diff --git a/blockem/blockem.php b/blockem/blockem.php
index 2a5fd8b60..fbba29f40 100644
--- a/blockem/blockem.php
+++ b/blockem/blockem.php
@@ -11,6 +11,7 @@ use Friendica\App;
 use Friendica\Core\Addon;
 use Friendica\Core\L10n;
 use Friendica\Core\PConfig;
+use Friendica\Util\Strings;
 
 function blockem_install()
 {
@@ -100,7 +101,7 @@ function blockem_enotify_store(App $a, array &$b)
 				continue;
 			}
 
-			if (link_compare($b['url'], $word)) {
+			if (Strings::compareLink($b['url'], $word)) {
 				$found = true;
 				break;
 			}
@@ -133,7 +134,7 @@ function blockem_prepare_body_content_filter(App $a, array &$hook_data)
 	$found = false;
 
 	foreach ($profiles_array as $word) {
-		if (link_compare($hook_data['item']['author-link'], trim($word))) {
+		if (Strings::compareLink($hook_data['item']['author-link'], trim($word))) {
 			$found = true;
 			break;
 		}
@@ -192,7 +193,7 @@ function blockem_item_photo_menu(App $a, array &$b)
 
 	if (!empty($a->data['blockem'])) {
 		foreach($a->data['blockem'] as $bloke) {
-			if (link_compare($bloke,$author)) {
+			if (Strings::compareLink($bloke,$author)) {
 				$blocked = true;
 				break;
 			}
@@ -231,7 +232,7 @@ function blockem_init(App $a)
 
 		if (count($arr)) {
 			foreach ($arr as $x) {
-				if (!link_compare(trim($x), trim($_GET['unblock']))) {
+				if (!Strings::compareLink(trim($x), trim($_GET['unblock']))) {
 					$newarr[] = $x;
 				}
 			}
diff --git a/buffer/buffer.php b/buffer/buffer.php
index bb9af8ab3..d9378cb12 100644
--- a/buffer/buffer.php
+++ b/buffer/buffer.php
@@ -19,6 +19,7 @@ use Friendica\Core\Renderer;
 use Friendica\Database\DBA;
 use Friendica\Model\ItemContent;
 use Friendica\Util\Proxy as ProxyUtils;
+use Friendica\Util\Strings;
 
 function buffer_install()
 {
@@ -83,8 +84,8 @@ function buffer_addon_admin(App $a, &$o)
 
 function buffer_addon_admin_post(App $a)
 {
-	$client_id     = ((!empty($_POST['client_id']))     ? notags(trim($_POST['client_id']))     : '');
-	$client_secret = ((!empty($_POST['client_secret'])) ? notags(trim($_POST['client_secret'])) : '');
+	$client_id     = ((!empty($_POST['client_id']))     ? Strings::escapeTags(trim($_POST['client_id']))     : '');
+	$client_secret = ((!empty($_POST['client_secret'])) ? Strings::escapeTags(trim($_POST['client_secret'])) : '');
 
 	Config::set('buffer', 'client_id'    , $client_id);
 	Config::set('buffer', 'client_secret', $client_secret);
diff --git a/forumdirectory/forumdirectory.php b/forumdirectory/forumdirectory.php
index 1c88dfafe..a901015f2 100644
--- a/forumdirectory/forumdirectory.php
+++ b/forumdirectory/forumdirectory.php
@@ -17,6 +17,7 @@ use Friendica\Core\Renderer;
 use Friendica\Database\DBA;
 use Friendica\Model\Contact;
 use Friendica\Model\Profile;
+use Friendica\Util\Strings;
 use Friendica\Util\Temporal;
 
 require_once 'boot.php';
@@ -72,9 +73,9 @@ function forumdirectory_content(App $a)
 	Nav::setSelected('directory');
 
 	if (!empty($a->data['search'])) {
-		$search = notags(trim($a->data['search']));
+		$search = Strings::escapeTags(trim($a->data['search']));
 	} else {
-		$search = ((!empty($_GET['search'])) ? notags(trim(rawurldecode($_GET['search']))) : '');
+		$search = ((!empty($_GET['search'])) ? Strings::escapeTags(trim(rawurldecode($_GET['search']))) : '');
 	}
 
 	$tpl = Renderer::getMarkupTemplate('directory_header.tpl');
diff --git a/geocoordinates/geocoordinates.php b/geocoordinates/geocoordinates.php
index 1a0b9daab..58c5a30c7 100644
--- a/geocoordinates/geocoordinates.php
+++ b/geocoordinates/geocoordinates.php
@@ -12,6 +12,7 @@ use Friendica\Core\L10n;
 use Friendica\Core\Logger;
 use Friendica\Core\Renderer;
 use Friendica\Util\Network;
+use Friendica\Util\Strings;
 
 function geocoordinates_install()
 {
@@ -99,10 +100,10 @@ function geocoordinates_addon_admin(&$a, &$o)
 
 function geocoordinates_addon_admin_post(&$a)
 {
-	$api_key  = ((x($_POST, 'api_key')) ? notags(trim($_POST['api_key']))   : '');
+	$api_key  = ((x($_POST, 'api_key')) ? Strings::escapeTags(trim($_POST['api_key']))   : '');
 	Config::set('geocoordinates', 'api_key', $api_key);
 
-	$language  = ((x($_POST, 'language')) ? notags(trim($_POST['language']))   : '');
+	$language  = ((x($_POST, 'language')) ? Strings::escapeTags(trim($_POST['language']))   : '');
 	Config::set('geocoordinates', 'language', $language);
 	info(L10n::t('Settings updated.'). EOL);
 }
diff --git a/gravatar/gravatar.php b/gravatar/gravatar.php
index d0d546899..49eec4a66 100644
--- a/gravatar/gravatar.php
+++ b/gravatar/gravatar.php
@@ -15,6 +15,7 @@ use Friendica\Core\Logger;
 use Friendica\Core\Renderer;
 use Friendica\Database\DBA;
 use Friendica\Util\Security;
+use Friendica\Util\Strings;
 
 /**
  * Installs the addon hook
@@ -121,8 +122,8 @@ function gravatar_addon_admin (&$a, &$o) {
 function gravatar_addon_admin_post (&$a) {
 	BaseModule::checkFormSecurityToken('gravatarsave');
 
-	$default_avatar = ((x($_POST, 'avatar')) ? notags(trim($_POST['avatar'])) : 'identicon');
-	$rating = ((x($_POST, 'rating')) ? notags(trim($_POST['rating'])) : 'g');
+	$default_avatar = ((x($_POST, 'avatar')) ? Strings::escapeTags(trim($_POST['avatar'])) : 'identicon');
+	$rating = ((x($_POST, 'rating')) ? Strings::escapeTags(trim($_POST['rating'])) : 'g');
 	Config::set('gravatar', 'default_avatar', $default_avatar);
 	Config::set('gravatar', 'rating', $rating);
 	info(L10n::t('Gravatar settings updated.') .EOL);
diff --git a/ifttt/ifttt.php b/ifttt/ifttt.php
index a5838c049..fd5700488 100644
--- a/ifttt/ifttt.php
+++ b/ifttt/ifttt.php
@@ -18,6 +18,7 @@ use Friendica\Core\PConfig;
 use Friendica\Core\Protocol;
 use Friendica\Database\DBA;
 use Friendica\Model\Item;
+use Friendica\Util\Strings;
 
 function ifttt_install()
 {
@@ -50,7 +51,7 @@ function ifttt_settings(App $a, &$s)
 	$key = PConfig::get(local_user(), 'ifttt', 'key');
 
 	if (!$key) {
-		$key = random_string(20);
+		$key = Strings::getRandomHex(20);
 		PConfig::set(local_user(), 'ifttt', 'key', $key);
 	}
 
diff --git a/impressum/impressum.php b/impressum/impressum.php
index 0efe5c3c6..3e04c64fe 100644
--- a/impressum/impressum.php
+++ b/impressum/impressum.php
@@ -14,6 +14,7 @@ use Friendica\Core\L10n;
 use Friendica\Core\Logger;
 use Friendica\Core\Renderer;
 use Friendica\Util\Proxy as ProxyUtils;
+use Friendica\Util\Strings;
 
 function impressum_install() {
 	Addon::registerHook('load_config', 'addon/impressum/impressum.php', 'impressum_load_config');
@@ -86,11 +87,11 @@ function impressum_show($a,&$b) {
 }
 
 function impressum_addon_admin_post (&$a) {
-    $owner = ((x($_POST, 'owner')) ? notags(trim($_POST['owner'])) : '');
-    $ownerprofile = ((x($_POST, 'ownerprofile')) ? notags(trim($_POST['ownerprofile'])) : '');
+    $owner = ((x($_POST, 'owner')) ? Strings::escapeTags(trim($_POST['owner'])) : '');
+    $ownerprofile = ((x($_POST, 'ownerprofile')) ? Strings::escapeTags(trim($_POST['ownerprofile'])) : '');
     $postal = ((x($_POST, 'postal')) ? (trim($_POST['postal'])) : '');
     $notes = ((x($_POST, 'notes')) ? (trim($_POST['notes'])) : '');
-    $email = ((x($_POST, 'email')) ? notags(trim($_POST['email'])) : '');
+    $email = ((x($_POST, 'email')) ? Strings::escapeTags(trim($_POST['email'])) : '');
     $footer_text = ((x($_POST, 'footer_text')) ? (trim($_POST['footer_text'])) : '');
     Config::set('impressum','owner',strip_tags($owner));
     Config::set('impressum','ownerprofile',strip_tags($ownerprofile));
diff --git a/libravatar/libravatar.php b/libravatar/libravatar.php
index 39f77a569..c711bf5ed 100644
--- a/libravatar/libravatar.php
+++ b/libravatar/libravatar.php
@@ -15,6 +15,7 @@ use Friendica\Core\Logger;
 use Friendica\Core\Renderer;
 use Friendica\Database\DBA;
 use Friendica\Util\Security;
+use Friendica\Util\Strings;
 
 /**
  * Installs the addon hook
@@ -124,7 +125,7 @@ function libravatar_addon_admin_post(&$a)
 {
 	BaseModule::checkFormSecurityToken('libravatarrsave');
 
-	$default_avatar = ((x($_POST, 'avatar')) ? notags(trim($_POST['avatar'])) : 'identicon');
+	$default_avatar = ((x($_POST, 'avatar')) ? Strings::escapeTags(trim($_POST['avatar'])) : 'identicon');
 	Config::set('libravatar', 'default_avatar', $default_avatar);
 	info(L10n::t('Libravatar settings updated.') .EOL);
 }
diff --git a/newmemberwidget/newmemberwidget.php b/newmemberwidget/newmemberwidget.php
index 73ae176cc..8ecbaaa9a 100644
--- a/newmemberwidget/newmemberwidget.php
+++ b/newmemberwidget/newmemberwidget.php
@@ -12,6 +12,7 @@ use Friendica\Core\Config;
 use Friendica\Core\L10n;
 use Friendica\Core\Logger;
 use Friendica\Core\Renderer;
+use Friendica\Util\Strings;
 
 function newmemberwidget_install()
 {
@@ -54,7 +55,7 @@ function newmemberwidget_network_mod_init ($a, $b)
 function newmemberwidget_addon_admin_post(&$a)
 {
 	$ft = ((x($_POST, 'freetext')) ? trim($_POST['freetext']) : "");
-	$lsn = ((x($_POST, 'localsupportname')) ? notags(trim($_POST['localsupportname'])) : "");
+	$lsn = ((x($_POST, 'localsupportname')) ? Strings::escapeTags(trim($_POST['localsupportname'])) : "");
 	$gs = intval($_POST['linkglobalsupport']);
 	$ls = intval($_POST['linklocalsupport']);
 	Config::set('newmemberwidget', 'freetext',           trim($ft));
diff --git a/openstreetmap/openstreetmap.php b/openstreetmap/openstreetmap.php
index 68edf8bfe..0410931e7 100644
--- a/openstreetmap/openstreetmap.php
+++ b/openstreetmap/openstreetmap.php
@@ -16,6 +16,7 @@ use Friendica\Core\Logger;
 use Friendica\Core\Renderer;
 use Friendica\Core\System;
 use Friendica\Util\Network;
+use Friendica\Util\Strings;
 
 const OSM_TMS = 'https://www.openstreetmap.org';
 const OSM_NOM = 'https://nominatim.openstreetmap.org/search.php';
@@ -176,7 +177,7 @@ function openstreetmap_generate_map(&$a, &$b)
 		$cardlink .= '?mlat=' . $lat . '&mlon=' . $lon;
 	}
 
-	$cardlink .= '#map=' . $zoom . '/' . $lat . '/' . $lon . '">' . ($b['location'] ? escape_tags($b['location']) : L10n::t('View Larger')) . '</a>';
+	$cardlink .= '#map=' . $zoom . '/' . $lat . '/' . $lon . '">' . ($b['location'] ? Strings::escapeHtml($b['location']) : L10n::t('View Larger')) . '</a>';
 	if (empty($b['mode'])) {
 		$b['html'] = '<iframe style="width:100%; height:300px; border:1px solid #ccc" src="' . $tmsserver .
 				'/export/embed.html?bbox=' . ($lon - 0.01) . '%2C' . ($lat - 0.01) . '%2C' . ($lon + 0.01) . '%2C' . ($lat + 0.01) .
diff --git a/piwik/piwik.php b/piwik/piwik.php
index 777552362..988c1e0e3 100644
--- a/piwik/piwik.php
+++ b/piwik/piwik.php
@@ -35,6 +35,7 @@ use Friendica\Core\Config;
 use Friendica\Core\L10n;
 use Friendica\Core\Logger;
 use Friendica\Core\Renderer;
+use Friendica\Util\Strings;
 
 function piwik_install() {
 	Addon::registerHook('load_config', 'addon/piwik/piwik.php', 'piwik_load_config');
@@ -107,7 +108,7 @@ function piwik_addon_admin (&$a, &$o) {
 	]);
 }
 function piwik_addon_admin_post (&$a) {
-	$url = ((x($_POST, 'baseurl')) ? notags(trim($_POST['baseurl'])) : '');
+	$url = ((x($_POST, 'baseurl')) ? Strings::escapeTags(trim($_POST['baseurl'])) : '');
 	$id = ((x($_POST, 'siteid')) ? trim($_POST['siteid']) : '');
 	$optout = ((x($_POST, 'optout')) ? trim($_POST['optout']) : '');
 	$async = ((x($_POST, 'async')) ? trim($_POST['async']) : '');
diff --git a/public_server/public_server.php b/public_server/public_server.php
index 3421dcc11..9b3aa4053 100644
--- a/public_server/public_server.php
+++ b/public_server/public_server.php
@@ -15,6 +15,7 @@ use Friendica\Core\Logger;
 use Friendica\Core\Renderer;
 use Friendica\Database\DBA;
 use Friendica\Util\DateTimeFormat;
+use Friendica\Util\Strings;
 
 function public_server_install()
 {
@@ -147,12 +148,12 @@ function public_server_login($a, $b)
 function public_server_addon_admin_post(&$a)
 {
 	BaseModule::checkFormSecurityTokenRedirectOnError('/admin/addons/publicserver', 'publicserver');
-	$expiredays = (x($_POST, 'expiredays') ? notags(trim($_POST['expiredays'])) : '');
-	$expireposts = (x($_POST, 'expireposts') ? notags(trim($_POST['expireposts'])) : '');
-	$nologin = (x($_POST, 'nologin') ? notags(trim($_POST['nologin'])) : '');
-	$flagusers = (x($_POST, 'flagusers') ? notags(trim($_POST['flagusers'])) : '');
-	$flagposts = (x($_POST, 'flagposts') ? notags(trim($_POST['flagposts'])) : '');
-	$flagpostsexpire = (x($_POST, 'flagpostsexpire') ? notags(trim($_POST['flagpostsexpire'])) : '');
+	$expiredays = (x($_POST, 'expiredays') ? Strings::escapeTags(trim($_POST['expiredays'])) : '');
+	$expireposts = (x($_POST, 'expireposts') ? Strings::escapeTags(trim($_POST['expireposts'])) : '');
+	$nologin = (x($_POST, 'nologin') ? Strings::escapeTags(trim($_POST['nologin'])) : '');
+	$flagusers = (x($_POST, 'flagusers') ? Strings::escapeTags(trim($_POST['flagusers'])) : '');
+	$flagposts = (x($_POST, 'flagposts') ? Strings::escapeTags(trim($_POST['flagposts'])) : '');
+	$flagpostsexpire = (x($_POST, 'flagpostsexpire') ? Strings::escapeTags(trim($_POST['flagpostsexpire'])) : '');
 	Config::set('public_server', 'expiredays', $expiredays);
 	Config::set('public_server', 'expireposts', $expireposts);
 	Config::set('public_server', 'nologin', $nologin);
diff --git a/pumpio/pumpio.php b/pumpio/pumpio.php
index 6d3fe62d3..71b5cf159 100644
--- a/pumpio/pumpio.php
+++ b/pumpio/pumpio.php
@@ -25,6 +25,7 @@ use Friendica\Model\Queue;
 use Friendica\Model\User;
 use Friendica\Util\DateTimeFormat;
 use Friendica\Util\Network;
+use Friendica\Util\Strings;
 use Friendica\Util\XML;
 
 require 'addon/pumpio/oauth/http.php';
@@ -878,11 +879,11 @@ function pumpio_dounlike(App $a, $uid, $self, $post, $own_id)
 
 	$contactid = 0;
 
-	if (link_compare($post->actor->url, $own_id)) {
+	if (Strings::compareLink($post->actor->url, $own_id)) {
 		$contactid = $self[0]['id'];
 	} else {
 		$r = q("SELECT * FROM `contact` WHERE `nurl` = '%s' AND `uid` = %d AND `blocked` = 0 AND `readonly` = 0 LIMIT 1",
-			DBA::escape(normalise_link($post->actor->url)),
+			DBA::escape(Strings::normaliseLink($post->actor->url)),
 			intval($uid)
 		);
 
@@ -930,14 +931,14 @@ function pumpio_dolike(App $a, $uid, $self, $post, $own_id, $threadcompletion =
 
 	$contactid = 0;
 
-	if (link_compare($post->actor->url, $own_id)) {
+	if (Strings::compareLink($post->actor->url, $own_id)) {
 		$contactid = $self[0]['id'];
 		$post->actor->displayName = $self[0]['name'];
 		$post->actor->url = $self[0]['url'];
 		$post->actor->image->url = $self[0]['photo'];
 	} else {
 		$r = q("SELECT * FROM `contact` WHERE `nurl` = '%s' AND `uid` = %d AND `blocked` = 0 AND `readonly` = 0 LIMIT 1",
-			DBA::escape(normalise_link($post->actor->url)),
+			DBA::escape(Strings::normaliseLink($post->actor->url)),
 			intval($uid)
 		);
 
@@ -1016,7 +1017,7 @@ function pumpio_get_contact($uid, $contact, $no_insert = false)
 	}
 
 	$r = q("SELECT * FROM `contact` WHERE `uid` = %d AND `nurl` = '%s' LIMIT 1",
-		intval($uid), DBA::escape(normalise_link($contact->url)));
+		intval($uid), DBA::escape(Strings::normaliseLink($contact->url)));
 
 	if (!DBA::isResult($r)) {
 		// create contact record
@@ -1027,7 +1028,7 @@ function pumpio_get_contact($uid, $contact, $no_insert = false)
 			intval($uid),
 			DBA::escape(DateTimeFormat::utcNow()),
 			DBA::escape($contact->url),
-			DBA::escape(normalise_link($contact->url)),
+			DBA::escape(Strings::normaliseLink($contact->url)),
 			DBA::escape(str_replace("acct:", "", $contact->id)),
 			DBA::escape(''),
 			DBA::escape($contact->id), // What is it for?
@@ -1044,7 +1045,7 @@ function pumpio_get_contact($uid, $contact, $no_insert = false)
 		);
 
 		$r = q("SELECT * FROM `contact` WHERE `nurl` = '%s' AND `uid` = %d LIMIT 1",
-			DBA::escape(normalise_link($contact->url)),
+			DBA::escape(Strings::normaliseLink($contact->url)),
 			intval($uid)
 			);
 
@@ -1164,7 +1165,7 @@ function pumpio_dopost(App $a, $client, $uid, $self, $post, $own_id, $threadcomp
 	} else {
 		$contact_id = pumpio_get_contact($uid, $post->actor, true);
 
-		if (link_compare($post->actor->url, $own_id)) {
+		if (Strings::compareLink($post->actor->url, $own_id)) {
 			$contact_id = $self[0]['id'];
 			$post->actor->displayName = $self[0]['name'];
 			$post->actor->url = $self[0]['url'];
@@ -1172,7 +1173,7 @@ function pumpio_dopost(App $a, $client, $uid, $self, $post, $own_id, $threadcomp
 		} elseif ($contact_id == 0) {
 			// Take an existing contact, the contact of the note or - as a fallback - the id of the user
 			$r = q("SELECT * FROM `contact` WHERE `nurl` = '%s' AND `uid` = %d AND `blocked` = 0 AND `readonly` = 0 LIMIT 1",
-				DBA::escape(normalise_link($post->actor->url)),
+				DBA::escape(Strings::normaliseLink($post->actor->url)),
 				intval($uid)
 			);
 
@@ -1180,7 +1181,7 @@ function pumpio_dopost(App $a, $client, $uid, $self, $post, $own_id, $threadcomp
 				$contact_id = $r[0]['id'];
 			} else {
 				$r = q("SELECT * FROM `contact` WHERE `nurl` = '%s' AND `uid` = %d AND `blocked` = 0 AND `readonly` = 0 LIMIT 1",
-					DBA::escape(normalise_link($post->actor->url)),
+					DBA::escape(Strings::normaliseLink($post->actor->url)),
 					intval($uid)
 				);
 
diff --git a/remote_permissions/remote_permissions.php b/remote_permissions/remote_permissions.php
index 91c2b4ce5..d08b40c9f 100644
--- a/remote_permissions/remote_permissions.php
+++ b/remote_permissions/remote_permissions.php
@@ -13,6 +13,7 @@ use Friendica\Core\L10n;
 use Friendica\Core\PConfig;
 use Friendica\Core\Renderer;
 use Friendica\Database\DBA;
+use Friendica\Util\Strings;
 
 function remote_permissions_install() {
 	Addon::registerHook('lockview_content', 'addon/remote_permissions/remote_permissions.php', 'remote_permissions_content');
@@ -206,7 +207,7 @@ function remote_permissions_addon_admin(&$a, &$o){
 }
 
 function remote_permissions_addon_admin_post(&$a){
-	$choice	=	((x($_POST,'remotepermschoice'))		? notags(trim($_POST['remotepermschoice']))	: '');
+	$choice	=	((x($_POST,'remotepermschoice'))		? Strings::escapeTags(trim($_POST['remotepermschoice']))	: '');
 	Config::set('remote_perms','global',($choice == 1 ? 1 : 0));
 	info(L10n::t('Settings updated.'). EOL);
 }
diff --git a/showmore/showmore.php b/showmore/showmore.php
index 8fc9cc91d..b46fe7400 100644
--- a/showmore/showmore.php
+++ b/showmore/showmore.php
@@ -10,6 +10,7 @@
 use Friendica\Core\Addon;
 use Friendica\Core\L10n;
 use Friendica\Core\PConfig;
+use Friendica\Util\Strings;
 
 function showmore_install()
 {
@@ -131,7 +132,7 @@ function showmore_prepare_body(\Friendica\App $a, &$hook_data)
 	}
 
 	if ($found) {
-		$rnd = random_string(8);
+		$rnd = Strings::getRandomHex(8);
 		$hook_data['html'] = '<span id="showmore-teaser-' . $rnd . '" class="showmore-teaser" style="display: block;">' . $shortened . " " .
 			'<span id="showmore-wrap-' . $rnd . '" style="white-space:nowrap;" class="showmore-wrap fakelink" onclick="openClose(\'showmore-' . $rnd . '\'); openClose(\'showmore-teaser-' . $rnd . '\');" >' . L10n::t('show more') . '</span></span>' .
 			'<div id="showmore-' . $rnd . '" class="showmore-content" style="display: none;">' . $hook_data['html'] . '</div>';
diff --git a/statusnet/statusnet.php b/statusnet/statusnet.php
index e07a6e73a..473ec18c8 100644
--- a/statusnet/statusnet.php
+++ b/statusnet/statusnet.php
@@ -60,6 +60,7 @@ use Friendica\Model\Photo;
 use Friendica\Model\User;
 use Friendica\Util\DateTimeFormat;
 use Friendica\Util\Network;
+use Friendica\Util\Strings;
 
 function statusnet_install()
 {
@@ -623,7 +624,7 @@ function statusnet_addon_admin_post(App $a)
 		}
 		$secret = trim($_POST['secret'][$id]);
 		$key = trim($_POST['key'][$id]);
-		//$applicationname = ((x($_POST, 'applicationname')) ? notags(trim($_POST['applicationname'][$id])):'');
+		//$applicationname = ((x($_POST, 'applicationname')) ? Strings::escapeTags(trim($_POST['applicationname'][$id])):'');
 		if ($sitename != "" &&
 			$apiurl != "" &&
 			$secret != "" &&
@@ -885,7 +886,7 @@ function statusnet_fetchtimeline(App $a, $uid)
 
 function statusnet_address($contact)
 {
-	$hostname = normalise_link($contact->statusnet_profile_url);
+	$hostname = Strings::normaliseLink($contact->statusnet_profile_url);
 	$nickname = $contact->screen_name;
 
 	$hostname = preg_replace("=https?://([\w\.]*)/.*=ism", "$1", $contact->statusnet_profile_url);
@@ -907,7 +908,7 @@ function statusnet_fetch_contact($uid, $contact, $create_user)
 		"location" => $contact->location, "about" => $contact->description,
 		"addr" => statusnet_address($contact), "generation" => 3]);
 
-	$r = q("SELECT * FROM `contact` WHERE `uid` = %d AND `alias` = '%s' AND `network` = '%s'LIMIT 1", intval($uid), DBA::escape(normalise_link($contact->statusnet_profile_url)), DBA::escape(Protocol::STATUSNET));
+	$r = q("SELECT * FROM `contact` WHERE `uid` = %d AND `alias` = '%s' AND `network` = '%s'LIMIT 1", intval($uid), DBA::escape(Strings::normaliseLink($contact->statusnet_profile_url)), DBA::escape(Protocol::STATUSNET));
 
 	if (!DBA::isResult($r) && !$create_user) {
 		return 0;
@@ -927,9 +928,9 @@ function statusnet_fetch_contact($uid, $contact, $create_user)
 			intval($uid),
 			DBA::escape(DateTimeFormat::utcNow()),
 			DBA::escape($contact->statusnet_profile_url),
-			DBA::escape(normalise_link($contact->statusnet_profile_url)),
+			DBA::escape(Strings::normaliseLink($contact->statusnet_profile_url)),
 			DBA::escape(statusnet_address($contact)),
-			DBA::escape(normalise_link($contact->statusnet_profile_url)),
+			DBA::escape(Strings::normaliseLink($contact->statusnet_profile_url)),
 			DBA::escape(''),
 			DBA::escape(''),
 			DBA::escape($contact->name),
@@ -1001,7 +1002,7 @@ function statusnet_fetch_contact($uid, $contact, $create_user)
 				DBA::escape(DateTimeFormat::utcNow()),
 				DBA::escape(DateTimeFormat::utcNow()),
 				DBA::escape($contact->statusnet_profile_url),
-				DBA::escape(normalise_link($contact->statusnet_profile_url)),
+				DBA::escape(Strings::normaliseLink($contact->statusnet_profile_url)),
 				DBA::escape(statusnet_address($contact)),
 				DBA::escape($contact->name),
 				DBA::escape($contact->screen_name),
@@ -1523,7 +1524,7 @@ function statusnet_fetch_own_contact(App $a, $uid)
 		// Fetching user data
 		$user = $connection->get('account/verify_credentials');
 
-		PConfig::set($uid, 'statusnet', 'own_url', normalise_link($user->statusnet_profile_url));
+		PConfig::set($uid, 'statusnet', 'own_url', Strings::normaliseLink($user->statusnet_profile_url));
 
 		$contact_id = statusnet_fetch_contact($uid, $user, true);
 	} else {
diff --git a/superblock/superblock.php b/superblock/superblock.php
index 8e42d4737..895f1ec67 100644
--- a/superblock/superblock.php
+++ b/superblock/superblock.php
@@ -9,6 +9,7 @@
 use Friendica\Core\Addon;
 use Friendica\Core\L10n;
 use Friendica\Core\PConfig;
+use Friendica\Util\Strings;
 
 function superblock_install()
 {
@@ -88,7 +89,7 @@ function superblock_enotify_store(&$a,&$b) {
 				continue;
 			}
 
-			if (link_compare($b['url'], $word)) {
+			if (Strings::compareLink($b['url'], $word)) {
 				$found = true;
 				break;
 			}
@@ -134,7 +135,7 @@ function superblock_item_photo_menu(&$a, &$b)
 	$author = $b['item']['author-link'];
 	if (!empty($a->data['superblock'])) {
 		foreach ($a->data['superblock'] as $bloke) {
-			if (link_compare($bloke, $author)) {
+			if (Strings::compareLink($bloke, $author)) {
 				$blocked = true;
 				break;
 			}
diff --git a/tumblr/tumblr.php b/tumblr/tumblr.php
index bac116348..97ac8bf49 100644
--- a/tumblr/tumblr.php
+++ b/tumblr/tumblr.php
@@ -18,6 +18,7 @@ use Friendica\Core\Logger;
 use Friendica\Core\PConfig;
 use Friendica\Core\Renderer;
 use Friendica\Database\DBA;
+use Friendica\Util\Strings;
 
 function tumblr_install()
 {
@@ -83,8 +84,8 @@ function tumblr_addon_admin(App $a, &$o)
 
 function tumblr_addon_admin_post(App $a)
 {
-	$consumer_key    =       ((!empty($_POST['consumer_key']))      ? notags(trim($_POST['consumer_key']))   : '');
-	$consumer_secret =       ((!empty($_POST['consumer_secret']))   ? notags(trim($_POST['consumer_secret'])): '');
+	$consumer_key    =       ((!empty($_POST['consumer_key']))      ? Strings::escapeTags(trim($_POST['consumer_key']))   : '');
+	$consumer_secret =       ((!empty($_POST['consumer_secret']))   ? Strings::escapeTags(trim($_POST['consumer_secret'])): '');
 
 	Config::set('tumblr', 'consumer_key',$consumer_key);
 	Config::set('tumblr', 'consumer_secret',$consumer_secret);
diff --git a/twitter/twitter.php b/twitter/twitter.php
index e556e402d..07c696abf 100644
--- a/twitter/twitter.php
+++ b/twitter/twitter.php
@@ -86,6 +86,7 @@ use Friendica\Model\User;
 use Friendica\Object\Image;
 use Friendica\Util\DateTimeFormat;
 use Friendica\Util\Network;
+use Friendica\Util\Strings;
 
 require_once 'boot.php';
 require_once 'include/dba.php';
@@ -657,8 +658,8 @@ function twitter_post_hook(App $a, array &$b)
 
 function twitter_addon_admin_post(App $a)
 {
-	$consumerkey    = x($_POST, 'consumerkey')    ? notags(trim($_POST['consumerkey']))    : '';
-	$consumersecret = x($_POST, 'consumersecret') ? notags(trim($_POST['consumersecret'])) : '';
+	$consumerkey    = x($_POST, 'consumerkey')    ? Strings::escapeTags(trim($_POST['consumerkey']))    : '';
+	$consumersecret = x($_POST, 'consumersecret') ? Strings::escapeTags(trim($_POST['consumersecret'])) : '';
 	Config::set('twitter', 'consumerkey', $consumerkey);
 	Config::set('twitter', 'consumersecret', $consumersecret);
 	info(L10n::t('Settings updated.') . EOL);
@@ -1058,7 +1059,7 @@ function twitter_fetch_contact($uid, $data, $create_user)
 		// create contact record
 		$fields['uid'] = $uid;
 		$fields['created'] = DateTimeFormat::utcNow();
-		$fields['nurl'] = normalise_link($url);
+		$fields['nurl'] = Strings::normaliseLink($url);
 		$fields['alias'] = 'twitter::' . $data->id_str;
 		$fields['poll'] = 'twitter::' . $data->id_str;
 		$fields['rel'] = Contact::FRIEND;
@@ -1264,7 +1265,7 @@ function twitter_expand_entities(App $a, $body, $item, $picture)
 	}
 
 	// it seems as if the entities aren't always covering all mentions. So the rest will be checked here
-	$tags = get_tags($body);
+	$tags = Strings::getTags($body);
 
 	if (count($tags)) {
 		foreach ($tags as $tag) {
diff --git a/webrtc/webrtc.php b/webrtc/webrtc.php
index d8c7d8a2c..d122870e1 100644
--- a/webrtc/webrtc.php
+++ b/webrtc/webrtc.php
@@ -10,6 +10,7 @@ use Friendica\Core\Addon;
 use Friendica\Core\Config;
 use Friendica\Core\L10n;
 use Friendica\Core\Renderer;
+use Friendica\Util\Strings;
 
 function webrtc_install() {
         Addon::registerHook('app_menu', 'addon/webrtc/webrtc.php', 'webrtc_app_menu');
@@ -32,7 +33,7 @@ function webrtc_addon_admin (&$a, &$o) {
 	]);
 }
 function webrtc_addon_admin_post (&$a) {
-        $url = ((x($_POST, 'webrtcurl')) ? notags(trim($_POST['webrtcurl'])) : '');
+        $url = ((x($_POST, 'webrtcurl')) ? Strings::escapeTags(trim($_POST['webrtcurl'])) : '');
 	    Config::set('webrtc', 'webrtcurl', $url);
 	    info(L10n::t('Settings updated.'). EOL);
 }
diff --git a/wppost/wppost.php b/wppost/wppost.php
index 41aa240fb..9e2262608 100644
--- a/wppost/wppost.php
+++ b/wppost/wppost.php
@@ -14,6 +14,7 @@ use Friendica\Core\Logger;
 use Friendica\Core\PConfig;
 use Friendica\Database\DBA;
 use Friendica\Util\Network;
+use Friendica\Util\Strings;
 use Friendica\Util\XML;
 
 function wppost_install() {
@@ -149,7 +150,7 @@ function wppost_settings_post(&$a,&$b) {
 		PConfig::set(local_user(),'wppost','wp_blog',trim($_POST['wp_blog']));
 		PConfig::set(local_user(),'wppost','backlink',trim($_POST['wp_backlink']));
 		PConfig::set(local_user(),'wppost','shortcheck',trim($_POST['wp_shortcheck']));
-		$wp_backlink_text = notags(trim($_POST['wp_backlink_text']));
+		$wp_backlink_text = Strings::escapeTags(trim($_POST['wp_backlink_text']));
 		$wp_backlink_text = BBCode::convert($wp_backlink_text, false, 8);
 		$wp_backlink_text = HTML::toPlaintext($wp_backlink_text, 0, true);
 		PConfig::set(local_user(),'wppost','wp_backlink_text', $wp_backlink_text);
diff --git a/xmpp/xmpp.php b/xmpp/xmpp.php
index d80abb64c..1342c26c0 100644
--- a/xmpp/xmpp.php
+++ b/xmpp/xmpp.php
@@ -12,6 +12,7 @@ use Friendica\Core\Config;
 use Friendica\Core\L10n;
 use Friendica\Core\PConfig;
 use Friendica\Core\Renderer;
+use Friendica\Util\Strings;
 
 function xmpp_install()
 {
@@ -98,7 +99,7 @@ function xmpp_addon_settings(App $a, &$s)
 function xmpp_login()
 {
 	if (empty($_SESSION['allow_api'])) {
-		$password = random_string(16);
+		$password = Strings::getRandomHex(16);
 		PConfig::set(local_user(), 'xmpp', 'password', $password);
 	}
 }
@@ -161,11 +162,11 @@ function xmpp_converse(App $a)
 		$password = PConfig::get(local_user(), "xmpp", "password", '', true);
 
 		if ($password == "") {
-			$password = random_string(16);
+			$password = Strings::getRandomHex(16);
 			PConfig::set(local_user(), "xmpp", "password", $password);
 		}
 
-		$jid = $a->user["nickname"] . "@" . $a->getHostName() . "/converse-" . random_string(5);
+		$jid = $a->user["nickname"] . "@" . $a->getHostName() . "/converse-" . Strings::getRandomHex(5);
 
 		$auto_login = "auto_login: true,
 			authentication: 'login',