You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <pageswithprop gpwpcontinue="681" />
  </query-continue>
  <query>
    <pages>
      <page pageid="498" ns="208" title="Brugger:Antinomios" contentmodel="wikitext" pagelanguage="es" touched="2016-05-22T22:05:36Z" lastrevid="521" counter="0" length="759" new="" />
      <page pageid="518" ns="208" title="Brugger:Carácter" contentmodel="wikitext" pagelanguage="es" touched="2016-05-22T22:05:19Z" lastrevid="541" counter="2" length="759" new="" />
      <page pageid="532" ns="208" title="Brugger:Ciencia (Teoría de la)" contentmodel="wikitext" pagelanguage="es" touched="2016-05-23T19:35:55Z" lastrevid="556" counter="0" length="759" new="" />
      <page pageid="552" ns="208" title="Brugger:Confucionismo" contentmodel="wikitext" pagelanguage="es" touched="2016-05-22T21:19:22Z" lastrevid="577" counter="0" length="759" new="" />
      <page pageid="554" ns="208" title="Brugger:Conocimiento del ser" contentmodel="wikitext" pagelanguage="es" touched="2016-05-22T22:05:41Z" lastrevid="579" counter="1" length="759" new="" />
      <page pageid="565" ns="208" title="Brugger:Cualidades esenciales" contentmodel="wikitext" pagelanguage="es" touched="2016-05-23T19:20:28Z" lastrevid="590" counter="0" length="759" new="" />
      <page pageid="580" ns="208" title="Brugger:Desarrollo (Psicología del)" contentmodel="wikitext" pagelanguage="es" touched="2016-05-23T19:38:34Z" lastrevid="605" counter="0" length="759" new="" />
      <page pageid="592" ns="208" title="Brugger:Dios (Prueba de la existencia de)" contentmodel="wikitext" pagelanguage="es" touched="2016-05-22T16:31:16Z" lastrevid="617" counter="0" length="759" new="" />
      <page pageid="659" ns="208" title="Brugger:Finalidad (principio de)" contentmodel="wikitext" pagelanguage="es" touched="2016-05-22T16:43:54Z" lastrevid="685" counter="0" length="759" new="" />
      <page pageid="679" ns="208" title="Brugger:Historicismo" contentmodel="wikitext" pagelanguage="es" touched="2016-05-22T21:44:30Z" lastrevid="705" counter="1" length="759" new="" />
    </pages>
  </query>
</api>