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>
    <allimages gaicontinue="Nuvola_apps_ktip.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="21" ns="6" title="File:Aon-jumper-web.png" />
      <page pageid="15" ns="6" title="File:Dtr on logic.jpg" />
      <page pageid="12" ns="6" title="File:Icon tools.png" />
      <page pageid="6" ns="6" title="File:Nuvola apps download manager.png" />
      <page pageid="8" ns="6" title="File:Nuvola apps edu science.png" />
      <page pageid="9" ns="6" title="File:Nuvola apps kcmprocessor.png" />
      <page pageid="13" ns="6" title="File:Nuvola apps kdict.png" />
      <page pageid="11" ns="6" title="File:Nuvola apps khelpcenter.png" />
      <page pageid="10" ns="6" title="File:Nuvola apps khexedit.png" />
      <page pageid="3" ns="6" title="File:Nuvola apps kpackage.png" />
    </pages>
  </query>
</api>