diff --git a/module/fid/src/Listener/ClientConfigListener.php b/module/fid/src/Listener/ClientConfigListener.php
index 4933f652946e274b5afff46958fcf4e0c3d96022..5945d1bdf9157d9925f39d919910441e65aec2e9 100644
--- a/module/fid/src/Listener/ClientConfigListener.php
+++ b/module/fid/src/Listener/ClientConfigListener.php
@@ -1,7 +1,11 @@
 <?php
 /**
+ * Fidis client config listener
+ *
  * Copyright (C) 2020 Leipzig University Library
  *
+ * PHP Version 7
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
@@ -15,8 +19,11 @@
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * @author  Sebastian Kehr <kehr@ub.uni-leipzig.de>
- * @license http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @category VuFind
+ * @package  Listener
+ * @author   Sebastian Kehr <kehr@ub.uni-leipzig.de>
+ * @license  http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @link     https://vufind.org/wiki/development Wiki
  */
 namespace fid\Listener;
 
@@ -30,6 +37,15 @@ use Zend\EventManager\EventManagerInterface;
 use Zend\Mvc\MvcEvent;
 use Zend\View\Model\ViewModel;
 
+/**
+ * Fidis client config listener
+ *
+ * @category VuFind
+ * @package  Listener
+ * @author   Sebastian Kehr <kehr@ub.uni-leipzig.de>
+ * @license  http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @link     https://vufind.org/wiki/development Wiki
+ */
 class ClientConfigListener extends AbstractListenerAggregate
 {
     protected const PARAM = 'fidis_base_url';
@@ -42,12 +58,12 @@ class ClientConfigListener extends AbstractListenerAggregate
 
     protected const STATUS = '%sFidis: %s';
 
-    /**
-     * @var array
-     */
+    /* @var array */
     protected $config;
 
     /**
+     * Get configuration
+     *
      * @return array
      */
     public function getConfig(): array
@@ -55,23 +71,32 @@ class ClientConfigListener extends AbstractListenerAggregate
         return $this->config;
     }
 
+    /**
+     * Attach onDispatch method to event (MvcEvent::EVENT_ROUTE)
+     *
+     * @param EventManagerInterface $events   Event manager
+     * @param $priority Used priority
+     *
+     * @return void
+     */
     public function attach(EventManagerInterface $events, $priority = 9000)
     {
         $events->attach(static::EVENT, [$this, 'onDispatch'], $priority);
     }
 
     /**
-     * @param MvcEvent $event
+     * Handling fidis base url update via GET parameter (if allowed in config)
+     *
+     * @param MvcEvent $event Event
      *
+     * @return void
      * @throws ClientException
      */
     public function onDispatch(MvcEvent $event)
     {
-        /**
-         * @var Config $config
-         * @var PluginManager $configManager
-         * @var ContainerInterface $container
-         */
+        /* @var Config $config */
+        /* @var PluginManager $configManager */
+        /* @var ContainerInterface $container */
         $request = $event->getRequest();
         $container = $event->getApplication()->getServiceManager();
         $configManager = $container->get(PluginManager::class);
@@ -98,10 +123,8 @@ class ClientConfigListener extends AbstractListenerAggregate
             $baseUrl = $config->baseUrl;
         }
 
-        /**
-         * @var ViewModel $viewModel
-         * @var CookieManager $cookieManager
-         */
+        /* @var ViewModel $viewModel */
+        /* @var CookieManager $cookieManager */
         $this->config['baseUrl'] = $baseUrl;
         $cookieManager = $container->get(CookieManager::class);
         $cookieManager->set(self::PARAM, $baseUrl);
diff --git a/module/fid/src/Listener/ErrorListener.php b/module/fid/src/Listener/ErrorListener.php
index 6b68145f75eedc70b151fef1fb4d554b16b1ab12..19a136d87d89c97bdb03b3a8c0f224a20027c705 100644
--- a/module/fid/src/Listener/ErrorListener.php
+++ b/module/fid/src/Listener/ErrorListener.php
@@ -1,7 +1,11 @@
 <?php
 /**
+ * Error listener
+ *
  * Copyright (C) 2019 Leipzig University Library
  *
+ * PHP Version 7
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
@@ -15,16 +19,29 @@
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * @author  Sebastian Kehr <kehr@ub.uni-leipzig.de>
- * @license http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @category VuFind
+ * @package  Listener
+ * @author   Sebastian Kehr <kehr@ub.uni-leipzig.de>
+ * @license  http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @link     https://vufind.org/wiki/development Wiki
  */
 namespace fid\Listener;
 
 use Zend\EventManager\AbstractListenerAggregate;
 use Zend\EventManager\EventInterface;
 use Zend\EventManager\EventManagerInterface;
+use Zend\Log\Filter\Priority;
 use Zend\Mvc\MvcEvent;
 
+/**
+ * Error listener
+ *
+ * @category VuFind
+ * @package  Listener
+ * @author   Sebastian Kehr <kehr@ub.uni-leipzig.de>
+ * @license  http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @link     https://vufind.org/wiki/development Wiki
+ */
 class ErrorListener extends AbstractListenerAggregate
 {
     protected const ERROR_EVENTS
@@ -33,6 +50,15 @@ class ErrorListener extends AbstractListenerAggregate
             MvcEvent::EVENT_RENDER_ERROR,
         ];
 
+    /**
+     * Attach onError method to events:
+     * MvcEvent::EVENT_DISPATCH_ERROR and MvcEvent::EVENT_RENDER_ERROR
+     *
+     * @param EventManagerInterface $events   Event manager
+     * @param $priority Used priority
+     *
+     * @return void
+     */
     public function attach(EventManagerInterface $events, $priority = 20000)
     {
         foreach (static::ERROR_EVENTS as $event) {
@@ -41,7 +67,11 @@ class ErrorListener extends AbstractListenerAggregate
     }
 
     /**
-     * @param EventInterface|MvcEvent $event
+     * On error event handling
+     *
+     * @param EventInterface|MvcEvent $event Event
+     *
+     * @return void
      */
     public function onError(EventInterface $event): void
     {
diff --git a/module/fid/src/Listener/LocaleListener.php b/module/fid/src/Listener/LocaleListener.php
index 3634bf9813f9dbc8551d05975db0608769df81ca..48c97fa4d6a8afa911374752afd727c92631394a 100644
--- a/module/fid/src/Listener/LocaleListener.php
+++ b/module/fid/src/Listener/LocaleListener.php
@@ -1,7 +1,11 @@
 <?php
 /**
+ * Locale listener
+ *
  * Copyright (C) 2019 Leipzig University Library
  *
+ * PHP Version 7
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
@@ -15,35 +19,58 @@
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * @author  Sebastian Kehr <kehr@ub.uni-leipzig.de>
- * @license http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @category VuFind
+ * @package  Listener
+ * @author   Sebastian Kehr <kehr@ub.uni-leipzig.de>
+ * @license  http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @link     https://vufind.org/wiki/development Wiki
  */
 namespace fid\Listener;
 
 use fid\Service\Client;
 use Zend\EventManager\AbstractListenerAggregate;
 use Zend\EventManager\EventManagerInterface;
+use Zend\Log\Filter\Priority;
 use Zend\Mvc\I18n\Translator;
 use Zend\Mvc\MvcEvent;
 
+/**
+ * Locale listener
+ *
+ * @category VuFind
+ * @package  Listener
+ * @author   Sebastian Kehr <kehr@ub.uni-leipzig.de>
+ * @license  http://opensource.org/licenses/gpl-2.0.php GNU GPLv2
+ * @link     https://vufind.org/wiki/development Wiki
+ */
 class LocaleListener extends AbstractListenerAggregate
 {
     protected const EVENT = MvcEvent::EVENT_DISPATCH;
 
+    /**
+     * Attach onDispatch method to event (MvcEvent::EVENT_DISPATCH)
+     *
+     * @param EventManagerInterface $events   Event manager
+     * @param $priority Used priority
+     *
+     * @return void
+     */
     public function attach(EventManagerInterface $events, $priority = 9000)
     {
         $events->attach(static::EVENT, [$this, 'onDispatch'], $priority);
     }
 
     /**
-     * @param MvcEvent $event
+     * Set fidis clients locale
+     *
+     * @param MvcEvent $event Event
+     *
+     * @return void
      */
     public function onDispatch(MvcEvent $event)
     {
         $container = $event->getApplication()->getServiceManager();
-        /**
-         * @var Client $client
-         */
+        /* @var Client $client */
         $client = $container->get(Client::class);
         $locale = $container->get(Translator::class)->getLocale();
         $client->setLocale($locale);