diff --git a/src/Model/Contact/Group.php b/src/Model/Contact/Group.php
index 2b7096a9a8..0f0b4965cd 100644
--- a/src/Model/Contact/Group.php
+++ b/src/Model/Contact/Group.php
@@ -36,7 +36,7 @@ class Group
 	 * @return array
 	 * @throws \Exception
 	 */
-	public static function getById(int $gid)
+	public static function getById(int $gid): array
 	{
 		$return = [];
 
diff --git a/src/Model/Contact/Relation.php b/src/Model/Contact/Relation.php
index d68555eb3e..4f41e25ba0 100644
--- a/src/Model/Contact/Relation.php
+++ b/src/Model/Contact/Relation.php
@@ -174,7 +174,7 @@ class Relation
 	 * @param array $rel
 	 * @return array contact list
 	 */
-	private static function getContacts(int $uid, array $rel)
+	private static function getContacts(int $uid, array $rel): array
 	{
 		$list = [];
 		$profile = Profile::getByUID($uid);
@@ -182,8 +182,15 @@ class Relation
 			return $list;
 		}
 
-		$condition = ['rel' => $rel, 'uid' => $uid, 'self' => false, 'deleted' => false,
-			'hidden' => false, 'archive' => false, 'pending' => false];
+		$condition = [
+			'rel' => $rel,
+			'uid' => $uid,
+			'self' => false,
+			'deleted' => false,
+			'hidden' => false,
+			'archive' => false,
+			'pending' => false,
+		];
 		$condition = DBA::mergeConditions($condition, ["`url` IN (SELECT `url` FROM `apcontact`)"]);
 		$contacts = DBA::select('contact', ['url'], $condition);
 		while ($contact = DBA::fetch($contacts)) {
@@ -201,7 +208,7 @@ class Relation
 	 * @param array  $contact Contact array
 	 * @return boolean True if contact is discoverable
 	 */
-	public static function isDiscoverable(string $url, array $contact = [])
+	public static function isDiscoverable(string $url, array $contact = []): bool
 	{
 		$contact_discovery = DI::config()->get('system', 'contact_discovery');
 
@@ -254,12 +261,14 @@ class Relation
 	}
 
 	/**
-	 * @param int $uid   user
+	 * Returns an array of sugguested contacts for given user id
+	 *
+	 * @param int $uid   User id
 	 * @param int $start optional, default 0
 	 * @param int $limit optional, default 80
 	 * @return array
 	 */
-	static public function getSuggestions(int $uid, int $start = 0, int $limit = 80)
+	static public function getSuggestions(int $uid, int $start = 0, int $limit = 80): array
 	{
 		$cid = Contact::getPublicIdByUserId($uid);
 		$totallimit = $start + $limit;
@@ -272,20 +281,30 @@ class Relation
 
 		// The query returns contacts where contacts interacted with whom the given user follows.
 		// Contacts who already are in the user's contact table are ignored.
-		$results = DBA::select('contact', [],
-			["`id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` IN
+		$results = DBA::select('contact', [], ["`id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` IN
 				(SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ?)
 					AND NOT `cid` IN (SELECT `id` FROM `contact` WHERE `uid` = ? AND `nurl` IN
 						(SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` IN (?, ?))))
 			AND NOT `hidden` AND `network` IN (?, ?, ?, ?)",
-			$cid, 0, $uid, Contact::FRIEND, Contact::SHARING,
-			Protocol::ACTIVITYPUB, Protocol::DFRN, $diaspora, $ostatus],
-			['order' => ['last-item' => true], 'limit' => $totallimit]
+			$cid,
+			0,
+			$uid,
+			Contact::FRIEND,
+			Contact::SHARING,
+			Protocol::ACTIVITYPUB,
+			Protocol::DFRN,
+			$diaspora,
+			$ostatus,
+			], [
+				'order' => ['last-item' => true],
+				'limit' => $totallimit,
+			]
 		);
 
 		while ($contact = DBA::fetch($results)) {
 			$contacts[$contact['id']] = $contact;
 		}
+
 		DBA::close($results);
 
 		Logger::info('Contacts of contacts who are followed by the given user', ['uid' => $uid, 'cid' => $cid, 'count' => count($contacts)]);
@@ -365,12 +384,12 @@ class Relation
 	 * @return int
 	 * @throws Exception
 	 */
-	public static function countFollows(int $cid, array $condition = [])
+	public static function countFollows(int $cid, array $condition = []): int
 	{
-		$condition = DBA::mergeConditions($condition,
-			['`id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ? AND `follows`)', 
-			$cid]
-		);
+		$condition = DBA::mergeConditions($condition, [
+			'`id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ? AND `follows`)', 
+			$cid,
+		]);
 
 		return DI::dba()->count('contact', $condition);
 	}
@@ -556,7 +575,7 @@ class Relation
 	 * @param int   $count
 	 * @param int   $offset
 	 * @param bool  $shuffle
-	 * @return array
+	 * @return array|bool Array on success, false on failure
 	 * @throws Exception
 	 */
 	public static function listCommon(int $sourceId, int $targetId, array $condition = [], int $count = 30, int $offset = 0, bool $shuffle = false)
@@ -581,7 +600,7 @@ class Relation
 	 * @return int
 	 * @throws Exception
 	 */
-	public static function countCommonFollows(int $sourceId, int $targetId, array $condition = [])
+	public static function countCommonFollows(int $sourceId, int $targetId, array $condition = []): int
 	{
 		$condition = DBA::mergeConditions($condition,
 			['`id` IN (SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ? AND `follows`) 
@@ -601,7 +620,7 @@ class Relation
 	 * @param int   $count
 	 * @param int   $offset
 	 * @param bool  $shuffle
-	 * @return array
+	 * @return array|bool Array on success, false on failure
 	 * @throws Exception
 	 */
 	public static function listCommonFollows(int $sourceId, int $targetId, array $condition = [], int $count = 30, int $offset = 0, bool $shuffle = false)
@@ -626,7 +645,7 @@ class Relation
 	 * @return int
 	 * @throws Exception
 	 */
-	public static function countCommonFollowers(int $sourceId, int $targetId, array $condition = [])
+	public static function countCommonFollowers(int $sourceId, int $targetId, array $condition = []): int
 	{
 		$condition = DBA::mergeConditions($condition,
 			["`id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ? AND `follows`) 
@@ -646,7 +665,7 @@ class Relation
 	 * @param int   $count
 	 * @param int   $offset
 	 * @param bool  $shuffle
-	 * @return array
+	 * @return array|bool Array on success, false on failure
 	 * @throws Exception
 	 */
 	public static function listCommonFollowers(int $sourceId, int $targetId, array $condition = [], int $count = 30, int $offset = 0, bool $shuffle = false)
diff --git a/src/Model/Contact/User.php b/src/Model/Contact/User.php
index 665b95624d..ab409077b5 100644
--- a/src/Model/Contact/User.php
+++ b/src/Model/Contact/User.php
@@ -82,11 +82,11 @@ class User
 	/**
 	 * Apply changes from contact update data to user-contact table
 	 *
-	 * @param array $fields 
-	 * @param array $condition 
-	 * @return void 
-	 * @throws PDOException 
-	 * @throws Exception 
+	 * @param array $fields Fields
+	 * @param array $condition Conditions
+	 * @return void
+	 * @throws PDOException
+	 * @throws Exception
 	 */
 	public static function updateByContactUpdate(array $fields, array $condition)
 	{
@@ -138,9 +138,10 @@ class User
 	 * @param int     $cid     Either public contact id or user's contact id
 	 * @param int     $uid     User ID
 	 * @param boolean $blocked Is the contact blocked or unblocked?
+	 * @return void
 	 * @throws \Exception
 	 */
-	public static function setBlocked($cid, $uid, $blocked)
+	public static function setBlocked(int $cid, int $uid, bool $blocked)
 	{
 		$cdata = Contact::getPublicAndUserContactID($cid, $uid);
 		if (empty($cdata)) {
@@ -170,7 +171,7 @@ class User
 	 * @return boolean is the contact id blocked for the given user?
 	 * @throws \Exception
 	 */
-	public static function isBlocked($cid, $uid)
+	public static function isBlocked(int $cid, int $uid): bool
 	{
 		$cdata = Contact::getPublicAndUserContactID($cid, $uid);
 		if (empty($cdata)) {
@@ -208,9 +209,10 @@ class User
 	 * @param int     $cid     Either public contact id or user's contact id
 	 * @param int     $uid     User ID
 	 * @param boolean $ignored Is the contact ignored or unignored?
+	 * @return void
 	 * @throws \Exception
 	 */
-	public static function setIgnored($cid, $uid, $ignored)
+	public static function setIgnored(int $cid, int $uid, bool $ignored)
 	{
 		$cdata = Contact::getPublicAndUserContactID($cid, $uid);
 		if (empty($cdata)) {
@@ -229,11 +231,10 @@ class User
 	 *
 	 * @param int $cid Either public contact id or user's contact id
 	 * @param int $uid User ID
-	 *
 	 * @return boolean is the contact id ignored for the given user?
 	 * @throws \Exception
 	 */
-	public static function isIgnored($cid, $uid)
+	public static function isIgnored(int $cid, int $uid): bool
 	{
 		$cdata = Contact::getPublicAndUserContactID($cid, $uid);
 		if (empty($cdata)) {
@@ -271,9 +272,10 @@ class User
 	 * @param int     $cid       Either public contact id or user's contact id
 	 * @param int     $uid       User ID
 	 * @param boolean $collapsed are the contact's posts collapsed or uncollapsed?
+	 * @return void
 	 * @throws \Exception
 	 */
-	public static function setCollapsed($cid, $uid, $collapsed)
+	public static function setCollapsed(int $cid, int $uid, bool $collapsed)
 	{
 		$cdata = Contact::getPublicAndUserContactID($cid, $uid);
 		if (empty($cdata)) {
@@ -288,16 +290,15 @@ class User
 	 *
 	 * @param int $cid Either public contact id or user's contact id
 	 * @param int $uid User ID
-	 *
 	 * @return boolean is the contact id blocked for the given user?
 	 * @throws HTTPException\InternalServerErrorException
 	 * @throws \ImagickException
 	 */
-	public static function isCollapsed($cid, $uid)
+	public static function isCollapsed(int $cid, int $uid): bool
 	{
 		$cdata = Contact::getPublicAndUserContactID($cid, $uid);
 		if (empty($cdata)) {
-			return;
+			return false;
 		}
 
 		$collapsed = false;
@@ -318,9 +319,10 @@ class User
 	 * @param int     $cid     Either public contact id or user's contact id
 	 * @param int     $uid     User ID
 	 * @param boolean $blocked Is the user blocked or unblocked by the contact?
+	 * @return void
 	 * @throws \Exception
 	 */
-	public static function setIsBlocked($cid, $uid, $blocked)
+	public static function setIsBlocked(int $cid, int $uid, bool $blocked)
 	{
 		$cdata = Contact::getPublicAndUserContactID($cid, $uid);
 		if (empty($cdata)) {
@@ -335,11 +337,10 @@ class User
 	 *
 	 * @param int $cid Either public contact id or user's contact id
 	 * @param int $uid User ID
-	 *
 	 * @return boolean Is the user blocked or unblocked by the contact?
 	 * @throws \Exception
 	 */
-	public static function isIsBlocked($cid, $uid)
+	public static function isIsBlocked(int $cid, int $uid): bool
 	{
 		$cdata = Contact::getPublicAndUserContactID($cid, $uid);
 		if (empty($cdata)) {
diff --git a/src/Model/Log/ParsedLogIterator.php b/src/Model/Log/ParsedLogIterator.php
index d3a5650397..4309e4cd00 100644
--- a/src/Model/Log/ParsedLogIterator.php
+++ b/src/Model/Log/ParsedLogIterator.php
@@ -45,7 +45,7 @@ class ParsedLogIterator implements \Iterator
 	private $filters = [];
 
 	/** @var string search term */
-	private $search = "";
+	private $search = '';
 
 
 	/**
@@ -108,10 +108,11 @@ class ParsedLogIterator implements \Iterator
 		$match = true;
 		foreach ($this->filters as $filter => $filtervalue) {
 			switch ($filter) {
-				case "level":
+				case 'level':
 					$match = $match && ($parsedlogline->level == strtoupper($filtervalue));
 					break;
-				case "context":
+
+				case 'context':
 					$match = $match && ($parsedlogline->context == $filtervalue);
 					break;
 			}
@@ -128,7 +129,7 @@ class ParsedLogIterator implements \Iterator
 	 */
 	private function search(ParsedLogLine $parsedlogline): bool
 	{
-		if ($this->search != "") {
+		if ($this->search != '') {
 			return strstr($parsedlogline->logline, $this->search) !== false;
 		}
 		return true;
@@ -138,7 +139,6 @@ class ParsedLogIterator implements \Iterator
 	 * Read a line from reader and parse.
 	 * Returns null if limit is reached or the reader is invalid.
 	 *
-	 * @param ParsedLogLine $parsedlogline
 	 * @return ?ParsedLogLine
 	 */
 	private function read()
@@ -191,7 +191,7 @@ class ParsedLogIterator implements \Iterator
 	 * @see ReversedFileReader::key()
 	 * @return int
 	 */
-	public function key()
+	public function key(): int
 	{
 		return $this->reader->key();
 	}
@@ -213,8 +213,8 @@ class ParsedLogIterator implements \Iterator
 	 * @see Iterator::valid()
 	 * @return bool
 	 */
-	public function valid()
+	public function valid(): bool
 	{
-		return ! is_null($this->value);
+		return !is_null($this->value);
 	}
 }
diff --git a/src/Module/Install.php b/src/Module/Install.php
index 09025ff493..59d6581056 100644
--- a/src/Module/Install.php
+++ b/src/Module/Install.php
@@ -363,7 +363,7 @@ class Install extends BaseModule
 	 * @return string The text for the next steps
 	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 	 */
-	private function whatNext()
+	private function whatNext(): string
 	{
 		$baseurl = $this->baseUrl->get();
 		return
@@ -383,6 +383,7 @@ class Install extends BaseModule
 	 * @param string                                   $cat         The category of the setting
 	 * @param string                                   $key         The key of the setting
 	 * @param null|string                              $default     The default value
+	 * @return void
 	 */
 	private function checkSetting(Cache $configCache, array $post, string $cat, string $key, ?string $default = null)
 	{
diff --git a/src/Module/Maintenance.php b/src/Module/Maintenance.php
index 05540a228b..4080869158 100644
--- a/src/Module/Maintenance.php
+++ b/src/Module/Maintenance.php
@@ -45,7 +45,7 @@ class Maintenance extends BaseModule
 
 		$exception = new HTTPException\ServiceUnavailableException($reason);
 
-		header($_SERVER["SERVER_PROTOCOL"] . ' ' . $exception->getCode() . ' ' . DI::l10n()->t('System down for maintenance'));
+		header($_SERVER['SERVER_PROTOCOL'] . ' ' . $exception->getCode() . ' ' . DI::l10n()->t('System down for maintenance'));
 
 		$tpl = Renderer::getMarkupTemplate('exception.tpl');
 
diff --git a/src/Module/NoScrape.php b/src/Module/NoScrape.php
index fbc01c2d3c..e3a01ceaab 100644
--- a/src/Module/NoScrape.php
+++ b/src/Module/NoScrape.php
@@ -131,7 +131,7 @@ class NoScrape extends BaseModule
 		$profile_fields = ['about', 'locality', 'region', 'postal-code', 'country-name', 'xmpp', 'matrix'];
 		foreach ($profile_fields as $field) {
 			if (!empty($owner[$field])) {
-				$json_info["$field"] = $owner[$field];
+				$json_info[$field] = $owner[$field];
 			}
 		}
 
diff --git a/src/Module/PermissionTooltip.php b/src/Module/PermissionTooltip.php
index 07faa72e3e..ec449aa15f 100644
--- a/src/Module/PermissionTooltip.php
+++ b/src/Module/PermissionTooltip.php
@@ -174,7 +174,7 @@ class PermissionTooltip extends \Friendica\BaseModule
 	 * @param int $uriId
 	 * @return string
 	 */
-	private function fetchReceivers(int $uriId):string
+	private function fetchReceivers(int $uriId): string
 	{
 		$own_url = '';
 		$uid = local_user();
diff --git a/src/Module/Photo.php b/src/Module/Photo.php
index bedc216fb2..341858259f 100644
--- a/src/Module/Photo.php
+++ b/src/Module/Photo.php
@@ -60,17 +60,17 @@ class Photo extends BaseModule
 	{
 		$totalstamp = microtime(true);
 
-		if (isset($_SERVER["HTTP_IF_MODIFIED_SINCE"])) {
-			header("Last-Modified: " . gmdate("D, d M Y H:i:s", time()) . " GMT");
-			if (!empty($_SERVER["HTTP_IF_NONE_MATCH"])) {
-				header("Etag: " . $_SERVER["HTTP_IF_NONE_MATCH"]);
+		if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE'])) {
+			header('Last-Modified: ' . gmdate('D, d M Y H:i:s', time()) . ' GMT');
+			if (!empty($_SERVER['HTTP_IF_NONE_MATCH'])) {
+				header('Etag: ' . $_SERVER['HTTP_IF_NONE_MATCH']);
 			}
-			header("Expires: " . gmdate("D, d M Y H:i:s", time() + (31536000)) . " GMT");
-			header("Cache-Control: max-age=31536000");
-			if (function_exists("header_remove")) {
-				header_remove("Last-Modified");
-				header_remove("Expires");
-				header_remove("Cache-Control");
+			header('Expires: ' . gmdate('D, d M Y H:i:s', time() + (31536000)) . ' GMT');
+			header('Cache-Control: max-age=31536000');
+			if (function_exists('header_remove')) {
+				header_remove('Last-Modified');
+				header_remove('Expires');
+				header_remove('Cache-Control');
 			}
 			throw new NotModifiedException();
 		}
@@ -132,7 +132,7 @@ class Photo extends BaseModule
 		} else {
 			$photoid = pathinfo($this->parameters['name'], PATHINFO_FILENAME);
 			$scale = 0;
-			if (substr($photoid, -2, 1) == "-") {
+			if (substr($photoid, -2, 1) == '-') {
 				$scale = intval(substr($photoid, -1, 1));
 				$photoid = substr($photoid, 0, -2);
 			}
@@ -148,7 +148,7 @@ class Photo extends BaseModule
 			throw new HTTPException\NotFoundException();
 		}
 
-		$cacheable = ($photo["allow_cid"] . $photo["allow_gid"] . $photo["deny_cid"] . $photo["deny_gid"] === "") && (isset($photo["cacheable"]) ? $photo["cacheable"] : true);
+		$cacheable = ($photo['allow_cid'] . $photo['allow_gid'] . $photo['deny_cid'] . $photo['deny_gid'] === '') && (isset($photo['cacheable']) ? $photo['cacheable'] : true);
 
 		$stamp = microtime(true);
 
@@ -179,35 +179,35 @@ class Photo extends BaseModule
 		}
 
 		// if customsize is set and image is not a gif, resize it
-		if ($photo['type'] !== "image/gif" && $customsize > 0 && $customsize <= Proxy::PIXEL_THUMB && $square_resize) {
+		if ($photo['type'] !== 'image/gif' && $customsize > 0 && $customsize <= Proxy::PIXEL_THUMB && $square_resize) {
 			$img = new Image($imgdata, $photo['type']);
 			$img->scaleToSquare($customsize);
 			$imgdata = $img->asString();
-		} elseif ($photo['type'] !== "image/gif" && $customsize > 0) {
+		} elseif ($photo['type'] !== 'image/gif' && $customsize > 0) {
 			$img = new Image($imgdata, $photo['type']);
 			$img->scaleDown($customsize);
 			$imgdata = $img->asString();
 		}
 
-		if (function_exists("header_remove")) {
-			header_remove("Pragma");
-			header_remove("pragma");
+		if (function_exists('header_remove')) {
+			header_remove('Pragma');
+			header_remove('pragma');
 		}
 
-		header("Content-type: " . $photo['type']);
+		header('Content-type: ' . $photo['type']);
 
 		$stamp = microtime(true);
 		if (!$cacheable) {
 			// it is a private photo that they have no permission to view.
 			// tell the browser not to cache it, in case they authenticate
 			// and subsequently have permission to see it
-			header("Cache-Control: no-store, no-cache, must-revalidate");
+			header('Cache-Control: no-store, no-cache, must-revalidate');
 		} else {
 			$md5 = $photo['hash'] ?: md5($imgdata);
-			header("Last-Modified: " . gmdate("D, d M Y H:i:s", time()) . " GMT");
+			header('Last-Modified: ' . gmdate('D, d M Y H:i:s', time()) . ' GMT');
 			header("Etag: \"{$md5}\"");
-			header("Expires: " . gmdate("D, d M Y H:i:s", time() + (31536000)) . " GMT");
-			header("Cache-Control: max-age=31536000");
+			header('Expires: ' . gmdate('D, d M Y H:i:s', time() + (31536000)) . ' GMT');
+			header('Cache-Control: max-age=31536000');
 		}
 		$checksum = microtime(true) - $stamp;
 
diff --git a/src/Module/Proxy.php b/src/Module/Proxy.php
index 90f1185800..cff5ed90b0 100644
--- a/src/Module/Proxy.php
+++ b/src/Module/Proxy.php
@@ -55,17 +55,17 @@ class Proxy extends BaseModule
 			throw new \Friendica\Network\HTTPException\NotFoundException();
 		}
 
-		if (isset($_SERVER["HTTP_IF_MODIFIED_SINCE"])) {
-			header("Last-Modified: " . gmdate("D, d M Y H:i:s", time()) . " GMT");
-			if (!empty($_SERVER["HTTP_IF_NONE_MATCH"])) {
-				header("Etag: " . $_SERVER["HTTP_IF_NONE_MATCH"]);
+		if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE'])) {
+			header('Last-Modified: ' . gmdate('D, d M Y H:i:s', time()) . ' GMT');
+			if (!empty($_SERVER['HTTP_IF_NONE_MATCH'])) {
+				header('Etag: ' . $_SERVER['HTTP_IF_NONE_MATCH']);
 			}
-			header("Expires: " . gmdate("D, d M Y H:i:s", time() + (31536000)) . " GMT");
-			header("Cache-Control: max-age=31536000");
-			if (function_exists("header_remove")) {
-				header_remove("Last-Modified");
-				header_remove("Expires");
-				header_remove("Cache-Control");
+			header('Expires: ' . gmdate('D, d M Y H:i:s', time() + (31536000)) . ' GMT');
+			header('Cache-Control: max-age=31536000');
+			if (function_exists('header_remove')) {
+				header_remove('Last-Modified');
+				header_remove('Expires');
+				header_remove('Cache-Control');
 			}
 			throw new NotModifiedException();
 		}
@@ -123,7 +123,7 @@ class Proxy extends BaseModule
 	 *    ]
 	 * @throws \Exception
 	 */
-	private function getRequestInfo()
+	private function getRequestInfo(): array
 	{
 		$size = ProxyUtils::PIXEL_LARGE;
 		$sizetype = '';
@@ -187,6 +187,7 @@ class Proxy extends BaseModule
 	 * Output the image with cache headers
 	 *
 	 * @param Image $img
+	 * @return void
 	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 	 */
 	private static function responseImageHttpCache(Image $img)