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="OF_doc1 fr:Accueil" missing="" contentmodel="wikitext" pagelanguage="en" />
      <page ns="0" title="OF_doc2 fr:Accueil" missing="" contentmodel="wikitext" pagelanguage="en" />
      <page ns="0" title="OF_doc3 fr:Accueil" missing="" contentmodel="wikitext" pagelanguage="en" />
      <page ns="0" title="OF_doc4 fr:Accueil" missing="" contentmodel="wikitext" pagelanguage="en" />
      <page pageid="2157" ns="0" title="Main Page1" contentmodel="wikitext" pagelanguage="en" touched="2016-12-02T14:07:08Z" lastrevid="8449" counter="" length="1024" />
      <page pageid="2156" ns="0" title="Main Page2" contentmodel="wikitext" pagelanguage="en" touched="2016-12-02T14:07:18Z" lastrevid="8450" counter="" length="1483" />
      <page pageid="2155" ns="0" title="Main Page3" contentmodel="wikitext" pagelanguage="en" touched="2016-12-02T14:06:52Z" lastrevid="8448" counter="" length="1253" />
      <page pageid="2154" ns="0" title="Main Page4" contentmodel="wikitext" pagelanguage="en" touched="2018-04-12T14:07:39Z" lastrevid="8910" counter="" length="1216" />
    </pages>
  </query>
</api>