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>
    <normalized>
      <n from="Main_Page" to="Main Page" />
    </normalized>
    <pages>
      <page pageid="1" ns="0" title="Main Page" anoncontributors="1">
        <contributors>
          <user userid="1" name="Admin" />
          <user userid="4" name="Gobo welder" />
          <user userid="9" name="Gobo sapper" />
          <user userid="11" name="Gobo fire" />
          <user userid="36" name="GobO Kiki-Jiki" />
          <user userid="104" name="GobO CommodoreGruff" />
        </contributors>
      </page>
    </pages>
  </query>
</api>