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>
    <alllinks alcontinue="Buenas_Prácticas_de_Automatización_con_GXtest|539" />
  </query-continue>
  <query>
    <alllinks>
      <l fromid="208" ns="0" title="Basic Configurations in GXtest Manager" />
      <l fromid="251" ns="0" title="Basic Configurations in GXtest Manager" />
      <l fromid="252" ns="0" title="Basic Configurations in GXtest Manager" />
      <l fromid="253" ns="0" title="Basic Configurations in GXtest Manager" />
      <l fromid="815" ns="0" title="Basic Configurations in GXtest Manager" />
      <l fromid="320" ns="0" title="Basics to the installation" />
      <l fromid="321" ns="0" title="Basics to the installation" />
      <l fromid="538" ns="0" title="Best Practices automating with GXtest" />
      <l fromid="539" ns="0" title="Best Practices automating with GXtest" />
      <l fromid="538" ns="0" title="Buenas Prácticas de Automatización con GXtest" />
    </alllinks>
  </query>
</api>