# Partial Sourcecode for Login to Spreadshirt API v1
$email = "EMAIL"; # login email address
$password = "PASSWORD"; # login password

// 0. Login to api
$loginURL = "https://api.spreadshirt.net/api/v1/sessions";
$loginXML = "<?xml version='1.0' encoding='UTF-8' standalone='yes'?>
<login xmlns:xlink='http://www.w3.org/1999/xlink' xmlns='http://api.spreadshirt.net'>
  <username>$email</username>
  <password>$password</password>
</login>";

$header = array();
$header[] = "Content-Type: application/xml";

echo "Login to $loginURL ".PHP_EOL;//.$result . ''.PHP_EOL;
$ch = curl_init($loginURL);
curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, $header);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_USERAGENT, $useragent);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $loginXML);
$result = curl_exec($ch);
curl_close($ch);
echo "  -> ".parseHttpHeaders($result, "HTTP").PHP_EOL;

$session = substr(parseHttpHeaders($result, "Location"), 44);
define('SESSION_ID', $session);

$url = "https://api.spreadshirt.net/api/v1/users/" . USER_ID . "/designs";

... der weitere Ablauf orientiert sich an https://pastebin.com/erK97gPG bzw. der API Dokumentation (https://developer.spreadshirt.net/display/API/Uploading+Designs+to+Spreadshirt+using+Spreadshirt+API+v1)