diff --git a/htdocs/composer.json b/htdocs/composer.json
new file mode 100644
index 000000000000..c865b09771c9
--- /dev/null
+++ b/htdocs/composer.json
@@ -0,0 +1,81 @@
+{
+    "name": "impresscms/impresscms",
+    "description": "ImpressCMS - A dynamic and user-friendly Content Management System",
+    "type": "project",
+    "keywords": ["cms", "content-management", "php", "mysql", "web"],
+    "homepage": "https://www.impresscms.org/",
+    "license": "GPL-2.0",
+    "authors": [
+        {
+            "name": "The ImpressCMS Project",
+            "homepage": "https://www.impresscms.org/",
+            "role": "Developer"
+        }
+    ],
+    "require": {
+        "php": ">=7.4.0",
+        "ext-gd": "*",
+        "ext-json": "*",
+        "ext-mbstring": "*",
+        "ext-mysqli": "*",
+        "ext-pcre": "*",
+        "ext-pdo": "*",
+        "ext-session": "*",
+        "ext-xml": "*",
+        "ext-zlib": "*"
+    },
+    "require-dev": {
+        "phpunit/phpunit": "^9.0",
+        "squizlabs/php_codesniffer": "^3.0"
+    },
+    "autoload": {
+        "psr-4": {
+            "Icms\\": "libraries/icms/"
+        },
+        "psr-0": {
+            "icms_": "libraries/"
+        },
+        "classmap": [
+            "libraries/icms.php"
+        ]
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "Icms\\Tests\\": "../tests/"
+        }
+    },
+    "config": {
+        "optimize-autoloader": true,
+        "classmap-authoritative": false,
+        "apcu-autoloader": true,
+        "sort-packages": true,
+        "allow-plugins": {
+            "*": false
+        },
+        "cache-dir": "var/cache/composer",
+        "vendor-dir": "vendor"
+    },
+    "scripts": {
+        "test": "phpunit",
+        "cs-check": "phpcs --standard=PSR12 libraries/icms/",
+        "cs-fix": "phpcbf --standard=PSR12 libraries/icms/",
+        "optimize-production": [
+            "composer dump-autoload --optimize --classmap-authoritative --apcu",
+            "@php -r \"echo 'Production autoloader optimized for ImpressCMS\\n';\""
+        ],
+        "optimize-development": [
+            "composer dump-autoload --optimize",
+            "@php -r \"echo 'Development autoloader optimized for ImpressCMS\\n';\""
+        ],
+        "post-autoload-dump": [
+            "@php -r \"echo 'Autoloader optimized for ImpressCMS\\n';\""
+        ]
+    },
+    "extra": {
+        "branch-alias": {
+            "dev-master": "2.0.x"
+        }
+    },
+    "minimum-stability": "stable",
+    "prefer-stable": true
+}
diff --git a/htdocs/include/functions.php b/htdocs/include/functions.php
index 79520a84d628..576c8dd2de2a 100644
--- a/htdocs/include/functions.php
+++ b/htdocs/include/functions.php
@@ -1612,17 +1612,25 @@ function &icms_getModuleHandler($name = null, $module_dir = null, $module_basena
 		if (class_exists($class)) {
 			$handlers[$module_dir][$name] = new $class(icms::$xoopsDB);
 		} else {
-			if($module_dir !== 'system') {
-				if (!file_exists($hnd_file = ICMS_ROOT_PATH . "/modules/{$module_dir}/class/". ucfirst(strtolower($name)) ."Handler.php")) {
-					$hnd_file = ICMS_ROOT_PATH . "/modules/{$module_dir}/class/{$name}.php";
-				}
+			// Try alternative class naming patterns with autoloading
+			$alternativeClass = ucfirst(strtolower($module_basename)) . ucfirst($name) . 'Handler';
+			if (class_exists($alternativeClass)) {
+				$handlers[$module_dir][$name] = new $alternativeClass(icms::$xoopsDB);
 			} else {
-				$hnd_file = ICMS_ROOT_PATH . "/modules/{$module_dir}/admin/{$name}/class/{$name}.php";
-			}
-			if (file_exists($hnd_file)) {include_once $hnd_file;}
-			$class = ucfirst(strtolower($module_basename)) . ucfirst($name) . 'Handler';
-			if (class_exists($class)) {
-				$handlers[$module_dir][$name] = new $class(icms::$xoopsDB);
+				// Fallback to manual include for legacy modules not yet using autoloading
+				if($module_dir !== 'system') {
+					if (!file_exists($hnd_file = ICMS_ROOT_PATH . "/modules/{$module_dir}/class/". ucfirst(strtolower($name)) ."Handler.php")) {
+						$hnd_file = ICMS_ROOT_PATH . "/modules/{$module_dir}/class/{$name}.php";
+					}
+				} else {
+					$hnd_file = ICMS_ROOT_PATH . "/modules/{$module_dir}/admin/{$name}/class/{$name}.php";
+				}
+				if (file_exists($hnd_file)) {
+					include_once $hnd_file;
+					if (class_exists($alternativeClass)) {
+						$handlers[$module_dir][$name] = new $alternativeClass(icms::$xoopsDB);
+					}
+				}
 			}
 		}
 	}
diff --git a/htdocs/install/common.inc.php b/htdocs/install/common.inc.php
index 5a9650eb4ae6..a691e859fac0 100644
--- a/htdocs/install/common.inc.php
+++ b/htdocs/install/common.inc.php
@@ -37,9 +37,21 @@
 require_once 'include/functions.php';
 include_once './class/IcmsInstallWizard.php';
 
+// Initialize the modern autoloading system
+if (file_exists('../vendor/autoload.php')) {
+    require_once '../vendor/autoload.php';
+}
+
+// Load the compatibility bridge
+require_once '../libraries/icms/ComposerAutoloadBridge.php';
+
+// Initialize legacy autoloader for backward compatibility
 require_once '../libraries/icms/Autoloader.php';
 icms_Autoloader::setup();
 
+// Initialize the bridge
+icms_ComposerAutoloadBridge::initialize();
+
 error_reporting(E_ALL);
 
 $pageHasHelp = false;
diff --git a/htdocs/libraries/icms.php b/htdocs/libraries/icms.php
index 42f9b13ceabf..4c90b871abbc 100644
--- a/htdocs/libraries/icms.php
+++ b/htdocs/libraries/icms.php
@@ -111,13 +111,35 @@ static public function setup() {
 		self::$paths['www']		= array(ICMS_ROOT_PATH, ICMS_URL);
 		self::$paths['modules']	= array(ICMS_ROOT_PATH . '/modules', ICMS_URL . '/modules');
 		self::$paths['themes']	= array(ICMS_THEME_PATH, ICMS_THEME_URL);
-		// Initialize the autoloader
-		require_once dirname(__FILE__ ) . '/icms/Autoloader.php';
-		icms_Autoloader::setup();
+
+		// Initialize autoloading system
+		self::initializeAutoloading();
+
 		register_shutdown_function(array(__CLASS__, 'shutdown'));
 		self::buildRelevantUrls();
 	}
 
+	/**
+	 * Initialize the autoloading system with Composer and legacy support
+	 */
+	static private function initializeAutoloading() {
+		// Try to load Composer autoloader first - now located in htdocs/vendor/
+		$composerAutoloadPath = ICMS_ROOT_PATH . '/vendor/autoload.php';
+		if (file_exists($composerAutoloadPath)) {
+			require_once $composerAutoloadPath;
+		}
+
+		// Load the compatibility bridge
+		require_once dirname(__FILE__) . '/icms/ComposerAutoloadBridge.php';
+
+		// Initialize legacy autoloader for backward compatibility
+		require_once dirname(__FILE__) . '/icms/Autoloader.php';
+		icms_Autoloader::setup();
+
+		// Initialize the bridge
+		icms_ComposerAutoloadBridge::initialize();
+	}
+
 	/**
 	 * Launch bootstrap and instanciate global services
 	 * @return void
diff --git a/htdocs/libraries/icms/AutoloadPerformanceMonitor.php b/htdocs/libraries/icms/AutoloadPerformanceMonitor.php
new file mode 100644
index 000000000000..4367d7dd77e8
--- /dev/null
+++ b/htdocs/libraries/icms/AutoloadPerformanceMonitor.php
@@ -0,0 +1,212 @@
+<?php
+/**
+ * ImpressCMS Autoload Performance Monitor
+ *
+ * This class provides performance monitoring and optimization tools
+ * for the autoloading system.
+ *
+ * @copyright	http://www.impresscms.org/ The ImpressCMS Project
+ * @license		http://www.gnu.org/licenses/old-licenses/gpl-2.0.html GNU General Public License (GPL)
+ * @category	ICMS
+ * @package		Core
+ * @since		1.5
+ */
+
+class icms_AutoloadPerformanceMonitor {
+    
+    /**
+     * Performance metrics
+     * @var array
+     */
+    private static $metrics = array(
+        'class_loads' => 0,
+        'load_times' => array(),
+        'failed_loads' => 0,
+        'cache_hits' => 0,
+        'cache_misses' => 0
+    );
+    
+    /**
+     * Whether monitoring is enabled
+     * @var bool
+     */
+    private static $enabled = false;
+    
+    /**
+     * Start performance monitoring
+     */
+    public static function enable() {
+        if (!self::$enabled) {
+            self::$enabled = true;
+            self::registerMonitoringAutoloader();
+        }
+    }
+    
+    /**
+     * Stop performance monitoring
+     */
+    public static function disable() {
+        self::$enabled = false;
+    }
+    
+    /**
+     * Register a monitoring autoloader
+     */
+    private static function registerMonitoringAutoloader() {
+        spl_autoload_register(array(__CLASS__, 'monitoringAutoloader'), true, true);
+    }
+    
+    /**
+     * Monitoring autoloader that tracks performance
+     * 
+     * @param string $class The class name
+     * @return bool
+     */
+    public static function monitoringAutoloader($class) {
+        if (!self::$enabled) {
+            return false;
+        }
+        
+        $startTime = microtime(true);
+        
+        // Let other autoloaders handle the actual loading
+        $loaded = false;
+        $autoloaders = spl_autoload_functions();
+        
+        foreach ($autoloaders as $autoloader) {
+            if ($autoloader === array(__CLASS__, 'monitoringAutoloader')) {
+                continue; // Skip ourselves
+            }
+            
+            if (is_callable($autoloader)) {
+                if (call_user_func($autoloader, $class)) {
+                    $loaded = true;
+                    break;
+                }
+            }
+        }
+        
+        $endTime = microtime(true);
+        $loadTime = ($endTime - $startTime) * 1000; // Convert to milliseconds
+        
+        // Record metrics
+        if ($loaded) {
+            self::$metrics['class_loads']++;
+            self::$metrics['load_times'][] = $loadTime;
+            
+            // Check if it was a cache hit (very fast load)
+            if ($loadTime < 0.1) {
+                self::$metrics['cache_hits']++;
+            } else {
+                self::$metrics['cache_misses']++;
+            }
+        } else {
+            self::$metrics['failed_loads']++;
+        }
+        
+        return $loaded;
+    }
+    
+    /**
+     * Get performance metrics
+     * 
+     * @return array
+     */
+    public static function getMetrics() {
+        $metrics = self::$metrics;
+        
+        if (!empty($metrics['load_times'])) {
+            $metrics['average_load_time'] = array_sum($metrics['load_times']) / count($metrics['load_times']);
+            $metrics['max_load_time'] = max($metrics['load_times']);
+            $metrics['min_load_time'] = min($metrics['load_times']);
+        }
+        
+        $metrics['cache_hit_ratio'] = 0;
+        if (($metrics['cache_hits'] + $metrics['cache_misses']) > 0) {
+            $metrics['cache_hit_ratio'] = $metrics['cache_hits'] / ($metrics['cache_hits'] + $metrics['cache_misses']);
+        }
+        
+        return $metrics;
+    }
+    
+    /**
+     * Reset performance metrics
+     */
+    public static function resetMetrics() {
+        self::$metrics = array(
+            'class_loads' => 0,
+            'load_times' => array(),
+            'failed_loads' => 0,
+            'cache_hits' => 0,
+            'cache_misses' => 0
+        );
+    }
+    
+    /**
+     * Generate a performance report
+     * 
+     * @return string
+     */
+    public static function generateReport() {
+        $metrics = self::getMetrics();
+        
+        $report = "ImpressCMS Autoload Performance Report\n";
+        $report .= "=====================================\n\n";
+        
+        $report .= "Classes Loaded: " . $metrics['class_loads'] . "\n";
+        $report .= "Failed Loads: " . $metrics['failed_loads'] . "\n";
+        $report .= "Cache Hits: " . $metrics['cache_hits'] . "\n";
+        $report .= "Cache Misses: " . $metrics['cache_misses'] . "\n";
+        $report .= "Cache Hit Ratio: " . number_format($metrics['cache_hit_ratio'] * 100, 2) . "%\n\n";
+        
+        if (isset($metrics['average_load_time'])) {
+            $report .= "Average Load Time: " . number_format($metrics['average_load_time'], 3) . "ms\n";
+            $report .= "Max Load Time: " . number_format($metrics['max_load_time'], 3) . "ms\n";
+            $report .= "Min Load Time: " . number_format($metrics['min_load_time'], 3) . "ms\n\n";
+        }
+        
+        // Performance recommendations
+        $report .= "Recommendations:\n";
+        $report .= "----------------\n";
+        
+        if ($metrics['cache_hit_ratio'] < 0.8) {
+            $report .= "- Consider enabling APCu for better caching performance\n";
+            $report .= "- Run 'composer optimize-production' for production environments\n";
+        }
+        
+        if (isset($metrics['average_load_time']) && $metrics['average_load_time'] > 1.0) {
+            $report .= "- Average load time is high, consider optimizing autoloader\n";
+            $report .= "- Check for unnecessary file system operations\n";
+        }
+        
+        if ($metrics['failed_loads'] > 0) {
+            $report .= "- " . $metrics['failed_loads'] . " failed loads detected, check class naming\n";
+        }
+        
+        return $report;
+    }
+    
+    /**
+     * Check if autoloader optimizations are available
+     * 
+     * @return array
+     */
+    public static function checkOptimizations() {
+        $optimizations = array();
+        
+        // Check for APCu
+        $optimizations['apcu_available'] = extension_loaded('apcu') && apcu_enabled();
+        
+        // Check for Composer optimizations
+        $optimizations['composer_optimized'] = false;
+        if (file_exists(ICMS_ROOT_PATH . '/vendor/composer/autoload_classmap.php')) {
+            $classmap = include ICMS_ROOT_PATH . '/vendor/composer/autoload_classmap.php';
+            $optimizations['composer_optimized'] = !empty($classmap);
+        }
+        
+        // Check for production mode
+        $optimizations['production_mode'] = !defined('ICMS_DEBUG') || !ICMS_DEBUG;
+        
+        return $optimizations;
+    }
+}
diff --git a/htdocs/libraries/icms/Autoloader.php b/htdocs/libraries/icms/Autoloader.php
index 53dc6f733001..64cdfbd1b463 100644
--- a/htdocs/libraries/icms/Autoloader.php
+++ b/htdocs/libraries/icms/Autoloader.php
@@ -34,10 +34,19 @@ class icms_Autoloader {
 
 	/**
 	 * Initialize the autoloader, and register its autoload method
+	 *
+	 * @deprecated 1.5.0 The legacy icms_Autoloader is deprecated in favor of Composer's PSR-4 autoloader.
+	 *                   It is maintained for backward compatibility but will be removed in a future version.
+	 *                   New code should rely on Composer's autoloading system.
 	 * @return void
 	 */
 	static public function setup() {
 		if (!self::$initialized) {
+			// Log deprecation notice in debug mode
+			if (defined('ICMS_DEBUG') && ICMS_DEBUG) {
+				error_log('DEPRECATED: icms_Autoloader is deprecated. Use Composer autoloader instead.');
+			}
+
 			self::register(dirname(dirname(__FILE__)));
 			spl_autoload_register(array('icms_Autoloader', 'autoload'));
 			spl_autoload_register(array('icms_Autoloader', 'registerLegacy'));
diff --git a/htdocs/libraries/icms/ComposerAutoloadBridge.php b/htdocs/libraries/icms/ComposerAutoloadBridge.php
new file mode 100644
index 000000000000..2123bfcc2547
--- /dev/null
+++ b/htdocs/libraries/icms/ComposerAutoloadBridge.php
@@ -0,0 +1,159 @@
+<?php
+/**
+ * ImpressCMS Composer Autoload Bridge
+ *
+ * This class provides backward compatibility between the legacy icms_Autoloader
+ * and Composer's PSR-4 autoloader, ensuring a smooth transition without breaking
+ * existing code.
+ *
+ * @copyright	http://www.impresscms.org/ The ImpressCMS Project
+ * @license		http://www.gnu.org/licenses/old-licenses/gpl-2.0.html GNU General Public License (GPL)
+ * @category	ICMS
+ * @package		Core
+ * @since		1.5
+ * @author		ImpressCMS Modernization Team
+ */
+
+class icms_ComposerAutoloadBridge {
+    
+    /**
+     * Whether the bridge has been initialized
+     * @var bool
+     */
+    private static $initialized = false;
+    
+    /**
+     * Legacy autoloader instance
+     * @var icms_Autoloader
+     */
+    private static $legacyAutoloader = null;
+    
+    /**
+     * Class aliases for backward compatibility
+     * @var array
+     */
+    private static $classAliases = array();
+    
+    /**
+     * Initialize the bridge between Composer and legacy autoloaders
+     */
+    public static function initialize() {
+        if (self::$initialized) {
+            return;
+        }
+        
+        // Register our bridge autoloader with high priority
+        spl_autoload_register(array(__CLASS__, 'autoload'), true, true);
+        
+        // Keep reference to legacy autoloader for fallback
+        if (class_exists('icms_Autoloader', false)) {
+            self::$legacyAutoloader = 'icms_Autoloader';
+        }
+        
+        // Set up class aliases for common patterns
+        self::setupClassAliases();
+        
+        self::$initialized = true;
+    }
+    
+    /**
+     * Bridge autoloader that handles both PSR-4 and legacy patterns
+     * 
+     * @param string $class The class name to load
+     * @return bool True if class was loaded, false otherwise
+     */
+    public static function autoload($class) {
+        // Handle class aliases first
+        if (isset(self::$classAliases[$class])) {
+            $realClass = self::$classAliases[$class];
+            if (class_exists($realClass, true)) {
+                class_alias($realClass, $class);
+                return true;
+            }
+        }
+        
+        // Try to convert PSR-4 style to PSR-0 for backward compatibility
+        if (strpos($class, '\\') !== false) {
+            $psr0Class = str_replace('\\', '_', $class);
+            if (class_exists($psr0Class, true)) {
+                class_alias($psr0Class, $class);
+                return true;
+            }
+        }
+        
+        // Try legacy autoloader as fallback
+        if (self::$legacyAutoloader && method_exists(self::$legacyAutoloader, 'autoload')) {
+            return call_user_func(array(self::$legacyAutoloader, 'autoload'), $class);
+        }
+        
+        return false;
+    }
+    
+    /**
+     * Set up class aliases for common naming patterns
+     */
+    private static function setupClassAliases() {
+        // Common aliases that might be needed
+        self::$classAliases = array(
+            // PSR-4 to PSR-0 mappings
+            'Icms\\Core\\Security' => 'icms_core_Security',
+            'Icms\\Core\\Logger' => 'icms_core_Logger',
+            'Icms\\Core\\Session' => 'icms_core_Session',
+            'Icms\\Auth\\Factory' => 'icms_auth_Factory',
+            'Icms\\Config\\Handler' => 'icms_config_Handler',
+            'Icms\\Module\\Object' => 'icms_module_Object',
+            'Icms\\Module\\Handler' => 'icms_module_Handler',
+            
+            // Legacy XOOPS compatibility
+            'XoopsObject' => 'icms_core_Object',
+            'XoopsObjectHandler' => 'icms_core_ObjectHandler',
+        );
+    }
+    
+    /**
+     * Register a class alias
+     * 
+     * @param string $alias The alias name
+     * @param string $realClass The real class name
+     */
+    public static function registerAlias($alias, $realClass) {
+        self::$classAliases[$alias] = $realClass;
+    }
+    
+    /**
+     * Register multiple class aliases
+     * 
+     * @param array $aliases Array of alias => realClass mappings
+     */
+    public static function registerAliases(array $aliases) {
+        self::$classAliases = array_merge(self::$classAliases, $aliases);
+    }
+    
+    /**
+     * Check if Composer autoloader is available
+     * 
+     * @return bool True if Composer autoloader is loaded
+     */
+    public static function isComposerAvailable() {
+        return class_exists('Composer\\Autoload\\ClassLoader', false);
+    }
+    
+    /**
+     * Get the legacy autoloader instance
+     * 
+     * @return string|null The legacy autoloader class name
+     */
+    public static function getLegacyAutoloader() {
+        return self::$legacyAutoloader;
+    }
+    
+    /**
+     * Disable the bridge (for testing purposes)
+     */
+    public static function disable() {
+        if (self::$initialized) {
+            spl_autoload_unregister(array(__CLASS__, 'autoload'));
+            self::$initialized = false;
+        }
+    }
+}
diff --git a/htdocs/libraries/icms/module/Object.php b/htdocs/libraries/icms/module/Object.php
index 68237685b80c..1502daf45587 100644
--- a/htdocs/libraries/icms/module/Object.php
+++ b/htdocs/libraries/icms/module/Object.php
@@ -129,12 +129,57 @@ public function registerClassPath($isactive = NULL) {
 		// check if module is active (only if applicable)
 		if ($isactive !== NULL && $this->getVar("isactive") != (int) $isactive) return;
 
-		// register class path
+		// register class path with both legacy and Composer autoloaders
 		if ($this->getVar("ipf")) {
 			$modname = ($this->getVar("modname") != "") ? $this->getVar("modname") : $this->getVar("dirname");
-			icms_Autoloader::register($class_path, "mod_" . $modname);
+			$namespace = "mod_" . $modname;
+
+			// Register with legacy autoloader for backward compatibility
+			icms_Autoloader::register($class_path, $namespace);
+
+			// Register with Composer autoloader if available
+			$this->registerWithComposer($class_path, $namespace);
 		} else {
+			// Register with legacy autoloader
 			icms_Autoloader::register($class_path);
+
+			// Register with Composer autoloader if available
+			$this->registerWithComposer($class_path);
+		}
+	}
+
+	/**
+	 * Register module classes with Composer autoloader
+	 *
+	 * @param string $class_path Path to the module classes
+	 * @param string $namespace Optional namespace prefix
+	 */
+	private function registerWithComposer($class_path, $namespace = '') {
+		// Check if Composer autoloader is available
+		if (!class_exists('Composer\\Autoload\\ClassLoader', false)) {
+			return;
+		}
+
+		// Get the Composer autoloader instance
+		$autoloadFiles = spl_autoload_functions();
+		$composerLoader = null;
+
+		foreach ($autoloadFiles as $autoloader) {
+			if (is_array($autoloader) &&
+				is_object($autoloader[0]) &&
+				$autoloader[0] instanceof Composer\Autoload\ClassLoader) {
+				$composerLoader = $autoloader[0];
+				break;
+			}
+		}
+
+		if ($composerLoader) {
+			// Add PSR-0 mapping for module classes
+			if ($namespace) {
+				$composerLoader->add($namespace . '_', $class_path);
+			} else {
+				$composerLoader->add('', $class_path);
+			}
 		}
 	}