diff --git a/composer.json b/composer.json
new file mode 100644
index 0000000..2b1f592
--- /dev/null
+++ b/composer.json
@@ -0,0 +1,20 @@
+{
+  "name": "seka19/tracking-sdk-php",
+  "authors": [
+    {
+      "name": "www.trackingmore.com",
+      "email": "info@trackingmore.org"
+    }
+  ],
+  "description": "Tracking PHP SDK",
+  "license": "MIT",
+  "require": {
+    "php": ">=7.1",
+    "ext-json": "*"
+  },
+  "autoload": {
+    "classmap": [
+      "lib/"
+    ]
+  }
+}
diff --git a/lib/Api.class.php b/lib/Api.class.php
index 4e4f1e0..c4dbb8d 100644
--- a/lib/Api.class.php
+++ b/lib/Api.class.php
@@ -128,7 +128,7 @@ public static function checkParamsRequirements($params)
 	/**
 	* Check if the data meets the requirements.
 	*
-	* @return json response.
+	* @return string response.
 	*/
 	public static function checkSendApi($data)
 	{
@@ -162,7 +162,7 @@ public static function getRequestHeader()
 	/**
 	* send api request.
 	*
-	* @return array $response.
+	* @return string $response.
 	*/
 	public static function sendApiRequest($params = [], $method = "GET")
 	{
@@ -175,7 +175,7 @@ public static function sendApiRequest($params = [], $method = "GET")
 	/**
 	* error params request.
 	*
-	* @return json response.
+	* @return string response.
 	*/
 	public static function errorResponse($code, $message = "", $data = [])
 	{
diff --git a/lib/RequestApi.class.php b/lib/RequestApi.class.php
index 077cb8f..583e876 100644
--- a/lib/RequestApi.class.php
+++ b/lib/RequestApi.class.php
@@ -23,7 +23,7 @@ class RequestApi
 	/**
 	* send api request.
 	*
-	* @return json $response.
+	* @return string $response.
 	*/
 	public static function send($method = "GET")
 	{
@@ -72,7 +72,7 @@ public static function send($method = "GET")
 		$response = curl_exec($curl);
 		curl_close($curl);
 		unset($curl); 
-		return $response;
+		return (string)$response;
 	}
 	
 }
\ No newline at end of file