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="17" ns="100" title="Portail:Contentieux administratif" contentmodel="wikitext" pagelanguage="fr" touched="2015-06-07T22:10:53Z" lastrevid="4342" counter="19145" length="518" />
      <page pageid="19" ns="100" title="Portail:Droit social" contentmodel="wikitext" pagelanguage="fr" touched="2020-02-15T15:57:26Z" lastrevid="4346" counter="21072" length="429" />
      <page pageid="20" ns="100" title="Portail:Droit civil" contentmodel="wikitext" pagelanguage="fr" touched="2015-06-07T22:13:03Z" lastrevid="7629" counter="20678" length="518" />
      <page pageid="21" ns="100" title="Portail:Droit public" contentmodel="wikitext" pagelanguage="fr" touched="2020-09-20T13:16:13Z" lastrevid="4341" counter="20393" length="518" />
      <page pageid="22" ns="100" title="Portail:Fonction publique" contentmodel="wikitext" pagelanguage="fr" touched="2020-04-17T13:56:52Z" lastrevid="4343" counter="20733" length="503" />
      <page pageid="25" ns="100" title="Portail:Service public" contentmodel="wikitext" pagelanguage="fr" touched="2020-04-01T16:34:16Z" lastrevid="4344" counter="18551" length="518" />
    </pages>
  </query>
</api>