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="10" ns="0" title="M24-2332A" />
      <page pageid="1480" ns="0" title="Trauungsmatrik Gayer 1280 1786-1851:f2019" />
      <page pageid="2262" ns="0" title="Taufmatrik Mährisch Hermersdorf 2337 1821-1846" />
      <page pageid="2263" ns="0" title="Taufmatrik Mährisch Hermersdorf M-24 2337 1821-1846:f0001" />
      <page pageid="2408" ns="0" title="Taufmatrik Hermersdorf 2331A 1614-1655" />
      <page pageid="2418" ns="0" title="Download" />
    </pages>
  </query>
</api>