diff --git a/.phan/config.php b/.phan/config.php
index 8c7f84a..611a873 100644
--- a/.phan/config.php
+++ b/.phan/config.php
@@ -367,5 +367,7 @@ return [
     // A list of individual files to include in analysis
     // with a path relative to the root directory of the
     // project.
-    'file_list' => [],
+    'file_list' => [
+        'phan-stubs.php',
+    ],
 ];
diff --git a/phan-stubs.php b/phan-stubs.php
new file mode 100644
index 0000000..7428783
--- /dev/null
+++ b/phan-stubs.php
@@ -0,0 +1,10 @@
+<?php
+
+if (!function_exists('getallheaders')) {
+    /**
+     * @return array<string, string>
+     */
+    function getallheaders(): array {
+        return [];
+    }
+}
\ No newline at end of file
diff --git a/php/federator/api.php b/php/federator/api.php
index 7e19e2a..f5b3e99 100644
--- a/php/federator/api.php
+++ b/php/federator/api.php
@@ -198,12 +198,13 @@ class Api extends Main
      * @param string[] $headers
      *          permission(s) to check for
      * @throws Exceptions\PermissionDenied
+     * @return string|Exceptions\PermissionDenied
      */
-    public function checkSignature($headers)
+    public static function checkSignature($headers)
     {
         $signatureHeader = $headers['Signature'] ?? null;
 
-        if (!$signatureHeader) {
+        if (!isset($signatureHeader)) {
             http_response_code(400);
             throw new Exceptions\PermissionDenied("Missing Signature header");
         }
@@ -219,15 +220,20 @@ class Api extends Main
         // Fetch public key from `keyId` (usually actor URL + #main-key)
         [$publicKeyData, $info] = \Federator\Main::getFromRemote($keyId, ['Accept: application/activity+json']);
 
-        if ($info['http_code'] !== 200) {
+        if ($info['http_code'] != 200) {
             http_response_code(500);
             throw new Exceptions\PermissionDenied("Failed to fetch public key from keyId: $keyId");
         }
 
         $actor = json_decode($publicKeyData, true);
+
+        if (!is_array($actor) || !isset($actor['id'])) {
+            throw new Exceptions\PermissionDenied("Invalid actor data");
+        }
+
         $publicKeyPem = $actor['publicKey']['publicKeyPem'] ?? null;
 
-        if (!$publicKeyPem) {
+        if (!isset($publicKeyPem)) {
             http_response_code(500);
             throw new Exceptions\PermissionDenied("Invalid public key format from actor with keyId: $keyId");
         }
@@ -235,8 +241,6 @@ class Api extends Main
         // Reconstruct the signed string
         $signedString = '';
         foreach ($signedHeaders as $header) {
-            $headerValue = '';
-
             if ($header === '(request-target)') {
                 $method = strtolower($_SERVER['REQUEST_METHOD']);
                 $path = $_SERVER['REQUEST_URI'];
@@ -252,16 +256,17 @@ class Api extends Main
         // Verify the signature
         $pubkeyRes = openssl_pkey_get_public($publicKeyPem);
         $verified = false;
-        if ($pubkeyRes) {
+        if ($pubkeyRes instanceof \OpenSSLAsymmetricKey && is_string($signature)) {
             $verified = openssl_verify($signedString, $signature, $pubkeyRes, OPENSSL_ALGO_SHA256);
         }
-        if ($verified !== 1) {
+        if ($verified != 1) {
             http_response_code(500);
             throw new Exceptions\PermissionDenied("Signature verification failed for publicKey with keyId: $keyId");
         }
 
+        $actorId = $actor['id'];
         // Signature is valid!
-        return "Signature verified from actor: " . $actor['id'];
+        return "Signature verified from actor: " . $actorId;
     }
 
     /**
diff --git a/php/federator/api/fedusers.php b/php/federator/api/fedusers.php
index 727c304..4c85117 100644
--- a/php/federator/api/fedusers.php
+++ b/php/federator/api/fedusers.php
@@ -16,7 +16,7 @@ class FedUsers implements APIInterface
     /**
      * main instance
      *
-     * @var \Federator\Main $main
+     * @var \Federator\Api $main
      */
     private $main;
 
@@ -49,6 +49,7 @@ class FedUsers implements APIInterface
     {
         $method = $_SERVER["REQUEST_METHOD"];
         $handler = null;
+        $username = '';
         switch (sizeof($paths)) {
             case 2:
                 if ($method === 'GET') {
@@ -75,8 +76,8 @@ class FedUsers implements APIInterface
                         break;
                     case 'inbox':
                         $handler = new FedUsers\Inbox($this->main);
-                        $user = $paths[1];
-                        if (!preg_match("#^([^@]+)@([^/]+)#", $user, $matches) === 1) {
+                        $username = $paths[1];
+                        if (preg_match("#^([^@]+)@([^/]+)#", $username, $matches) != 1) {
                             $hostUrl = $this->main->getHost();
                             if ($hostUrl !== false) {
                                 $host = parse_url($hostUrl, PHP_URL_HOST);
@@ -84,14 +85,14 @@ class FedUsers implements APIInterface
                                 if ($port !== null) {
                                     $host .= `:$port`;
                                 }
-                                $user = `$user@$host`;
+                                $username = `$username@$host`;
                             }
                         }
                         break;
                     case 'outbox':
                         $handler = new FedUsers\Outbox($this->main);
-                        $user = $paths[1];
-                        if (!preg_match("#^([^@]+)@([^/]+)#", $user, $matches) === 1) {
+                        $username = $paths[1];
+                        if (preg_match("#^([^@]+)@([^/]+)#", $username, $matches) != 1) {
                             $hostUrl = $this->main->getHost();
                             if ($hostUrl !== false) {
                                 $host = parse_url($hostUrl, PHP_URL_HOST);
@@ -99,7 +100,7 @@ class FedUsers implements APIInterface
                                 if ($port !== null) {
                                     $host .= `:$port`;
                                 }
-                                $user = `$user@$host`;
+                                $username = `$username@$host`;
                             }
                         }
                         break;
@@ -114,10 +115,10 @@ class FedUsers implements APIInterface
             $ret = false;
             switch ($method) {
                 case 'GET':
-                    $ret = $handler->get($user);
+                    $ret = $handler->get($username);
                     break;
                 case 'POST':
-                    $ret = $handler->post($user);
+                    $ret = $handler->post($username);
                     break;
             }
             if ($ret !== false) {
diff --git a/php/federator/api/fedusers/inbox.php b/php/federator/api/fedusers/inbox.php
index d75f769..94abe43 100644
--- a/php/federator/api/fedusers/inbox.php
+++ b/php/federator/api/fedusers/inbox.php
@@ -16,7 +16,7 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
     /**
      * main instance
      *
-     * @var \Federator\Main $main
+     * @var \Federator\Api $main
      */
     private $main;
 
@@ -32,7 +32,7 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
     /**
      * handle get call
      *
-     * @param string $_user user to fetch inbox for @unused-param
+     * @param string|null $_user user to fetch inbox for @unused-param
      * @return string|false response
      */
     public function get($_user)
@@ -43,7 +43,7 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
     /**
      * handle post call
      *
-     * @param string $_user user to add data to inbox
+     * @param string|null $_user user to add data to inbox
      * @return string|false response
      */
     public function post($_user)
@@ -60,10 +60,12 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
             exit("Access denied");
         }
 
-        $activity = json_decode($_rawInput, true);
+        $activity = is_string($_rawInput) ? json_decode($_rawInput, true) : null;
         $host = $_SERVER['SERVER_NAME'];
 
-        $sendTo = [];
+        if (!is_array($activity)) {
+            throw new \RuntimeException('Invalid activity format.');
+        }
 
         switch ($activity['type']) {
             case 'Create':
@@ -72,11 +74,12 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
                 }
 
                 $obj = $activity['object'];
+                $published = strtotime($activity['published'] ?? $obj['published'] ?? 'now');
                 $create = new \Federator\Data\ActivityPub\Common\Create();
-                $create->setID($activity['id'])
+                $create->setAActor($activity['actor'])
+                    ->setID($activity['id'])
                     ->setURL($activity['id'])
-                    ->setPublished(strtotime($activity['published'] ?? $obj['published'] ?? 'now'))
-                    ->setAActor($activity['actor']);
+                    ->setPublished($published !== false ? $published : time());
 
                 if (array_key_exists('cc', $activity)) {
                     foreach ($activity['cc'] as $cc) {
@@ -92,9 +95,10 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
 
                 switch ($obj['type']) {
                     case 'Note':
+                        $published = strtotime($obj['published'] ?? 'now');
                         $apNote = new \Federator\Data\ActivityPub\Common\Note();
                         $apNote->setID($obj['id'])
-                            ->setPublished(strtotime($obj['published'] ?? 'now'))
+                            ->setPublished($published !== false ? $published : time())
                             ->setContent($obj['content'] ?? '')
                             ->setSummary($obj['summary'])
                             ->setURL($obj['url'])
@@ -168,11 +172,12 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
                     break;
                 }
 
+                $published = strtotime((string) $activity['published']);
                 $announce = new \Federator\Data\ActivityPub\Common\Announce();
-                $announce->setID($activity['id'])
-                    ->setURL($activity['id'])
-                    ->setPublished(strtotime($activity['published'] ?? 'now'))
-                    ->setAActor($activity['actor']);
+                $announce->setAActor((string) $activity['actor'])
+                    ->setPublished($published !== false ? $published : time())
+                    ->setID((string) $activity['id'])
+                    ->setURL((string) $activity['id']);
 
                 if (array_key_exists('cc', $activity)) {
                     foreach ($activity['cc'] as $cc) {
@@ -188,11 +193,12 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
                 // Parse the shared object as a Note or something else
                 switch ($objData['type']) {
                     case 'Note':
+                        $published = strtotime($objData['published'] ?? 'now');
                         $note = new \Federator\Data\ActivityPub\Common\Note();
-                        $note->setID($objData['id'])
+                        $note->setPublished($published !== false ? $published : time())
+                            ->setID($objData['id'])
                             ->setSummary($objData['summary'])
                             ->setContent($objData['content'] ?? '')
-                            ->setPublished(strtotime($objData['published'] ?? 'now'))
                             ->setURL($objData['url'] ?? $objData['id'])
                             ->setAttributedTo($objData['attributedTo'] ?? null)
                             ->addTo("https://www.w3.org/ns/activitystreams#Public");
@@ -220,9 +226,9 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
                 }
 
                 $undo = new \Federator\Data\ActivityPub\Common\Undo();
-                $undo->setID($activity['id'] ?? "test")
-                    ->setURL($activity['url'] ?? $activity['id'])
-                    ->setActor($activity['actor'] ?? null);
+                $undo->setActor($activity['actor'] ?? null)
+                    ->setID($activity['id'] ?? "test")
+                    ->setURL($activity['url'] ?? $activity['id']);
 
                 if (array_key_exists('cc', $activity)) {
                     foreach ($activity['cc'] as $cc) {
@@ -240,11 +246,12 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
                 if (is_array($undone) && isset($undone['type'])) {
                     switch ($undone['type']) {
                         case 'Announce':
+                            $published = strtotime($undone['published'] ?? 'now');
                             $announce = new \Federator\Data\ActivityPub\Common\Announce();
-                            $announce->setID($undone['id'] ?? null)
-                                ->setAActor($undone['actor'] ?? null)
-                                ->setURL($undone['url'] ?? $undone['id'])
-                                ->setPublished(strtotime($undone['published'] ?? 'now'));
+                            $announce->setAActor($undone['actor'] ?? null)
+                                ->setPublished($published !== false ? $published : time())
+                                ->setID($undone['id'] ?? null)
+                                ->setURL($undone['url'] ?? $undone['id']);
 
                             if (array_key_exists('cc', $undone)) {
                                 foreach ($undone['cc'] as $cc) {
@@ -269,11 +276,14 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
                 break;
             default:
                 error_log("Inbox::post we currently don't support the activity type " . $activity['type'] . "\n");
+                $apObject = new \Federator\Data\ActivityPub\Common\Activity($activity['type']);
+                $apObject->setID($activity['id'] ?? null);
+                $inboxActivity = $apObject;
                 break;
         }
 
         // Shared inbox
-        if (!$_user) {
+        if (!isset($_user)) {
             $rootDir = $_SERVER['DOCUMENT_ROOT'] . '../';
             file_put_contents(
                 $rootDir . 'logs/inbox.log',
@@ -289,28 +299,40 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
             );
         }
 
+        if (!isset($inboxActivity)) {
+            error_log("Inbox::post couldn't create inboxActivity, aborting");
+            return false;
+        }
+
         $sendTo = $inboxActivity->getCC();
         if ($inboxActivity->getType() === 'Undo') {
-            $sendTo = $inboxActivity->getObject()->getCC();
+            $object = $inboxActivity->getObject();
+            if ($object !== null) {
+                $sendTo = $object->getCC();
+            }
         }
 
         $users = [];
 
         foreach ($sendTo as $receiver) {
-            if (!$receiver || !is_string($receiver)) {
+            if ($receiver === '' || !is_string($receiver)) {
                 continue;
             }
 
             if (str_ends_with($receiver, '/followers')) {
-                $users = array_merge($users, $this->fetchAllFollowers($receiver, $host));
+                $followers = $this->fetchAllFollowers($receiver, $host);
+                if (is_array($followers)) {
+                    $users = array_merge($users, $followers);
+                }
             }
         }
-        if ($_user !== false && !in_array($_user, $users)) {
+        if ($_user !== false && !in_array($_user, $users, true)) {
             $users[] = $_user;
         }
         foreach ($users as $user) {
-            if (!$user)
+            if (!isset($user)) {
                 continue;
+            }
 
             $this->postForUser($user, $inboxActivity);
         }
@@ -322,11 +344,11 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
      *
      * @param string $_user user to add data to inbox
      * @param \Federator\Data\ActivityPub\Common\Activity $inboxActivity the activity that we received
-     * @return string|false response
+     * @return boolean response
      */
     private function postForUser($_user, $inboxActivity)
     {
-        if ($_user) {
+        if (isset($_user)) {
             $dbh = $this->main->getDatabase();
             $cache = $this->main->getCache();
             $connector = $this->main->getConnector();
@@ -360,14 +382,14 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
      *
      * @param string $collectionUrl The url of f.e. the posters followers
      * @param string $host our current host-url
-     * @return array|false the names of the followers that are hosted on our server
+     * @return string[] the names of the followers that are hosted on our server
      */
-    private function fetchAllFollowers(string $collectionUrl, string $host): array
+    private static function fetchAllFollowers(string $collectionUrl, string $host): array
     {
         $users = [];
 
         [$collectionResponse, $collectionInfo] = \Federator\Main::getFromRemote($collectionUrl, ['Accept: application/activity+json']);
-        if ($collectionInfo['http_code'] !== 200) {
+        if ($collectionInfo['http_code'] != 200) {
             error_log("Inbox::fetchAllFollowers Failed to fetch follower collection metadata from $collectionUrl");
             return [];
         }
@@ -375,7 +397,7 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
         $collectionData = json_decode($collectionResponse, true);
         $nextPage = $collectionData['first'] ?? $collectionData['current'] ?? null;
 
-        if (!$nextPage) {
+        if (!isset($nextPage)) {
             error_log("Inbox::fetchAllFollowers No 'first' or 'current' page in collection at $collectionUrl");
             return [];
         }
@@ -383,7 +405,7 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
         // Loop through all pages
         while ($nextPage) {
             [$pageResponse, $pageInfo] = \Federator\Main::getFromRemote($nextPage, ['Accept: application/activity+json']);
-            if ($pageInfo['http_code'] !== 200) {
+            if ($pageInfo['http_code'] != 200) {
                 error_log("Inbox::fetchAllFollowers Failed to fetch follower page at $nextPage");
                 break;
             }
@@ -398,7 +420,7 @@ class Inbox implements \Federator\Api\FedUsers\FedUsersInterface
                 }
 
                 [$actorResponse, $actorInfo] = \Federator\Main::getFromRemote($followerUrl, ['Accept: application/activity+json']);
-                if ($actorInfo['http_code'] !== 200) {
+                if ($actorInfo['http_code'] != 200) {
                     error_log("Inbox::fetchAllFollowers Failed to fetch actor data for follower: $followerUrl");
                     continue;
                 }
diff --git a/php/federator/api/fedusers/outbox.php b/php/federator/api/fedusers/outbox.php
index c0e1df9..f88d0c7 100644
--- a/php/federator/api/fedusers/outbox.php
+++ b/php/federator/api/fedusers/outbox.php
@@ -16,13 +16,13 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
     /**
      * main instance
      *
-     * @var \Federator\Main $main
+     * @var \Federator\Api $main
      */
     private $main;
 
     /**
      * constructor
-     * @param \Federator\Main $main main instance
+     * @param \Federator\Api $main main instance
      */
     public function __construct($main)
     {
@@ -32,11 +32,14 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
     /**
      * handle get call
      *
-     * @param string $_user user to fetch outbox for
+     * @param string|null $_user user to fetch outbox for
      * @return string|false response
      */
     public function get($_user)
     {
+        if (!isset($_user)) {
+            return false;
+        }
         $dbh = $this->main->getDatabase();
         $cache = $this->main->getCache();
         $connector = $this->main->getConnector();
@@ -87,7 +90,7 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
     /**
      * handle post call
      *
-     * @param string $_user user to add data to outbox
+     * @param string|null $_user user to add data to outbox
      * @return string|false response
      */
     public function post($_user)
@@ -104,10 +107,12 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
             exit("Access denied");
         }
 
-        $activity = json_decode($_rawInput, true);
+        $activity = is_string($_rawInput) ? json_decode($_rawInput, true) : null;
         $host = $_SERVER['SERVER_NAME'];
 
-        $sendTo = [];
+        if (!is_array($activity)) {
+            throw new \RuntimeException('Invalid activity format.');
+        }
 
         switch ($activity['type']) {
             case 'Create':
@@ -116,11 +121,12 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
                 }
 
                 $obj = $activity['object'];
+                $published = strtotime($activity['published'] ?? $obj['published'] ?? 'now');
                 $create = new \Federator\Data\ActivityPub\Common\Create();
-                $create->setID($activity['id'])
+                $create->setAActor($activity['actor'])
+                    ->setID($activity['id'])
                     ->setURL($activity['id'])
-                    ->setPublished(published: strtotime($activity['published'] ?? $obj['published'] ?? 'now'))
-                    ->setAActor($activity['actor']);
+                    ->setPublished($published !== false ? $published : time());
 
                 if (array_key_exists('cc', $activity)) {
                     foreach ($activity['cc'] as $cc) {
@@ -136,9 +142,10 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
 
                 switch ($obj['type']) {
                     case 'Note':
+                        $published = strtotime($obj['published'] ?? 'now');
                         $apNote = new \Federator\Data\ActivityPub\Common\Note();
                         $apNote->setID($obj['id'])
-                            ->setPublished(strtotime($obj['published'] ?? 'now'))
+                            ->setPublished($published !== false ? $published : time())
                             ->setContent($obj['content'] ?? '')
                             ->setSummary($obj['summary'])
                             ->setURL($obj['url'])
@@ -212,11 +219,12 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
                     break;
                 }
 
+                $published = strtotime((string) $activity['published']);
                 $announce = new \Federator\Data\ActivityPub\Common\Announce();
-                $announce->setID($activity['id'])
-                    ->setURL($activity['id'])
-                    ->setPublished(strtotime($activity['published'] ?? 'now'))
-                    ->setAActor($activity['actor']);
+                $announce->setAActor((string) $activity['actor'])
+                    ->setPublished($published !== false ? $published : time())
+                    ->setID((string) $activity['id'])
+                    ->setURL((string) $activity['id']);
 
                 if (array_key_exists('cc', $activity)) {
                     foreach ($activity['cc'] as $cc) {
@@ -232,11 +240,12 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
                 // Parse the shared object as a Note or something else
                 switch ($objData['type']) {
                     case 'Note':
+                        $published = strtotime($objData['published'] ?? 'now');
                         $note = new \Federator\Data\ActivityPub\Common\Note();
-                        $note->setID($objData['id'])
+                        $note->setPublished($published !== false ? $published : time())
+                            ->setID($objData['id'])
                             ->setSummary($objData['summary'])
                             ->setContent($objData['content'] ?? '')
-                            ->setPublished(strtotime($objData['published'] ?? 'now'))
                             ->setURL($objData['url'] ?? $objData['id'])
                             ->setAttributedTo($objData['attributedTo'] ?? null)
                             ->addTo("https://www.w3.org/ns/activitystreams#Public");
@@ -264,9 +273,9 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
                 }
 
                 $undo = new \Federator\Data\ActivityPub\Common\Undo();
-                $undo->setID($activity['id'] ?? "test")
-                    ->setURL($activity['url'] ?? $activity['id'])
-                    ->setActor($activity['actor'] ?? null);
+                $undo->setActor($activity['actor'] ?? null)
+                    ->setID($activity['id'] ?? "test")
+                    ->setURL($activity['url'] ?? $activity['id']);
 
                 if (array_key_exists('cc', $activity)) {
                     foreach ($activity['cc'] as $cc) {
@@ -284,11 +293,12 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
                 if (is_array($undone) && isset($undone['type'])) {
                     switch ($undone['type']) {
                         case 'Announce':
+                            $published = strtotime($undone['published'] ?? 'now');
                             $announce = new \Federator\Data\ActivityPub\Common\Announce();
-                            $announce->setID($undone['id'] ?? null)
-                                ->setAActor($undone['actor'] ?? null)
-                                ->setURL($undone['url'] ?? $undone['id'])
-                                ->setPublished(strtotime($undone['published'] ?? 'now'));
+                            $announce->setAActor($undone['actor'] ?? null)
+                                ->setPublished($published !== false ? $published : time())
+                                ->setID($undone['id'] ?? null)
+                                ->setURL($undone['url'] ?? $undone['id']);
 
                             if (array_key_exists('cc', $undone)) {
                                 foreach ($undone['cc'] as $cc) {
@@ -313,31 +323,46 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
                 break;
             default:
                 error_log("Outbox::post we currently don't support the activity type " . $activity['type'] . "\n");
+                $apObject = new \Federator\Data\ActivityPub\Common\Activity($activity['type']);
+                $apObject->setID($activity['id'] ?? null);
+                $outboxActivity = $apObject;
                 break;
         }
 
+        if (!isset($outboxActivity)) {
+            error_log("Outbox::post couldn't create outboxActivity, aborting");
+            return false;
+        }
+
         $sendTo = $outboxActivity->getCC();
         if ($outboxActivity->getType() === 'Undo') {
-            $sendTo = $outboxActivity->getObject()->getCC();
+            $object = $outboxActivity->getObject();
+            if ($object !== null) {
+                $sendTo = $object->getCC();
+            }
         }
 
         $users = [];
 
         foreach ($sendTo as $receiver) {
-            if (!$receiver || !is_string($receiver)) {
+            if ($receiver === '' || !is_string($receiver)) {
                 continue;
             }
 
             if (str_ends_with($receiver, '/followers')) {
-                $users = array_merge($users, $this->fetchAllFollowers($receiver, $host));
+                $followers = $this->fetchAllFollowers($receiver, $host);
+                if (is_array($followers)) {
+                    $users = array_merge($users, $followers);
+                }
             }
         }
-        if ($_user !== false && !in_array($_user, $users)) {
+        if ($_user !== false && !in_array($_user, $users, true)) {
             $users[] = $_user;
         }
         foreach ($users as $user) {
-            if (!$user)
+            if (!isset($user)) {
                 continue;
+            }
 
             $this->postForUser($user, $outboxActivity);
         }
@@ -349,11 +374,11 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
      *
      * @param string $_user user to add data to outbox
      * @param \Federator\Data\ActivityPub\Common\Activity $outboxActivity the activity that we received
-     * @return string|false response
+     * @return boolean response
      */
     private function postForUser($_user, $outboxActivity)
     {
-        if ($_user) {
+        if (isset($_user)) {
             $dbh = $this->main->getDatabase();
             $cache = $this->main->getCache();
             $connector = $this->main->getConnector();
@@ -387,14 +412,14 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
      *
      * @param string $collectionUrl The url of f.e. the posters followers
      * @param string $host our current host-url
-     * @return array|false the names of the followers that are hosted on our server
+     * @return string[] the names of the followers that are hosted on our server
      */
-    private function fetchAllFollowers(string $collectionUrl, string $host): array
+    private static function fetchAllFollowers(string $collectionUrl, string $host): array
     {
         $users = [];
 
         [$collectionResponse, $collectionInfo] = \Federator\Main::getFromRemote($collectionUrl, ['Accept: application/activity+json']);
-        if ($collectionInfo['http_code'] !== 200) {
+        if ($collectionInfo['http_code'] != 200) {
             error_log("Outbox::fetchAllFollowers Failed to fetch follower collection metadata from $collectionUrl");
             return [];
         }
@@ -402,7 +427,7 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
         $collectionData = json_decode($collectionResponse, true);
         $nextPage = $collectionData['first'] ?? $collectionData['current'] ?? null;
 
-        if (!$nextPage) {
+        if (!isset($nextPage)) {
             error_log("Outbox::fetchAllFollowers No 'first' or 'current' page in collection at $collectionUrl");
             return [];
         }
@@ -410,7 +435,7 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
         // Loop through all pages
         while ($nextPage) {
             [$pageResponse, $pageInfo] = \Federator\Main::getFromRemote($nextPage, ['Accept: application/activity+json']);
-            if ($pageInfo['http_code'] !== 200) {
+            if ($pageInfo['http_code'] != 200) {
                 error_log("Outbox::fetchAllFollowers Failed to fetch follower page at $nextPage");
                 break;
             }
@@ -425,7 +450,7 @@ class Outbox implements \Federator\Api\FedUsers\FedUsersInterface
                 }
 
                 [$actorResponse, $actorInfo] = \Federator\Main::getFromRemote($followerUrl, ['Accept: application/activity+json']);
-                if ($actorInfo['http_code'] !== 200) {
+                if ($actorInfo['http_code'] != 200) {
                     error_log("Outbox::fetchAllFollowers Failed to fetch actor data for follower: $followerUrl");
                     continue;
                 }
diff --git a/php/federator/api/v1/dummy.php b/php/federator/api/v1/dummy.php
index 3a0d4b7..68a8dc3 100644
--- a/php/federator/api/v1/dummy.php
+++ b/php/federator/api/v1/dummy.php
@@ -23,9 +23,9 @@ class Dummy implements \Federator\Api\APIInterface
     /**
      * internal message to output
      *
-     * @var string $response
+     * @var string $message
      */
-    private $message = [];
+    private $message = '';
 
     /**
      * constructor
@@ -41,7 +41,7 @@ class Dummy implements \Federator\Api\APIInterface
      * run given url path
      *
      * @param array<string> $paths path array split by /
-     * @param \Federator\Data\User|false $user user who is calling us
+     * @param \Federator\Data\User|false $user user who is calling us @unused-param
      * @return bool true on success
      */
     public function exec($paths, $user): bool
@@ -151,16 +151,26 @@ class Dummy implements \Federator\Api\APIInterface
      */
     public function getDummy()
     {
-        $this->message = json_encode([
+        $dummyResponse = json_encode([
             'r1' => '             (__)       ',
             'r2' => '      `------(oo)       ',
             'r3' => '       || __ (__)       ',
             'r4' => '       ||w  ||          ',
             'r5' => '                        '
         ], JSON_PRETTY_PRINT);
+        if ($dummyResponse !== false) {
+            $this->message = $dummyResponse;
+        }
         return true;
     }
 
+
+    /**
+     * get function for "/v1/dummy/moo"
+     *
+     * @param string $_name user-id which we try to retrieve
+     * @return bool
+     */
     public function getUser($_name)
     {
         error_log("Someone tried to get user: " . $_name);
@@ -184,7 +194,7 @@ X5FLRXVzpFziJsIpWZ6ojU9KRX8l4yvv9FL4dZIn7edbcosvnNDpnvEl+NsGnf4R
 1wIDAQAB
 -----END PUBLIC KEY-----
 PEM;
-$publicKeyPemJsonSafe = json_encode($publicKeyPem); // gives string with \n inside
+        $publicKeyPemJsonSafe = json_encode($publicKeyPem); // gives string with \n inside
         $data = [
             'iconMediaType' => $user->iconMediaType,
             'iconURL' => $user->iconURL,
@@ -360,9 +370,13 @@ $publicKeyPemJsonSafe = json_encode($publicKeyPem); // gives string with \n insi
             FILE_APPEND
         );
 
-        $this->message = json_encode([
+        $successMsg = json_encode([
             'status' => 'received',
         ]);
+
+        if ($successMsg !== false) {
+            $this->message = $successMsg;
+        }
         return true;
     }
 
@@ -381,9 +395,13 @@ $publicKeyPemJsonSafe = json_encode($publicKeyPem); // gives string with \n insi
             FILE_APPEND
         );
 
-        $this->message = json_encode([
+        $successMsg = json_encode([
             'status' => 'received',
         ]);
+
+        if ($successMsg !== false) {
+            $this->message = $successMsg;
+        }
         return true;
     }
 
@@ -402,9 +420,13 @@ $publicKeyPemJsonSafe = json_encode($publicKeyPem); // gives string with \n insi
             FILE_APPEND
         );
 
-        $this->message = json_encode([
+        $successMsg = json_encode([
             'status' => 'received',
         ]);
+
+        if ($successMsg !== false) {
+            $this->message = $successMsg;
+        }
         return true;
     }
 
@@ -423,9 +445,13 @@ $publicKeyPemJsonSafe = json_encode($publicKeyPem); // gives string with \n insi
             FILE_APPEND
         );
 
-        $this->message = json_encode([
+        $successMsg = json_encode([
             'status' => 'received',
         ]);
+
+        if ($successMsg !== false) {
+            $this->message = $successMsg;
+        }
         return true;
     }
 
@@ -444,9 +470,13 @@ $publicKeyPemJsonSafe = json_encode($publicKeyPem); // gives string with \n insi
             FILE_APPEND
         );
 
-        $this->message = json_encode([
+        $successMsg = json_encode([
             'status' => 'received',
         ]);
+
+        if ($successMsg !== false) {
+            $this->message = $successMsg;
+        }
         return true;
     }
 
@@ -465,9 +495,13 @@ $publicKeyPemJsonSafe = json_encode($publicKeyPem); // gives string with \n insi
             FILE_APPEND
         );
 
-        $this->message = json_encode([
+        $successMsg = json_encode([
             'status' => 'received',
         ]);
+
+        if ($successMsg !== false) {
+            $this->message = $successMsg;
+        }
         return true;
     }
 
@@ -486,9 +520,13 @@ $publicKeyPemJsonSafe = json_encode($publicKeyPem); // gives string with \n insi
             FILE_APPEND
         );
 
-        $this->message = json_encode([
+        $successMsg = json_encode([
             'status' => 'received',
         ]);
+
+        if ($successMsg !== false) {
+            $this->message = $successMsg;
+        }
         return true;
     }
 
@@ -507,9 +545,13 @@ $publicKeyPemJsonSafe = json_encode($publicKeyPem); // gives string with \n insi
             FILE_APPEND
         );
 
-        $this->message = json_encode([
+        $successMsg = json_encode([
             'status' => 'received',
         ]);
+
+        if ($successMsg !== false) {
+            $this->message = $successMsg;
+        }
         return true;
     }
 
@@ -528,9 +570,13 @@ $publicKeyPemJsonSafe = json_encode($publicKeyPem); // gives string with \n insi
             FILE_APPEND
         );
 
-        $this->message = json_encode([
+        $successMsg = json_encode([
             'status' => 'received',
         ]);
+
+        if ($successMsg !== false) {
+            $this->message = $successMsg;
+        }
         return true;
     }
 
@@ -549,9 +595,13 @@ $publicKeyPemJsonSafe = json_encode($publicKeyPem); // gives string with \n insi
             FILE_APPEND
         );
 
-        $this->message = json_encode([
+        $successMsg = json_encode([
             'status' => 'received',
         ]);
+
+        if ($successMsg !== false) {
+            $this->message = $successMsg;
+        }
         return true;
     }
 
diff --git a/php/federator/main.php b/php/federator/main.php
index c7da143..d588c30 100644
--- a/php/federator/main.php
+++ b/php/federator/main.php
@@ -246,7 +246,7 @@ class Main
 
     /**
      * set cache
-     * 
+     *
      * @param \Federator\Cache\Cache $cache the new cache
      */
     public function setCache(Cache\Cache $cache): void
@@ -256,12 +256,12 @@ class Main
 
     /**
      * set connector
-     * 
+     *
      * @param \Federator\Connector\Connector $connector the new connector
      */
     public function setConnector(Connector\Connector $connector) : void
     {
-        if ($this->connector) {
+        if (isset($this->connector)) {
             # echo "main::setConnector Setting new connector will override old one.\n"; // TODO CHANGE TO LOG WARNING
         }
         $this->connector = $connector;
@@ -269,12 +269,12 @@ class Main
 
     /**
      * set host
-     * 
+     *
      * @param string $host the new host url
      */
     public function setHost(string $host) : void
     {
-        if ($this->host) {
+        if (isset($this->host)) {
             # echo "main::setHost Setting new host will override old one.\n"; // TODO CHANGE TO LOG WARNING
         }
         $this->host = $host;
diff --git a/plugins/federator/contentnation.php b/plugins/federator/contentnation.php
index dc7ef5f..e03c34f 100644
--- a/plugins/federator/contentnation.php
+++ b/plugins/federator/contentnation.php
@@ -60,7 +60,7 @@ class ContentNation implements Connector
      */
     public function getRemotePostsByUser($userId, $min, $max)
     {
-        if (preg_match("#^([^@]+)@([^/]+)#", $userId, $matches) === 1) {
+        if (preg_match("#^([^@]+)@([^/]+)#", $userId, $matches) == 1) {
             $userId = $matches[1];
         }
         $remoteURL = $this->service . '/api/profile/' . urlencode($userId) . '/activities';
@@ -129,9 +129,12 @@ class ContentNation implements Connector
                             ->setURL($idurl);
                         $image = $activity['image'] ?? $activity['profileimg'];
                         $path = $imgpath . $activity['profile'] . '/' . $image;
-                        $mediaType = (file_exists($path) && ($type = mime_content_type($path)) && !str_starts_with($type, 'text/'))
+
+                        $type = file_exists($path) ? mime_content_type($path) : false;
+                        $mediaType = ($type !== false && !str_starts_with($type, 'text/'))
                             ? $type
                             : 'image/jpeg';
+
                         $img = new \Federator\Data\ActivityPub\Common\Image();
                         $img->setMediaType($mediaType)
                             ->setName($articleimage)
@@ -228,7 +231,7 @@ class ContentNation implements Connector
      */
     public function getRemoteUserByName(string $_name)
     {
-        if (preg_match("#^([^@]+)@([^/]+)#", $_name, $matches) === 1) {
+        if (preg_match("#^([^@]+)@([^/]+)#", $_name, $matches) == 1) {
             $_name = $matches[1];
         }
         // validate name