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="919" ns="6" title="File:OpenCellID I want to use the data2.png" contentmodel="wikitext" pagelanguage="en" touched="2018-04-25T12:44:36Z" lastrevid="3580" counter="307" length="0" new="" />
      <page pageid="916" ns="6" title="File:OpenCellID how to contribute2.png" contentmodel="wikitext" pagelanguage="en" touched="2018-04-25T12:44:36Z" lastrevid="3577" counter="180" length="0" new="" />
      <page pageid="915" ns="6" title="File:OpenCellID how to join2.png" contentmodel="wikitext" pagelanguage="en" touched="2018-04-25T12:44:36Z" lastrevid="3576" counter="177" length="0" new="" />
      <page pageid="918" ns="6" title="File:OpenCellID scoring lists2.png" contentmodel="wikitext" pagelanguage="en" touched="2018-04-25T12:44:36Z" lastrevid="3579" counter="363" length="0" new="" />
      <page pageid="917" ns="6" title="File:OpenCellID view the data2.png" contentmodel="wikitext" pagelanguage="en" touched="2018-04-25T12:44:36Z" lastrevid="3578" counter="183" length="0" new="" />
      <page pageid="914" ns="6" title="File:What is OpenCellID2.png" contentmodel="wikitext" pagelanguage="en" touched="2018-04-25T12:44:36Z" lastrevid="3575" counter="98" length="0" new="" />
    </pages>
  </query>
</api>