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>
    <allpages gapcontinue="Związek_Biur_Porad_Obywatelskich" />
  </query-continue>
  <query>
    <pages>
      <page pageid="27" ns="0" title="Think tank" contentmodel="wikitext" pagelanguage="pl" touched="2015-12-12T14:12:08Z" lastrevid="51" counter="600" length="393" new="" />
      <page pageid="37" ns="0" title="Uniwersyteckie poradnie prawne" contentmodel="wikitext" pagelanguage="pl" touched="2015-12-12T14:22:23Z" lastrevid="62" counter="721" length="1815" />
      <page pageid="40" ns="0" title="Via Iuris" contentmodel="wikitext" pagelanguage="pl" touched="2015-12-12T14:25:27Z" lastrevid="65" counter="521" length="311" new="" />
      <page pageid="10" ns="0" title="Wysłuchanie publiczne" contentmodel="wikitext" pagelanguage="pl" touched="2015-10-12T19:14:11Z" lastrevid="14" counter="822" length="733" new="" />
    </pages>
  </query>
</api>