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>
    <blocks>
      <block id="14" user="Beau2988wlxiz" by="Dieter" timestamp="2015-02-17T21:58:17Z" expiry="infinity" reason="" nocreate="" autoblock="" />
      <block id="13" user="AkylaKQ4FU" by="Dieter" timestamp="2011-08-10T14:20:55Z" expiry="infinity" reason="Massenweises Einfügen externer Links" nocreate="" autoblock="" noemail="" />
      <block id="11" user="Puwok2008c19cu" by="Dieter" timestamp="2011-08-10T14:19:45Z" expiry="infinity" reason="Massenweises Einfügen externer Links" nocreate="" autoblock="" noemail="" />
      <block id="9" user="Anna1ttx" by="Dieter" timestamp="2011-08-07T19:02:05Z" expiry="infinity" reason="Ungebührliches Verhalten" nocreate="" autoblock="" noemail="" />
      <block id="8" user="Puwok200801oZ" by="Dieter" timestamp="2011-08-04T17:03:53Z" expiry="infinity" reason="Einstellen unsinniger Inhalte in Seiten" nocreate="" autoblock="" noemail="" />
      <block id="6" user="Akylaejnf" by="Dieter" timestamp="2011-08-04T17:03:31Z" expiry="infinity" reason="Einstellen unsinniger Inhalte in Seiten" nocreate="" autoblock="" noemail="" />
      <block id="5" user="KennethGc1I" by="Dieter" timestamp="2011-04-09T17:54:56Z" expiry="infinity" reason="Einstellen unsinniger Seiten" nocreate="" autoblock="" noemail="" />
      <block id="3" user="Toby Hogan" by="Dieter" timestamp="2011-01-19T00:26:53Z" expiry="infinity" reason="Proxy, wegen Vandalismus einzelner Benutzer längerfristig gesperrt" nocreate="" autoblock="" noemail="" />
      <block id="2" user="61.7.161.226" by="Admin" timestamp="2009-07-28T07:08:23Z" expiry="infinity" reason="Einstellen unsinniger Seiten" anononly="" nocreate="" allowusertalk="" />
      <block id="1" user="151.96.0.8" by="Admin" timestamp="2009-04-12T19:33:53Z" expiry="infinity" reason="Einstellen unsinniger Seiten" nocreate="" allowusertalk="" />
    </blocks>
  </query>
</api>