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>
    <allredirects arcontinue="Stuttgart_21/Faktencheck" />
  </query-continue>
  <query>
    <allredirects>
      <r ns="0" title="Deutsche Bahn/Strategie" />
      <r ns="0" title="Empfohlene Dokumentationen" />
      <r ns="0" title="Hauptseite" />
      <r ns="0" title="Stuttgart 21/Anhörung PFA 1.3/Analyse 09.2015" />
      <r ns="0" title="Stuttgart 21/Anhörung PFA 1.3/DB 09.2015 Analyse" />
      <r ns="0" title="Stuttgart 21/Brandschutz/Entfluchtung" />
      <r ns="0" title="Stuttgart 21/Brandschutz Tiefbahnhof" />
      <r ns="0" title="Stuttgart 21/Brandschutz Tiefbahnhof/Chronologie" />
      <r ns="0" title="Stuttgart 21/Brandschutz Tiefbahnhof/Entfluchtung" />
      <r ns="0" title="Stuttgart 21/Brandschutz Tunnel" />
    </allredirects>
  </query>
</api>