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="75%.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="22" ns="6" title="File:00%.png">
        <duplicatefiles>
          <df name="00%.png" user="Al" timestamp="2009-04-23T14:15:53Z" shared="" />
        </duplicatefiles>
      </page>
      <page pageid="26" ns="6" title="File:100%.png">
        <duplicatefiles>
          <df name="100%.png" user="Al" timestamp="2009-04-23T14:17:04Z" shared="" />
        </duplicatefiles>
      </page>
      <page pageid="2329" ns="6" title="File:1 Circular 1-2010 redes y servicios AAPP.pdf">
        <duplicatefiles>
          <df name="1_Circular_1-2010_redes_y_servicios_AAPP.pdf" user="Al" timestamp="2014-02-27T23:06:53Z" shared="" />
        </duplicatefiles>
      </page>
      <page pageid="2242" ns="6" title="File:20101100 elperiodico suplement masdigital3.pdf">
        <duplicatefiles>
          <df name="20101100_elperiodico_suplement_masdigital3.pdf" user="Al" timestamp="2014-02-27T22:22:13Z" shared="" />
        </duplicatefiles>
      </page>
      <page pageid="2546" ns="6" title="File:20120715memoriamejoradelaaplicaciondemapasdeguifinet.pdf">
        <duplicatefiles>
          <df name="20120715memoriamejoradelaaplicaciondemapasdeguifinet.pdf" user="Emagrada" timestamp="2015-11-19T22:04:13Z" shared="" />
        </duplicatefiles>
      </page>
      <page pageid="23" ns="6" title="File:25%.png">
        <duplicatefiles>
          <df name="25%.png" user="Al" timestamp="2009-04-23T14:16:16Z" shared="" />
        </duplicatefiles>
      </page>
      <page pageid="1800" ns="6" title="File:2553434081 004360f405 b.jpg">
        <duplicatefiles>
          <df name="2553434081_004360f405_b.jpg" user="Pablog" timestamp="2012-03-17T21:19:25Z" shared="" />
        </duplicatefiles>
      </page>
      <page pageid="2316" ns="6" title="File:4-cantons guifi.net web.png">
        <duplicatefiles>
          <df name="4-cantons_guifi.net_web.png" user="Al" timestamp="2014-02-27T23:06:46Z" shared="" />
        </duplicatefiles>
      </page>
      <page pageid="24" ns="6" title="File:50%.png">
        <duplicatefiles>
          <df name="50%.png" user="Al" timestamp="2009-04-23T14:16:30Z" shared="" />
        </duplicatefiles>
      </page>
      <page pageid="1961" ns="6" title="File:6504773967 6733d231aa b.jpg">
        <duplicatefiles>
          <df name="6504773967_6733d231aa_b.jpg" user="Pablog" timestamp="2012-07-25T17:49:11Z" shared="" />
        </duplicatefiles>
      </page>
    </pages>
  </query>
</api>