diff --git a/Api/Admin.php b/Api/Admin.php
index 6976d73..24bf5e6 100644
--- a/Api/Admin.php
+++ b/Api/Admin.php
@@ -29,7 +29,7 @@ class Admin extends \Api_Abstract
      *
      * @return string[]
      */
-    public function get_something($data)
+    public function get_something($data): array
     {
         $result = [
             'apple',
diff --git a/Api/Client.php b/Api/Client.php
index 9c244a7..ee6262f 100644
--- a/Api/Client.php
+++ b/Api/Client.php
@@ -31,7 +31,7 @@ class Client extends \Api_Abstract
      *
      * Be careful not to expose sensitive data from the Admin API.
      */
-    public function get_info($data)
+    public function get_info($data): array
     {
         // call custom event hook. All active modules will be notified
         $this->di['events_manager']->fire(['event' => 'onAfterClientCalledExampleModule', 'params' => ['key' => 'value']]);
diff --git a/Api/Guest.php b/Api/Guest.php
index c58cb94..fc74d18 100644
--- a/Api/Guest.php
+++ b/Api/Guest.php
@@ -33,15 +33,13 @@ class Guest extends \Api_Abstract
      *
      * @return string
      */
-    public function readme($data)
+    public function readme(): string
     {
         // We'll be using the file_get_contents to fetch the full content of the README file
         // Our example admin and client area pages will use this function to fetch the README data
         // Then, we'll tell Twig to parse and display the markdown output
 
-        $readme = file_get_contents(PATH_MODS . '/Example/README.md');
-
-        return $readme;
+        return file_get_contents(PATH_MODS . '/Example/README.md');
     }
 
     /**
@@ -49,7 +47,7 @@ public function readme($data)
      *
      * @return int
      */
-    public function random_number()
+    public function random_number(): int
     {
         return random_int(1, 100);
     }
diff --git a/Controller/Admin.php b/Controller/Admin.php
index 5a2a242..fe76d9d 100644
--- a/Controller/Admin.php
+++ b/Controller/Admin.php
@@ -48,7 +48,7 @@ public function getDi()
      *
      * @return array
      */
-    public function fetchNavigation()
+    public function fetchNavigation(): array
     {
         return [
             'group' => [
@@ -77,7 +77,7 @@ public function fetchNavigation()
      * @example $app->get('/example/test',      'get_test', null, get_class($this)); // calls get_test method on this class
      * @example $app->get('/example/:id',        'get_index', array('id'=>'[0-9]+'), get_class($this));
      */
-    public function register(\Box_App &$app)
+    public function register(\Box_App &$app): void
     {
         $app->get('/example', 'get_index', [], static::class);
         $app->get('/example/test', 'get_test', [], static::class);
diff --git a/Controller/Client.php b/Controller/Client.php
index d0260e3..843a66f 100644
--- a/Controller/Client.php
+++ b/Controller/Client.php
@@ -48,7 +48,7 @@ public function getDi()
      *
      * @param \Box_App $app - returned by reference
      */
-    public function register(\Box_App &$app)
+    public function register(\Box_App &$app): void
     {
         $app->get('/example', 'get_index', [], static::class);
         $app->get('/example/protected', 'get_protected', [], static::class);
diff --git a/README.md b/README.md
index a97efcd..cbbf977 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,3 @@
-
 # Example module README file
 
 This module provides a starting point for the developers on creating their FOSSBilling module.
diff --git a/Service.php b/Service.php
index 7cf9056..6f11dbd 100644
--- a/Service.php
+++ b/Service.php
@@ -43,7 +43,7 @@ public function setDi(mixed $di)
      *
      * @throws \Box_Exception
      */
-    public function install()
+    public function install(): bool
     {
         // Execute SQL script if needed
         $db = $this->di['db'];
@@ -56,7 +56,7 @@ public function install()
     /**
      * Method to uninstall module. In most cases you will use this
      * to remove database tables for your module.
-     * 
+     *
      * You also can opt to keep the data in the database if you want
      * to keep the data for future use.
      *
@@ -64,7 +64,7 @@ public function install()
      *
      * @throws \Box_Exception
      */
-    public function uninstall()
+    public function uninstall(): bool
     {
         // throw new \Box_Exception("Throw exception to terminate module uninstallation process with a message", array(), 124);
         return true;
@@ -81,7 +81,7 @@ public function uninstall()
      *
      * @throws \Box_Exception
      */
-    public function update($manifest)
+    public function update(array $manifest): bool
     {
         // throw new \Box_Exception("Throw exception to terminate module update process with a message", array(), 125);
         return true;
@@ -95,12 +95,12 @@ public function update($manifest)
      *
      * @return array() = list of 2 parameters: array($sql, $params)
      */
-    public function getSearchQuery($data)
+    public function getSearchQuery(array $data): array
     {
         $params = [];
         $sql = "SELECT meta_key, meta_value
             FROM extension_meta
-            WHERE extension = 'example' ";
+            WHERE extension = 'example'";
 
         $client_id = $data['client_id'] ?? null;
 
@@ -117,13 +117,13 @@ public function getSearchQuery($data)
     /**
      * Methods is a delegate for one database row.
      *
-     * @param array  $row  - array representing one database row
+     * @param array $row - array representing one database row
      * @param string $role - guest|client|admin who is calling this method
-     * @param bool   $deep - true|false deep or light version of result to return to API
+     * @param bool $deep - true|false deep or light version of result to return to API
      *
      * @return array
      */
-    public function toApiArray($row, $role = 'guest', $deep = true)
+    public function toApiArray(array $row, string $role = 'guest', bool $deep = true): array
     {
         return $row;
     }
@@ -144,7 +144,7 @@ public function toApiArray($row, $role = 'guest', $deep = true)
      *
      * @throws \Box_Exception
      */
-    public static function onEventClientLoginFailed(\Box_Event $event)
+    public static function onEventClientLoginFailed(\Box_Event $event): void
     {
         // getting Dependency Injector
         $di = $event->getDi();
@@ -199,7 +199,7 @@ public static function onEventClientLoginFailed(\Box_Event $event)
     /**
      * This event hook is registered in example module client API call.
      */
-    public static function onAfterClientCalledExampleModule(\Box_Event $event)
+    public static function onAfterClientCalledExampleModule(\Box_Event $event): void
     {
         // error_log('Called event from example module');