diff --git a/system/engine/abstracthelper.php b/system/engine/abstracthelper.php
index 693fde6..ae93fc6 100644
--- a/system/engine/abstracthelper.php
+++ b/system/engine/abstracthelper.php
@@ -8,6 +8,8 @@
 
 namespace Phacil\Framework;
 
+use Phacil\Framework\Registry;
+
 /** 
  * Abstract class for helpers
  * 
@@ -15,7 +17,7 @@ namespace Phacil\Framework;
  * @abstract
  * @api
  */
-abstract class AbstractHelper {
+abstract class AbstractHelper implements \Phacil\Framework\Interfaces\Helper {
 	
 	/**
 	 * 
@@ -45,7 +47,7 @@ abstract class AbstractHelper {
 
 	/**
 	 * 
-	 * @return object 
+	 * {@inheritdoc}
 	 */
 	static public function getInstance()
 	{
diff --git a/system/engine/autoload.php b/system/engine/autoload.php
index 12f4499..d47166c 100644
--- a/system/engine/autoload.php
+++ b/system/engine/autoload.php
@@ -86,6 +86,10 @@
 		'traits\\action',
 		'interfaces\\databases',
 		'interfaces\\serializer',
+		'interfaces\\common\\registers',
+		'interfaces\\controller',
+		'interfaces\\helper',
+		'interfaces\\model',
 		'exception',
 		'render',
 		'debug',
diff --git a/system/engine/controller.php b/system/engine/controller.php
index 62e0b7b..2d8bf62 100644
--- a/system/engine/controller.php
+++ b/system/engine/controller.php
@@ -8,7 +8,8 @@
 
 namespace Phacil\Framework;
 
-use \Phacil\Framework\Config;
+use Phacil\Framework\Config;
+use Phacil\Framework\Registry;
 
 /** 
  * Extend this class to create interation with your module controller to Phacil engine controller.
@@ -35,7 +36,7 @@ use \Phacil\Framework\Config;
  * @since 0.1.0
  * @api
  */
-abstract class Controller {
+abstract class Controller implements \Phacil\Framework\Interfaces\Controller {
     /**
      * 
      * @var Registry
@@ -135,7 +136,7 @@ abstract class Controller {
 
     /**
      * 
-     * @return object 
+     * {@inheritdoc}
      */
     static public function getInstance() {
         $class = get_called_class();
@@ -143,9 +144,8 @@ abstract class Controller {
     }
 
     /**
-     * 
      * @param string $key 
-     * @return Registry 
+     * @return object 
      * @final
      */
     final public function __get($key) {
@@ -156,6 +156,20 @@ abstract class Controller {
         return $this->registry->get($key);
     }
 
+    /**
+     * @param string $key 
+     * @return object 
+     * @final
+     * @todo Not yet...
+     */
+    /* final public function __call($key, array $arguments) {
+        if (!$this->registry) {
+            $this->__getRegistryClass();
+        }
+
+        return $this->registry->get($key);
+    } */
+
     /**
      * 
      * @param string $key 
diff --git a/system/engine/interfaces/common/registers.php b/system/engine/interfaces/common/registers.php
new file mode 100644
index 0000000..a806b6f
--- /dev/null
+++ b/system/engine/interfaces/common/registers.php
@@ -0,0 +1,39 @@
+<?php
+/**
+ * Copyright © 2023 ExacTI Technology Solutions. All rights reserved.
+ * GPLv3 General License.
+ * https://exacti.com.br
+ * Phacil PHP Framework - https://github.com/exacti/phacil-framework
+ */
+
+
+namespace Phacil\Framework\Interfaces\Common;
+
+
+/** 
+ * @since 2.0.0
+ * @property \Phacil\Framework\Interfaces\Databases $db 
+ * @property \Phacil\Framework\Session $session
+ * @property \Phacil\Framework\Request $request
+ * @property \Phacil\Framework\Url $url
+ * @property \Phacil\Framework\Mail $mail
+ * @property \Phacil\Framework\Loader $loader
+ * @property \Phacil\Framework\startEngineExacTI $engine 
+ * @property \Phacil\Framework\Config $config
+ * @property \Phacil\Framework\Log $log
+ * @property \Phacil\Framework\Caches $cache
+ * @property \Phacil\Framework\Response $response
+ * @property \Phacil\Framework\Document $document
+ * @property \Phacil\Framework\Front $front
+ * @property \Phacil\Framework\Translate $translate
+ * @package Phacil\Framework\Interfaces 
+ */
+interface Registers {
+
+	/**
+	 * 
+	 * @return $this
+	 */
+	static public function getInstance();
+
+}
\ No newline at end of file
diff --git a/system/engine/interfaces/controller.php b/system/engine/interfaces/controller.php
new file mode 100644
index 0000000..34b82ae
--- /dev/null
+++ b/system/engine/interfaces/controller.php
@@ -0,0 +1,23 @@
+<?php
+/**
+ * Copyright © 2023 ExacTI Technology Solutions. All rights reserved.
+ * GPLv3 General License.
+ * https://exacti.com.br
+ * Phacil PHP Framework - https://github.com/exacti/phacil-framework
+ */
+
+
+namespace Phacil\Framework\Interfaces;
+
+/**
+ * 
+ * @package Phacil\Framework\Interfaces
+ */
+interface Controller extends \Phacil\Framework\Interfaces\Common\Registers {
+
+	/**
+	 * 
+	 * {@inheritdoc}
+	 */
+	static public function getInstance();
+}
\ No newline at end of file
diff --git a/system/engine/interfaces/helper.php b/system/engine/interfaces/helper.php
new file mode 100644
index 0000000..e0267fc
--- /dev/null
+++ b/system/engine/interfaces/helper.php
@@ -0,0 +1,17 @@
+<?php
+/**
+ * Copyright © 2023 ExacTI Technology Solutions. All rights reserved.
+ * GPLv3 General License.
+ * https://exacti.com.br
+ * Phacil PHP Framework - https://github.com/exacti/phacil-framework
+ */
+
+
+namespace Phacil\Framework\Interfaces;
+
+use Phacil\Framework\Interfaces\Common\Registers as CommonRegisters;
+
+/** @package Phacil\Framework\Interfaces */
+interface Helper extends CommonRegisters {
+
+}
\ No newline at end of file
diff --git a/system/engine/interfaces/model.php b/system/engine/interfaces/model.php
new file mode 100644
index 0000000..b59194b
--- /dev/null
+++ b/system/engine/interfaces/model.php
@@ -0,0 +1,20 @@
+<?php
+/**
+ * Copyright © 2023 ExacTI Technology Solutions. All rights reserved.
+ * GPLv3 General License.
+ * https://exacti.com.br
+ * Phacil PHP Framework - https://github.com/exacti/phacil-framework
+ */
+
+
+namespace Phacil\Framework\Interfaces;
+
+use Phacil\Framework\Interfaces\Common\Registers as CommonRegisters;
+
+/**
+ * 
+ * @package Phacil\Framework\Interfaces
+ */
+interface Model extends CommonRegisters {
+
+}
\ No newline at end of file
diff --git a/system/engine/model.php b/system/engine/model.php
index cf454dd..df643a7 100644
--- a/system/engine/model.php
+++ b/system/engine/model.php
@@ -9,6 +9,9 @@
 
 namespace Phacil\Framework;
 
+use Phacil\Framework\Registry;
+use Phacil\Framework\Interfaces\Model as ModelInterface;
+
 /** 
  * The default model class.
  * 
@@ -18,7 +21,7 @@ namespace Phacil\Framework;
  * @abstract
  * @api
  */
-abstract class Model {
+abstract class Model implements ModelInterface {
 	
 	/**
 	 * 
@@ -50,7 +53,7 @@ abstract class Model {
 
 	/**
 	 * 
-	 * @return object
+	 * {@inheritdoc}
 	 */
 	static public function getInstance()
 	{
diff --git a/system/engine/registry.php b/system/engine/registry.php
index 269010a..2a854f5 100644
--- a/system/engine/registry.php
+++ b/system/engine/registry.php
@@ -69,7 +69,7 @@ final class Registry {
 
 	/**
 	 * @param string $key 
-	 * @param string $value 
+	 * @param mixed $value 
 	 * @return void 
 	 */
 	public function set($key, $value) {
diff --git a/system/engine/restful.php b/system/engine/restful.php
index a7abdc5..f1507ac 100644
--- a/system/engine/restful.php
+++ b/system/engine/restful.php
@@ -10,6 +10,8 @@
 namespace Phacil\Framework;
 
 use Phacil\Framework\Controller;
+use Phacil\Framework\Request;
+use Phacil\Framework\ReflectionMethod;
 
 /**
  * Create a simple and faster REST API controller.
@@ -86,6 +88,7 @@ abstract class RESTful extends Controller {
 						$data = Request::HEADER($value->getName());
 						break;
 					
+					case 'POST':
 					default:
 						try {
 							$data = (Request::POST($value->getName())) ?: Request::INPUT($value->getName());
diff --git a/system/language/autoload.php b/system/language/autoload.php
index b33c74a..f6d6fa6 100644
--- a/system/language/autoload.php
+++ b/system/language/autoload.php
@@ -1,4 +1,10 @@
 <?php
+/**
+ * Copyright © 2022 ExacTI Technology Solutions. All rights reserved.
+ * GPLv3 General License.
+ * https://exacti.com.br
+ * Phacil PHP Framework - https://github.com/exacti/phacil-framework
+ */
 
 namespace Phacil\Framework;
 
@@ -7,7 +13,7 @@ use Phacil\Framework\Config;
  * @since 2.0.0
  * @package Phacil\Framework
  */
-final class Language
+class Language
 {
 	public $directory;
 	private $data = array();
diff --git a/system/session/autoload.php b/system/session/autoload.php
index 3461a41..defc677 100644
--- a/system/session/autoload.php
+++ b/system/session/autoload.php
@@ -240,4 +240,24 @@ final class Session
     {
         return session_id();
     }
+
+    /**
+     * 
+     * @param string $key 
+     * @return mixed|null 
+     */
+    public function getData($key) {
+        return $this->data[$key] ?? null;
+    }
+
+    /**
+     * 
+     * @param string $key 
+     * @param mixed $value 
+     * @return $this 
+     */
+    public function setData($key, $value) {
+        $this->data[$key] = $value;
+        return $this;
+    }
 }