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>
    <links gplcontinue="1|0|Custom_Data_Formatter_Standard_Option" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1369" ns="0" title="Administration Client" contentmodel="wikitext" pagelanguage="en" touched="2018-10-05T08:55:07Z" lastrevid="6645" counter="42163" length="5368" />
      <page pageid="3503" ns="0" title="AS400 Action" contentmodel="wikitext" pagelanguage="en" touched="2015-08-21T12:50:29Z" lastrevid="6535" counter="75489" length="3299" />
      <page pageid="1475" ns="0" title="Basic XML Writer" contentmodel="wikitext" pagelanguage="en" touched="2015-08-19T16:13:22Z" lastrevid="6296" counter="7381" length="1816" />
      <page pageid="1401" ns="0" title="Best Use" contentmodel="wikitext" pagelanguage="en" touched="2009-03-18T12:32:29Z" lastrevid="1429" counter="6748" length="218" />
      <page pageid="1484" ns="0" title="Broadcast Messages" contentmodel="wikitext" pagelanguage="en" touched="2015-08-21T12:56:51Z" lastrevid="6539" counter="14327" length="4892" />
      <page pageid="1497" ns="0" title="Call Native Program" contentmodel="wikitext" pagelanguage="en" touched="2015-08-21T14:24:20Z" lastrevid="6592" counter="7749" length="4078" />
      <page pageid="1474" ns="0" title="Context XML Nodes" contentmodel="wikitext" pagelanguage="en" touched="2015-08-21T13:28:22Z" lastrevid="6547" counter="6496" length="1415" />
      <page pageid="1495" ns="0" title="Copy File" contentmodel="wikitext" pagelanguage="en" touched="2013-04-30T15:40:46Z" lastrevid="4056" counter="7623" length="1673" />
      <page pageid="1919" ns="0" title="Create Graph" contentmodel="wikitext" pagelanguage="en" touched="2015-08-21T14:26:57Z" lastrevid="6593" counter="27312" length="13773" />
      <page pageid="1441" ns="0" title="CSV Writer" contentmodel="wikitext" pagelanguage="en" touched="2014-06-18T12:03:48Z" lastrevid="4166" counter="8506" length="2413" />
    </pages>
  </query>
</api>