diff --git a/activitypub.php b/activitypub.php
index f30ef42..9c6b525 100644
--- a/activitypub.php
+++ b/activitypub.php
@@ -22,11 +22,14 @@ function init() {
 	\defined( 'ACTIVITYPUB_HASHTAGS_REGEXP' ) || \define( 'ACTIVITYPUB_HASHTAGS_REGEXP', '(?:(?<=\s)|^)#(\w*[A-Za-z_]+\w*)' );
 	\defined( 'ACTIVITYPUB_ALLOWED_HTML' ) || \define( 'ACTIVITYPUB_ALLOWED_HTML', '<strong><a><p><ul><ol><li><code><blockquote><pre><img>' );
 	\defined( 'ACTIVITYPUB_CUSTOM_POST_CONTENT' ) || \define( 'ACTIVITYPUB_CUSTOM_POST_CONTENT', "<p><strong>%title%</strong></p>\n\n%content%\n\n<p>%hashtags%</p>\n\n<p>%shortlink%</p>" );
+	\defined( 'ACTIVITYPUB_PLUGIN' ) || \define( 'ACTIVITYPUB_PLUGIN', __FILE__ );
+
 
 	require_once \dirname( __FILE__ ) . '/includes/table/followers-list.php';
 	require_once \dirname( __FILE__ ) . '/includes/class-signature.php';
 	require_once \dirname( __FILE__ ) . '/includes/peer/class-followers.php';
 	require_once \dirname( __FILE__ ) . '/includes/functions.php';
+	require_once \dirname( __FILE__ ) . '/includes/class-migrate.php';
 
 	require_once \dirname( __FILE__ ) . '/includes/model/class-activity.php';
 	require_once \dirname( __FILE__ ) . '/includes/model/class-post.php';
@@ -123,6 +126,19 @@ function flush_rewrite_rules() {
 	\flush_rewrite_rules();
 }
 \register_activation_hook( __FILE__, '\Activitypub\flush_rewrite_rules' );
+
+/**
+ * Activate plugin;
+ */
+function activate_plugin() {
+	if( ! function_exists('get_plugin_data') ){
+		require_once( ABSPATH . 'wp-admin/includes/plugin.php' );
+	}
+	$plugin_data = \get_plugin_data( __FILE__ );
+	\add_option( 'activitypub_version', $plugin_data['Version'] );
+}
+\register_activation_hook( __FILE__, '\Activitypub\activate_plugin' );
+
 \register_deactivation_hook( __FILE__, '\flush_rewrite_rules' );
 
 /**
diff --git a/includes/class-admin.php b/includes/class-admin.php
index 17476b3..7c3968b 100644
--- a/includes/class-admin.php
+++ b/includes/class-admin.php
@@ -13,6 +13,7 @@ class Admin {
 	public static function init() {
 		\add_action( 'admin_menu', array( '\Activitypub\Admin', 'admin_menu' ) );
 		\add_action( 'admin_init', array( '\Activitypub\Admin', 'register_settings' ) );
+		\add_action( 'admin_init', array( '\Activitypub\Admin', 'version_check' ), 1 );
 		\add_action( 'show_user_profile', array( '\Activitypub\Admin', 'add_fediverse_profile' ) );
 		\add_action( 'admin_enqueue_scripts', array( '\Activitypub\Admin', 'scripts_reply_comments' ), 10, 2 );
 		\add_filter( 'comment_row_actions', array( '\Activitypub\Admin', 'reply_comments_actions' ), 10, 2 );
@@ -124,6 +125,33 @@ class Admin {
 		);
 	}
 
+	/**
+	 * Update ActivityPub plugin
+	 */
+	public static function version_check() {
+		if( ! function_exists('get_plugin_data') ){
+			require_once( ABSPATH . 'wp-admin/includes/plugin.php' );
+		}
+		$plugin_data = \get_plugin_data( ACTIVITYPUB_PLUGIN );		
+		$activitypub_db_version = \get_option( 'activitypub_version' );
+		
+		// Needs update
+		if ( empty( $activitypub_db_version ) || $plugin_data['Version'] > $activitypub_db_version ) {
+			// Check for specific migrations
+			
+			if ( '0.13.5' > $activitypub_db_version ) {
+				// This updates post_meta with _activitypub_permalink_compat. 
+				// Posts that have this meta will be backwards compatible with their permalink based ActivityPub ID (URI)
+				
+				// This will create false positives, where the permalink has changed (slug, permalink structure) since federation, 
+				// for those cases a delete_url will allow for federating a delete based on the federated object ID
+
+				\Activitypub\Migrate\Posts::backcompat_posts();
+			}
+		}
+		\update_option( 'activitypub_version', $plugin_data['Version'] );
+	}
+
 	public static function add_settings_help_tab() {
 		\get_current_screen()->add_help_tab(
 			array(
diff --git a/includes/class-migrate.php b/includes/class-migrate.php
new file mode 100644
index 0000000..b3a3d76
--- /dev/null
+++ b/includes/class-migrate.php
@@ -0,0 +1,97 @@
+<?php
+namespace Activitypub\Migrate;
+
+/**
+ * ActivityPub Migrate DB-Class
+ *
+ * @author Django Doucet
+ */
+class Posts {
+
+	/**
+	 * Updates ActivityPub Posts for backwards compatibility
+	 */
+	public static function backcompat_posts() {
+		$post_types = \get_option( 'activitypub_support_post_types', array( 'post', 'page' ) );
+		$args = array(
+			'numberposts'  => -1,
+			'post_type' => $post_types,
+			'order'   => 'ASC',
+		);
+		$posts_to_migrate = \get_posts( $args );
+		foreach ( $posts_to_migrate as $post ) {
+			$permalink = \get_permalink( $post->ID );
+			\update_post_meta( $post->ID, '_activitypub_permalink_compat', $permalink );
+		}
+	}
+
+	public static function get_posts( $args = null ) {
+		$post_types = \get_option( 'activitypub_support_post_types', array( 'post', 'page' ) );
+		$args = array(
+			'numberposts'  => -1,
+			'post_type' => $post_types,
+			'meta_key' => '_activitypub_permalink_compat',
+			'order'   => 'ASC',
+		);
+		$posts_to_migrate = \get_posts( $args );
+		return $posts_to_migrate;
+	}
+
+	// public static function get_posts_with_comments( $args = null ) {
+	// 	$page =  ( \get_query_var( 'page' ) ? \get_query_var( 'page' ) : 1 );
+	//     if ( is_null( $args ) ) {
+	//         $args = array(
+	//             'number'  => '10',
+	//             'offset'  => $page,
+	//             'type'    => 'activitypub',
+	//             'order'   => 'ASC',
+	//         );
+	//     }
+	//     $comments = \get_comments( $args );
+	//     $compat = array();
+	//     foreach ( $comments as $comment ) {
+	// 		$post_id = $comment->comment_post_ID;
+	// 		if ( \get_post_meta( $post_id, '_activitypub_permalink_compat', true ) ) {
+	// 			// if has url needs migration
+	// 			$compat[] = $post_id;
+	// 		}
+	//     }
+	//     $posts_migrate = \get_posts( \array_unique( $compat ) );
+	// 	return $posts_migrate;
+	// }
+
+	public static function count_posts() {
+		$posts = self::get_posts();
+		return \count( $posts );
+	}
+
+	/**
+	 * migrate_post
+	 * first send Delete (obj)
+	 * then send Announce (obj)
+	 *
+	 * @param int $post_id
+	 * @param str $url
+	 */
+	// public static function migrate_post( $post_id, $url ) {
+	// 	self::delete_url( $post_id, $url );
+	// 	$post = \get_post( $post_id );
+	// 	$activitypub_post = new \Activitypub\Model\Post( $post );
+	// 	\wp_schedule_single_event( \time() + 1, 'send_announce_activity', array( $activitypub_post ) );
+	// 	//return \count( $posts );
+	// }
+
+	/**
+	 * delete_url
+	 * Send a Delete activity to the Fediverse
+	 *
+	 * @param str $activitypub_permalink_compat
+	 */
+	// public static function delete_url( $post_id, $url ) {
+	// 	$post = \get_post( $post_id );
+	// 	$activitypub_post = new \Activitypub\Model\Post( $post );
+	// 	\wp_schedule_single_event( \time(), 'activitypub_send_delete_activity', array( $activitypub_post, $url ) );
+	// 	\wp_schedule_single_event( \time() + 1, 'delete_post_meta', array( $post_id, '_activitypub_permalink_compat' ) );
+	// 	// return admin_notice?;
+	// }
+}
diff --git a/includes/model/class-post.php b/includes/model/class-post.php
index c7780e8..9003e25 100644
--- a/includes/model/class-post.php
+++ b/includes/model/class-post.php
@@ -17,7 +17,7 @@ class Post {
 	private $object_type;
 	private $deleted;
 	private $updated;
-	private $slug;
+	private $permalink;
 
 	public function __construct( $post = null ) {
 		$this->post = \get_post( $post );
@@ -32,6 +32,7 @@ class Post {
 		$this->replies     = $this->generate_replies();
 		$this->updated     = $this->generate_updated();
 		$this->delete      = $this->get_deleted();
+		$this->permalink   = $this->get_the_post_link();
 	}
 
 	public function __call( $method, $params ) {
@@ -56,7 +57,7 @@ class Post {
 			'attributedTo' => \get_author_posts_url( $post->post_author ),
 			'summary' => $this->summary,
 			'inReplyTo' => null,
-			'url' => \get_permalink( $post->ID ),
+			'url' => $this->permalink,
 			'content' => $this->content,
 			'contentMap' => array(
 				\strstr( \get_locale(), '_', true ) => $this->content,