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 garcontinue="ModTweaker:Metallurgy_4_Support|21" />
  </query-continue>
  <query>
    <pages>
      <page pageid="3" ns="0" title="Blood Magic" />
      <page pageid="4" ns="0" title="Botania" />
      <page pageid="11" ns="0" title="Ex Nihilo" />
      <page pageid="12" ns="0" title="Factorization" />
      <page pageid="17" ns="0" title="Hardcore Ender Expansion" />
      <page pageid="19" ns="0" title="Mariculture" />
      <page pageid="20" ns="0" title="Mekanism" />
      <page pageid="30" ns="0" title="ModTweaker:BloodMagic Support" />
      <page pageid="38" ns="0" title="ModTweaker:Chisel 2 Support 1.10.2" />
      <page pageid="69" ns="0" title="Mod Tweaker" />
    </pages>
  </query>
</api>