diff --git a/common.php b/common.php
index 4ad1a9dd6..f65d6fb75 100644
--- a/common.php
+++ b/common.php
@@ -197,9 +197,24 @@ switch ($bb_cfg['datastore_type']) {
         $datastore = new TorrentPier\Legacy\Datastore\File($bb_cfg['cache']['db_dir'] . 'datastore/', $bb_cfg['cache']['prefix']);
 }
 
-function is_ajax(): bool
-{
-    return (!empty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest');
+if (CHECK_REQIREMENTS['status'] && !CACHE('bb_cache')->get('system_req')) {
+    // [1] Check PHP Version
+    if (!\TorrentPier\Helpers\IsHelper::isPHP(CHECK_REQIREMENTS['php_min_version'])) {
+        die("TorrentPier requires PHP version " . CHECK_REQIREMENTS['php_min_version'] . "+ Your PHP version " . PHP_VERSION);
+    }
+
+    // [2] Check installed PHP Extensions on server
+    $data = [];
+    foreach (CHECK_REQIREMENTS['ext_list'] as $ext) {
+        if (!extension_loaded($ext)) {
+            $data[] = $ext;
+        }
+    }
+    if (!empty($data)) {
+        die(sprintf("TorrentPier requires %s extension(s) installed on server", implode(', ', $data)));
+    }
+
+    CACHE('bb_cache')->set('system_req', true);
 }
 
 function sql_dbg_enabled()
diff --git a/library/defines.php b/library/defines.php
index ae12adccc..405900375 100644
--- a/library/defines.php
+++ b/library/defines.php
@@ -11,6 +11,24 @@ if (!defined('BB_ROOT')) {
     die(basename(__FILE__));
 }
 
+// System
+define('CHECK_REQIREMENTS', [
+    'status' => true,
+    'php_min_version' => '7.4.0',
+    'ext_list' => [
+        'json',
+        'gd',
+        'zlib',
+        'curl',
+        'tidy',
+        'mysqli',
+        'bcmath',
+        'intl',
+        'xml',
+        'xmlwriter',
+    ],
+]);
+
 // Root path
 $rootPath = __DIR__;
 if (DIRECTORY_SEPARATOR != '/') $rootPath = str_replace(DIRECTORY_SEPARATOR, '/', $rootPath);
diff --git a/library/includes/init_bb.php b/library/includes/init_bb.php
index da914c743..f387c6792 100644
--- a/library/includes/init_bb.php
+++ b/library/includes/init_bb.php
@@ -11,13 +11,6 @@ if (!defined('BB_ROOT')) {
     die(basename(__FILE__));
 }
 
-/**
- * Check PHP version
- */
-if (PHP_VERSION_ID < 70400) {
-    die('TorrentPier requires PHP version 7.4+. Your PHP version ' . PHP_VERSION);
-}
-
 /**
  * Define some basic configuration arrays
  */
diff --git a/src/Helpers/IsHelper.php b/src/Helpers/IsHelper.php
new file mode 100644
index 000000000..fa81566bc
--- /dev/null
+++ b/src/Helpers/IsHelper.php
@@ -0,0 +1,93 @@
+<?php
+/**
+ * TorrentPier – Bull-powered BitTorrent tracker engine
+ *
+ * @copyright Copyright (c) 2005-2023 TorrentPier (https://torrentpier.com)
+ * @link      https://github.com/torrentpier/torrentpier for the canonical source repository
+ * @license   https://github.com/torrentpier/torrentpier/blob/master/LICENSE MIT License
+ */
+
+namespace TorrentPier\Helpers;
+
+/**
+ * Class IsHelper
+ * @package TorrentPier\Helpers
+ */
+class IsHelper
+{
+    /**
+     * Determines if the current version of PHP is equal to or greater than the supplied value
+     *
+     * @param string $version
+     * @return bool TRUE if the current version is $version or higher
+     */
+    public static function isPHP(string $version): bool
+    {
+        static $_is_php;
+        $version = (string)$version;
+        if (!isset($_is_php[$version])) {
+            $_is_php[$version] = version_compare(PHP_VERSION, $version, '>=');
+        }
+        return $_is_php[$version];
+    }
+
+    /**
+     * Return true if ajax request
+     *
+     * @return bool
+     */
+    public static function isAJAX(): bool
+    {
+        return (!empty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest');
+    }
+
+    /**
+     * Return true if server have SSL
+     *
+     * @return bool
+     */
+    public static function isHTTPS(): bool
+    {
+        $is_secure = false;
+        if (isset($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) == 'on') {
+            $is_secure = true;
+        } elseif (!empty($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https' || !empty($_SERVER['HTTP_X_FORWARDED_SSL']) && $_SERVER['HTTP_X_FORWARDED_SSL'] == 'on') {
+            $is_secure = true;
+        }
+        return $is_secure;
+    }
+
+    /**
+     * Return true if $value contains numbers
+     *
+     * @param string $value
+     * @return bool
+     */
+    public static function isContainsNums(string $value): bool
+    {
+        return preg_match('@[[:digit:]]@', $value);
+    }
+
+    /**
+     * Return true if $value contains letters (Uppercase included)
+     *
+     * @param string $value
+     * @param bool $uppercase
+     * @return bool
+     */
+    public static function isContainsLetters(string $value, bool $uppercase = false): bool
+    {
+        return $uppercase ? preg_match('@[A-Z]@', $value) : preg_match('@[a-z]@', $value);
+    }
+
+    /**
+     * Return true if $value contains special symbols
+     *
+     * @param string $value
+     * @return bool
+     */
+    public static function isContainsSpecSymbols(string $value): bool
+    {
+        return preg_match('@[[:punct:]]@', $value);
+    }
+}
diff --git a/src/Legacy/Ajax.php b/src/Legacy/Ajax.php
index 5d612d077..dcec7d568 100644
--- a/src/Legacy/Ajax.php
+++ b/src/Legacy/Ajax.php
@@ -74,7 +74,7 @@ class Ajax
         // Action params
         $action_params = null;
 
-        if (!is_ajax()) {
+        if (!\TorrentPier\Helpers\IsHelper::isAJAX()) {
             $this->ajax_die('Not AJAX request', E_AJAX_NOT_REQUEST);
         }