diff --git a/Classes/AdditionalPageIndexer.php b/Classes/AdditionalPageIndexer.php
deleted file mode 100644
index 6f71cdec4a..0000000000
--- a/Classes/AdditionalPageIndexer.php
+++ /dev/null
@@ -1,36 +0,0 @@
-<?php
-
-/*
- * This file is part of the TYPO3 CMS project.
- *
- * It is free software; you can redistribute it and/or modify it under
- * the terms of the GNU General Public License, either version 2
- * of the License, or any later version.
- *
- * For the full copyright and license information, please read the
- * LICENSE.txt file that was distributed with this source code.
- *
- * The TYPO3 project - inspiring people to share!
- */
-
-namespace ApacheSolrForTypo3\Solr;
-
-use ApacheSolrForTypo3\Solr\System\Solr\Document\Document;
-
-/**
- * Interface that defines the method an indexer must implement to provide
- * additional documents to index for a page being indexed.
- *
- * @author Ingo Renner <ingo@typo3.org>
- */
-interface AdditionalPageIndexer
-{
-    /**
-     * Provides additional documents that should be indexed together with a page.
-     *
-     * @param Document $pageDocument The original page document.
-     * @param array $allDocuments An array containing all the documents collected until here, including the page document
-     * @return array An array of additional \ApacheSolrForTypo3\Solr\System\Solr\Document\Document objects
-     */
-    public function getAdditionalPageDocuments(Document $pageDocument, array $allDocuments): array;
-}
diff --git a/Classes/Event/Indexing/BeforeDocumentIsProcessedForIndexingEvent.php b/Classes/Event/Indexing/BeforeDocumentIsProcessedForIndexingEvent.php
new file mode 100644
index 0000000000..a642566a6f
--- /dev/null
+++ b/Classes/Event/Indexing/BeforeDocumentIsProcessedForIndexingEvent.php
@@ -0,0 +1,83 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the TYPO3 CMS project.
+ *
+ * It is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License, either version 2
+ * of the License, or any later version.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * The TYPO3 project - inspiring people to share!
+ */
+
+namespace ApacheSolrForTypo3\Solr\Event\Indexing;
+
+use ApacheSolrForTypo3\Solr\IndexQueue\Item;
+use ApacheSolrForTypo3\Solr\System\Solr\Document\Document;
+use TYPO3\CMS\Core\Site\Entity\Site;
+use TYPO3\CMS\Core\Site\Entity\SiteLanguage;
+
+/**
+ * Allows third party extensions to provide additional documents which
+ * should be indexed for the current item.
+ *
+ * Previously used with
+ * $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['IndexQueueIndexer']['indexItemAddDocuments']
+ */
+class BeforeDocumentIsProcessedForIndexingEvent
+{
+    /**
+     * @var Document[]
+     */
+    private array $documents = [];
+
+    public function __construct(
+        private readonly Document $document,
+        private readonly Site $site,
+        private readonly SiteLanguage $siteLanguage,
+        private readonly Item $indexQueueItem
+    ) {
+        $this->documents[] = $this->document;
+    }
+
+    public function getSite(): Site
+    {
+        return $this->site;
+    }
+
+    public function getSiteLanguage(): SiteLanguage
+    {
+        return $this->siteLanguage;
+    }
+
+    public function getIndexQueueItem(): Item
+    {
+        return $this->indexQueueItem;
+    }
+
+    public function getDocument(): Document
+    {
+        return $this->document;
+    }
+
+    /**
+     * @param Document[] $documents
+     */
+    public function addDocuments(array $documents): void
+    {
+        $this->documents = array_merge($this->documents, $documents);
+    }
+
+    /**
+     * @return Document[]
+     */
+    public function getDocuments(): array
+    {
+        return $this->documents;
+    }
+}
diff --git a/Classes/Event/Indexing/BeforeDocumentsAreIndexedEvent.php b/Classes/Event/Indexing/BeforeDocumentsAreIndexedEvent.php
new file mode 100644
index 0000000000..153f5d81d1
--- /dev/null
+++ b/Classes/Event/Indexing/BeforeDocumentsAreIndexedEvent.php
@@ -0,0 +1,78 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the TYPO3 CMS project.
+ *
+ * It is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License, either version 2
+ * of the License, or any later version.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * The TYPO3 project - inspiring people to share!
+ */
+
+namespace ApacheSolrForTypo3\Solr\Event\Indexing;
+
+use ApacheSolrForTypo3\Solr\IndexQueue\Item;
+use ApacheSolrForTypo3\Solr\System\Solr\Document\Document;
+use TYPO3\CMS\Core\Site\Entity\Site;
+use TYPO3\CMS\Core\Site\Entity\SiteLanguage;
+
+/**
+ * An event to manipulate documents right before they get added to the Solr index.
+ *
+ * Previously used with
+ * $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['IndexQueueIndexer']['preAddModifyDocuments']
+ */
+class BeforeDocumentsAreIndexedEvent
+{
+    public function __construct(
+        private readonly Document $document,
+        private readonly Site $site,
+        private readonly SiteLanguage $siteLanguage,
+        private readonly Item $indexQueueItem,
+        /**  @var Document[] */
+        private array $documents,
+    ) {
+    }
+
+    public function getSite(): Site
+    {
+        return $this->site;
+    }
+
+    public function getSiteLanguage(): SiteLanguage
+    {
+        return $this->siteLanguage;
+    }
+
+    public function getIndexQueueItem(): Item
+    {
+        return $this->indexQueueItem;
+    }
+
+    public function getDocument(): Document
+    {
+        return $this->document;
+    }
+
+    /**
+     * @param Document[] $documents
+     */
+    public function addDocuments(array $documents): void
+    {
+        $this->documents = array_merge($this->documents, $documents);
+    }
+
+    /**
+     * @return Document[]
+     */
+    public function getDocuments(): array
+    {
+        return $this->documents;
+    }
+}
diff --git a/Classes/Event/Indexing/BeforePageDocumentIsProcessedForIndexingEvent.php b/Classes/Event/Indexing/BeforePageDocumentIsProcessedForIndexingEvent.php
new file mode 100644
index 0000000000..4c8e7e3d92
--- /dev/null
+++ b/Classes/Event/Indexing/BeforePageDocumentIsProcessedForIndexingEvent.php
@@ -0,0 +1,82 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the TYPO3 CMS project.
+ *
+ * It is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License, either version 2
+ * of the License, or any later version.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * The TYPO3 project - inspiring people to share!
+ */
+
+namespace ApacheSolrForTypo3\Solr\Event\Indexing;
+
+use ApacheSolrForTypo3\Solr\IndexQueue\Item;
+use ApacheSolrForTypo3\Solr\System\Solr\Document\Document;
+use TYPO3\CMS\Core\Site\Entity\Site;
+use TYPO3\CMS\Core\Site\Entity\SiteLanguage;
+
+/**
+ * Allows to add more documents to the Solr index.
+ *
+ * Previously used with
+ * $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['Indexer']['indexPageAddDocuments']
+ */
+class BeforePageDocumentIsProcessedForIndexingEvent
+{
+    /**
+     * @var Document[]
+     */
+    private array $documents = [];
+
+    public function __construct(
+        private readonly Document $document,
+        private readonly Site $site,
+        private readonly SiteLanguage $siteLanguage,
+        private readonly Item $indexQueueItem
+    ) {
+        $this->documents[] = $this->document;
+    }
+
+    public function getSite(): Site
+    {
+        return $this->site;
+    }
+
+    public function getSiteLanguage(): SiteLanguage
+    {
+        return $this->siteLanguage;
+    }
+
+    public function getIndexQueueItem(): Item
+    {
+        return $this->indexQueueItem;
+    }
+
+    public function getDocument(): Document
+    {
+        return $this->document;
+    }
+
+    /**
+     * @param Document[] $documents
+     */
+    public function addDocuments(array $documents): void
+    {
+        $this->documents = array_merge($this->documents, $documents);
+    }
+
+    /**
+     * @return Document[]
+     */
+    public function getDocuments(): array
+    {
+        return $this->documents;
+    }
+}
diff --git a/Classes/IndexQueue/AdditionalIndexQueueItemIndexer.php b/Classes/IndexQueue/AdditionalIndexQueueItemIndexer.php
deleted file mode 100644
index 736bb3b641..0000000000
--- a/Classes/IndexQueue/AdditionalIndexQueueItemIndexer.php
+++ /dev/null
@@ -1,37 +0,0 @@
-<?php
-
-/*
- * This file is part of the TYPO3 CMS project.
- *
- * It is free software; you can redistribute it and/or modify it under
- * the terms of the GNU General Public License, either version 2
- * of the License, or any later version.
- *
- * For the full copyright and license information, please read the
- * LICENSE.txt file that was distributed with this source code.
- *
- * The TYPO3 project - inspiring people to share!
- */
-
-namespace ApacheSolrForTypo3\Solr\IndexQueue;
-
-use ApacheSolrForTypo3\Solr\System\Solr\Document\Document;
-
-/**
- * Interface that defines the method an indexer must implement to provide
- * additional documents to index for an item being indexed by the Index Queue.
- *
- * @author Ingo Renner <ingo@typo3.org>
- */
-interface AdditionalIndexQueueItemIndexer
-{
-    /**
-     * Provides additional documents that should be indexed together with an Index Queue item.
-     *
-     * @param Item $item The item currently being indexed.
-     * @param int $language The language uid of the documents
-     * @param Document $itemDocument The original item document.
-     * @return Document[] array An array of additional Document objects
-     */
-    public function getAdditionalItemDocuments(Item $item, int $language, Document $itemDocument): array;
-}
diff --git a/Classes/IndexQueue/Indexer.php b/Classes/IndexQueue/Indexer.php
index 065cdca188..6871fd8dcb 100644
--- a/Classes/IndexQueue/Indexer.php
+++ b/Classes/IndexQueue/Indexer.php
@@ -21,6 +21,8 @@
 use ApacheSolrForTypo3\Solr\Domain\Search\ApacheSolrDocument\Builder;
 use ApacheSolrForTypo3\Solr\Domain\Site\Site;
 use ApacheSolrForTypo3\Solr\Domain\Site\SiteRepository;
+use ApacheSolrForTypo3\Solr\Event\Indexing\BeforeDocumentIsProcessedForIndexingEvent;
+use ApacheSolrForTypo3\Solr\Event\Indexing\BeforeDocumentsAreIndexedEvent;
 use ApacheSolrForTypo3\Solr\Exception as EXTSolrException;
 use ApacheSolrForTypo3\Solr\FieldProcessor\Service;
 use ApacheSolrForTypo3\Solr\FrontendEnvironment;
@@ -34,7 +36,7 @@
 use ApacheSolrForTypo3\Solr\System\Solr\ResponseAdapter;
 use ApacheSolrForTypo3\Solr\System\Solr\SolrConnection;
 use Doctrine\DBAL\Exception as DBALException;
-use InvalidArgumentException;
+use Psr\EventDispatcher\EventDispatcherInterface;
 use RuntimeException;
 use Throwable;
 use TYPO3\CMS\Core\Context\LanguageAspectFactory;
@@ -42,13 +44,12 @@
 use TYPO3\CMS\Core\Site\SiteFinder;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
 use TYPO3\CMS\Core\Utility\RootlineUtility;
-use UnexpectedValueException;
 
 /**
  * A general purpose indexer to be used for indexing of any kind of regular
- * records like tt_news, tt_address, and so on.
+ * records like news records, tt_address, and so on.
  * Specialized indexers can extend this class to handle advanced stuff like
- * category resolution in tt_news or file indexing.
+ * category resolution in news records or file indexing.
  *
  * @author Ingo Renner <ingo@typo3.org>
  * @copyright  (c) 2009-2015 Ingo Renner <ingo@typo3.org>
@@ -79,6 +80,7 @@ class Indexer extends AbstractIndexer
     protected bool $loggingEnabled = false;
 
     protected SolrLogManager $logger;
+    protected EventDispatcherInterface $eventDispatcher;
 
     public function __construct(
         array $options = [],
@@ -87,6 +89,7 @@ public function __construct(
         ConnectionManager $connectionManager = null,
         FrontendEnvironment $frontendEnvironment = null,
         SolrLogManager $logger = null,
+        EventDispatcherInterface $eventDispatcher = null,
     ) {
         $this->options = $options;
         $this->pagesRepository = $pagesRepository ?? GeneralUtility::makeInstance(PagesRepository::class);
@@ -94,6 +97,7 @@ public function __construct(
         $this->connectionManager = $connectionManager ?? GeneralUtility::makeInstance(ConnectionManager::class);
         $this->frontendEnvironment = $frontendEnvironment ?? GeneralUtility::makeInstance(FrontendEnvironment::class);
         $this->logger = $logger ?? GeneralUtility::makeInstance(SolrLogManager::class, __CLASS__);
+        $this->eventDispatcher = $eventDispatcher ?? GeneralUtility::makeInstance(EventDispatcherInterface::class);
     }
 
     /**
@@ -149,8 +153,6 @@ public function index(Item $item): bool
      */
     protected function indexItem(Item $item, int $language = 0): bool
     {
-        $documents = [];
-
         $itemDocument = $this->itemToDocument($item, $language);
         if (is_null($itemDocument)) {
             /*
@@ -162,10 +164,13 @@ protected function indexItem(Item $item, int $language = 0): bool
             return true;
         }
 
-        $documents[] = $itemDocument;
-        $documents = array_merge($documents, $this->getAdditionalDocuments($item, $language, $itemDocument));
+        $documents = $this->getAdditionalDocuments($itemDocument, $item, $language);
+
         $documents = $this->processDocuments($item, $documents);
-        $documents = self::preAddModifyDocuments($item, $language, $documents);
+
+        $event = new BeforeDocumentsAreIndexedEvent($itemDocument, $item->getSite()->getTypo3SiteObject(), $item->getSite()->getTypo3SiteObject()->getLanguageById($language), $item, $documents);
+        $event = $this->eventDispatcher->dispatch($event);
+        $documents = $event->getDocuments();
 
         $response = $this->currentlyUsedSolrConnection->getWriteService()->addDocuments($documents);
         if ($response->getHttpStatus() !== 200) {
@@ -406,6 +411,24 @@ protected function getAccessRootline(Item $item): string
         return 'r:' . $accessRestriction;
     }
 
+    /**
+     * Adds the document to the list of all documents (done in the event constructor),
+     * and allows to add more documents before processing all of them.
+     *
+     * @return Document[]
+     */
+    protected function getAdditionalDocuments(Document $itemDocument, Item $item, int $language): array
+    {
+        $event = new BeforeDocumentIsProcessedForIndexingEvent(
+            $itemDocument,
+            $item->getSite()->getTypo3SiteObject(),
+            $item->getSite()->getTypo3SiteObject()->getLanguageById($language),
+            $item
+        );
+        $event = $this->eventDispatcher->dispatch($event);
+        return $event->getDocuments();
+    }
+
     /**
      * Sends the documents to the field processing service which takes care of
      * manipulating fields as defined in the field's configuration.
@@ -436,79 +459,6 @@ protected function processDocuments(Item $item, array $documents): array
         return $documents;
     }
 
-    /**
-     * Allows third party extensions to provide additional documents which
-     * should be indexed for the current item.
-     *
-     * @param Item $item The item currently being indexed.
-     * @param int $language The language uid currently being indexed.
-     * @param Document $itemDocument The document representing the item for the given language.
-     *
-     * @return Document[] array An array of additional Document objects to index.
-     */
-    protected function getAdditionalDocuments(Item $item, int $language, Document $itemDocument): array
-    {
-        $documents = [];
-
-        if (is_array($GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['IndexQueueIndexer']['indexItemAddDocuments'] ?? null)) {
-            foreach ($GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['IndexQueueIndexer']['indexItemAddDocuments'] as $classReference) {
-                if (!class_exists($classReference)) {
-                    throw new InvalidArgumentException('Class does not exits' . $classReference, 1490363487);
-                }
-                $additionalIndexer = GeneralUtility::makeInstance($classReference);
-                if ($additionalIndexer instanceof AdditionalIndexQueueItemIndexer) {
-                    $additionalDocuments = $additionalIndexer->getAdditionalItemDocuments($item, $language, $itemDocument);
-
-                    if (is_array($additionalDocuments)) {
-                        $documents = array_merge(
-                            $documents,
-                            $additionalDocuments
-                        );
-                    }
-                } else {
-                    throw new UnexpectedValueException(
-                        get_class($additionalIndexer) . ' must implement interface ' . AdditionalIndexQueueItemIndexer::class,
-                        1326284551
-                    );
-                }
-            }
-        }
-        return $documents;
-    }
-
-    /**
-     * Provides a hook to manipulate documents right before they get added to
-     * the Solr index.
-     *
-     * @param Item $item The item currently being indexed.
-     * @param int $language The language uid of the documents
-     * @param array $documents An array of documents to be indexed
-     *
-     * @return array An array of modified documents
-     */
-    public static function preAddModifyDocuments(Item $item, int $language, array $documents): array
-    {
-        if (is_array($GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['IndexQueueIndexer']['preAddModifyDocuments'] ?? null)) {
-            foreach ($GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['IndexQueueIndexer']['preAddModifyDocuments'] as $classReference) {
-                $documentsModifier = GeneralUtility::makeInstance($classReference);
-
-                if ($documentsModifier instanceof PageIndexerDocumentsModifier) {
-                    $documents = $documentsModifier->modifyDocuments($item, $language, $documents);
-                } else {
-                    throw new RuntimeException(
-                        'The class "' . get_class($documentsModifier)
-                        . '" registered as document modifier in hook
-							preAddModifyDocuments must implement interface
-							ApacheSolrForTypo3\Solr\IndexQueue\PageIndexerDocumentsModifier',
-                        1309522677
-                    );
-                }
-            }
-        }
-
-        return $documents;
-    }
-
     // Initialization
 
     /**
@@ -683,7 +633,7 @@ protected function setLogging(Item $item): void
      * Logs the item and what document was created from it
      *
      * @param Item $item The item that is being indexed.
-     * @param array $itemDocuments An array of Solr documents created from the item's data
+     * @param Document[] $itemDocuments An array of Solr documents created from the item's data
      * @param ResponseAdapter $response The Solr response for the particular index document
      */
     protected function log(Item $item, array $itemDocuments, ResponseAdapter $response): void
diff --git a/Classes/IndexQueue/PageIndexerDocumentsModifier.php b/Classes/IndexQueue/PageIndexerDocumentsModifier.php
deleted file mode 100644
index 3073266a11..0000000000
--- a/Classes/IndexQueue/PageIndexerDocumentsModifier.php
+++ /dev/null
@@ -1,35 +0,0 @@
-<?php
-
-/*
- * This file is part of the TYPO3 CMS project.
- *
- * It is free software; you can redistribute it and/or modify it under
- * the terms of the GNU General Public License, either version 2
- * of the License, or any later version.
- *
- * For the full copyright and license information, please read the
- * LICENSE.txt file that was distributed with this source code.
- *
- * The TYPO3 project - inspiring people to share!
- */
-
-namespace ApacheSolrForTypo3\Solr\IndexQueue;
-
-/**
- * IndexQueuePageIndexerDocumentsModifier interface, allows to modify documents
- * before adding them to the Solr index in the index queue page indexer.
- *
- * @author Ingo Renner <ingo@typo3.org>
- */
-interface PageIndexerDocumentsModifier
-{
-    /**
-     * Modifies the given documents
-     *
-     * @param Item $item The currently being indexed item.
-     * @param int $language The language uid of the documents
-     * @param array $documents An array of documents to be indexed
-     * @return array An array of modified documents
-     */
-    public function modifyDocuments(Item $item, int $language, array $documents): array;
-}
diff --git a/Classes/Typo3PageIndexer.php b/Classes/Typo3PageIndexer.php
index 75b4ba45ed..1e2e0c557e 100644
--- a/Classes/Typo3PageIndexer.php
+++ b/Classes/Typo3PageIndexer.php
@@ -19,9 +19,10 @@
 
 use ApacheSolrForTypo3\Solr\Access\Rootline;
 use ApacheSolrForTypo3\Solr\Domain\Search\ApacheSolrDocument\Builder;
+use ApacheSolrForTypo3\Solr\Event\Indexing\BeforeDocumentsAreIndexedEvent;
+use ApacheSolrForTypo3\Solr\Event\Indexing\BeforePageDocumentIsProcessedForIndexingEvent;
 use ApacheSolrForTypo3\Solr\FieldProcessor\Service;
 use ApacheSolrForTypo3\Solr\IndexQueue\FrontendHelper\PageFieldMappingIndexer;
-use ApacheSolrForTypo3\Solr\IndexQueue\Indexer;
 use ApacheSolrForTypo3\Solr\IndexQueue\Item;
 use ApacheSolrForTypo3\Solr\System\Configuration\TypoScriptConfiguration;
 use ApacheSolrForTypo3\Solr\System\Logging\DebugWriter;
@@ -29,6 +30,7 @@
 use ApacheSolrForTypo3\Solr\System\Solr\Document\Document;
 use ApacheSolrForTypo3\Solr\System\Solr\SolrConnection;
 use Doctrine\DBAL\Exception as DBALException;
+use Psr\EventDispatcher\EventDispatcherInterface;
 use RuntimeException;
 use Throwable;
 use TYPO3\CMS\Core\Context\Exception\AspectNotFoundException;
@@ -205,8 +207,6 @@ public function setSolrConnection(SolrConnection $solrConnection): void
      */
     public function indexPage(): bool
     {
-        $documents = []; // this will become useful as soon as when starting to index individual records instead of whole pages
-
         if (is_null($this->solrConnection)) {
             // intended early return as it doesn't make sense to continue
             // and waste processing time if the solr server isn't available
@@ -219,14 +219,15 @@ public function indexPage(): bool
         $pageDocument = $this->substitutePageDocument($pageDocument);
 
         self::$pageSolrDocument = $pageDocument;
-        $documents[] = $pageDocument;
-        $documents = $this->getAdditionalDocuments($pageDocument, $documents);
+        $event = new BeforePageDocumentIsProcessedForIndexingEvent($pageDocument, $this->page->getSite(), $this->page->getLanguage(), $this->indexQueueItem);
+        $event = $this->getEventDispatcher()->dispatch($event);
+        $documents = $event->getDocuments();
+
         $this->processDocuments($documents);
-        $documents = Indexer::preAddModifyDocuments(
-            $this->indexQueueItem,
-            $this->page->getLanguage()->getLanguageId(),
-            $documents
-        );
+
+        $event = new BeforeDocumentsAreIndexedEvent($pageDocument, $this->page->getSite(), $this->page->getLanguage(), $this->indexQueueItem, $documents);
+        $event = $this->getEventDispatcher()->dispatch($event);
+        $documents = $event->getDocuments();
 
         $pageIndexed = $this->addDocumentsToSolrIndex($documents);
         $this->documentsSentToSolr = $documents;
@@ -296,8 +297,7 @@ protected function substitutePageDocument(Document $pageDocument): Document
                 $substituteIndexer->setPageIndexingConfigurationName($indexConfigurationName);
             }
 
-            $substituteDocument = $substituteIndexer->getPageDocument($pageDocument);
-            $pageDocument = $substituteDocument;
+            $pageDocument = $substituteIndexer->getPageDocument($pageDocument);
         }
 
         return $pageDocument;
@@ -311,44 +311,11 @@ protected function getIndexConfigurationNameForCurrentPage(): string
         return isset($this->indexQueueItem) ? $this->indexQueueItem->getIndexingConfigurationName() : 'pages';
     }
 
-    /**
-     * Allows third party extensions to provide additional documents which
-     * should be indexed for the current page.
-     *
-     * @param Document $pageDocument The main document representing this page.
-     * @param Document[] $existingDocuments An array of documents already created for this page.
-     * @return array An array of additional Document objects to index
-     */
-    protected function getAdditionalDocuments(Document $pageDocument, array $existingDocuments): array
-    {
-        $documents = $existingDocuments;
-
-        if (!is_array($GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['Indexer']['indexPageAddDocuments'] ?? null)) {
-            return $documents;
-        }
-
-        foreach ($GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['Indexer']['indexPageAddDocuments'] as $classReference) {
-            $additionalIndexer = GeneralUtility::makeInstance($classReference);
-
-            if (!$additionalIndexer instanceof AdditionalPageIndexer) {
-                $message = get_class($additionalIndexer) . ' must implement interface ' . AdditionalPageIndexer::class;
-                throw new UnexpectedValueException($message, 1310491024);
-            }
-
-            $additionalDocuments = $additionalIndexer->getAdditionalPageDocuments($pageDocument, $documents);
-            if (!empty($additionalDocuments)) {
-                $documents = array_merge($documents, $additionalDocuments);
-            }
-        }
-
-        return $documents;
-    }
-
     /**
      * Sends the given documents to the field processing service which takes
      * care of manipulating fields as defined in the field's configuration.
      *
-     * @param array $documents An array of documents to manipulate
+     * @param Document[] $documents An array of documents to manipulate
      * @throws DBALException
      * @throws Exception
      */
@@ -364,7 +331,7 @@ protected function processDocuments(array $documents): void
     /**
      * Adds the collected documents to the Solr index.
      *
-     * @param array $documents An array of Document objects.
+     * @param Document[] $documents An array of Document objects.
      * @return bool TRUE if documents were added successfully, FALSE otherwise
      */
     protected function addDocumentsToSolrIndex(array $documents): bool
@@ -442,10 +409,15 @@ public function setPageAccessRootline(Rootline $accessRootline): void
     /**
      * Gets the documents that have been sent to Solr
      *
-     * @return array An array of Document objects
+     * @return Document[] An array of Document objects
      */
     public function getDocumentsSentToSolr(): array
     {
         return $this->documentsSentToSolr;
     }
+
+    protected function getEventDispatcher(): EventDispatcherInterface
+    {
+        return GeneralUtility::makeInstance(EventDispatcherInterface::class);
+    }
 }
diff --git a/Documentation/Development/Indexing.rst b/Documentation/Development/Indexing.rst
index e126d89871..05016731d8 100644
--- a/Documentation/Development/Indexing.rst
+++ b/Documentation/Development/Indexing.rst
@@ -4,21 +4,44 @@
 Indexing
 ========
 
-In this section i describe the possibilities to extend page indexing in EXT:solr with custom code.
+In this section i describe the possibilities to extend page indexing in EXT:solr with custom code via TYPO3 Hooks or PSR-14 events.
 
 Page Indexing
 =============
 
 There are several points to extend the Typo3PageIndexer class and register own classes that are used during the indexing.
 
-indexPageAddDocuments
----------------------
+BeforePageDocumentIsProcessedForIndexingEvent
+---------------------------------------------
 
-Registered classes can be used to add additional documents to solr when a page get's indexed.
+Registered Event Listeners can be used to add additional documents to solr when a page gets indexed.
 
-Registration with: $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['Indexer']['indexPageAddDocuments']
-Required Interface: AdditionalPageIndexer
+Registration of an event listener in your extension's :file:`Services.yaml`:
 
+..  code-block:: yaml
+
+    MyVendor\MyPackage\EventListeners\MyEventListener:
+      tags:
+        - name: event.listener
+          identifier: 'my-package/modify-documents'
+
+The corresponding event listener class:
+
+..  code-block:: php
+
+    use ApacheSolrForTypo3\Solr\Event\Indexing\BeforePageDocumentIsProcessedForIndexingEvent;
+    use ApacheSolrForTypo3\Solr\System\Solr\Document\Document;
+
+    class MyEventListener {
+
+        public function __invoke(BeforePageDocumentIsProcessedForIndexingEvent $event): void
+        {
+            $additionalDocument = new Document();
+            $event->addDocuments([$additionalDocument]);
+        }
+    }
+
+For other records than pages, the PSR-14 Event :php:class:`ApacheSolrForTypo3\Solr\Event\Indexing\BeforeDocumentIsProcessedForIndexingEvent` can be used.
 
 indexPageSubstitutePageDocument
 -------------------------------
@@ -30,13 +53,35 @@ Registration with: $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['Indexer']['in
 Required Interface: SubstitutePageIndexer
 
 
-preAddModifyDocuments
----------------------
+BeforeDocumentsAreIndexedEvent
+------------------------------
+
+Registered Event Listeners can be used to process Solr documents (pages and records) before they are added to index.
+
+Registration of an event listener in your extension's :file:`Services.yaml`:
+
+..  code-block:: yaml
+
+    MyVendor\MyPackage\EventListeners\MyEventListener:
+      tags:
+        - name: event.listener
+          identifier: 'my-package/modify-documents'
+
+The corresponding event listener class:
+
+..  code-block:: php
+
+    use ApacheSolrForTypo3\Solr\Event\Indexing\BeforeDocumentsAreIndexedEvent;
 
-Registered classes can be used to process Solr documents (pages and records) before they are added to index.
+    class MyEventListener {
 
-Registration with: $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['IndexQueueIndexer']['preAddModifyDocuments']
-Required Interface: PageIndexerDocumentsModifier
+        public function __invoke(BeforeDocumentsAreIndexedEvent $event): void
+        {
+            foreach ($event->getDocuments() as $document) {
+               $document->addField('my_custom_field', 'my_custom_value');
+            }
+        }
+    }
 
 
 Independent indexer
@@ -59,8 +104,7 @@ If external data should be indexed or the RecordIndexer is not required, it is p
    class Indexer
    {
 
-       /** @var ConnectionManager */
-       protected $connectionManager;
+       protected ConnectionManager $connectionManager;
 
        public function __construct()
        {
@@ -96,7 +140,7 @@ If external data should be indexed or the RecordIndexer is not required, it is p
            $connections = $this->connectionManager->getAllConnections();
            foreach ($connections as $connectionLanguage => $connection) {
                /** @var SolrConnection */
-               $connection->getWriteService()->deleteByType('cutom_type');
+               $connection->getWriteService()->deleteByType('custom_type');
            }
        }
 
@@ -148,9 +192,9 @@ If external data should be indexed or the RecordIndexer is not required, it is p
            $document = GeneralUtility::makeInstance(Document::class);
 
            // required fields
-           $document->setField('id', 'cutom_type_' . $itemRecord['uid']);
-           $document->setField('variantId', 'cutom_type' . $itemRecord['uid']);
-           $document->setField('type', 'cutom_type');
+           $document->setField('id', 'custom_type_' . $itemRecord['uid']);
+           $document->setField('variantId', 'custom_type' . $itemRecord['uid']);
+           $document->setField('type', 'custom_type');
            $document->setField('appKey', 'EXT:solr');
            $document->setField('access', ['r:0']);
 
diff --git a/Tests/Integration/Fixtures/Extensions/fake_extension2/Classes/EventListeners/AddAdditionalTestDocumentsToIndexer.php b/Tests/Integration/Fixtures/Extensions/fake_extension2/Classes/EventListeners/AddAdditionalTestDocumentsToIndexer.php
new file mode 100644
index 0000000000..060471d59e
--- /dev/null
+++ b/Tests/Integration/Fixtures/Extensions/fake_extension2/Classes/EventListeners/AddAdditionalTestDocumentsToIndexer.php
@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the TYPO3 CMS project.
+ *
+ * It is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License, either version 2
+ * of the License, or any later version.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * The TYPO3 project - inspiring people to share!
+ */
+
+namespace ApacheSolrForTypo3\SolrFakeExtension2\EventListeners;
+
+use ApacheSolrForTypo3\Solr\Event\Indexing\BeforeDocumentIsProcessedForIndexingEvent;
+use ApacheSolrForTypo3\Solr\System\Solr\Document\Document;
+
+final class AddAdditionalTestDocumentsToIndexer
+{
+    public function __invoke(BeforeDocumentIsProcessedForIndexingEvent $event): void
+    {
+        if (($event->getIndexQueueItem()->getRecord()['activate-event-listener'] ?? '') === true) {
+            $event->addDocuments([new Document(['can-be-an-alternative-record' => 'additional-test-document'])]);
+        }
+    }
+}
diff --git a/Tests/Integration/Fixtures/Extensions/fake_extension2/Configuration/Services.yaml b/Tests/Integration/Fixtures/Extensions/fake_extension2/Configuration/Services.yaml
new file mode 100644
index 0000000000..4b12ac4851
--- /dev/null
+++ b/Tests/Integration/Fixtures/Extensions/fake_extension2/Configuration/Services.yaml
@@ -0,0 +1,10 @@
+services:
+  _defaults:
+    autowire: true
+    autoconfigure: true
+    public: false
+
+  ApacheSolrForTypo3\SolrFakeExtension2\EventListeners\AddAdditionalTestDocumentsToIndexer:
+    tags:
+      - name: event.listener
+        identifier: 'fake-extension2/example-documents-before-indexing'
diff --git a/Tests/Integration/Fixtures/Extensions/fake_extension2/composer.json b/Tests/Integration/Fixtures/Extensions/fake_extension2/composer.json
index d61effbe0c..94cbf3a150 100644
--- a/Tests/Integration/Fixtures/Extensions/fake_extension2/composer.json
+++ b/Tests/Integration/Fixtures/Extensions/fake_extension2/composer.json
@@ -3,6 +3,14 @@
   "type": "typo3-cms-extension",
   "description": "Fake Extension 2",
   "license": "GPL-2.0-or-later",
+  "require": {
+    "typo3/cms-core": "*"
+  },
+  "autoload": {
+    "psr-4": {
+      "ApacheSolrForTypo3\\SolrFakeExtension2\\": "Classes/"
+    }
+  },
   "extra": {
     "typo3/cms": {
       "extension-key": "fake_extension2"
diff --git a/Tests/Integration/IndexQueue/FrontendHelper/TestAdditionalPageIndexer.php b/Tests/Integration/Fixtures/Extensions/fake_extension3/Classes/EventListeners/AddExampleDocumentsBeforePageIndexing.php
similarity index 56%
rename from Tests/Integration/IndexQueue/FrontendHelper/TestAdditionalPageIndexer.php
rename to Tests/Integration/Fixtures/Extensions/fake_extension3/Classes/EventListeners/AddExampleDocumentsBeforePageIndexing.php
index 1e345808cd..fb95bdc6d2 100644
--- a/Tests/Integration/IndexQueue/FrontendHelper/TestAdditionalPageIndexer.php
+++ b/Tests/Integration/Fixtures/Extensions/fake_extension3/Classes/EventListeners/AddExampleDocumentsBeforePageIndexing.php
@@ -15,25 +15,21 @@
  * The TYPO3 project - inspiring people to share!
  */
 
-namespace ApacheSolrForTypo3\Solr\Tests\Integration\IndexQueue\FrontendHelper;
+namespace ApacheSolrForTypo3\SolrFakeExtension3\EventListeners;
 
-use ApacheSolrForTypo3\Solr\AdditionalPageIndexer;
-use ApacheSolrForTypo3\Solr\System\Solr\Document\Document;
+use ApacheSolrForTypo3\Solr\Event\Indexing\BeforePageDocumentIsProcessedForIndexingEvent;
 
-class TestAdditionalPageIndexer implements AdditionalPageIndexer
+final class AddExampleDocumentsBeforePageIndexing
 {
     /**
      * Provides additional documents that should be indexed together with a page.
-     *
-     * @param Document $pageDocument The original page document.
-     * @param array $allDocuments An array containing all the documents collected until here, including the page document
-     * @return Document[] array An array of additional Document objects
      */
-    public function getAdditionalPageDocuments(Document $pageDocument, array $allDocuments): array
+    public function __invoke(BeforePageDocumentIsProcessedForIndexingEvent $event): void
     {
         if (!($_GET['additionalTestPageIndexer'] ?? false)) {
-            return [];
+            return;
         }
+        $pageDocument = $event->getDocument();
         $secondDocument = clone $pageDocument;
 
         $id = $pageDocument['id'];
@@ -41,6 +37,6 @@ public function getAdditionalPageDocuments(Document $pageDocument, array $allDoc
 
         $secondDocument->setField('id', $copyId);
         $secondDocument->setField('custom_stringS', 'additional text');
-        return [$secondDocument];
+        $event->addDocuments([$secondDocument]);
     }
 }
diff --git a/Tests/Integration/Fixtures/Extensions/fake_extension3/Classes/EventListeners/TestModificationOfDocuments.php b/Tests/Integration/Fixtures/Extensions/fake_extension3/Classes/EventListeners/TestModificationOfDocuments.php
new file mode 100644
index 0000000000..019d4cbb39
--- /dev/null
+++ b/Tests/Integration/Fixtures/Extensions/fake_extension3/Classes/EventListeners/TestModificationOfDocuments.php
@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the TYPO3 CMS project.
+ *
+ * It is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License, either version 2
+ * of the License, or any later version.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * The TYPO3 project - inspiring people to share!
+ */
+
+namespace ApacheSolrForTypo3\SolrFakeExtension3\EventListeners;
+
+use ApacheSolrForTypo3\Solr\Event\Indexing\BeforeDocumentsAreIndexedEvent;
+
+final class TestModificationOfDocuments
+{
+    /**
+     * Allows Modification of the Documents before they go into index
+     */
+    public function __invoke(BeforeDocumentsAreIndexedEvent $event): void
+    {
+        foreach ($event->getDocuments() as $document) {
+            $document->addField('postProcessorField_stringS', 'postprocessed');
+        }
+    }
+}
diff --git a/Tests/Integration/Fixtures/Extensions/fake_extension3/Configuration/Services.yaml b/Tests/Integration/Fixtures/Extensions/fake_extension3/Configuration/Services.yaml
new file mode 100644
index 0000000000..f848a6c538
--- /dev/null
+++ b/Tests/Integration/Fixtures/Extensions/fake_extension3/Configuration/Services.yaml
@@ -0,0 +1,15 @@
+services:
+  _defaults:
+    autowire: true
+    autoconfigure: true
+    public: false
+
+  ApacheSolrForTypo3\SolrFakeExtension3\EventListeners\AddExampleDocumentsBeforePageIndexing:
+    tags:
+      - name: event.listener
+        identifier: 'fake-extension3/example-documents-before-page-indexing'
+
+  ApacheSolrForTypo3\SolrFakeExtension3\EventListeners\TestModificationOfDocuments:
+    tags:
+      - name: event.listener
+        identifier: 'fake-extension3/test-modification-of-documents'
diff --git a/Tests/Integration/Fixtures/Extensions/fake_extension3/composer.json b/Tests/Integration/Fixtures/Extensions/fake_extension3/composer.json
index f2c25071d7..c479fe8081 100644
--- a/Tests/Integration/Fixtures/Extensions/fake_extension3/composer.json
+++ b/Tests/Integration/Fixtures/Extensions/fake_extension3/composer.json
@@ -3,6 +3,14 @@
   "type": "typo3-cms-extension",
   "description": "Fake Extension 3 Test",
   "license": "GPL-2.0-or-later",
+  "require": {
+    "typo3/cms-core": "*"
+  },
+  "autoload": {
+    "psr-4": {
+      "ApacheSolrForTypo3\\SolrFakeExtension3\\": "Classes/"
+    }
+  },
   "extra": {
     "typo3/cms": {
       "extension-key": "fake_extension3"
diff --git a/Tests/Integration/Fixtures/Extensions/fake_extension3/ext_localconf.php b/Tests/Integration/Fixtures/Extensions/fake_extension3/ext_localconf.php
index 61adfc065c..c0e8060b99 100644
--- a/Tests/Integration/Fixtures/Extensions/fake_extension3/ext_localconf.php
+++ b/Tests/Integration/Fixtures/Extensions/fake_extension3/ext_localconf.php
@@ -1,11 +1,5 @@
 <?php
 
-use ApacheSolrForTypo3\Solr\Tests\Integration\IndexQueue\FrontendHelper\TestAdditionalPageIndexer;
-use ApacheSolrForTypo3\Solr\Tests\Integration\IndexQueue\FrontendHelper\TestPageIndexerDocumentsModifier;
-
 defined('TYPO3') || die();
 
-$GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['Indexer']['indexPageAddDocuments']['TestAdditionalPageIndexer'] = TestAdditionalPageIndexer::class;
-$GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['IndexQueueIndexer']['preAddModifyDocuments']['TestPageIndexerDocumentsModifier'] = TestPageIndexerDocumentsModifier::class;
-
-$GLOBALS['TYPO3_CONF_VARS']['FE']['enable_mount_pids'] = 1;
+$GLOBALS['TYPO3_CONF_VARS']['FE']['enable_mount_pids'] = true;
diff --git a/Tests/Integration/IndexQueue/FrontendHelper/TestPageIndexerDocumentsModifier.php b/Tests/Integration/IndexQueue/FrontendHelper/TestPageIndexerDocumentsModifier.php
deleted file mode 100644
index 6015ee7bbd..0000000000
--- a/Tests/Integration/IndexQueue/FrontendHelper/TestPageIndexerDocumentsModifier.php
+++ /dev/null
@@ -1,26 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace ApacheSolrForTypo3\Solr\Tests\Integration\IndexQueue\FrontendHelper;
-
-use ApacheSolrForTypo3\Solr\IndexQueue\Item;
-use ApacheSolrForTypo3\Solr\IndexQueue\PageIndexerDocumentsModifier;
-use ApacheSolrForTypo3\Solr\System\Solr\Document\Document;
-
-class TestPageIndexerDocumentsModifier implements PageIndexerDocumentsModifier
-{
-    /**
-     * Allows Modification of the Documents before they go into index
-     *
-     * @param Document[] $documents
-     */
-    public function modifyDocuments(Item $item, int $language, array $documents): array
-    {
-        foreach ($documents as $document) {
-            $document->addField('postProcessorField_stringS', 'postprocessed');
-        }
-
-        return $documents;
-    }
-}
diff --git a/Tests/Integration/IndexQueue/Helpers/DummyAdditionalIndexQueueItemIndexer.php b/Tests/Integration/IndexQueue/Helpers/DummyAdditionalIndexQueueItemIndexer.php
deleted file mode 100644
index 5dc7155800..0000000000
--- a/Tests/Integration/IndexQueue/Helpers/DummyAdditionalIndexQueueItemIndexer.php
+++ /dev/null
@@ -1,41 +0,0 @@
-<?php
-
-/*
- * This file is part of the TYPO3 CMS project.
- *
- * It is free software; you can redistribute it and/or modify it under
- * the terms of the GNU General Public License, either version 2
- * of the License, or any later version.
- *
- * For the full copyright and license information, please read the
- * LICENSE.txt file that was distributed with this source code.
- *
- * The TYPO3 project - inspiring people to share!
- */
-
-namespace ApacheSolrForTypo3\Solr\Tests\Integration\IndexQueue\Helpers;
-
-use ApacheSolrForTypo3\Solr\IndexQueue\AdditionalIndexQueueItemIndexer;
-use ApacheSolrForTypo3\Solr\IndexQueue\Item;
-use ApacheSolrForTypo3\Solr\System\Solr\Document\Document;
-
-/**
- * Class DummyAdditionalIndexQueueItemIndexer for testing purpose
- * @author Thomas Hohn <tho@systime.dk>
- */
-class DummyAdditionalIndexQueueItemIndexer implements AdditionalIndexQueueItemIndexer
-{
-    /**
-     * Provides additional documents that should be indexed together with an Index Queue item.
-     *
-     * @param Item $item The item currently being indexed.
-     * @param int $language The language uid of the documents
-     * @param Document $itemDocument The original item document.
-     *
-     * @return Document[] An array of additional Apache Solr Document objects
-     */
-    public function getAdditionalItemDocuments(Item $item, int $language, Document $itemDocument): array
-    {
-        return [];
-    }
-}
diff --git a/Tests/Integration/IndexQueue/Helpers/DummyIndexer.php b/Tests/Integration/IndexQueue/Helpers/DummyIndexer.php
deleted file mode 100644
index 7ff120b9e4..0000000000
--- a/Tests/Integration/IndexQueue/Helpers/DummyIndexer.php
+++ /dev/null
@@ -1,24 +0,0 @@
-<?php
-
-/*
- * This file is part of the TYPO3 CMS project.
- *
- * It is free software; you can redistribute it and/or modify it under
- * the terms of the GNU General Public License, either version 2
- * of the License, or any later version.
- *
- * For the full copyright and license information, please read the
- * LICENSE.txt file that was distributed with this source code.
- *
- * The TYPO3 project - inspiring people to share!
- */
-
-namespace ApacheSolrForTypo3\Solr\Tests\Integration\IndexQueue\Helpers;
-
-/**
- * Class DummyIndexer for testing purpose
- * @author Thomas Hohn <tho@systime.dk>
- */
-class DummyIndexer
-{
-}
diff --git a/Tests/Integration/IndexQueue/IndexerTest.php b/Tests/Integration/IndexQueue/IndexerTest.php
index 04e23088bc..963b5cc0f2 100644
--- a/Tests/Integration/IndexQueue/IndexerTest.php
+++ b/Tests/Integration/IndexQueue/IndexerTest.php
@@ -15,23 +15,18 @@
 
 namespace ApacheSolrForTypo3\Solr\Tests\Integration\IndexQueue;
 
-use ApacheSolrForTypo3\Solr\IndexQueue\AdditionalIndexQueueItemIndexer;
 use ApacheSolrForTypo3\Solr\IndexQueue\Indexer;
 use ApacheSolrForTypo3\Solr\IndexQueue\Item;
 use ApacheSolrForTypo3\Solr\IndexQueue\Queue;
 use ApacheSolrForTypo3\Solr\System\Solr\Document\Document;
 use ApacheSolrForTypo3\Solr\System\Solr\SolrConnection;
-use ApacheSolrForTypo3\Solr\Tests\Integration\IndexQueue\Helpers\DummyAdditionalIndexQueueItemIndexer;
-use ApacheSolrForTypo3\Solr\Tests\Integration\IndexQueue\Helpers\DummyIndexer;
 use ApacheSolrForTypo3\Solr\Tests\Integration\IntegrationTest;
-use InvalidArgumentException;
 use Psr\Http\Server\RequestHandlerInterface;
 use TYPO3\CMS\Core\Authentication\BackendUserAuthentication;
 use TYPO3\CMS\Core\Http\ServerRequestFactory;
 use TYPO3\CMS\Core\Localization\LanguageServiceFactory;
 use TYPO3\CMS\Core\Middleware\NormalizedParamsAttribute;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
-use UnexpectedValueException;
 
 /**
  * Testcase for the record indexer
@@ -412,59 +407,20 @@ public function canUseConfigurationFromTemplateInRootLine(): void
     /**
      * @test
      */
-    public function canGetAdditionalDocumentsInterfaceOnly(): void
+    public function canGetAdditionalDocumentsViaPsr14EventListener(): void
     {
-        $this->expectException(InvalidArgumentException::class);
-        $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['IndexQueueIndexer']['indexItemAddDocuments'][] = AdditionalIndexQueueItemIndexer::class;
+        $this->importCSVDataSet(__DIR__ . '/../Fixtures/sites_setup_and_data_set/01_integration_tree_one.csv');
         $document = new Document();
-        $metaData = ['item_type' => 'pages'];
-        $record = [];
-        $item = GeneralUtility::makeInstance(Item::class, $metaData, $record);
-        $this->callInaccessibleMethod($this->indexer, 'getAdditionalDocuments', $item, 0, $document);
-    }
-
-    /**
-     * @test
-     */
-    public function canGetAdditionalDocumentsNotImplementingInterface(): void
-    {
-        $this->expectException(UnexpectedValueException::class);
-        $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['IndexQueueIndexer']['indexItemAddDocuments'][] = DummyIndexer::class;
-        $document = new Document();
-        $metaData = ['item_type' => 'pages'];
-        $record = [];
-        $item = GeneralUtility::makeInstance(Item::class, $metaData, $record);
-        $this->callInaccessibleMethod($this->indexer, 'getAdditionalDocuments', $item, 0, $document);
-    }
-
-    /**
-     * @test
-     */
-    public function canGetAdditionalDocumentsNonExistingClass(): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['IndexQueueIndexer']['indexItemAddDocuments'][] = 'NonExistingClass';
-        $document = new Document();
-        $metaData = ['item_type' => 'pages'];
-        $record = [];
-        $item = GeneralUtility::makeInstance(Item::class, $metaData, $record);
-
-        $this->callInaccessibleMethod($this->indexer, 'getAdditionalDocuments', $item, 0, $document);
-    }
-
-    /**
-     * @test
-     */
-    public function canGetAdditionalDocuments(): void
-    {
-        $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['IndexQueueIndexer']['indexItemAddDocuments'][] = DummyAdditionalIndexQueueItemIndexer::class;
-        $document = new Document();
-        $metaData = ['item_type' => 'pages'];
-        $record = [];
-        $item = GeneralUtility::makeInstance(Item::class, $metaData, $record);
-
-        $result = $this->callInaccessibleMethod($this->indexer, 'getAdditionalDocuments', $item, 0, $document);
-        self::assertSame([], $result);
+        $document->setField('original-document', true);
+        $metaData = ['item_type' => 'pages', 'root' => 1];
+        $record = ['uid' => 1, 'pid' => 0, 'activate-event-listener' => true];
+        $item = new Item($metaData, $record);
+
+        $result = $this->callInaccessibleMethod($this->indexer, 'getAdditionalDocuments', $document, $item, 0);
+        // Result contains two documents, one from the event listener and the original one above
+        self::assertCount(2, $result);
+        self::assertSame($document, $result[0]);
+        self::assertEquals(['can-be-an-alternative-record' => 'additional-test-document'], $result[1]->getFields());
     }
 
     /**
diff --git a/Tests/Unit/IndexQueue/IndexerTest.php b/Tests/Unit/IndexQueue/IndexerTest.php
index 518dcff3e4..ec48e4ec03 100644
--- a/Tests/Unit/IndexQueue/IndexerTest.php
+++ b/Tests/Unit/IndexQueue/IndexerTest.php
@@ -16,13 +16,15 @@
 namespace ApacheSolrForTypo3\Solr\Tests\Unit\IndexQueue;
 
 use ApacheSolrForTypo3\Solr\ConnectionManager;
+use ApacheSolrForTypo3\Solr\Domain\Index\Queue\IndexQueueIndexingPropertyRepository;
+use ApacheSolrForTypo3\Solr\Domain\Index\Queue\QueueItemRepository;
 use ApacheSolrForTypo3\Solr\Domain\Search\ApacheSolrDocument\Builder;
+use ApacheSolrForTypo3\Solr\Domain\Site\Site;
+use ApacheSolrForTypo3\Solr\Event\Indexing\BeforeDocumentIsProcessedForIndexingEvent;
 use ApacheSolrForTypo3\Solr\FrontendEnvironment;
-use ApacheSolrForTypo3\Solr\IndexQueue\AdditionalIndexQueueItemIndexer;
 use ApacheSolrForTypo3\Solr\IndexQueue\Exception\IndexingException;
 use ApacheSolrForTypo3\Solr\IndexQueue\Indexer;
 use ApacheSolrForTypo3\Solr\IndexQueue\Item;
-use ApacheSolrForTypo3\Solr\IndexQueue\PageIndexerDocumentsModifier;
 use ApacheSolrForTypo3\Solr\System\Logging\SolrLogManager;
 use ApacheSolrForTypo3\Solr\System\Records\Pages\PagesRepository;
 use ApacheSolrForTypo3\Solr\System\Solr\Document\Document;
@@ -30,11 +32,10 @@
 use ApacheSolrForTypo3\Solr\System\Solr\Service\SolrWriteService;
 use ApacheSolrForTypo3\Solr\System\Solr\SolrConnection;
 use ApacheSolrForTypo3\Solr\Tests\Unit\SetUpUnitTestCase;
-use InvalidArgumentException;
+use Psr\EventDispatcher\EventDispatcherInterface;
 use ReflectionClass;
-use RuntimeException;
+use TYPO3\CMS\Core\Tests\Unit\Fixtures\EventDispatcher\MockEventDispatcher;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
-use UnexpectedValueException;
 
 /**
  * Class IndexerTest
@@ -62,11 +63,14 @@ public function canTriggerIndexingAndIndicateIndexStatus(int $httpStatus, bool $
 
         $indexer = $this->getAccessibleMock(
             Indexer::class,
-            ['itemToDocument', 'processDocuments', 'getAdditionalDocuments'],
+            ['itemToDocument', 'processDocuments'],
             [],
             '',
             false
         );
+        $eventDispatcher = $this->createMock(EventDispatcherInterface::class);
+        $eventDispatcher->expects(self::any())->method('dispatch')->willReturnArgument(0);
+        $indexer->_set('eventDispatcher', $eventDispatcher);
 
         $solrConnectionMock = $this->createMock(SolrConnection::class);
         $solrConnectionMock
@@ -75,7 +79,9 @@ public function canTriggerIndexingAndIndicateIndexStatus(int $httpStatus, bool $
             ->willReturn($writeServiceMock);
         $indexer->_set('currentlyUsedSolrConnection', $solrConnectionMock);
 
+        $siteMock = $this->createMock(Site::class);
         $itemMock = $this->createMock(Item::class);
+        $itemMock->expects(self::any())->method('getSite')->willReturn($siteMock);
         $itemDocumentMock = $this->createMock(Document::class);
         $indexer
             ->expects(self::once())
@@ -83,12 +89,6 @@ public function canTriggerIndexingAndIndicateIndexStatus(int $httpStatus, bool $
             ->with($itemMock, 0)
             ->willReturn($itemDocumentMock);
 
-        $indexer
-            ->expects(self::once())
-            ->method('getAdditionalDocuments')
-            ->with($itemMock, 0, $itemDocumentMock)
-            ->willReturn([]);
-
         $indexer
             ->expects(self::once())
             ->method('processDocuments')
@@ -134,20 +134,8 @@ public function canTriggerIndexingAndIndicateIndexStatusDataProvider(): \Generat
      * @test
      * @dataProvider canGetAdditionalDocumentsDataProvider
      */
-    public function canGetAdditionalDocuments(\stdClass|string|AdditionalIndexQueueItemIndexer|null $class, ?string $expectedException, int $expectedResultCount): void
+    public function canGetAdditionalDocuments(\Closure|null $listener, ?string $expectedException, int $expectedResultCount): void
     {
-        if ($class !== null) {
-            if (is_object($class)) {
-                $classReference = get_class($class);
-                GeneralUtility::addInstance($classReference, $class);
-            } else {
-                $classReference = $class;
-            }
-            $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['IndexQueueIndexer']['indexItemAddDocuments'] = [
-                $classReference,
-            ];
-        }
-
         $indexer = $this->getAccessibleMock(
             Indexer::class,
             null,
@@ -156,17 +144,37 @@ public function canGetAdditionalDocuments(\stdClass|string|AdditionalIndexQueueI
             false
         );
 
+        $eventDispatcher = new MockEventDispatcher();
+        if ($listener) {
+            $eventDispatcher->addListener($listener);
+        }
+        $indexer->_set('eventDispatcher', $eventDispatcher);
+
         if ($expectedException !== null) {
             self::expectException($expectedException);
         }
 
+        $itemMock = new class ([], [], $this->createMock(IndexQueueIndexingPropertyRepository::class), $this->createMock(QueueItemRepository::class)) extends Item {
+            protected $site;
+            public function setSite(Site $site): void
+            {
+                $this->site = $site;
+            }
+            public function getSite(): ?Site
+            {
+                return $this->site;
+            }
+        };
+        $itemMock->setSite($this->createMock(Site::class));
+
+        // new $itemMock()
         $documents = $indexer->_call(
             'getAdditionalDocuments',
-            $this->createMock(Item::class),
+            new Document(),
+            $itemMock,
             0,
-            $this->createMock(Document::class)
         );
-        self::assertEquals($expectedResultCount, count($documents));
+        self::assertCount($expectedResultCount, $documents);
         foreach ($documents as $document) {
             self::assertTrue($document instanceof Document);
         }
@@ -177,87 +185,28 @@ public function canGetAdditionalDocuments(\stdClass|string|AdditionalIndexQueueI
      */
     public function canGetAdditionalDocumentsDataProvider(): \Generator
     {
-        yield 'no AdditionalIndexQueueItemIndexer registered' => [
+        yield 'no listener registered' => [
             null,
             null,
-            0,
-        ];
-
-        yield 'unknown class as AdditionalIndexQueueItemIndexer registered' => [
-            'invalidClass',
-            InvalidArgumentException::class,
-            0,
-        ];
-
-        yield 'invalid AdditionalIndexQueueItemIndexer registered' => [
-            new \stdClass(),
-            UnexpectedValueException::class,
-            0,
+            1,
         ];
 
-        $indexerMock = $this->createMock(AdditionalIndexQueueItemIndexer::class);
-        $indexerMock
-            ->expects(self::once())
-            ->method('getAdditionalItemDocuments');
-        yield 'valid AdditionalIndexQueueItemIndexer, no additional documents' => [
-            $indexerMock,
+        yield 'valid listener, no additional documents' => [
+            function (BeforeDocumentIsProcessedForIndexingEvent $event) {
+                // Does nothing
+            },
             null,
-            0,
+            1,
         ];
-
-        $indexerMock = $this->createMock(AdditionalIndexQueueItemIndexer::class);
-        $indexerMock
-            ->expects(self::once())
-            ->method('getAdditionalItemDocuments')
-            ->willReturn([$this->createMock(Document::class)]);
-        yield 'valid AdditionalIndexQueueItemIndexer, one additional documents' => [
-            $indexerMock,
+        yield 'valid listener, adds an additional document' => [
+            function (BeforeDocumentIsProcessedForIndexingEvent $event) {
+                $event->addDocuments([new Document()]);
+            },
             null,
-            1,
+            2,
         ];
     }
 
-    /**
-     * @test
-     * @dataProvider canCallDocumentsModifierHookDataProvider
-     */
-    public function canCallDocumentsModifierHook(?object $modifier, ?string $expectedException): void
-    {
-        $itemMock = $this->createMock(Item::class);
-        if ($modifier !== null) {
-            $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['IndexQueueIndexer']['preAddModifyDocuments'] = [
-                get_class($modifier),
-            ];
-        } else {
-            $modifier = $this->createMock(PageIndexerDocumentsModifier::class);
-            $modifier->expects(self::never())->method('modifyDocuments');
-        }
-        GeneralUtility::addInstance(get_class($modifier), $modifier);
-
-        if ($expectedException !== null) {
-            self::expectException($expectedException);
-        }
-
-        Indexer::preAddModifyDocuments($itemMock, 0, []);
-    }
-
-    /**
-     * Data provider for "canCallDocumentsModifierHook"
-     */
-    public function canCallDocumentsModifierHookDataProvider(): \Generator
-    {
-        yield 'no modifier' => [null, null];
-
-        yield 'invalid modifier' => [new \stdClass(), RuntimeException::class];
-
-        $modifierMock = $this->createMock(PageIndexerDocumentsModifier::class);
-        $modifierMock
-            ->expects(self::once())
-            ->method('modifyDocuments')
-            ->willReturn([]);
-        yield 'valid modifier' => [$modifierMock, null];
-    }
-
     /**
      * @test
      * @skip
diff --git a/Tests/Unit/IndexQueue/PageIndexerTest.php b/Tests/Unit/IndexQueue/PageIndexerTest.php
index f53779cf72..61b0690922 100644
--- a/Tests/Unit/IndexQueue/PageIndexerTest.php
+++ b/Tests/Unit/IndexQueue/PageIndexerTest.php
@@ -29,6 +29,7 @@
 use ApacheSolrForTypo3\Solr\System\Records\Pages\PagesRepository;
 use ApacheSolrForTypo3\Solr\Tests\Unit\SetUpUnitTestCase;
 use PHPUnit\Framework\MockObject\MockObject;
+use Psr\EventDispatcher\EventDispatcherInterface;
 
 class PageIndexerTest extends SetUpUnitTestCase
 {
@@ -64,6 +65,7 @@ protected function getPageIndexerWithMockedDependencies(array $options = []): Pa
                     $this->connectionManagerMock,
                     $this->frontendEnvironmentMock,
                     $this->solrLogManagerMock,
+                    $this->createMock(EventDispatcherInterface::class),
                 ]
             )
             ->onlyMethods(['getPageIndexerRequest', 'getAccessRootlineByPageId', 'getUriStrategy'])
diff --git a/composer.json b/composer.json
index 2e60998cf3..8dba6a87a0 100644
--- a/composer.json
+++ b/composer.json
@@ -42,7 +42,7 @@
     "phpunit/phpunit": "^9.5",
     "typo3/cms-fluid-styled-content": "*",
     "typo3/coding-standards": "~0.7.1",
-    "typo3/testing-framework": "^7.0",
+    "typo3/testing-framework": "^7.0.2",
     "phpstan/phpstan": "^1.10",
     "phpstan/phpstan-phpunit": "^1.3"
   },
@@ -59,6 +59,8 @@
   "autoload-dev": {
     "psr-4": {
       "ApacheSolrForTypo3\\Solr\\Tests\\": "Tests/",
+      "ApacheSolrForTypo3\\SolrFakeExtension2\\": "Tests/Integration/Fixtures/Extensions/fake_extension2/Classes/",
+      "ApacheSolrForTypo3\\SolrFakeExtension3\\": "Tests/Integration/Fixtures/Extensions/fake_extension3/Classes/",
       "TYPO3\\CMS\\Core\\Tests\\": ".Build/vendor/typo3/cms-core/Tests/"
     }
   },