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>
    <pages>
      <page pageid="1" ns="0" title="Main Page">
        <revisions>
          <rev user="Ziggy" comment="Changed protection level for &quot;[[Main Page]]&quot; (‎[edit=sysop] (indefinite) ‎[move=sysop] (indefinite))" />
        </revisions>
      </page>
    </pages>
    <general mainpage="Main Page" base="http://en.rbem.org/wiki/Main_Page" sitename="The Crowdsourced Resource-Based Economy Knowledgebase" generator="MediaWiki 1.20.6" phpversion="5.6.40-32+ubuntu18.04.1+deb.sury.org+1" phpsapi="fpm-fcgi" dbtype="postgres" dbversion="12.4 (Ubuntu 12.4-1.pgdg18.04+1)" case="first-letter" rights="Creative Commons Zero (Public Domain)" lang="en-gb" fallback8bitEncoding="windows-1252" writeapi="" timezone="Australia/Melbourne" timeoffset="600" articlepath="/wiki/$1" scriptpath="/w" script="/w/index.php" variantarticlepath="" server="http://en.rbem.org" wikiid="rbemwiki" time="2024-04-28T17:18:36Z" maxuploadsize="104857600">
      <fallback>
        <lang code="en" />
      </fallback>
    </general>
  </query>
</api>