diff --git a/.forgejo/workflows/phpunit.yml b/.forgejo/workflows/phpunit.yml
index 125474c..361014b 100644
--- a/.forgejo/workflows/phpunit.yml
+++ b/.forgejo/workflows/phpunit.yml
@@ -37,7 +37,7 @@ jobs:
           path: |
             ${{ env.WP_CORE_DIR }}
             ${{ env.WP_TESTS_DIR }}
-          key: cache-wordpress-5
+          key: cache-wordpress-8
 
       - name: Cache Composer
         id: cache-composer-phpunit
@@ -101,5 +101,10 @@ jobs:
 
       - name: Run Integration tests for WP Event Manager
         run: cd /workspace/Event-Federation/wordpress-activitypub-event-bridge/ && ./vendor/bin/phpunit --filter=wp_event_manager
+        env:
+          PHP_VERSION: ${{ matrix.php-version }}
+
+      - name: Run Integration tests for Eventin (WP Event Solution)
+        run: cd /workspace/Event-Federation/wordpress-activitypub-event-bridge/ && ./vendor/bin/phpunit --filter=eventin
         env:
           PHP_VERSION: ${{ matrix.php-version }}
\ No newline at end of file
diff --git a/bin/install-wp-tests.sh b/bin/install-wp-tests.sh
index 0e0e4ad..759ad25 100755
--- a/bin/install-wp-tests.sh
+++ b/bin/install-wp-tests.sh
@@ -239,6 +239,7 @@ install_wp_plugins() {
 	install_wp_plugin gatherpress
 	install_wp_plugin events-manager
 	install_wp_plugin wp-event-manager
+	install_wp_plugin wp-event-solution
 }
 
 install_wp
diff --git a/composer.json b/composer.json
index 30c3b01..57868bf 100644
--- a/composer.json
+++ b/composer.json
@@ -1,5 +1,6 @@
 {
     "name": "menrath/wordpress-activitypub-event-bridge",
+    "version": "1.0.0",
     "description": "The ActivityPub Event Bridge help for event custom post types to federate properly.",
     "type": "wordpress-plugin",
     "require": {
@@ -51,17 +52,20 @@
             "@test-the-events-calendar",
             "@test-gatherpress",
             "@test-events-manager",
-            "@test-wp-event-manager"
+            "@test-wp-event-manager",
+            "@test-eventin"
         ],
         "test-debug": [
             "@prepare-test",
-            "@test-features"
+            "@test-wp-event-manager"
         ],
         "test-features": "phpunit --filter=reminder",
         "test-vs-event-list": "phpunit --filter=vs_event_list",
         "test-the-events-calendar": "phpunit --filter=the_events_calendar",
         "test-gatherpress": "phpunit --filter=gatherpress",
         "test-events-manager": "phpunit --filter=events_manager",
-        "test-wp-event-manager": "phpunit --filter=wp_event_manager"
+        "test-wp-event-manager": "phpunit --filter=wp_event_manager",
+        "test-eventin": "phpunit --filter=eventin",
+        "test-all": "phpunit"
     }
 }
diff --git a/includes/activitypub/transformer/class-eventin.php b/includes/activitypub/transformer/class-eventin.php
new file mode 100644
index 0000000..b47d93e
--- /dev/null
+++ b/includes/activitypub/transformer/class-eventin.php
@@ -0,0 +1,164 @@
+<?php
+/**
+ * ActivityPub Transformer for Events managed with Eventin.
+ *
+ * @link https://support.themewinter.com/docs/plugins/docs-category/eventin/
+ *
+ * @package ActivityPub_Event_Bridge
+ * @license AGPL-3.0-or-later
+ */
+
+namespace ActivityPub_Event_Bridge\Activitypub\Transformer;
+
+// Exit if accessed directly.
+defined( 'ABSPATH' ) || exit; // @codeCoverageIgnore
+
+use Activitypub\Activity\Extended_Object\Place;
+use ActivityPub_Event_Bridge\Activitypub\Transformer\Event;
+use DateTime;
+use DateTimeZone;
+use Etn\Core\Event\Event_Model;
+
+use function Activitypub\esc_hashtag;
+
+/**
+ * ActivityPub Transformer for Events managed with Eventin.
+ *
+ * @since 1.0.0
+ */
+final class Eventin extends Event {
+
+	/**
+	 * Holds the EM_Event object.
+	 *
+	 * @var Event_Model
+	 */
+	protected $event_model;
+
+	/**
+	 * Extend the constructor, to also set the Event Model.
+	 *
+	 * This is a special class object form The Events Calendar which
+	 * has a lot of useful functions, we make use of our getter functions.
+	 *
+	 * @param WP_Post $wp_object The WordPress object.
+	 * @param string  $wp_taxonomy The taxonomy slug of the event post type.
+	 */
+	public function __construct( $wp_object, $wp_taxonomy ) {
+		parent::__construct( $wp_object, $wp_taxonomy );
+		$this->event_model = new Event_Model( $this->wp_object->ID );
+	}
+
+	/**
+	 * Get the end time from the event object.
+	 */
+	public function get_start_time(): string {
+		return \gmdate( 'Y-m-d\TH:i:s\Z', strtotime( $this->event_model->get_start_datetime() ) );
+	}
+
+	/**
+	 * Get the end time from the event object.
+	 */
+	public function get_end_time(): string {
+		return \gmdate( 'Y-m-d\TH:i:s\Z', strtotime( $this->event_model->get_end_datetime() ) );
+	}
+
+	/**
+	 * Get the timezone of the event.
+	 */
+	public function get_timezone(): string {
+		return $this->event_model->get_timezone();
+	}
+
+	/**
+	 * Get whether the event is online.
+	 *
+	 * @return bool
+	 */
+	public function get_is_online(): bool {
+		return 'online' === $this->event_model->__get( 'event_type' ) ? true : false;
+	}
+
+	/**
+	 * Maybe add online link to attachments.
+	 *
+	 * @return array
+	 */
+	public function get_attachment(): array {
+		$attachment = parent::get_attachment();
+
+		$location = (array) $this->event_model->__get( 'location' );
+		if ( array_key_exists( 'integration', $location ) && array_key_exists( $location['integration'], $location ) ) {
+			$online_link  = array(
+				'type'      => 'Link',
+				'mediaType' => 'text/html',
+				'name'      => $location[ $location['integration'] ],
+				'href'      => $location[ $location['integration'] ],
+			);
+			$attachment[] = $online_link;
+		}
+		return $attachment;
+	}
+
+	/**
+	 * Compose the events tags.
+	 */
+	public function get_tag() {
+		// The parent tag function also fetches the mentions.
+		$tags = parent::get_tag();
+
+		$post_tags       = \wp_get_post_terms( $this->wp_object->ID, 'etn_tags' );
+		$post_categories = \wp_get_post_terms( $this->wp_object->ID, 'etn_category' );
+
+		if ( ! is_wp_error( $post_tags ) && $post_tags ) {
+			foreach ( $post_tags as $term ) {
+				$tag    = array(
+					'type' => 'Hashtag',
+					'href' => \esc_url( \get_tag_link( $term->term_id ) ),
+					'name' => esc_hashtag( $term->name ),
+				);
+				$tags[] = $tag;
+			}
+		}
+
+		if ( ! is_wp_error( $post_categories ) && $post_categories ) {
+			foreach ( $post_categories as $term ) {
+				$tag    = array(
+					'type' => 'Hashtag',
+					'href' => \esc_url( \get_tag_link( $term->term_id ) ),
+					'name' => esc_hashtag( $term->name ),
+				);
+				$tags[] = $tag;
+			}
+		}
+
+		if ( empty( $tags ) ) {
+			return null;
+		}
+
+		return $tags;
+	}
+
+	/**
+	 * Get the location.
+	 *
+	 * @return ?Place
+	 */
+	public function get_location(): ?Place {
+		$location = (array) $this->event_model->__get( 'location' );
+
+		if ( ! array_key_exists( 'address', $location ) ) {
+			return null;
+		}
+
+		$place = new Place();
+
+		$address = $location['address'];
+
+		$place->set_name( $address );
+		$place->set_address( $address );
+		$place->set_sensitive( null );
+
+		return $place;
+	}
+}
diff --git a/includes/class-setup.php b/includes/class-setup.php
index 47712f9..8b665fa 100644
--- a/includes/class-setup.php
+++ b/includes/class-setup.php
@@ -162,6 +162,7 @@ class Setup {
 		'\ActivityPub_Event_Bridge\Plugins\The_Events_Calendar',
 		'\ActivityPub_Event_Bridge\Plugins\VS_Event_List',
 		'\ActivityPub_Event_Bridge\Plugins\WP_Event_Manager',
+		'\ActivityPub_Event_Bridge\Plugins\Eventin',
 	);
 
 	/**
diff --git a/includes/plugins/class-eventin.php b/includes/plugins/class-eventin.php
new file mode 100644
index 0000000..fcab7c8
--- /dev/null
+++ b/includes/plugins/class-eventin.php
@@ -0,0 +1,60 @@
+<?php
+/**
+ * The Events Calendar.
+ *
+ * Defines all the necessary meta information for the events calendar.
+ *
+ * @link    https://wordpress.org/plugins/the-events-calendar/
+ * @package ActivityPub_Event_Bridge
+ * @since   1.0.0
+ */
+
+namespace ActivityPub_Event_Bridge\Plugins;
+
+// Exit if accessed directly.
+defined( 'ABSPATH' ) || exit; // @codeCoverageIgnore
+
+/**
+ * Interface for a supported event plugin.
+ *
+ * This interface defines which information is necessary for a supported event plugin.
+ *
+ * @since 1.0.0
+ */
+final class Eventin extends Event_plugin {
+	/**
+	 * Returns the full plugin file.
+	 *
+	 * @return string
+	 */
+	public static function get_plugin_file(): string {
+		return 'wp-event-solution/eventin.php';
+	}
+
+	/**
+	 * Returns the event post type of the plugin.
+	 *
+	 * @return string
+	 */
+	public static function get_post_type(): string {
+		return 'etn';
+	}
+
+	/**
+	 * Returns the ID of the main settings page of the plugin.
+	 *
+	 * @return string The settings page url.
+	 */
+	public static function get_settings_page(): string {
+		return 'eventin'; // Base always is wp-admin/admin.php?page=eventin.
+	}
+
+	/**
+	 * Returns the taxonomy used for the plugin's event categories.
+	 *
+	 * @return string
+	 */
+	public static function get_event_category_taxonomy(): string {
+		return 'etn_category';
+	}
+}
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 560ce4a..2019639 100755
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -43,6 +43,10 @@ function _manually_load_plugin() {
 		}
 	}
 
+	// Hot fixes for eventin.
+	update_option( 'purchase_history_table_structure_migration_done', true );
+	update_option( 'etn_wizard', 'active' );
+
 	$plugin_file = null;
 	// See if we want to run integration tests for a specific event-plugin.
 	switch ( $activitypub_event_extension_integration_filter ) {
@@ -52,6 +56,9 @@ function _manually_load_plugin() {
 		case 'events_manager':
 			$plugin_file = 'events-manager/events-manager.php';
 			break;
+		case 'eventin':
+			$plugin_file = 'wp-event-solution/eventin.php';
+			break;
 		case 'gatherpress':
 			$plugin_file = 'gatherpress/gatherpress.php';
 			break;
@@ -66,6 +73,7 @@ function _manually_load_plugin() {
 	if ( $plugin_file ) {
 		// Manually load the event plugin.
 		require_once $plugin_dir . $plugin_file;
+		update_option( 'purchase_history_table_structure_migration_done', true );
 		$current   = get_option( 'active_plugins', array() );
 		$current[] = $plugin_file;
 		sort( $current );
diff --git a/tests/test-class-plugin-eventin.php b/tests/test-class-plugin-eventin.php
new file mode 100644
index 0000000..d844922
--- /dev/null
+++ b/tests/test-class-plugin-eventin.php
@@ -0,0 +1,175 @@
+<?php
+/**
+ * Tests for WP Event Solution.
+ *
+ * @package ActivityPub_Event_Bridge
+ */
+
+/**
+ * Test cases for WP Event Solution.
+ */
+class Test_Eventin extends WP_UnitTestCase {
+	/**
+	 * Basic Mock-up event.
+	 */
+	private function get_mockup_event(): array {
+		return array(
+			'post_status'    => 'publish',
+			'post_title'     => 'Eventin Test Event Title',
+			'post_content'   => 'Eventin Test Event Description',
+			'etn_start_date' => \gmdate( 'Y-m-d', strtotime( '+10 days 15:00:00' ) ),
+			'etn_end_date'   => \gmdate( 'Y-m-d', strtotime( '+10 days 16:00:00' ) ),
+			'etn_start_time' => \gmdate( 'H:i', strtotime( '+10 days 15:00:00' ) ),
+			'etn_end_time'   => \gmdate( 'H:i', strtotime( '+10 days 16:00:00' ) ),
+			'event_timezone' => 'Europe/Vienna',
+		);
+	}
+
+	/**
+	 * Override the setup function, so that tests don't run if the Events Calendar is not active.
+	 */
+	public function set_up() {
+		parent::set_up();
+
+		if ( ! class_exists( '\Wpeventin' ) ) {
+			self::markTestSkipped( 'Eventin plugin is not active.' );
+		}
+
+		// Make sure that ActivityPub support is enabled for The Events Calendar.
+		$aec = \ActivityPub_Event_Bridge\Setup::get_instance();
+		$aec->activate_activitypub_support_for_active_event_plugins();
+
+		// Delete all posts afterwards.
+		_delete_all_posts();
+	}
+
+	/**
+	 * Test that the right transformer gets applied.
+	 */
+	public function test_eventin_transformer_class() {
+		// We only test for one event plugin being active at the same time,
+		// even though we support multiple onces in theory.
+		// But testing all combinations is beyond scope.
+		$active_event_plugins = \ActivityPub_Event_Bridge\Setup::get_instance()->get_active_event_plugins();
+		$this->assertEquals( 1, count( $active_event_plugins ) );
+
+		// Enable ActivityPub support for the event plugin.
+		$this->assertContains( 'etn', get_option( 'activitypub_support_post_types' ) );
+
+		// Create a Eventin Event without content.
+		$event = new \Etn\Core\Event\Event_Model();
+		$event->create( $this->get_mockup_event() );
+
+		// Call the transformer Factory.
+		$transformer = \Activitypub\Transformer\Factory::get_transformer( get_post( $event->id ) );
+
+		// Check that we got the right transformer.
+		$this->assertInstanceOf( \ActivityPub_Event_Bridge\Activitypub\Transformer\Eventin::class, $transformer );
+	}
+
+	/**
+	 * Test that the right transformer gets applied.
+	 */
+	public function test_eventin_test_minimal_event() {
+		// Create a Eventin Event without content.
+		$event = new \Etn\Core\Event\Event_Model();
+		$event->create( $this->get_mockup_event() );
+
+		// Call the transformer Factory.
+		$event_array = \Activitypub\Transformer\Factory::get_transformer( get_post( $event->id ) )->to_object()->to_array();
+
+		$this->assertEquals( 'Event', $event_array['type'] );
+		$this->assertEquals( 'Eventin Test Event Title', $event_array['name'] );
+		$this->assertEquals( 'Eventin Test Event Description', wp_strip_all_tags( $event_array['content'] ) );
+		$this->assertEquals( gmdate( 'Y-m-d\TH:i:s\Z', strtotime( '+10 days 15:00:00' ) ), $event_array['startTime'] );
+		$this->assertEquals( gmdate( 'Y-m-d\TH:i:s\Z', strtotime( '+10 days 16:00:00' ) ), $event_array['endTime'] );
+		$this->assertEquals( 'Europe/Vienna', $event_array['timezone'] );
+		$this->assertEquals( comments_open( $event->id ), $event_array['commentsEnabled'] );
+		$this->assertEquals( comments_open( $event->id ) ? 'allow_all' : 'closed', $event_array['repliesModerationOption'] );
+		$this->assertEquals( 'external', $event_array['joinMode'] );
+		$this->assertArrayNotHasKey( 'location', $event_array );
+		$this->assertEquals( 'MEETING', $event_array['category'] );
+		$this->assertEquals( false, $event_array['isOnline'] );
+	}
+
+	/**
+	 * Test that the right transformer gets applied.
+	 */
+	public function test_eventin_test_online_event_with_custom_link() {
+		// Create a Eventin Event without content.
+		$event = new \Etn\Core\Event\Event_Model();
+		$args  = array_merge(
+			$this->get_mockup_event(),
+			array(
+				'event_type' => 'online',
+				'location'   => array(
+					'integration' => 'custom_url',
+					'custom_url'  => 'https://jit.si/eventmeeting',
+				),
+			)
+		);
+		$event->create( $args );
+
+		// Call the transformer Factory.
+		$event_array = \Activitypub\Transformer\Factory::get_transformer( get_post( $event->id ) )->to_object()->to_array();
+
+		$this->assertEquals( 'Event', $event_array['type'] );
+		$this->assertEquals( 'Eventin Test Event Title', $event_array['name'] );
+		$this->assertEquals( 'Eventin Test Event Description', wp_strip_all_tags( $event_array['content'] ) );
+		$this->assertEquals( gmdate( 'Y-m-d\TH:i:s\Z', strtotime( '+10 days 15:00:00' ) ), $event_array['startTime'] );
+		$this->assertEquals( gmdate( 'Y-m-d\TH:i:s\Z', strtotime( '+10 days 16:00:00' ) ), $event_array['endTime'] );
+		$this->assertEquals( 'Europe/Vienna', $event_array['timezone'] );
+		$this->assertEquals( comments_open( $event->id ), $event_array['commentsEnabled'] );
+		$this->assertEquals( comments_open( $event->id ) ? 'allow_all' : 'closed', $event_array['repliesModerationOption'] );
+		$this->assertEquals( 'external', $event_array['joinMode'] );
+		$this->assertArrayNotHasKey( 'location', $event_array );
+		$this->assertEquals( 'MEETING', $event_array['category'] );
+		$this->assertEquals( true, $event_array['isOnline'] );
+		$this->assertContains(
+			array(
+				'type'      => 'Link',
+				'mediaType' => 'text/html',
+				'name'      => 'https://jit.si/eventmeeting',
+				'href'      => 'https://jit.si/eventmeeting',
+			),
+			$event_array['attachment']
+		);
+	}
+
+
+	/**
+	 * Test that the right transformer gets applied.
+	 */
+	public function test_eventin_test_online_event_with_physical_location() {
+		// Create a Eventin Event without content.
+		$event = new \Etn\Core\Event\Event_Model();
+		$args  = array_merge(
+			$this->get_mockup_event(),
+			array(
+				'event_type' => 'offline',
+				'location'   => array(
+					'address' => 'The NlNet center',
+				),
+			)
+		);
+		$event->create( $args );
+
+		// Call the transformer Factory.
+		$event_array = \Activitypub\Transformer\Factory::get_transformer( get_post( $event->id ) )->to_object()->to_array();
+
+		$this->assertEquals( 'Event', $event_array['type'] );
+		$this->assertEquals( 'Eventin Test Event Title', $event_array['name'] );
+		$this->assertEquals( 'Eventin Test Event Description', wp_strip_all_tags( $event_array['content'] ) );
+		$this->assertEquals( gmdate( 'Y-m-d\TH:i:s\Z', strtotime( '+10 days 15:00:00' ) ), $event_array['startTime'] );
+		$this->assertEquals( gmdate( 'Y-m-d\TH:i:s\Z', strtotime( '+10 days 16:00:00' ) ), $event_array['endTime'] );
+		$this->assertEquals( 'Europe/Vienna', $event_array['timezone'] );
+		$this->assertEquals( comments_open( $event->id ), $event_array['commentsEnabled'] );
+		$this->assertEquals( comments_open( $event->id ) ? 'allow_all' : 'closed', $event_array['repliesModerationOption'] );
+		$this->assertEquals( 'external', $event_array['joinMode'] );
+		$this->assertArrayHasKey( 'location', $event_array );
+		$this->assertEquals( 'MEETING', $event_array['category'] );
+		$this->assertEquals( false, $event_array['isOnline'] );
+		$this->assertEquals( 'The NlNet center', $event_array['location']['address'] );
+		$this->assertEquals( 'The NlNet center', $event_array['location']['name'] );
+	}
+}