How do I create a node using web services and Anonymous user?
I have posted to /node and it works for anonymous after granted that permission and cleared cache by the way you don't have to set the field uid and it's not necessary if you set


  $request_url = 'domain/endpoint/node';


// Node data
$node_data = array(
  'title' =&gt; 'product testing',
  'type' =&gt; 'product',
    "uid" =&gt; 0,
    "language" =&gt; "en",
    "sticky" =&gt; 0    
);
//$node_data = http_build_query($node_data);
$data = json_encode($node_data);

// cURL
$curl = curl_init($request_url);
curl_setopt($curl, CURLOPT_HTTPHEADER, array(                                                                          
    'Content-Type: application/json')                                                                       
);
curl_setopt($curl, CURLOPT_POST, 1); // Do a regular HTTP POST
curl_setopt($curl, CURLOPT_POSTFIELDS, $data); // Set POST data
curl_setopt($curl, CURLOPT_HEADER, FALSE);  // Ask to not return Header
curl_setopt($curl, CURLOPT_RETURNTRANSFER, TRUE);
curl_setopt($curl, CURLOPT_FAILONERROR, TRUE);

$response = curl_exec($curl);