diff --git a/lib/ShippingEasy.php b/lib/ShippingEasy.php
index bee24dc..84b7ccc 100644
--- a/lib/ShippingEasy.php
+++ b/lib/ShippingEasy.php
@@ -13,21 +13,21 @@
   throw new Exception('ShippingEasy needs the Multibyte String PHP extension.');
 }
 
-require(dirname(__FILE__) . '/ShippingEasy/ShippingEasy.php');
+require(__DIR__ . '/ShippingEasy/ShippingEasy.php');
 
 // Errors
-require(dirname(__FILE__) . '/ShippingEasy/Error.php');
-require(dirname(__FILE__) . '/ShippingEasy/ApiError.php');
-require(dirname(__FILE__) . '/ShippingEasy/ApiConnectionError.php');
-require(dirname(__FILE__) . '/ShippingEasy/AuthenticationError.php');
-require(dirname(__FILE__) . '/ShippingEasy/InvalidRequestError.php');
+require(__DIR__ . '/ShippingEasy/Error.php');
+require(__DIR__ . '/ShippingEasy/ApiError.php');
+require(__DIR__ . '/ShippingEasy/ApiConnectionError.php');
+require(__DIR__ . '/ShippingEasy/AuthenticationError.php');
+require(__DIR__ . '/ShippingEasy/InvalidRequestError.php');
 
-require(dirname(__FILE__) . '/ShippingEasy/ApiRequestor.php');
-require(dirname(__FILE__) . '/ShippingEasy/Authenticator.php');
-require(dirname(__FILE__) . '/ShippingEasy/Object.php');
-require(dirname(__FILE__) . '/ShippingEasy/Order.php');
-require(dirname(__FILE__) . '/ShippingEasy/PartnerSession.php');
-require(dirname(__FILE__) . '/ShippingEasy/PartnerAccount.php');
-require(dirname(__FILE__) . '/ShippingEasy/Signature.php');
-require(dirname(__FILE__) . '/ShippingEasy/SignedUrl.php');
-require(dirname(__FILE__) . '/ShippingEasy/Cancellation.php');
\ No newline at end of file
+require(__DIR__ . '/ShippingEasy/ApiRequestor.php');
+require(__DIR__ . '/ShippingEasy/Authenticator.php');
+require(__DIR__ . '/ShippingEasy/Object.php');
+require(__DIR__ . '/ShippingEasy/Order.php');
+require(__DIR__ . '/ShippingEasy/PartnerSession.php');
+require(__DIR__ . '/ShippingEasy/PartnerAccount.php');
+require(__DIR__ . '/ShippingEasy/Signature.php');
+require(__DIR__ . '/ShippingEasy/SignedUrl.php');
+require(__DIR__ . '/ShippingEasy/Cancellation.php');
\ No newline at end of file
diff --git a/lib/ShippingEasy/ApiRequestor.php b/lib/ShippingEasy/ApiRequestor.php
index 34480a8..e6ed8f3 100644
--- a/lib/ShippingEasy/ApiRequestor.php
+++ b/lib/ShippingEasy/ApiRequestor.php
@@ -18,7 +18,7 @@ public static function encode($arr, $prefix=null)
     if (!is_array($arr))
       return $arr;
 
-    $r = array();
+    $r = [];
     foreach ($arr as $k => $v) {
       if (is_null($v))
         continue;
@@ -29,9 +29,9 @@ public static function encode($arr, $prefix=null)
         $k = $prefix."[]";
 
       if (is_array($v)) {
-        $r[] = self::encode($v, $k, true);
+        $r[] = self::encode($v, $k);
       } else {
-        $r[] = urlencode($k)."=".urlencode($v);
+        $r[] = urlencode($k)."=".urlencode((string) $v);
       }
     }
 
@@ -40,7 +40,7 @@ public static function encode($arr, $prefix=null)
 
   public function request($meth, $path, $params=null, $payload = null, $apiKey = null, $apiSecret = null)
   {
-    list($rbody, $rcode) = $this->_requestRaw($meth, $path, $params, $payload, $apiKey, $apiSecret);
+    [$rbody, $rcode] = $this->_requestRaw($meth, $path, $params, $payload, $apiKey, $apiSecret);
     $resp = $this->_interpretResponse($rbody, $rcode);
     return $resp;
   }
@@ -52,11 +52,11 @@ public function handleApiError($rbody, $rcode, $resp)
       throw new ShippingEasy_ApiError("Invalid response object from API: $rbody (HTTP response code was $rcode)", $rcode, $rbody, $resp);
 
     $error = $resp['errors'];
-    $message = isset($error[0]['message']) ? $error[0]['message'] : null;
+    $message = $error[0]['message'] ?? null;
 
     switch ($rcode) {
     case 400:
-      throw new ShippingEasy_InvalidRequestError(json_encode($error), $rcode, $rbody, $resp);
+      throw new ShippingEasy_InvalidRequestError(json_encode($error, JSON_THROW_ON_ERROR), $rcode, $rbody, $resp);
     case 404:
       throw new ShippingEasy_InvalidRequestError($message, $rcode, $rbody, $resp);
     case 401:
@@ -74,28 +74,22 @@ private function _requestRaw($http_method, $path, $params, $payload, $apiKey, $a
     $langVersion = phpversion();
     $uname = php_uname();
 
-    $ua = array('bindings_version' => ShippingEasy::VERSION,
-		            'lang' => 'php',
-            		'lang_version' => $langVersion,
-            		'publisher' => 'ShippingEasy',
-            		'uname' => $uname);
+    $ua = ['bindings_version' => ShippingEasy::VERSION, 'lang' => 'php', 'lang_version' => $langVersion, 'publisher' => 'ShippingEasy', 'uname' => $uname];
 
-    $headers = array('X-ShippingEasy-Client-User-Agent: ' . json_encode($ua),
-                     'User-Agent: ShippingEasy/v1 PhpBindings/' . ShippingEasy::VERSION,
-                     'Authorization: Bearer ' . $apiKey);
+    $headers = ['X-ShippingEasy-Client-User-Agent: ' . json_encode($ua, JSON_THROW_ON_ERROR), 'User-Agent: ShippingEasy/v1 PhpBindings/' . ShippingEasy::VERSION, 'Authorization: Bearer ' . $apiKey];
 
     if (ShippingEasy::$apiVersion)
       $headers[] = 'ShippingEasy-Version: ' . ShippingEasy::$apiVersion;
 
-    list($rbody, $rcode) = $this->_curlRequest($http_method, $absUrl, $headers, $payload);
-    return array($rbody, $rcode);
+    [$rbody, $rcode] = $this->_curlRequest($http_method, $absUrl, $headers, $payload);
+    return [$rbody, $rcode];
   }
 
   private function _interpretResponse($rbody, $rcode)
   {
     try {
-      $resp = json_decode($rbody, true);
-    } catch (Exception $e) {
+      $resp = json_decode((string) $rbody, true, 512, JSON_THROW_ON_ERROR);
+    } catch (Exception) {
       throw new ShippingEasy_ApiError("Invalid response body from API: $rbody (HTTP response code was $rcode)", $rcode, $rbody);
     }
     if ($rcode < 200 || $rcode >= 300) {
@@ -106,16 +100,17 @@ private function _interpretResponse($rbody, $rcode)
 
   private function _curlRequest($meth, $absUrl, $headers, $payload)
   {
+    $params = null;
     $curl = curl_init();
-    $meth = strtolower($meth);
-    $opts = array();
+    $meth = strtolower((string) $meth);
+    $opts = [];
 
     if ($meth == 'get') {
       $opts[CURLOPT_HTTPGET] = 1;
     } else if ($meth == 'post') {
       $opts[CURLOPT_POST] = 1;
       if ($payload)
-        $payload = json_encode($payload);
+        $payload = json_encode($payload, JSON_THROW_ON_ERROR);
 
       $headers[] = 'Content-Type: application/json';
       $headers[] = 'Content-Length: ' . strlen($payload);
@@ -123,14 +118,14 @@ private function _curlRequest($meth, $absUrl, $headers, $payload)
     } else if ($meth == 'put') {
       $opts[CURLOPT_CUSTOMREQUEST] = 'PUT';
       if ($payload)
-        $payload = json_encode($payload);
+        $payload = json_encode($payload, JSON_THROW_ON_ERROR);
 
       $headers[] = 'Content-Type: application/json';
       $headers[] = 'Content-Length: ' . strlen($payload);
       $opts[CURLOPT_POSTFIELDS] = $payload;
     } else if ($meth == 'delete')  {
       $opts[CURLOPT_CUSTOMREQUEST] = 'DELETE';
-      if (count($params) > 0) {
+      if (($params === null ? 0 : count($params)) > 0) {
 	      $encoded = self::encode($params);
 	      $absUrl = "$absUrl?$encoded";
       }
@@ -160,25 +155,17 @@ private function _curlRequest($meth, $absUrl, $headers, $payload)
 
     $rcode = curl_getinfo($curl, CURLINFO_HTTP_CODE);
     curl_close($curl);
-    return array($rbody, $rcode);
+    return [$rbody, $rcode];
   }
 
   public function handleCurlError($errno, $message)
   {
     $apiBase = ShippingEasy::$apiBase;
-    switch ($errno) {
-    case CURLE_COULDNT_CONNECT:
-    case CURLE_COULDNT_RESOLVE_HOST:
-    case CURLE_OPERATION_TIMEOUTED:
-      $msg = "Could not connect to ShippingEasy ($apiBase).  Please check your internet connection and try again.  If this problem persists, let us know at support@shippingeasy.com.";
-      break;
-    case CURLE_SSL_CACERT:
-    case CURLE_SSL_PEER_CERTIFICATE:
-      $msg = "Could not verify ShippingEasy's SSL certificate.  Please make sure that your network is not intercepting certificates.  (Try going to $apiBase in your browser.)  If this problem persists, let us know at support@shippingeasy.com.";
-      break;
-    default:
-      $msg = "Unexpected error communicating with ShippingEasy.  If this problem persists, let us know at support@shippingeasy.com.";
-    }
+    $msg = match ($errno) {
+        CURLE_COULDNT_CONNECT, CURLE_COULDNT_RESOLVE_HOST, CURLE_OPERATION_TIMEOUTED => "Could not connect to ShippingEasy ($apiBase).  Please check your internet connection and try again.  If this problem persists, let us know at support@shippingeasy.com.",
+        CURLE_SSL_CACERT, CURLE_SSL_PEER_CERTIFICATE => "Could not verify ShippingEasy's SSL certificate.  Please make sure that your network is not intercepting certificates.  (Try going to $apiBase in your browser.)  If this problem persists, let us know at support@shippingeasy.com.",
+        default => "Unexpected error communicating with ShippingEasy.  If this problem persists, let us know at support@shippingeasy.com.",
+    };
 
     $msg .= "\n\n(Network error [errno $errno]: $message)";
     throw new ShippingEasy_ApiConnectionError($msg);
diff --git a/lib/ShippingEasy/Authenticator.php b/lib/ShippingEasy/Authenticator.php
index 5ed5c68..fe5bdc9 100644
--- a/lib/ShippingEasy/Authenticator.php
+++ b/lib/ShippingEasy/Authenticator.php
@@ -2,7 +2,9 @@
 
 class ShippingEasy_Authenticator
 {
-  
+  public $supplied_signature_string;
+  public $expected_signature;
+
   # Instantiates a new authenticator object. 
   # 
   # http_method - The method of the http request. E.g. "post" or "get".
@@ -13,7 +15,7 @@ class ShippingEasy_Authenticator
   #
   public function __construct($http_method=null, $path=null, $params=null, $json_body=null, $api_secret=null)
   {
-    $api_secret = isset($api_secret) ? $api_secret : ShippingEasy::$apiSecret;
+    $api_secret ??= ShippingEasy::$apiSecret;
     $this->supplied_signature_string = $params["api_signature"];
     unset($params["api_signature"]);
     $this->expected_signature = new ShippingEasy_Signature($api_secret, $http_method, $path, $params, $json_body);
diff --git a/lib/ShippingEasy/Cancellation.php b/lib/ShippingEasy/Cancellation.php
index ad412d9..4969f43 100644
--- a/lib/ShippingEasy/Cancellation.php
+++ b/lib/ShippingEasy/Cancellation.php
@@ -2,6 +2,8 @@
 
 class ShippingEasy_Cancellation extends ShippingEasy_Object
 {
+  public $store_api_key;
+  public $external_order_identifier;
 
   public function __construct($store_api_key, $external_order_identifier) {
     $this->store_api_key = $store_api_key;
diff --git a/lib/ShippingEasy/Error.php b/lib/ShippingEasy/Error.php
index 9f9760f..28b25ee 100644
--- a/lib/ShippingEasy/Error.php
+++ b/lib/ShippingEasy/Error.php
@@ -2,6 +2,10 @@
 
 class ShippingEasy_Error extends Exception
 {
+  public $http_status;
+  public $http_body;
+  public $json_body;
+
   public function __construct($message=null, $http_status=null, $http_body=null, $json_body=null)
   {
     parent::__construct($message);
diff --git a/lib/ShippingEasy/Order.php b/lib/ShippingEasy/Order.php
index f03aa70..d8f9bc9 100644
--- a/lib/ShippingEasy/Order.php
+++ b/lib/ShippingEasy/Order.php
@@ -2,6 +2,9 @@
 
 class ShippingEasy_Order extends ShippingEasy_Object
 {
+  public $store_api_key;
+  public $values;
+
   public function __construct($store_api_key=null, $values=null) {
     $this->store_api_key = $store_api_key;
     $this->values = $values;
@@ -9,17 +12,17 @@ public function __construct($store_api_key=null, $values=null) {
 
   public function create()
   {
-    return $this->request("post", "/api/stores/$this->store_api_key/orders", null, array("order" => $this->values));
+    return $this->request("post", "/api/stores/$this->store_api_key/orders", null, ["order" => $this->values]);
   }
 
   public function updateRecipient($external_order_id, $recipient_data)
   {
-    return $this->request("put", "/api/stores/$this->store_api_key/orders/$external_order_id/recipient", null, array("recipient" => $recipient_data));
+    return $this->request("put", "/api/stores/$this->store_api_key/orders/$external_order_id/recipient", null, ["recipient" => $recipient_data]);
   }
 
   public function updateStatus($external_order_id, $new_status)
   {
-      return $this->request("put", "/api/stores/$this->store_api_key/orders/$external_order_id/status", null, array("order" => array("order_status" => $new_status)));
+      return $this->request("put", "/api/stores/$this->store_api_key/orders/$external_order_id/status", null, ["order" => ["order_status" => $new_status]]);
   }
 
   public function find($id)
@@ -32,12 +35,12 @@ public function findByStore($external_order_id)
       return $this->request("get", "/api/stores/$this->store_api_key/orders/$external_order_id");
   }
 
-  public function findAllByStore($params=array())
+  public function findAllByStore($params=[])
   {
     return $this->request("get", "/api/stores/$this->store_api_key/orders", $params);
   }
 
-  public function findAll($params=array())
+  public function findAll($params=[])
   {
     return $this->request("get", "/api/orders", $params);
   }
diff --git a/lib/ShippingEasy/PartnerAccount.php b/lib/ShippingEasy/PartnerAccount.php
index 9c12e3f..73b5709 100644
--- a/lib/ShippingEasy/PartnerAccount.php
+++ b/lib/ShippingEasy/PartnerAccount.php
@@ -2,8 +2,8 @@
 
 class ShippingEasy_PartnerAccount extends ShippingEasy_Object
 {
-  public function create($data = array())
+  public function create($data = [])
   {
-    return $this->request("post", "/partners/api/accounts", null, array("account" => $data), ShippingEasy::$partnerApiKey, ShippingEasy::$partnerApiSecret);
+    return $this->request("post", "/partners/api/accounts", null, ["account" => $data], ShippingEasy::$partnerApiKey, ShippingEasy::$partnerApiSecret);
   }
 }
diff --git a/lib/ShippingEasy/PartnerSession.php b/lib/ShippingEasy/PartnerSession.php
index 4b5aeea..e984642 100644
--- a/lib/ShippingEasy/PartnerSession.php
+++ b/lib/ShippingEasy/PartnerSession.php
@@ -2,8 +2,8 @@
 
 class ShippingEasy_PartnerSession extends ShippingEasy_Object
 {
-  public function create($data = array())
+  public function create($data = [])
   {
-    return $this->request("post", "/partners/api/sessions", null, array("session" => $data), ShippingEasy::$partnerApiKey, ShippingEasy::$partnerApiSecret);
+    return $this->request("post", "/partners/api/sessions", null, ["session" => $data], ShippingEasy::$partnerApiKey, ShippingEasy::$partnerApiSecret);
   }
 }
diff --git a/lib/ShippingEasy/ShippingEasy.php b/lib/ShippingEasy/ShippingEasy.php
index 40e794c..3975696 100644
--- a/lib/ShippingEasy/ShippingEasy.php
+++ b/lib/ShippingEasy/ShippingEasy.php
@@ -8,7 +8,7 @@ abstract class ShippingEasy
   public static $partnerApiSecret;
   public static $apiBase = 'https://api.shippingeasy.com';
   public static $apiVersion = null;
-  const VERSION = '0.4.3';
+  final const VERSION = '0.4.3';
 
   public static function getApiKey()
   {
diff --git a/lib/ShippingEasy/Signature.php b/lib/ShippingEasy/Signature.php
index 5fdbe61..9c9a7d7 100644
--- a/lib/ShippingEasy/Signature.php
+++ b/lib/ShippingEasy/Signature.php
@@ -2,10 +2,16 @@
 
 class ShippingEasy_Signature
 {
+  public $api_secret;
+  public $http_method;
+  public $path;
+  public $params;
+  public $json_body;
+
   public function __construct($api_secret=null, $http_method=null, $path=null, $params=null, $json_body=null)
   {
     $this->api_secret = $api_secret;
-    $this->http_method = strtoupper($http_method);
+    $this->http_method = strtoupper((string) $http_method);
     $this->path = $path;
     ksort($params);
     $this->params = $params;
@@ -13,7 +19,7 @@ public function __construct($api_secret=null, $http_method=null, $path=null, $pa
     if (is_string($json_body)) {
       $this->json_body = str_replace("\/","/", $json_body);
     } else {
-      $this->json_body = json_encode($json_body);
+      $this->json_body = json_encode($json_body, JSON_THROW_ON_ERROR);
     }
   }
 
@@ -44,7 +50,7 @@ public function getJsonBody()
 
   public function plaintext()
   {
-    $parts = array($this->getHttpMethod());
+    $parts = [$this->getHttpMethod()];
     $parts[] = $this->getPath();
     
     if (!empty($this->getParams()))
@@ -58,7 +64,7 @@ public function plaintext()
 
   public function encrypted()
   {
-    return hash_hmac('sha256', $this->plaintext(), $this->getApiSecret());
+    return hash_hmac('sha256', (string) $this->plaintext(), (string) $this->getApiSecret());
   }
 
   public function equals($signature)
diff --git a/lib/ShippingEasy/SignedUrl.php b/lib/ShippingEasy/SignedUrl.php
index 0d52cde..d80983b 100644
--- a/lib/ShippingEasy/SignedUrl.php
+++ b/lib/ShippingEasy/SignedUrl.php
@@ -2,11 +2,14 @@
 
 class ShippingEasy_SignedUrl
 {
+  public $params;
+  public $path;
+
   public function __construct($http_method=null, $path=null, $params=null, $json_body=null, $api_timestamp=null, $api_key = null, $api_secret = null)
   {
-    $api_secret = isset($api_secret) ? $api_secret : ShippingEasy::$apiSecret;    
-    $params["api_key"] = isset($api_key) ? $api_key : ShippingEasy::$apiKey;
-    $params["api_timestamp"] = isset($api_timestamp) ? $api_timestamp : time();
+    $api_secret ??= ShippingEasy::$apiSecret;    
+    $params["api_key"] = $api_key ?? ShippingEasy::$apiKey;
+    $params["api_timestamp"] = $api_timestamp ?? time();
     $signature_object = new ShippingEasy_Signature($api_secret, $http_method, $path, $params, $json_body);
     $params["api_signature"] = $signature_object->encrypted();