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>
    <blocks bkstart="2012-03-02T18:51:10Z" />
  </query-continue>
  <query>
    <blocks>
      <block id="90" user="A.Burgermeister" by="Karl Kirst" timestamp="2014-12-23T06:07:22Z" expiry="infinity" reason="Schutz vor möglichem Missbrauch" nocreate="" autoblock="" />
      <block id="89" user="DanialGRYe" by="Karl Kirst" timestamp="2013-12-02T23:02:42Z" expiry="infinity" reason="Spam oder Spam-Verdacht" nocreate="" autoblock="" />
      <block id="88" user="Home-Loans-For-PeoplWith-Bad-Credit.Org" by="Karl Kirst" timestamp="2012-03-03T20:52:00Z" expiry="infinity" reason="Einstellen unsinniger Seiten" nocreate="" autoblock="" noemail="" />
      <block id="86" user="CheckItoutbeforedownloading" by="Karl Kirst" timestamp="2012-03-03T20:51:47Z" expiry="infinity" reason="Einstellen unsinniger Seiten" nocreate="" autoblock="" noemail="" />
      <block id="84" user="SheehyChambless885" by="Karl Kirst" timestamp="2012-03-02T18:54:55Z" expiry="infinity" reason="(unerwünschte) Werbung" nocreate="" autoblock="" noemail="" />
      <block id="82" user="HorvathRahn445" by="Karl Kirst" timestamp="2012-03-02T18:54:18Z" expiry="infinity" reason="(unerwünschte) Werbung" nocreate="" autoblock="" noemail="" />
      <block id="79" user="GardenersInnorthlondon" by="Karl Kirst" timestamp="2012-03-02T18:53:32Z" expiry="infinity" reason="(unerwünschte) Werbung" nocreate="" autoblock="" noemail="" />
      <block id="76" user="LandscapeGardenersinnorthlondon" by="Karl Kirst" timestamp="2012-03-02T18:52:51Z" expiry="infinity" reason="" nocreate="" autoblock="" noemail="" />
      <block id="73" user="HomeLoansforpeoplewithbadcredit" by="Karl Kirst" timestamp="2012-03-02T18:52:05Z" expiry="infinity" reason="(unerwünschte) Werbung" nocreate="" autoblock="" noemail="" />
      <block id="71" user="JeaneMoulton404" by="Karl Kirst" timestamp="2012-03-02T18:51:35Z" expiry="infinity" reason="(unerwünschte) Werbung" nocreate="" autoblock="" noemail="" />
    </blocks>
  </query>
</api>