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>
    <allpages gapcontinue="Voorlopige_lijst" />
  </query-continue>
  <query>
    <pages>
      <page pageid="13" ns="0" title="Thomas Hazart" contentmodel="wikitext" pagelanguage="nl" touched="2016-09-06T20:19:47Z" lastrevid="37" counter="696" length="91" new="" />
      <page pageid="57" ns="0" title="Tongerlo" contentmodel="wikitext" pagelanguage="nl" touched="2017-09-11T16:37:08Z" lastrevid="277" counter="23539" length="585859" />
      <page pageid="58" ns="0" title="Twee in 1907 door de kerkfabriek Sint-Andreas verkochte schilderijen" contentmodel="wikitext" pagelanguage="nl" touched="2017-04-20T18:58:48Z" lastrevid="276" counter="3232" length="18642" />
      <page pageid="52" ns="0" title="Vermeldingen van Mechels renaissancebeeldhouwwerk in de literatuur" contentmodel="wikitext" pagelanguage="nl" touched="2016-12-19T11:38:56Z" lastrevid="223" counter="1391" length="316" new="" />
    </pages>
  </query>
</api>