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 ns="0" title="API" missing="" />
      <page pageid="1" ns="0" title="Main Page">
        <revisions>
          <rev user="Ngekht" timestamp="2019-08-22T15:03:02Z" comment="" contentformat="text/x-wiki" contentmodel="wikitext" xml:space="preserve">&lt;strong&gt;Gehtsoft USA wiki.&lt;/strong&gt;

[[:Category:Курсы|Курсы для сотрудников]]

[[:Category:Инструменты|Инструменты]]

[[:Category:Шаблоны|Шаблоны для работы в Microsoft Word]]

== Getting started ==
* [//meta.wikimedia.org/wiki/Help:Contents User's Guide]
* [//www.mediawiki.org/wiki/Special:MyLanguage/Manual:Configuration_settings Configuration settings list]
* [//www.mediawiki.org/wiki/Special:MyLanguage/Manual:FAQ MediaWiki FAQ]
* [https://lists.wikimedia.org/mailman/listinfo/mediawiki-announce MediaWiki release mailing list]
* [//www.mediawiki.org/wiki/Special:MyLanguage/Localisation#Translation_resources Localise MediaWiki for your language]</rev>
        </revisions>
      </page>
    </pages>
  </query>
</api>