string" style= "query" required= "true" /> < param name= "type" style= "query" default= "all" > <option value= "all" /> <option value= "any" /> <option value= "phrase" /> </param> <param name= "results" style= "query" type= "xsd:int" default= "10" /> <param name= "start" style= "query" type= "xsd:int" default= "1" /> <param name= "sort" style= "query" default= "rank" > <option value= "rank" /> <option value= "date" /> </param> <param name= "language" style= " query" type= "xsd:string" /> </request> <response status= "200" > <representation mediaType= "application/xml" element= "yn:ResultSet" /> </response> <response status= " 400" > <representation mediaType= "application/xml" element= "ya:Error" /> </response> </method> </resource> </reso urces> </aplikace>