HttpConnection not working on some URLs?

Here's a question: I tried the below code on the 3 URLs which are inside the code, and it only works on the putsreq site. Is this true for others, and why?

#target bridge
function test(){
  if ( !ExternalObject.webaccesslib )
    ExternalObject.webaccesslib = new ExternalObject('lib:webaccesslib');
  var response = null;
  var responseHeaders = null;
    // var http = new HttpConnection('https://requestb.in/sfeof5sf') ; // not working
    // var http = new HttpConnection('https://jsonplaceholder.typicode.com/posts/1') ; // not working
    var http = new HttpConnection("http://putsreq.com/85Np9n50u2q2E48HBaiI"); // working
    
    http.timeout = 22;
    http.execute() ;
    response = http.response;
    $.write(response);
};
test();