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>
    <allredirects garcontinue="SDR_Frontends|30" />
  </query-continue>
  <query>
    <pages>
      <page pageid="102" ns="0" title="Installing GnuRadio" />
      <page pageid="63" ns="0" title="Amazing developments" />
      <page pageid="40" ns="0" title="Video Grabber" />
      <page pageid="69" ns="0" title="KIARA" />
      <page pageid="73" ns="0" title="Leidse repeater" />
      <page pageid="105" ns="0" title="Radio Crypto" />
      <page pageid="66" ns="0" title="Special radio" />
      <page pageid="29" ns="0" title="GnuRadio" />
      <page pageid="52" ns="0" title="GNURadio" />
      <page pageid="106" ns="0" title="Installing Gnu Radio on Ubuntu" />
    </pages>
  </query>
</api>