diff --git a/src/Model/Database.php b/src/Model/Database.php
index 1fd83da7..6d186801 100644
--- a/src/Model/Database.php
+++ b/src/Model/Database.php
@@ -8,10 +8,8 @@ use \Pdo;
 
 class Database
 {
-    // Dependencies
-    public Pdo $connection;
+    protected Pdo $_connection;
 
-    // Requirements
     public Database\Auth $auth;
     public Database\Bookmark $bookmark;
     public Database\Cache $cache;
@@ -30,7 +28,7 @@ class Database
         );
 
         // Init dependencies
-        $this->connection = new Pdo(
+        $this->_connection = new Pdo(
             sprintf(
                 'sqlite:%s',
                 $filename
@@ -39,39 +37,39 @@ class Database
             $password
         );
 
-        $this->connection->setAttribute(
+        $this->_connection->setAttribute(
             Pdo::ATTR_ERRMODE,
             Pdo::ERRMODE_EXCEPTION
         );
 
-        $this->connection->setAttribute(
+        $this->_connection->setAttribute(
             Pdo::ATTR_DEFAULT_FETCH_MODE,
             Pdo::FETCH_OBJ
         );
 
         // Init requirements
         $this->auth = new Database\Auth(
-            $this->connection
+            $this->_connection
         );
 
         $this->bookmark = new Database\Bookmark(
-            $this->connection
+            $this->_connection
         );
 
         $this->cache = new Database\Cache(
-            $this->connection
+            $this->_connection
         );
 
         $this->history = new Database\History(
-            $this->connection
+            $this->_connection
         );
 
         $this->identity = new Database\Identity(
-            $this->connection
+            $this->_connection
         );
 
         $this->session = new Database\Session(
-            $this->connection
+            $this->_connection
         );
 
         // Init data
diff --git a/src/Model/Database/Auth.php b/src/Model/Database/Auth.php
index 94b91c11..99b153b3 100644
--- a/src/Model/Database/Auth.php
+++ b/src/Model/Database/Auth.php
@@ -8,16 +8,16 @@ use \Pdo;
 
 class Auth
 {
-    public Pdo $connection;
+    protected Pdo $_connection;
 
     public function __construct(
         Pdo $connection
     ) {
         // Init parent connection
-        $this->connection = $connection;
+        $this->_connection = $connection;
 
         // Init database structure
-        $this->connection->query('
+        $this->_connection->query('
             CREATE TABLE IF NOT EXISTS `auth`
             (
                 `id`       INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
diff --git a/src/Model/Database/Bookmark.php b/src/Model/Database/Bookmark.php
index 8e94cb3b..473e563d 100644
--- a/src/Model/Database/Bookmark.php
+++ b/src/Model/Database/Bookmark.php
@@ -8,16 +8,16 @@ use \Pdo;
 
 class Bookmark
 {
-    public Pdo $connection;
+    protected Pdo $_connection;
 
     public function __construct(
         Pdo $connection
     ) {
         // Init parent connection
-        $this->connection = $connection;
+        $this->_connection = $connection;
 
         // Init database structure
-        $this->connection->query('
+        $this->_connection->query('
             CREATE TABLE IF NOT EXISTS `bookmark`
             (
                 `id`      INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
@@ -34,7 +34,7 @@ class Bookmark
         ?int $time = null
     ): int
     {
-        $query = $this->connection->prepare(
+        $query = $this->_connection->prepare(
             'INSERT INTO `bookmark` (
                 `time`,
                 `request`,
@@ -55,7 +55,7 @@ class Bookmark
         );
 
         return intval(
-            $this->connection->lastInsertId()
+            $this->_connection->lastInsertId()
         );
     }
 
@@ -63,7 +63,7 @@ class Bookmark
         ?string $request = null
     ): ?object
     {
-        $query = $this->connection->prepare(
+        $query = $this->_connection->prepare(
             'SELECT * FROM `bookmark` WHERE `request` LIKE :request'
         );
 
@@ -87,7 +87,7 @@ class Bookmark
         int $limit = 1000
     ): array
     {
-        $query = $this->connection->prepare(
+        $query = $this->_connection->prepare(
             sprintf(
                 'SELECT * FROM `bookmark`
                           WHERE `request` LIKE :value OR `title` LIKE :value
@@ -116,7 +116,7 @@ class Bookmark
         int $id
     ): int
     {
-        $query = $this->connection->query(
+        $query = $this->_connection->query(
             sprintf(
                 'DELETE FROM `bookmark` WHERE `id` = %d',
                 $id
diff --git a/src/Model/Database/Cache.php b/src/Model/Database/Cache.php
index c180a5c9..b7c353e1 100644
--- a/src/Model/Database/Cache.php
+++ b/src/Model/Database/Cache.php
@@ -8,16 +8,16 @@ use \Pdo;
 
 class Cache
 {
-    public Pdo $connection;
+    protected Pdo $_connection;
 
     public function __construct(
         Pdo $connection
     ) {
         // Init parent connection
-        $this->connection = $connection;
+        $this->_connection = $connection;
 
         // Init database structure
-        $this->connection->query('
+        $this->_connection->query('
             CREATE TABLE IF NOT EXISTS `cache`
             (
                 `id`       INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
@@ -42,7 +42,7 @@ class Cache
         ?int $time = null
     ): int
     {
-        $query = $this->connection->prepare(
+        $query = $this->_connection->prepare(
             'INSERT INTO `cache` (
                 `time`,
                 `request`,
@@ -75,7 +75,7 @@ class Cache
         );
 
         return intval(
-            $this->connection->lastInsertId()
+            $this->_connection->lastInsertId()
         );
     }
 
@@ -83,7 +83,7 @@ class Cache
         string $request = ''
     ): ?object
     {
-        $query = $this->connection->prepare(
+        $query = $this->_connection->prepare(
             'SELECT * FROM `cache` WHERE `request` LIKE :request'
         );
 
@@ -105,7 +105,7 @@ class Cache
         int $id
     ): int
     {
-        $query = $this->connection->query(
+        $query = $this->_connection->query(
             sprintf(
                 'DELETE FROM `cache` WHERE `id` = %d',
                 $id
@@ -119,7 +119,7 @@ class Cache
         int $timeout = 0
     ): int
     {
-        $query = $this->connection->query(
+        $query = $this->_connection->query(
             sprintf(
                 'DELETE FROM `cache` WHERE `time` + %d < %d',
                 $timeout,
@@ -141,7 +141,7 @@ class Cache
     ): void
     {
         // Find same records match URL
-        $query = $this->connection->prepare(
+        $query = $this->_connection->prepare(
             'SELECT * FROM `cache` WHERE `request` LIKE :request'
         );
 
diff --git a/src/Model/Database/History.php b/src/Model/Database/History.php
index 9a6ccd5d..806b553a 100644
--- a/src/Model/Database/History.php
+++ b/src/Model/Database/History.php
@@ -8,16 +8,16 @@ use \Pdo;
 
 class History
 {
-    public Pdo $connection;
+    protected Pdo $_connection;
 
     public function __construct(
         Pdo $connection
     ) {
         // Init parent connection
-        $this->connection = $connection;
+        $this->_connection = $connection;
 
         // Init database structure
-        $this->connection->query('
+        $this->_connection->query('
             CREATE TABLE IF NOT EXISTS `history`
             (
                 `id`    INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
@@ -33,7 +33,7 @@ class History
         ?string $title = null
     ): int
     {
-        $query = $this->connection->prepare(
+        $query = $this->_connection->prepare(
             'INSERT INTO `history` (`time`, `url`, `title`) VALUES (:time, :url, :title)'
         );
 
@@ -46,7 +46,7 @@ class History
         );
 
         return intval(
-            $this->connection->lastInsertId()
+            $this->_connection->lastInsertId()
         );
     }
 
@@ -56,7 +56,7 @@ class History
         int $limit = 1000
     ): array
     {
-        $query = $this->connection->prepare(
+        $query = $this->_connection->prepare(
             sprintf(
                 'SELECT * FROM `history`
                           WHERE `url` LIKE :value OR `title` LIKE :value
@@ -83,7 +83,7 @@ class History
         int $id
     ): int
     {
-        $query = $this->connection->query(
+        $query = $this->_connection->query(
             sprintf(
                 'DELETE FROM `history` WHERE `id` = %d',
                 $id
@@ -97,7 +97,7 @@ class History
         int $timeout = 0
     ): int
     {
-        $query = $this->connection->query(
+        $query = $this->_connection->query(
             sprintf(
                 'DELETE FROM `history` WHERE `time` + %d < %d',
                 $timeout,
@@ -115,7 +115,7 @@ class History
     ): void
     {
         // Find same records match URL
-        $query = $this->connection->prepare(
+        $query = $this->_connection->prepare(
             'SELECT * FROM `history` WHERE `url` LIKE :url'
         );
 
diff --git a/src/Model/Database/Identity.php b/src/Model/Database/Identity.php
index aadd72e4..2bb154ca 100644
--- a/src/Model/Database/Identity.php
+++ b/src/Model/Database/Identity.php
@@ -8,16 +8,16 @@ use \Pdo;
 
 class Identity
 {
-    public Pdo $connection;
+    protected Pdo $_connection;
 
     public function __construct(
         Pdo $connection
     ) {
         // Init parent connection
-        $this->connection = $connection;
+        $this->_connection = $connection;
 
         // Init database structure
-        $this->connection->query('
+        $this->_connection->query('
             CREATE TABLE IF NOT EXISTS `identity`
             (
                 `id`     INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
diff --git a/src/Model/Database/Session.php b/src/Model/Database/Session.php
index 92e8c1c5..f1cd319c 100644
--- a/src/Model/Database/Session.php
+++ b/src/Model/Database/Session.php
@@ -8,16 +8,16 @@ use \Pdo;
 
 class Session
 {
-    public Pdo $connection;
+    protected Pdo $_connection;
 
     public function __construct(
         Pdo $connection
     ) {
         // Init parent connection
-        $this->connection = $connection;
+        $this->_connection = $connection;
 
         // Init database structure
-        $this->connection->query('
+        $this->_connection->query('
             CREATE TABLE IF NOT EXISTS `session`
             (
                 `id`      INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
@@ -32,7 +32,7 @@ class Session
         ?int $time = null
     ): int
     {
-        $query = $this->connection->prepare(
+        $query = $this->_connection->prepare(
             'INSERT INTO `session` (`time`, `request`) VALUES (:time, :request)'
         );
 
@@ -44,13 +44,13 @@ class Session
         );
 
         return intval(
-            $this->connection->lastInsertId()
+            $this->_connection->lastInsertId()
         );
     }
 
     public function get(): array
     {
-        $query = $this->connection->query(
+        $query = $this->_connection->query(
             'SELECT * FROM `session`'
         );
 
@@ -64,7 +64,7 @@ class Session
 
     public function clean(): int
     {
-        $query = $this->connection->query(
+        $query = $this->_connection->query(
             'DELETE FROM `session`'
         );