diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..c323621
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,12 @@
+/assets export-ignore
+/test export-ignore
+.gitattributes export-ignore
+.gitignore export-ignore
+.travis.yml export-ignore
+composer.json export-ignore
+composer.lock export-ignore
+CONTRIBUTING.md export-ignore
+package.json export-ignore
+phpcs.xml export-ignore
+phpunit.xml export-ignore
+RoboFile.php export-ignore
diff --git a/.gitignore b/.gitignore
index 29ba421..283f98c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,4 +4,5 @@ composer.lock
 /dist/
 .idea
 tests-clover.xml
-tests-junit.xml
\ No newline at end of file
+tests-junit.xml
+.phpunit.result.cache
diff --git a/.travis.yml b/.travis.yml
index a1f594f..79000c5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,12 +1,13 @@
 language: php
-dist: trusty
 php:
-  - '5.5'
   - '5.6'
-  - '7.0'
-  - '7.1'
   - '7.2'
+  - '7.3'
+  - '7.4'
 before_script:
   - composer install
 script:
   - composer test-all
+notifications:
+  slack:
+    secure: "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"
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index b70affd..8e24a86 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -33,17 +33,19 @@ If the changes introduce new functionality or affect major parts of existing cod
 
 For adding new functionality a new test case the corresponding PHPUnit test would be nice (no hard criterion though).
 
+The `master` branch should also be target for most pull requests.
+However it it features new functionality you might want to target the `develop` branch instead (see next section for details on branches).
+
 ### Branches
 
 The `master` branch represents the current state of development.
 Please ensure your initial code is up to date with it at the time you start development.
-The `master` should also be target for most pull requests.
 
 In addition, this project features a `develop` branch, which holds bleeding edge developments, not necessarily considered stable or even compatible.
 Do not expect this code to run smoothly, but you might have a look into the history to see if some work on an issue has already been started there.
 
-For fixes and features, there might be additional branches, likely prefixed by `ft-` (feature) or `hf-` (hotfix) followed by an issue number (if applicable) and/or a title.
-Feel free to adapt these naming scheme to your forks.
+For fixes and features, there might be additional branches, likely prefixed by `hotfix/` or `feature/` followed by an issue number (if applicable) and/or a title.
+Feel free to adapt this naming scheme to your forks.
 
 ### Merge Requirements
 
diff --git a/Gulpfile.js b/Gulpfile.js
deleted file mode 100644
index 2fe2690..0000000
--- a/Gulpfile.js
+++ /dev/null
@@ -1,65 +0,0 @@
-var gulp = require('gulp');
-var clean = require('gulp-clean');
-var copy = require('gulp-copy');
-var zip = require('gulp-zip');
-var composer = require('gulp-composer');
-var phpunit = require('gulp-phpunit');
-var exec = require('child_process').exec;
-var phpcs = require('gulp-phpcs');
-var config = require('./package.json');
-
-// Clean the target directory.
-gulp.task('clean', function () {
-	console.log('Cleaning up target directory  ...');
-	return gulp.src('dist', {read: false})
-		.pipe(clean());
-});
-
-// Prepare composer.
-gulp.task('compose', function () {
-	console.log('Preparing Composer ...');
-	return composer('install');
-});
-
-// Execute unit tests.
-gulp.task('test', ['compose'], function () {
-	console.log('Running PHPUnit tests ...');
-	return gulp.src('phpunit.xml')
-		.pipe(phpunit('./vendor/bin/phpunit', {debug: false}));
-});
-
-// Execute PHP Code Sniffer.
-gulp.task('test-cs', function (cb) {
-	return exec('./vendor/bin/phpcs --config-set installed_paths vendor/wimg/php-compatibility,vendor/wp-coding-standards/wpcs', function (err, stdout, stderr) {
-		console.log(stdout);
-		console.log(stderr);
-		if (null === err) {
-			console.log('Running PHP Code Sniffer tests ...');
-			// exec('./vendor/bin/phpcs  --standard=phpcs.xml', function(err, stdout, stderr) {
-			// 	console.log(stdout);
-			// 	console.log(stderr);
-			// });
-			gulp.src(['statify-blacklist.php', 'inc/**/*.php'])
-				.pipe(phpcs({bin: './vendor/bin/phpcs', standard: 'phpcs.xml'}))
-				.pipe(phpcs.reporter('log'));
-		}
-		cb(err);
-	});
-});
-
-// Bundle files as required for plugin distribution..
-gulp.task('bundle', ['clean'], function () {
-	console.log('Collecting files for package dist/' + config.name + config.version + ' ...');
-	return gulp.src(['**/*.php', '!RoboFile.php', '!test/**', '!vendor/**', 'README.md', 'LICENSE.md'], {base: './'})
-		.pipe(copy('./dist/' + config.name + '.' + config.version + '/' + config.name));
-});
-
-// Create a ZIP package of the relevant files for plugin distribution.
-gulp.task('package', ['bundle'], function () {
-	console.log('Building package dist/' + config.name + config.version + '.zip ...');
-	return gulp.src('./dist/' + config.name + '.' + config.version + '/**')
-		.pipe(zip(config.name + '.' + config.version + '.zip'))
-		.pipe(gulp.dest('./dist'));
-});
-
-gulp.task('default', ['clean', 'compose', 'test', 'test-cs', 'bundle', 'package']);
diff --git a/LICENSE.md b/LICENSE.md
index 5544f2d..28fbeca 100644
--- a/LICENSE.md
+++ b/LICENSE.md
@@ -357,5 +357,5 @@ into proprietary programs. If your program is a subroutine library,
 you may consider it more useful to permit linking proprietary
 applications with the library. If this is what you want to do, use the
 [GNU Lesser General Public
-License](http://www.gnu.org/licenses/lgpl.html) instead of this
+License](https://www.gnu.org/licenses/lgpl.html) instead of this
 License.
diff --git a/README.md b/README.md
index 50b4654..443086e 100644
--- a/README.md
+++ b/README.md
@@ -1,16 +1,21 @@
+[![Build Status](https://travis-ci.org/stklcode/statify-blacklist.svg?branch=master)](https://travis-ci.org/stklcode/statify-blacklist)
+[![Quality Gate](https://sonarcloud.io/api/project_badges/measure?project=de.stklcode.web.wordpress.plugins%3Astatify-blacklist&metric=alert_status)](https://sonarcloud.io/dashboard?id=de.stklcode.web.wordpress.plugins%3Astatify-blacklist)
+[![Packagist Version](https://img.shields.io/packagist/v/stklcode/statify-blacklist.svg)](https://packagist.org/packages/stklcode/statify-blacklist)
+[![License](https://img.shields.io/badge/license-GPL%20v2-blue.svg)](https://github.com/stklcode/statify-blacklist/blob/master/LICENSE.md)
+
 # Statify Blacklist #
 * Contributors:      Stefan Kalscheuer
-* Requires at least: 4.4
+* Requires at least: 4.7
 * Tested up to:      5.4
 * Requires PHP:      5.5
-* Stable tag:        1.4.4
+* Stable tag:        1.5.0
 * License:           GPLv2 or later
-* License URI:       http://www.gnu.org/licenses/gpl-2.0.html
+* License URI:       https://www.gnu.org/licenses/gpl-2.0.html
 
 ## Description ##
 A blacklist extension for the famous [Statify](https://wordpress.org/plugins/statify/) Wordpress plugin.
 
-This plugin adds customizable blacklist to Statify to allow blocking of referer spam or internal interactions.
+This plugin adds a customizable blacklist to Statify to allow blocking of referer spam or internal interactions.
 
 ### Features ##
 
@@ -27,7 +32,7 @@ Add a list of IP addresses or subnets (e.g. _192.0.2.123_, _198.51.100.0/24_, _2
 Filters can be applied to data stored in database after modifying filter rules or for one-time clean-up.
 
 #### Compatibility ####
-This plugin requires Statify to be installed. The extension has been tested with Statify up to version 1.5.1
+This plugin requires Statify to be installed. The extension has been tested with Statify up to version 1.7
 The plugin is capable of handling multisite installations.
 
 ### Support & Contributions ###
@@ -37,51 +42,62 @@ The plugin is capable of handling multisite installations.
 
 ### Credits ###
 * Author: Stefan Kalscheuer
-* Special Thanks to [pluginkollektiv](https://github.com/pluginkollektiv) for maintaining _Statify_
+* Special Thanks to [pluginkollektiv](https://pluginkollektiv.org/) for maintaining _Statify_
 
 ## Installation ##
-* If you don’t know how to install a plugin for WordPress, [here’s how](http://codex.wordpress.org/Managing_Plugins#Installing_Plugins).
-* Make sure _Statify_ plugin is installed and active 
+* If you don’t know how to install a plugin for WordPress, [here’s how](https://wordpress.org/support/article/managing-plugins/#installing-plugins).
+* Make sure _Statify_ plugin is installed and active
 * Goto _Settings_ -> _Statify Blacklist_ to configure the plugin
 
 ### Requirements ###
 * PHP 5.5 or above
-* WordPress 4.4 or above
-* Statify plugin installed and activated (1.5.0 or above)
+* WordPress 4.7 or above
+* _Statify_ plugin installed and activated (1.5 or above)
 
 ## Frequently Asked Questions ##
 
 ### What is blocked by default? ###
-Nothing. By default all blacklists are empty and disabled. They can and have to be filled by the blog administrator.
+Nothing. By default, all blacklists are empty and disabled. They can and have to be filled by the blog administrator.
 
 A default blacklist is not provided, as the plugin itself is totally neutral. If you want to filter out referer spam, 
-visitors from search engines, just "false" referers from 301 redirects or you own IP address used for testing only depends on you.
+visitors from search engines, just "false" referrers from 301 redirects or you own IP address used for testing only depends on you.
 
 ### Does the filter effect user experience? ###
-No. It only prevent's _Statify_ from tracking, nothing more or less.
+No. It only prevents _Statify_ from tracking, nothing more or less.
 
 ### Does live filtering impact performance? ###
-Yes, but probalby not noticeable. Checking a single referer string against a (usually small) list should be negligible compared to the total loading procedure.
+Yes, but probably not noticeable. Checking a single referer string against a (usually small) list should be negligible compared to the total loading procedure.
 If this still is an issue for you, consider deactivating the filter and only run the one-time-cleanup or activate the cron job.
  
 ### Is any personal data collected? ###
 No. The privacy policy of _Statify_ is untouched. Data is only processed, not stored or exposed to anyone.
 
 ### Are regular expression filters possible? ###
-Yes, it is. Just select if you want to filter using regular expressions case sensitive or insensitive.
-
-Note, that regular expression matching is significantly slower than the plain domain filter. Hence it is only recommended for asynchronous cron or manual execution and not for live filtering.
+Yes, it is. Just select regular expressions (case-sensitive or insensitive) as matching method instead of exact or keyword match.
 
 ### Why is IP filtering only available as live filter? ###
-As you might know, Statify does not store any personal information, including IP addresses in the database.
+As you might know, _Statify_ does not store any personal information, including IP addresses in the database.
 Because of this, an IP blacklist can only be applied while processing the request and not afterwards.
 
+### Can whole IP subnet be blocked? ###
+Yes. The plugin features subnet blacklists using CIDR notation.
+For example _198.51.100.0/24_ blacklists all sources from _198.51.100.1_ to _198.51.100.254_.
+Same for IPv6 prefixes like _2001:db8:a0b:12f0::/64_.
+
 
 ## Screenshots ##
 1. Statify Blacklist settings page
 
 ## Changelog ##
 
+### 1.5.0 / 13.05.2020 ###
+* Minimum required WordPress version is 4.7
+* Removed `load_plugin_textdomain()` and `Domain Path` header
+* Added automatic compatibility check for WP and PHP version (#17)
+* Added keyword filter mode for referer blacklist (#15)
+* Layout adjustments on settings page
+* Regular expression filters are validated before saving (#13)
+
 ### 1.4.4 / 19.05.2018 ###
 * Fix live filter chain when regular expressions are active (#12)
 
@@ -115,7 +131,7 @@ Because of this, an IP blacklist can only be applied while processing the reques
 
 ### 1.2.0 / 29.08.2016 ###
 * Switched from `in_array()` to faster `isset()` for referer checking
-* Optional cron execiton implemented
+* Optional cron execution implemented
 
 ### 1.1.2 / 17.08.2016 ###
 * Prepared for localization
diff --git a/RoboFile.php b/RoboFile.php
index e991634..5c76074 100644
--- a/RoboFile.php
+++ b/RoboFile.php
@@ -8,7 +8,7 @@
  * @author    Stefan Kalscheuer <stefan@stklcode.de>
  *
  * @package   Statify_Blacklist
- * @version   1.4.4
+ * @version   1.5.0
  */
 
 use Robo\Exception\TaskException;
@@ -19,10 +19,10 @@
  */
 class RoboFile extends Tasks {
 	const PROJECT_NAME = 'statify-blacklist';
-	const SVN_URL = 'https://plugins.svn.wordpress.org/statify-blacklist';
+	const SVN_URL      = 'https://plugins.svn.wordpress.org/statify-blacklist';
 
-	const OPT_TARGET = 'target';
-	const OPT_SKIPTEST = 'skipTests';
+	const OPT_TARGET    = 'target';
+	const OPT_SKIPTEST  = 'skipTests';
 	const OPT_SKIPSTYLE = 'skipStyle';
 
 	/**
@@ -134,13 +134,21 @@ public function build(
 	 */
 	private function bundle() {
 		$this->say( 'Bundling resources...' );
-		$this->taskCopyDir( [
-			'inc'   => $this->target_dir . '/' . $this->final_name . '/inc',
-			'views' => $this->target_dir . '/' . $this->final_name . '/views',
-		] )->run();
+		$this->taskCopyDir(
+			[
+				'inc'   => $this->target_dir . '/' . $this->final_name . '/inc',
+				'views' => $this->target_dir . '/' . $this->final_name . '/views',
+			]
+		)->run();
 		$this->_copy( 'statify-blacklist.php', $this->target_dir . '/' . $this->final_name . '/statify-blacklist.php' );
-		$this->_copy( 'README.md', $this->target_dir . '/' . $this->final_name . '/README.md' );
 		$this->_copy( 'LICENSE.md', $this->target_dir . '/' . $this->final_name . '/LICENSE.md' );
+		$this->_copy( 'README.md', $this->target_dir . '/' . $this->final_name . '/README.md' );
+
+		// Remove content before title (e.g. badges) from README file.
+		$this->taskReplaceInFile( $this->target_dir . '/' . $this->final_name . '/README.md' )
+			->regex( '/^[^\\#]*/' )
+			->to( '' )
+			->run();
 	}
 
 	/**
diff --git a/assets/screenshot-1.png b/assets/screenshot-1.png
index 6147f4c..b03eb2c 100644
Binary files a/assets/screenshot-1.png and b/assets/screenshot-1.png differ
diff --git a/composer.json b/composer.json
index 0bf7586..bd136ef 100644
--- a/composer.json
+++ b/composer.json
@@ -1,6 +1,6 @@
 {
   "name": "stklcode/statify-blacklist",
-  "version": "1.4.4",
+  "version": "1.5.0",
   "description": "A blacklist extension for the famous Statify WordPress plugin",
   "keywords": [
     "wordpress",
@@ -19,17 +19,17 @@
   "type": "wordpress-plugin",
   "require": {
     "php": ">=5.5",
-    "composer/installers": "~1.0"
+    "composer/installers": "~1.7"
   },
   "require-dev": {
-    "dealerdirect/phpcodesniffer-composer-installer": "^0.4",
-    "consolidation/robo": "^1.0.0",
+    "dealerdirect/phpcodesniffer-composer-installer": "^0.5",
+    "consolidation/robo": "^1.4",
     "phpunit/phpunit": "*",
     "phpunit/php-code-coverage": "*",
     "slowprog/composer-copy-file": "~0.2",
-    "squizlabs/php_codesniffer": "^3.1",
-    "wimg/php-compatibility": "^8.0",
-    "wp-coding-standards/wpcs": "~0.14"
+    "squizlabs/php_codesniffer": "^3.5",
+    "phpcompatibility/php-compatibility": "^9.3",
+    "wp-coding-standards/wpcs": "^2.1"
   },
   "scripts": {
     "build": [
diff --git a/inc/class-statifyblacklist-admin.php b/inc/class-statifyblacklist-admin.php
index e807ef9..caed7fc 100644
--- a/inc/class-statifyblacklist-admin.php
+++ b/inc/class-statifyblacklist-admin.php
@@ -9,8 +9,10 @@
  * @since     1.0.0
  */
 
-// Quit.
-defined( 'ABSPATH' ) || exit;
+// Quit if accessed directly.
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
 
 /**
  * Statify Blacklist admin configuration.
@@ -18,37 +20,101 @@
  * @since   1.0.0
  */
 class StatifyBlacklist_Admin extends StatifyBlacklist {
+
+	/**
+	 * Initialize admin-only components of the plugin.
+	 *
+	 * @since 1.5.0
+	 *
+	 * @return void
+	 */
+	public static function init() {
+		// Add actions.
+		add_action( 'wpmu_new_blog', array( 'StatifyBlacklist_System', 'install_site' ) );
+		add_action( 'delete_blog', array( 'StatifyBlacklist_System', 'uninstall_site' ) );
+		add_filter( 'plugin_row_meta', array( 'StatifyBlacklist_Admin', 'plugin_meta_link' ), 10, 2 );
+
+		if ( self::$multisite ) {
+			add_action( 'network_admin_menu', array( 'StatifyBlacklist_Admin', 'add_menu_page' ) );
+			add_filter(
+				'network_admin_plugin_action_links',
+				array(
+					'StatifyBlacklist_Admin',
+					'plugin_actions_links',
+				),
+				10,
+				2
+			);
+		} else {
+			add_action( 'admin_menu', array( 'StatifyBlacklist_Admin', 'add_menu_page' ) );
+			add_filter( 'plugin_action_links', array( 'StatifyBlacklist_Admin', 'plugin_actions_links' ), 10, 2 );
+		}
+	}
+
 	/**
 	 * Update options.
 	 *
+	 * @since 1.1.1
+	 *
 	 * @param  array $options Optional. New options to save.
 	 *
 	 * @return array|bool  array of sanitized array on errors, FALSE if there were none.
-	 * @since 1.1.1
 	 */
 	public static function update_options( $options = null ) {
 		if ( isset( $options ) && current_user_can( 'manage_options' ) ) {
-			// Sanitize URLs and remove empty inputs.
-			$given_referer = $options['referer']['blacklist'];
-			if ( 0 === $options['referer']['regexp'] ) {
-				$sanitized_referer = self::sanitizeURLs( $given_referer );
+
+			// Sanitize referer list.
+			$given_referer   = $options['referer']['blacklist'];
+			$invalid_referer = array();
+			if ( self::MODE_NORMAL === $options['referer']['regexp'] ) {
+				// Sanitize URLs and remove empty inputs.
+				$sanitized_referer = self::sanitize_urls( $given_referer );
+			} elseif ( self::MODE_REGEX === $options['referer']['regexp'] || self::MODE_REGEX_CI === $options['referer']['regexp'] ) {
+				$sanitized_referer = $given_referer;
+				// Check regular expressions.
+				$invalid_referer = self::sanitize_regex( $given_referer );
 			} else {
 				$sanitized_referer = $given_referer;
 			}
 
-			// Sanitize IPs and Subnets and remove empty inputs.
+			// Sanitize target list.
+			$given_target   = $options['target']['blacklist'];
+			$invalid_target = array();
+			if ( self::MODE_REGEX === $options['target']['regexp'] || self::MODE_REGEX_CI === $options['target']['regexp'] ) {
+				$sanitized_target = $given_target;
+				// Check regular expressions.
+				$invalid_target = self::sanitize_regex( $given_target );
+			} else {
+				$sanitized_target = $given_target;
+			}
+
+			// Sanitize IPs and subnets and remove empty inputs.
 			$given_ip     = $options['ip']['blacklist'];
-			$sanitized_ip = self::sanitizeIPs( $given_ip );
+			$sanitized_ip = self::sanitize_ips( $given_ip );
 
 			// Abort on errors.
-			if ( ! empty( array_diff( array_keys( $given_referer ), array_keys( $sanitized_referer ) ) ) ) {
-				return array(
-					'referer' => $sanitized_referer,
-				);
-			} elseif ( ! empty( array_diff( $given_ip, $sanitized_ip ) ) ) {
-				return array(
-					'ip' => array_diff( $given_ip, $sanitized_ip ),
-				);
+			$errors = array(
+				'referer' => array(
+					'sanitized' => $sanitized_referer,
+					'diff'      => array_diff( $given_referer, $sanitized_referer ),
+					'invalid'   => $invalid_referer,
+				),
+				'target'  => array(
+					'sanitized' => $sanitized_target,
+					'diff'      => array_diff( $given_target, $sanitized_target ),
+					'invalid'   => $invalid_target,
+				),
+				'ip'      => array(
+					'sanitized' => $sanitized_ip,
+					'diff'      => array_diff( $given_ip, $sanitized_ip ),
+				),
+			);
+			if ( ! empty( $errors['referer']['diff'] )
+				|| ! empty( $errors['referer']['invalid'] )
+				|| ! empty( $errors['target']['diff'] )
+				|| ! empty( $errors['target']['invalid'] )
+				|| ! empty( $errors['ip']['diff'] ) ) {
+				return $errors;
 			}
 
 			// Update database on success.
@@ -74,14 +140,24 @@ public static function add_menu_page() {
 		$title = __( 'Statify Blacklist', 'statify-blacklist' );
 		if ( self::$multisite ) {
 			add_submenu_page(
-				'settings.php', $title, $title, 'manage_network_plugins', 'statify-blacklist-settings', array(
+				'settings.php',
+				$title,
+				$title,
+				'manage_network_plugins',
+				'statify-blacklist-settings',
+				array(
 					'StatifyBlacklist_Admin',
 					'settings_page',
 				)
 			);
 		} else {
 			add_submenu_page(
-				'options-general.php', $title, $title, 'manage_options', 'statify-blacklist', array(
+				'options-general.php',
+				$title,
+				$title,
+				'manage_options',
+				'statify-blacklist',
+				array(
 					'StatifyBlacklist_Admin',
 					'settings_page',
 				)
@@ -154,20 +230,20 @@ public static function cleanup_database() {
 		}
 
 		if ( defined( 'DOING_CRON' ) && DOING_CRON ) {
-			$clean_ref = ( 1 === self::$_options['referer']['cron'] );
-			$clean_trg = ( 1 === self::$_options['target']['cron'] );
+			$clean_ref = ( 1 === self::$options['referer']['cron'] );
+			$clean_trg = ( 1 === self::$options['target']['cron'] );
 		} else {
 			$clean_ref = true;
 			$clean_trg = true;
 		}
 
 		if ( $clean_ref ) {
-			if ( isset( self::$_options['referer']['regexp'] ) && self::$_options['referer']['regexp'] > 0 ) {
+			if ( isset( self::$options['referer']['regexp'] ) && self::$options['referer']['regexp'] > 0 ) {
 				// Merge given regular expressions into one.
-				$referer_regexp = implode( '|', array_keys( self::$_options['referer']['blacklist'] ) );
+				$referer_regexp = implode( '|', array_keys( self::$options['referer']['blacklist'] ) );
 			} else {
 				// Sanitize URLs.
-				$referer = self::sanitizeURLs( self::$_options['referer']['blacklist'] );
+				$referer = self::sanitize_urls( self::$options['referer']['blacklist'] );
 
 				// Build filter regexp.
 				$referer_regexp = str_replace( '.', '\.', implode( '|', array_flip( $referer ) ) );
@@ -175,12 +251,12 @@ public static function cleanup_database() {
 		}
 
 		if ( $clean_trg ) {
-			if ( isset( self::$_options['target']['regexp'] ) && self::$_options['target']['regexp'] > 0 ) {
+			if ( isset( self::$options['target']['regexp'] ) && self::$options['target']['regexp'] > 0 ) {
 				// Merge given regular expressions into one.
-				$target_regexp = implode( '|', array_keys( self::$_options['target']['blacklist'] ) );
+				$target_regexp = implode( '|', array_keys( self::$options['target']['blacklist'] ) );
 			} else {
 				// Build filter regexp.
-				$target_regexp = str_replace( '.', '\.', implode( '|', array_flip( self::$_options['target']['blacklist'] ) ) );
+				$target_regexp = str_replace( '.', '\.', implode( '|', array_flip( self::$options['target']['blacklist'] ) ) );
 			}
 		}
 
@@ -188,13 +264,14 @@ public static function cleanup_database() {
 			global $wpdb;
 
 			// Execute filter on database.
-			// @codingStandardsIgnoreStart These statements prouce warnings, rework in future release (TODO).
+			// phpcs:disable WordPress.DB.PreparedSQL.NotPrepared -- These statements produce warnings, rework in future release (TODO).
 			if ( ! empty( $referer_regexp ) ) {
 				$wpdb->query(
 					$wpdb->prepare(
 						"DELETE FROM `$wpdb->statify` WHERE "
-						. ( ( 1 === self::$_options['referer']['regexp'] ) ? ' BINARY ' : '' )
-						. 'referrer REGEXP %s', $referer_regexp
+						. ( ( 1 === self::$options['referer']['regexp'] ) ? ' BINARY ' : '' )
+						. 'referrer REGEXP %s',
+						$referer_regexp
 					)
 				);
 			}
@@ -202,12 +279,13 @@ public static function cleanup_database() {
 				$wpdb->query(
 					$wpdb->prepare(
 						"DELETE FROM `$wpdb->statify` WHERE "
-						. ( ( 1 === self::$_options['target']['regexp'] ) ? ' BINARY ' : '' )
-						. 'target REGEXP %s', $target_regexp
+						. ( ( 1 === self::$options['target']['regexp'] ) ? ' BINARY ' : '' )
+						. 'target REGEXP %s',
+						$target_regexp
 					)
 				);
 			}
-			// @codingStandardsIgnoreEnd
+			// phpcs:enable WordPress.DB.PreparedSQL.NotPrepared
 
 			// Optimize DB.
 			$wpdb->query( "OPTIMIZE TABLE `$wpdb->statify`" );
@@ -227,7 +305,7 @@ public static function cleanup_database() {
 	 *
 	 * @return array  sanitized array.
 	 */
-	private static function sanitizeURLs( $urls ) {
+	private static function sanitize_urls( $urls ) {
 		return array_flip(
 			array_filter(
 				array_map(
@@ -249,15 +327,39 @@ function ( $r ) {
 	 *
 	 * @return array  sanitized array.
 	 */
-	private static function sanitizeIPs( $ips ) {
+	private static function sanitize_ips( $ips ) {
 		return array_filter(
-			$ips, function ( $ip ) {
+			$ips,
+			function ( $ip ) {
 				return preg_match(
-					'/^((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])(\/([0-9]|[1-2][0-9]|3[0-2]))?$/', $ip
+					'/^((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])(\/([0-9]|[1-2][0-9]|3[0-2]))?$/',
+					$ip
 				) ||
-					preg_match(
-						'/^(([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))(\/([0-9]|[1-9][0-9]|1[0-1][0-9]|12[0-8]))?$/', $ip
-					);
+				preg_match(
+					'/^(([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))(\/([0-9]|[1-9][0-9]|1[0-1][0-9]|12[0-8]))?$/',
+					$ip
+				);
+			}
+		);
+	}
+
+	/**
+	 * Validate regular expressions, i.e. remove duplicates and empty values and validate others.
+	 *
+	 * @since 1.5.0 #13
+	 *
+	 * @param array $expressions Given pre-sanitized array of regular expressions.
+	 *
+	 * @return array Array of invalid expressions.
+	 */
+	private static function sanitize_regex( $expressions ) {
+		return array_filter(
+			array_flip( $expressions ),
+			function ( $re ) {
+				// Check of preg_match() fails (warnings suppressed).
+
+				// phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
+				return false === @preg_match( StatifyBlacklist::regex( $re, false ), null );
 			}
 		);
 	}
diff --git a/inc/class-statifyblacklist-system.php b/inc/class-statifyblacklist-system.php
index a9160b1..842310b 100644
--- a/inc/class-statifyblacklist-system.php
+++ b/inc/class-statifyblacklist-system.php
@@ -1,6 +1,6 @@
 <?php
 /**
- * Statify Blacklist: StatifyBlacklist_Syste, class
+ * Statify Blacklist: StatifyBlacklist_System class
  *
  * This file contains the derived class for the plugin's system operations.
  *
@@ -9,8 +9,10 @@
  * @since     1.0.0
  */
 
-// Quit.
-defined( 'ABSPATH' ) || exit;
+// Quit if accessed directly.
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
 
 /**
  * Statify Blacklist system configuration.
@@ -25,15 +27,14 @@ class StatifyBlacklist_System extends StatifyBlacklist {
 	 * @since 1.0.0
 	 *
 	 * @param bool $network_wide Whether the plugin was activated network-wide or not.
+	 *
+	 * @return void
 	 */
 	public static function install( $network_wide = false ) {
 		// Create tables for each site in a network.
 		if ( $network_wide && is_multisite() ) {
 			if ( function_exists( 'get_sites' ) ) {
 				$sites = get_sites();
-			} elseif ( function_exists( 'wp_get_sites' ) ) {
-				// @codingStandardsIgnoreLine Legacy support for WP < 4.6.
-				$sites = wp_get_sites();
 			} else {
 				return;
 			}
@@ -62,6 +63,8 @@ public static function install( $network_wide = false ) {
 	 * @since 1.4.3
 	 *
 	 * @param integer $site_id Site ID.
+	 *
+	 * @return void
 	 */
 	public static function install_site( $site_id ) {
 		switch_to_blog( (int) $site_id );
@@ -77,6 +80,8 @@ public static function install_site( $site_id ) {
 	 * Plugin uninstall handler.
 	 *
 	 * @since 1.0.0
+	 *
+	 * @return void
 	 */
 	public static function uninstall() {
 		if ( is_multisite() ) {
@@ -85,7 +90,7 @@ public static function uninstall() {
 			if ( function_exists( 'get_sites' ) ) {
 				$sites = get_sites();
 			} elseif ( function_exists( 'wp_get_sites' ) ) {
-				// @codingStandardsIgnoreLine Legacy support for WP < 4.6.
+				// phpcs:ignore WordPress.WP.DeprecatedFunctions.wp_get_sitesFound -- Legacy support for WP < 4.6.
 				$sites = wp_get_sites();
 			} else {
 				return;
@@ -112,6 +117,8 @@ public static function uninstall() {
 	 * @since 1.4.3
 	 *
 	 * @param integer $site_id Site ID.
+	 *
+	 * @return void
 	 */
 	public static function uninstall_site( $site_id ) {
 		$old = get_current_blog_id();
@@ -124,14 +131,16 @@ public static function uninstall_site( $site_id ) {
 	 * Upgrade plugin options.
 	 *
 	 * @since 1.2.0
+	 *
+	 * @return void
 	 */
 	public static function upgrade() {
 		self::update_options();
 		// Check if config array is not associative (pre 1.2.0).
-		if ( array_keys( self::$_options['referer'] ) === range( 0, count( self::$_options['referer'] ) - 1 ) ) {
+		if ( array_keys( self::$options['referer'] ) === range( 0, count( self::$options['referer'] ) - 1 ) ) {
 			// Flip referer array to make domains keys.
-			$options            = self::$_options;
-			$options['referer'] = array_flip( self::$_options['referer'] );
+			$options            = self::$options;
+			$options['referer'] = array_flip( self::$options['referer'] );
 			if ( self::$multisite ) {
 				update_site_option( 'statify-blacklist', $options );
 			} else {
@@ -140,14 +149,14 @@ public static function upgrade() {
 		}
 
 		// Version not set (pre 1.3.0) or older than 1.4.
-		if ( ! isset( self::$_options['version'] ) || self::$_options['version'] < 1.4 ) {
+		if ( ! isset( self::$options['version'] ) || self::$options['version'] < 1.4 ) {
 			// Upgrade options to new schema.
 			$options = array(
 				'referer' => array(
-					'active'    => self::$_options['active_referer'],
-					'cron'      => self::$_options['cron_referer'],
-					'regexp'    => self::$_options['referer_regexp'],
-					'blacklist' => self::$_options['referer'],
+					'active'    => self::$options['active_referer'],
+					'cron'      => self::$options['cron_referer'],
+					'regexp'    => self::$options['referer_regexp'],
+					'blacklist' => self::$options['referer'],
 				),
 				'target'  => array(
 					'active'    => 0,
@@ -170,9 +179,9 @@ public static function upgrade() {
 		}
 
 		// Version older than current major release.
-		if ( self::VERSION_MAIN > self::$_options['version'] ) {
+		if ( self::VERSION_MAIN > self::$options['version'] ) {
 			// Merge default options with current config, assuming only additive changes.
-			$options            = array_merge_recursive( self::default_options(), self::$_options );
+			$options            = array_merge_recursive( self::default_options(), self::$options );
 			$options['version'] = self::VERSION_MAIN;
 			if ( self::$multisite ) {
 				update_site_option( 'statify-blacklist', $options );
diff --git a/inc/class-statifyblacklist.php b/inc/class-statifyblacklist.php
index 3ebea16..abc7780 100644
--- a/inc/class-statifyblacklist.php
+++ b/inc/class-statifyblacklist.php
@@ -8,8 +8,10 @@
  * @since   1.0.0
  */
 
-// Quit.
-defined( 'ABSPATH' ) || exit;
+// Quit if accessed directly.
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
 
 /**
  * Statify Blacklist.
@@ -27,45 +29,56 @@ class StatifyBlacklist {
 	const VERSION_MAIN = 1.4;
 
 	/**
-	 * Plugin options.
+	 * Operation mode "normal".
 	 *
-	 * @since 1.0.0
-	 * @var array $_options
+	 * @var integer MODE_NORMAL
 	 */
-	public static $_options;
+	const MODE_NORMAL = 0;
 
 	/**
-	 * Multisite Status.
+	 * Operation mode "regular expression".
 	 *
-	 * @since 1.0.0
-	 * @var bool $multisite
+	 * @var integer MODE_REGEX
 	 */
-	public static $multisite;
+	const MODE_REGEX = 1;
+
+	/**
+	 * Operation mode "regular expression case insensitive".
+	 *
+	 * @var integer MODE_REGEX_CI
+	 */
+	const MODE_REGEX_CI = 2;
+
+	/**
+	 * Operation mode "keyword".
+	 *
+	 * @since 1.5.0
+	 * @var integer MODE_KEYWORD
+	 */
+	const MODE_KEYWORD = 3;
 
 	/**
-	 * Class self initialize.
+	 * Plugin options.
 	 *
 	 * @since 1.0.0
-	 * @deprecated 1.4.2 Replaced by init().
+	 * @var array $options
 	 */
-	public static function instance() {
-		self::init();
-	}
+	public static $options;
 
 	/**
-	 * Class constructor.
+	 * Multisite Status.
 	 *
 	 * @since 1.0.0
-	 * @deprecated 1.4.2 Replaced by init().
+	 * @var bool $multisite
 	 */
-	public function __construct() {
-		self::init();
-	}
+	public static $multisite;
 
 	/**
 	 * Plugin initialization.
 	 *
 	 * @since 1.4.2
+	 *
+	 * @return void
 	 */
 	public static function init() {
 		// Skip on autosave or AJAX.
@@ -80,41 +93,19 @@ public static function init() {
 		self::update_options();
 
 		// Add Filter to statify hook if enabled.
-		if ( 0 !== self::$_options['referer']['active'] || 0 !== self::$_options['target']['active'] || 0 !== self::$_options['ip']['active'] ) {
+		if ( 0 !== self::$options['referer']['active'] || 0 !== self::$options['target']['active'] || 0 !== self::$options['ip']['active'] ) {
 			add_filter( 'statify__skip_tracking', array( 'StatifyBlacklist', 'apply_blacklist_filter' ) );
 		}
 
 		// Admin only filters.
 		if ( is_admin() ) {
-			// Load Textdomain (only needed for backend.
-			load_plugin_textdomain( 'statifyblacklist', false, STATIFYBLACKLIST_DIR . '/lang/' );
-
-			// Add actions.
-			add_action( 'wpmu_new_blog', array( 'StatifyBlacklist_System', 'install_site' ) );
-			add_action( 'delete_blog', array( 'StatifyBlacklist_System', 'uninstall_site' ) );
-			add_filter( 'plugin_row_meta', array( 'StatifyBlacklist_Admin', 'plugin_meta_link' ), 10, 2 );
-
-			if ( self::$multisite ) {
-				add_action( 'network_admin_menu', array( 'StatifyBlacklist_Admin', 'add_menu_page' ) );
-				add_filter(
-					'network_admin_plugin_action_links', array(
-						'StatifyBlacklist_Admin',
-						'plugin_actions_links',
-					),
-					10,
-					2
-				);
-			} else {
-				add_action( 'admin_menu', array( 'StatifyBlacklist_Admin', 'add_menu_page' ) );
-				add_filter( 'plugin_action_links', array( 'StatifyBlacklist_Admin', 'plugin_actions_links' ), 10, 2 );
-			}
+			StatifyBlacklist_Admin::init();
 		}
 
 		// CronJob to clean up database.
-		if ( defined( 'DOING_CRON' ) && DOING_CRON ) {
-			if ( 1 === self::$_options['referer']['cron'] || 1 === self::$_options['target']['cron'] ) {
-				add_action( 'statify_cleanup', array( 'StatifyBlacklist_Admin', 'cleanup_database' ) );
-			}
+		if ( defined( 'DOING_CRON' ) && DOING_CRON &&
+			( 1 === self::$options['referer']['cron'] || 1 === self::$options['target']['cron'] ) ) {
+			add_action( 'statify_cleanup', array( 'StatifyBlacklist_Admin', 'cleanup_database' ) );
 		}
 	}
 
@@ -125,6 +116,8 @@ public static function init() {
 	 * @since 1.2.1 update_options($options = null) Parameter with default value introduced.
 	 *
 	 * @param array $options Optional. New options to save.
+	 *
+	 * @return void
 	 */
 	public static function update_options( $options = null ) {
 		if ( self::$multisite ) {
@@ -132,7 +125,7 @@ public static function update_options( $options = null ) {
 		} else {
 			$o = get_option( 'statify-blacklist' );
 		}
-		self::$_options = wp_parse_args( $o, self::default_options() );
+		self::$options = wp_parse_args( $o, self::default_options() );
 	}
 
 	/**
@@ -173,52 +166,72 @@ protected static function default_options() {
 	 */
 	public static function apply_blacklist_filter() {
 		// Referer blacklist.
-		if ( isset( self::$_options['referer']['active'] ) && 0 !== self::$_options['referer']['active'] ) {
-			// Regular Expression filtering since 1.3.0.
-			if ( isset( self::$_options['referer']['regexp'] ) && self::$_options['referer']['regexp'] > 0 ) {
-				// Get full referer string.
-				$referer = wp_get_raw_referer();
-				if ( ! $referer ) {
-					$referer = '';
-				}
-				// Merge given regular expressions into one.
-				$regexp = '/' . implode( '|', array_keys( self::$_options['referer']['blacklist'] ) ) . '/';
-				if ( 2 === self::$_options['referer']['regexp'] ) {
-					$regexp .= 'i';
-				}
+		if ( isset( self::$options['referer']['active'] ) && 0 !== self::$options['referer']['active'] ) {
+			// Determine filter mode.
+			$mode = isset( self::$options['referer']['regexp'] ) ? intval( self::$options['referer']['regexp'] ) : 0;
+
+			// Get full referer string.
+			$referer = wp_get_raw_referer();
+			if ( ! $referer ) {
+				$referer = '';
+			}
 
-				// Check blacklist (no return to continue filtering #12).
-				if ( 1 === preg_match( $regexp, $referer ) ) {
-					return true;
-				}
-			} else {
-				// Extract relevant domain parts.
-				$referer = wp_parse_url( wp_get_raw_referer() );
-				$referer = strtolower( ( isset( $referer['host'] ) ? $referer['host'] : '' ) );
+			switch ( $mode ) {
 
-				// Get blacklist.
-				$blacklist = self::$_options['referer']['blacklist'];
+				// Regular Expression filtering since 1.3.0.
+				case self::MODE_REGEX:
+				case self::MODE_REGEX_CI:
+					// Merge given regular expressions into one.
+					$regexp = self::regex(
+						array_keys( self::$options['referer']['blacklist'] ),
+						self::MODE_REGEX_CI === self::$options['referer']['regexp']
+					);
 
-				// Check blacklist.
-				if ( isset( $blacklist[ $referer ] ) ) {
-					return true;
-				}
+					// Check blacklist (no return to continue filtering #12).
+					if ( 1 === preg_match( $regexp, $referer ) ) {
+						return true;
+					}
+					break;
+
+				// Keyword filter since 1.5.0 (#15).
+				case self::MODE_KEYWORD:
+					// Get blacklist.
+					$blacklist = self::$options['referer']['blacklist'];
+
+					foreach ( array_keys( $blacklist ) as $keyword ) {
+						if ( false !== strpos( strtolower( $referer ), strtolower( $keyword ) ) ) {
+							return true;
+						}
+					}
+					break;
+
+				// Standard domain filter.
+				default:
+					// Extract relevant domain parts.
+					$referer = wp_parse_url( $referer );
+					$referer = strtolower( ( isset( $referer['host'] ) ? $referer['host'] : '' ) );
+
+					// Get blacklist.
+					$blacklist = self::$options['referer']['blacklist'];
+
+					// Check blacklist.
+					if ( isset( $blacklist[ $referer ] ) ) {
+						return true;
+					}
 			}
 		}
 
 		// Target blacklist (since 1.4.0).
-		if ( isset( self::$_options['target']['active'] ) && 0 !== self::$_options['target']['active'] ) {
+		if ( isset( self::$options['target']['active'] ) && 0 !== self::$options['target']['active'] ) {
 			// Regular Expression filtering since 1.3.0.
-			if ( isset( self::$_options['target']['regexp'] ) && 0 < self::$_options['target']['regexp'] ) {
+			if ( isset( self::$options['target']['regexp'] ) && 0 < self::$options['target']['regexp'] ) {
 				// Get full referer string.
-				// @codingStandardsIgnoreStart The globals are checked.
-				$target = ( isset( $_SERVER['REQUEST_URI'] ) ? $_SERVER['REQUEST_URI'] : '/' );
-				// @codingStandardsIgnoreEnd
+				$target = ( isset( $_SERVER['REQUEST_URI'] ) ? filter_var( wp_unslash( $_SERVER['REQUEST_URI'] ), FILTER_SANITIZE_URL ) : '/' );
 				// Merge given regular expressions into one.
-				$regexp = '/' . implode( '|', array_keys( self::$_options['target']['blacklist'] ) ) . '/';
-				if ( 2 === self::$_options['target']['regexp'] ) {
-					$regexp .= 'i';
-				}
+				$regexp = self::regex(
+					array_keys( self::$options['target']['blacklist'] ),
+					self::MODE_REGEX_CI === self::$options['target']['regexp']
+				);
 
 				// Check blacklist (no return to continue filtering #12).
 				if ( 1 === preg_match( $regexp, $target ) ) {
@@ -226,11 +239,9 @@ public static function apply_blacklist_filter() {
 				}
 			} else {
 				// Extract target page.
-				// @codingStandardsIgnoreStart The globals are checked.
-				$target = ( isset( $_SERVER['REQUEST_URI'] ) ? $_SERVER['REQUEST_URI'] : '/' );
-				// @codingStandardsIgnoreEnd
+				$target = ( isset( $_SERVER['REQUEST_URI'] ) ? filter_var( wp_unslash( $_SERVER['REQUEST_URI'] ), FILTER_SANITIZE_URL ) : '/' );
 				// Get blacklist.
-				$blacklist = self::$_options['target']['blacklist'];
+				$blacklist = self::$options['target']['blacklist'];
 				// Check blacklist.
 				if ( isset( $blacklist[ $target ] ) ) {
 					return true;
@@ -239,10 +250,10 @@ public static function apply_blacklist_filter() {
 		}
 
 		// IP blacklist (since 1.4.0).
-		if ( isset( self::$_options['ip']['active'] ) && 0 !== self::$_options['ip']['active'] ) {
+		if ( isset( self::$options['ip']['active'] ) && 0 !== self::$options['ip']['active'] ) {
 			$ip = self::get_ip();
 			if ( false !== ( $ip ) ) {
-				foreach ( self::$_options['ip']['blacklist'] as $net ) {
+				foreach ( self::$options['ip']['blacklist'] as $net ) {
 					if ( self::cidr_match( $ip, $net ) ) {
 						return true;
 					}
@@ -254,6 +265,37 @@ public static function apply_blacklist_filter() {
 		return null;
 	}
 
+	/**
+	 * Preprocess regular expression provided by the user, i.e. add delimiters and optional ci flag.
+	 *
+	 * @param string|array $expression       Original expression string or array of expressions.
+	 * @param string|array $case_insensitive Make expression match case-insensitive.
+	 *
+	 * @return string Preprocessed expression ready for preg_match().
+	 */
+	protected static function regex( $expression, $case_insensitive ) {
+		$res = '/';
+		if ( is_string( $expression ) ) {
+			$res .= str_replace( '/', '\/', $expression );
+		} elseif ( is_array( $expression ) ) {
+			$res .= implode(
+				'|',
+				array_map(
+					function ( $e ) {
+						return str_replace( '/', '\/', $e );
+					},
+					$expression
+				)
+			);
+		}
+		$res .= '/';
+		if ( $case_insensitive ) {
+			$res .= 'i';
+		}
+
+		return $res;
+	}
+
 	/**
 	 * Helper method to determine the client's IP address.
 	 *
@@ -277,15 +319,14 @@ private static function get_ip() {
 				'REMOTE_ADDR',
 			) as $k
 		) {
-			// @codingStandardsIgnoreStart The globals are checked.
 			if ( isset( $_SERVER[ $k ] ) ) {
+				// phpcs:ignore
 				foreach ( explode( ',', $_SERVER[ $k ] ) as $ip ) {
 					if ( false !== filter_var( $ip, FILTER_VALIDATE_IP ) ) {
 						return $ip;
 					}
 				}
 			}
-			// @codingStandardsIgnoreEnd
 		}
 
 		return false;
@@ -361,6 +402,6 @@ private static function cidr_match( $ip, $net ) {
 			}
 
 			return ( 0 === substr_compare( sprintf( '%032b', ip2long( $ip ) ), sprintf( '%032b', ip2long( $base ) ), 0, $mask ) );
-		} // End if().
+		}
 	}
 }
diff --git a/package.json b/package.json
index 9176cf4..b49920e 100644
--- a/package.json
+++ b/package.json
@@ -1,17 +1,7 @@
 {
   "name": "statify-blacklist",
-  "version": "1.4.4",
+  "version": "1.5.0",
   "description": "A blacklist extension for the famous Statify WordPress plugin",
   "author": "Stefan Kalscheuer",
-  "license": "GPL-2.0+",
-  "devDependencies": {
-    "gulp": "^3.9.1",
-    "gulp-clean": "^0.3.2",
-    "gulp-copy": "^1.0.1",
-    "gulp-zip": "^4.0.0",
-    "gulp-composer": "^0.4.4",
-    "gulp-phpunit": "^0.24.1",
-    "gulp-phpcs": "^2.1.0",
-    "child_process": "^1.0.2"
-  }
+  "license": "GPL-2.0+"
 }
diff --git a/phpcs.xml b/phpcs.xml
index a40b6c5..3e2fb67 100644
--- a/phpcs.xml
+++ b/phpcs.xml
@@ -2,23 +2,20 @@
 <ruleset name="StatifyBlacklist">
 	<description>Derived from WordPress Coding Standard</description>
 
-	<arg value="psvn"/>
+	<arg value="psv"/>
 	<arg name="colors"/>
 
 	<!-- Files to sniff -->
-	<file>inc</file>
 	<file>statify-blacklist.php</file>
+	<file>inc</file>
+	<file>views</file>
 
 	<!-- Compliance with WordPress Coding Standard -->
-	<config name="minimum_supported_wp_version" value="4.4"/>
+	<config name="minimum_supported_wp_version" value="4.7"/>
 	<rule ref="WordPress">
-		<!-- The plugin uses switch_to_blog for multisite handling. -->
-		<exclude name="WordPress.VIP.RestrictedFunctions.switch_to_blog"/>
-		<exclude name="WordPress.VIP.RestrictedFunctions.switch_to_blog_switch_to_blog"/>
-
 		<!-- Direct queries used to clean up statify table. -->
-		<exclude name="WordPress.VIP.DirectDatabaseQuery.DirectQuery"/>
-		<exclude name="WordPress.VIP.DirectDatabaseQuery.NoCaching"/>
+		<exclude name="WordPress.DB.DirectDatabaseQuery.DirectQuery"/>
+		<exclude name="WordPress.DB.DirectDatabaseQuery.NoCaching"/>
 	</rule>
 
 	<!-- PHP compatibility level -->
diff --git a/phpunit.xml b/phpunit.xml
index 4ea43f9..f6cdc73 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -12,6 +12,6 @@
 	</filter>
 	<logging>
 		<log type="coverage-clover" target="tests-clover.xml"/>
-		<log type="junit" target="tests-junit.xml" logIncompleteSkipped="false"/>
+		<log type="junit" target="tests-junit.xml"/>
 	</logging>
 </phpunit>
diff --git a/statify-blacklist.php b/statify-blacklist.php
index 6d84741..6217898 100644
--- a/statify-blacklist.php
+++ b/statify-blacklist.php
@@ -10,11 +10,10 @@
  * Plugin Name: Statify Blacklist
  * Plugin URI:  https://wordpress.org/plugins/statify-blacklist/
  * Description: Extension for the Statify plugin to add a customizable blacklists.
- * Version:     1.4.4
+ * Version:     1.5.0
  * Author:      Stefan Kalscheuer (@stklcode)
  * Author URI:  https://www.stklcode.de
  * Text Domain: statify-blacklist
- * Domain Path: /lang
  * License:     GPLv2 or later
  *
  * Statify Blacklist is free software: you can redistribute it and/or modify
@@ -28,34 +27,42 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with Statify Blacklist. If not, see http://www.gnu.org/licenses/gpl-2.0.html.
+ * along with Statify Blacklist. If not, see https://www.gnu.org/licenses/gpl-2.0.html.
  */
 
-// Quit.
-defined( 'ABSPATH' ) || exit;
+// Quit if accessed directly.
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
 
 // Constants.
 define( 'STATIFYBLACKLIST_FILE', __FILE__ );
 define( 'STATIFYBLACKLIST_DIR', dirname( __FILE__ ) );
 define( 'STATIFYBLACKLIST_BASE', plugin_basename( __FILE__ ) );
 
-// System Hooks.
-add_action( 'plugins_loaded', array( 'StatifyBlacklist', 'init' ) );
+// Check for compatibility.
+if ( statify_blacklist_compatibility_check() ) {
+	// System Hooks.
+	add_action( 'plugins_loaded', array( 'StatifyBlacklist', 'init' ) );
 
-register_activation_hook( STATIFYBLACKLIST_FILE, array( 'StatifyBlacklist_System', 'install' ) );
+	register_activation_hook( STATIFYBLACKLIST_FILE, array( 'StatifyBlacklist_System', 'install' ) );
 
-register_uninstall_hook( STATIFYBLACKLIST_FILE, array( 'StatifyBlacklist_System', 'uninstall' ) );
+	register_uninstall_hook( STATIFYBLACKLIST_FILE, array( 'StatifyBlacklist_System', 'uninstall' ) );
 
-// Upgrade hook.
-register_activation_hook( STATIFYBLACKLIST_FILE, array( 'StatifyBlacklist_System', 'upgrade' ) );
+	// Upgrade hook.
+	register_activation_hook( STATIFYBLACKLIST_FILE, array( 'StatifyBlacklist_System', 'upgrade' ) );
 
-// Autoload.
-spl_autoload_register( 'statify_blacklist_autoload' );
+	// Autoload.
+	spl_autoload_register( 'statify_blacklist_autoload' );
+} else {
+	// Disable plugin, if active.
+	add_action( 'admin_init', 'statify_blacklist_disable' );
+}
 
 /**
  * Autoloader for StatifyBlacklist classes.
  *
- * @param string $class  Name of the class to load.
+ * @param string $class Name of the class to load.
  *
  * @since 1.0.0
  */
@@ -74,3 +81,59 @@ function statify_blacklist_autoload( $class ) {
 		);
 	}
 }
+
+/**
+ * Check for compatibility with PHP and WP version.
+ *
+ * @since 1.5.0
+ *
+ * @return boolean Whether minimum WP and PHP versions are met.
+ */
+function statify_blacklist_compatibility_check() {
+	return version_compare( $GLOBALS['wp_version'], '4.7', '>=' ) &&
+		version_compare( phpversion(), '5.5', '>=' );
+}
+
+/**
+ * Disable plugin if active and incompatible.
+ *
+ * @since 1.5.0
+ *
+ * @return void
+ */
+function statify_blacklist_disable() {
+	if ( is_plugin_active( STATIFYBLACKLIST_BASE ) ) {
+		deactivate_plugins( STATIFYBLACKLIST_BASE );
+		add_action( 'admin_notices', 'statify_blacklist_disabled_notice' );
+		// phpcs:disable WordPress.Security.NonceVerification.Recommended
+		if ( isset( $_GET['activate'] ) ) {
+			unset( $_GET['activate'] );
+		}
+		// phpcs:enable
+	}
+}
+
+/**
+ * Admin notification for unmet requirements.
+ *
+ * @since 1.5.0
+ *
+ * @return void
+ */
+function statify_blacklist_disabled_notice() {
+	echo '<div class="notice notice-error is-dismissible"><p><strong>';
+	printf(
+		/* translators: minimum version numbers for WordPress and PHP inserted at placeholders */
+		esc_html__( 'Statify Blacklist requires at least WordPress %1$s and PHP %2$s.', 'statify-blacklist' ),
+		'4.7',
+		'5.5'
+	);
+	echo '<br>';
+	printf(
+		/* translators: current version numbers for WordPress and PHP inserted at placeholders */
+		esc_html__( 'Your site is running WordPress %1$s on PHP %2$s, thus the plugin has been disabled.', 'statify-blacklist' ),
+		esc_html( $GLOBALS['wp_version'] ),
+		esc_html( phpversion() )
+	);
+	echo '</strong></p></div>';
+}
diff --git a/test/statifyblacklist-test.php b/test/statifyblacklist-test.php
index 2e71a65..a7a18e4 100644
--- a/test/statifyblacklist-test.php
+++ b/test/statifyblacklist-test.php
@@ -20,17 +20,17 @@
 /**
  * The StatifyBlacklist base class.
  */
-require_once( 'inc/class-statifyblacklist.php' );
+require_once __DIR__ . '/../inc/class-statifyblacklist.php';
 
 /**
  * The StatifyBlacklist system class.
  */
-require_once( 'inc/class-statifyblacklist-system.php' );
+require_once __DIR__ . '/../inc/class-statifyblacklist-system.php';
 
 /**
  * The StatifyBlacklist admin class.
  */
-require_once( 'inc/class-statifyblacklist-admin.php' );
+require_once __DIR__ . '/../inc/class-statifyblacklist-admin.php';
 
 /**
  * Class StatifyBlacklistTest.
@@ -43,10 +43,12 @@ class StatifyBlacklist_Test extends PHPUnit\Framework\TestCase {
 
 	/**
 	 * Test simple referer filter.
+	 *
+	 * @return void
 	 */
 	public function test_referer_filter() {
 		// Prepare Options: 2 blacklisted domains, disabled.
-		StatifyBlacklist::$_options = array(
+		StatifyBlacklist::$options = array(
 			'referer' => array(
 				'active'    => 0,
 				'cron'      => 0,
@@ -86,7 +88,7 @@ public function test_referer_filter() {
 		$this->assertNull( StatifyBlacklist::apply_blacklist_filter() );
 
 		// Activate filter and run tests again.
-		StatifyBlacklist::$_options['referer']['active'] = 1;
+		StatifyBlacklist::$options['referer']['active'] = 1;
 
 		unset( $_SERVER['HTTP_REFERER'] );
 		$this->assertNull( StatifyBlacklist::apply_blacklist_filter() );
@@ -103,10 +105,12 @@ public function test_referer_filter() {
 
 	/**
 	 * Test referer filter using regular expressions.
+	 *
+	 * @return void
 	 */
-	public function testRefererRegexFilter() {
+	public function test_referer_regex_filter() {
 		// Prepare Options: 2 regular expressions.
-		StatifyBlacklist::$_options = array(
+		StatifyBlacklist::$options = array(
 			'referer' => array(
 				'active'    => 1,
 				'cron'      => 0,
@@ -147,19 +151,74 @@ public function testRefererRegexFilter() {
 		// Matching both.
 		$_SERVER['HTTP_REFERER'] = 'http://example.net/test/me';
 		$this->assertTrue( StatifyBlacklist::apply_blacklist_filter() );
-		// Mathinc with wrong case.
+		// Matching with wrong case.
 		$_SERVER['HTTP_REFERER'] = 'http://eXaMpLe.NeT/tEsT/mE';
 		$this->assertNull( StatifyBlacklist::apply_blacklist_filter() );
 
 		// Set RegExp filter to case insensitive.
-		StatifyBlacklist::$_options['referer']['regexp'] = 2;
+		StatifyBlacklist::$options['referer']['regexp'] = 2;
+		$this->assertTrue( StatifyBlacklist::apply_blacklist_filter() );
+	}
+
+	/**
+	 * Test referer filter using keywords.
+	 *
+	 * @return void
+	 */
+	public function test_referer_keyword_filter() {
+		// Prepare Options: 2 regular expressions.
+		StatifyBlacklist::$options = array(
+			'referer' => array(
+				'active'    => 1,
+				'cron'      => 0,
+				'regexp'    => StatifyBlacklist::MODE_KEYWORD,
+				'blacklist' => array(
+					'example' => 0,
+					'test'    => 1,
+				),
+			),
+			'target'  => array(
+				'active'    => 0,
+				'cron'      => 0,
+				'regexp'    => StatifyBlacklist::MODE_NORMAL,
+				'blacklist' => array(),
+			),
+			'ip'      => array(
+				'active'    => 0,
+				'blacklist' => array(),
+			),
+			'version' => StatifyBlacklist::VERSION_MAIN,
+		);
+
+		// No multisite.
+		StatifyBlacklist::$multisite = false;
+
+		// No referer.
+		unset( $_SERVER['HTTP_REFERER'] );
+		$this->assertNull( StatifyBlacklist::apply_blacklist_filter() );
+		// Non-blacklisted referer.
+		$_SERVER['HTTP_REFERER'] = 'http://not.evil';
+		$this->assertNull( StatifyBlacklist::apply_blacklist_filter() );
+		// Blacklisted referer.
+		$_SERVER['HTTP_REFERER'] = 'http://example.com';
+		$this->assertTrue( StatifyBlacklist::apply_blacklist_filter() );
+		// Blacklisted referer with path.
+		$_SERVER['HTTP_REFERER'] = 'http://foobar.net/test/me';
+		$this->assertTrue( StatifyBlacklist::apply_blacklist_filter() );
+		// Matching both.
+		$_SERVER['HTTP_REFERER'] = 'http://example.net/test/me';
+		$this->assertTrue( StatifyBlacklist::apply_blacklist_filter() );
+		// Matching with wrong case.
+		$_SERVER['HTTP_REFERER'] = 'http://eXaMpLe.NeT/tEsT/mE';
 		$this->assertTrue( StatifyBlacklist::apply_blacklist_filter() );
 	}
 
 	/**
 	 * Test the upgrade methodology for configuration options.
+	 *
+	 * @return void
 	 */
-	public function testUpgrade() {
+	public function test_upgrade() {
 		// Create configuration of version 1.3.
 		$options13 = array(
 			'active_referer' => 1,
@@ -179,138 +238,141 @@ public function testUpgrade() {
 		StatifyBlacklist_System::upgrade();
 
 		// Retrieve updated options.
-		$optionsUpdated = get_option( 'statify-blacklist' );
+		$options_updated = get_option( 'statify-blacklist' );
 
 		// Verify size against default options (no junk left).
-		$this->assertEquals( 4, count( $optionsUpdated ) );
-		$this->assertEquals( 4, count( $optionsUpdated['referer'] ) );
-		$this->assertEquals( 4, count( $optionsUpdated['target'] ) );
-		$this->assertEquals( 2, count( $optionsUpdated['ip'] ) );
+		$this->assertEquals( 4, count( $options_updated ) );
+		$this->assertEquals( 4, count( $options_updated['referer'] ) );
+		$this->assertEquals( 4, count( $options_updated['target'] ) );
+		$this->assertEquals( 2, count( $options_updated['ip'] ) );
 
 		// Verify that original attributes are unchanged.
-		$this->assertEquals( $options13['active_referer'], $optionsUpdated['referer']['active'] );
-		$this->assertEquals( $options13['cron_referer'], $optionsUpdated['referer']['cron'] );
-		$this->assertEquals( $options13['referer'], $optionsUpdated['referer']['blacklist'] );
-		$this->assertEquals( $options13['referer_regexp'], $optionsUpdated['referer']['regexp'] );
+		$this->assertEquals( $options13['active_referer'], $options_updated['referer']['active'] );
+		$this->assertEquals( $options13['cron_referer'], $options_updated['referer']['cron'] );
+		$this->assertEquals( $options13['referer'], $options_updated['referer']['blacklist'] );
+		$this->assertEquals( $options13['referer_regexp'], $options_updated['referer']['regexp'] );
 
 		// Verify that new attributes are present in config and filled with default values (disabled, empty).
-		$this->assertEquals( 0, $optionsUpdated['target']['active'] );
-		$this->assertEquals( 0, $optionsUpdated['target']['cron'] );
-		$this->assertEquals( 0, $optionsUpdated['target']['regexp'] );
-		$this->assertEquals( array(), $optionsUpdated['target']['blacklist'] );
-		$this->assertEquals( 0, $optionsUpdated['ip']['active'] );
-		$this->assertEquals( array(), $optionsUpdated['ip']['blacklist'] );
+		$this->assertEquals( 0, $options_updated['target']['active'] );
+		$this->assertEquals( 0, $options_updated['target']['cron'] );
+		$this->assertEquals( 0, $options_updated['target']['regexp'] );
+		$this->assertEquals( array(), $options_updated['target']['blacklist'] );
+		$this->assertEquals( 0, $options_updated['ip']['active'] );
+		$this->assertEquals( array(), $options_updated['ip']['blacklist'] );
 
 		// Verify that version number has changed to current release.
-		$this->assertEquals( StatifyBlacklist::VERSION_MAIN, $optionsUpdated['version'] );
+		$this->assertEquals( StatifyBlacklist::VERSION_MAIN, $options_updated['version'] );
 	}
 
 	/**
-	 * Test CIDR address matching for IP filter (#7)
+	 * Test CIDR address matching for IP filter (#7).
+	 *
+	 * @return void
 	 */
-	public function testCidrMatch() {
+	public function test_cidr_match() {
 		// IPv4 tests.
-		$this->assertTrue( invokeStatic( StatifyBlacklist::class, 'cidr_match', array( '127.0.0.1', '127.0.0.1' ) ) );
-		$this->assertTrue( invokeStatic( StatifyBlacklist::class, 'cidr_match', array( '127.0.0.1', '127.0.0.1/32' ) ) );
+		$this->assertTrue( invoke_static( StatifyBlacklist::class, 'cidr_match', array( '127.0.0.1', '127.0.0.1' ) ) );
+		$this->assertTrue( invoke_static( StatifyBlacklist::class, 'cidr_match', array( '127.0.0.1', '127.0.0.1/32' ) ) );
 		$this->assertFalse(
-			invokeStatic(
-				StatifyBlacklist::class, 'cidr_match', array(
-					'127.0.0.1',
-					'127.0.0.1/33',
-				)
+			invoke_static(
+				StatifyBlacklist::class,
+				'cidr_match',
+				array( '127.0.0.1', '127.0.0.1/33' )
 			)
 		);
 		$this->assertFalse(
-			invokeStatic(
-				StatifyBlacklist::class, 'cidr_match', array(
-					'127.0.0.1',
-					'127.0.0.1/-1',
-				)
+			invoke_static(
+				StatifyBlacklist::class,
+				'cidr_match',
+				array( '127.0.0.1', '127.0.0.1/-1' )
 			)
 		);
 		$this->assertTrue(
-			invokeStatic(
-				StatifyBlacklist::class, 'cidr_match', array(
-					'192.0.2.123',
-					'192.0.2.0/24',
-				)
+			invoke_static(
+				StatifyBlacklist::class,
+				'cidr_match',
+				array( '192.0.2.123', '192.0.2.0/24' )
 			)
 		);
 		$this->assertFalse(
-			invokeStatic(
-				StatifyBlacklist::class, 'cidr_match', array(
-					'192.0.3.123',
-					'192.0.2.0/24',
-				)
+			invoke_static(
+				StatifyBlacklist::class,
+				'cidr_match',
+				array( '192.0.3.123', '192.0.2.0/24' )
 			)
 		);
 		$this->assertTrue(
-			invokeStatic(
-				StatifyBlacklist::class, 'cidr_match', array(
-					'192.0.2.123',
-					'192.0.2.120/29',
-				)
+			invoke_static(
+				StatifyBlacklist::class,
+				'cidr_match',
+				array( '192.0.2.123', '192.0.2.120/29' )
 			)
 		);
 		$this->assertFalse(
-			invokeStatic(
-				StatifyBlacklist::class, 'cidr_match', array(
-					'192.0.2.128',
-					'192.0.2.120/29',
-				)
+			invoke_static(
+				StatifyBlacklist::class,
+				'cidr_match',
+				array( '192.0.2.128', '192.0.2.120/29' )
 			)
 		);
-		$this->assertTrue( invokeStatic( StatifyBlacklist::class, 'cidr_match', array( '10.11.12.13', '10.0.0.0/8' ) ) );
+		$this->assertTrue( invoke_static( StatifyBlacklist::class, 'cidr_match', array( '10.11.12.13', '10.0.0.0/8' ) ) );
 		$this->assertFalse(
-			invokeStatic(
-				StatifyBlacklist::class, 'cidr_match', array(
-					'10.11.12.345',
-					'10.0.0.0/8',
-				)
+			invoke_static(
+				StatifyBlacklist::class,
+				'cidr_match',
+				array( '10.11.12.345', '10.0.0.0/8' )
 			)
 		);
 
 		// IPv6 tests.
-		$this->assertTrue( invokeStatic( StatifyBlacklist::class, 'cidr_match', array( '::1', '::1' ) ) );
-		$this->assertTrue( invokeStatic( StatifyBlacklist::class, 'cidr_match', array( '::1', '::1/128' ) ) );
-		$this->assertFalse( invokeStatic( StatifyBlacklist::class, 'cidr_match', array( '::1', '::1/129' ) ) );
-		$this->assertFalse( invokeStatic( StatifyBlacklist::class, 'cidr_match', array( '::1', '::1/-1' ) ) );
+		$this->assertTrue( invoke_static( StatifyBlacklist::class, 'cidr_match', array( '::1', '::1' ) ) );
+		$this->assertTrue( invoke_static( StatifyBlacklist::class, 'cidr_match', array( '::1', '::1/128' ) ) );
+		$this->assertFalse( invoke_static( StatifyBlacklist::class, 'cidr_match', array( '::1', '::1/129' ) ) );
+		$this->assertFalse( invoke_static( StatifyBlacklist::class, 'cidr_match', array( '::1', '::1/-1' ) ) );
 		$this->assertTrue(
-			invokeStatic(
-				StatifyBlacklist::class, 'cidr_match', array(
-					'2001:db8:a0b:12f0:1:2:3:4',
-					'2001:db8:a0b:12f0::1/64 ',
-				)
+			invoke_static(
+				StatifyBlacklist::class,
+				'cidr_match',
+				array( '2001:db8:a0b:12f0:1:2:3:4', '2001:db8:a0b:12f0::1/64 ' )
 			)
 		);
 		$this->assertTrue(
-			invokeStatic(
-				StatifyBlacklist::class, 'cidr_match', array(
-					'2001:db8:a0b:12f0::123:456',
-					'2001:db8:a0b:12f0::1/96 ',
-				)
+			invoke_static(
+				StatifyBlacklist::class,
+				'cidr_match',
+				array( '2001:db8:a0b:12f0::123:456', '2001:db8:a0b:12f0::1/96 ' )
 			)
 		);
 		$this->assertFalse(
-			invokeStatic(
-				StatifyBlacklist::class, 'cidr_match', array(
-					'2001:db8:a0b:12f0::1:132:465',
-					'2001:db8:a0b:12f0::1/96 ',
-				)
+			invoke_static(
+				StatifyBlacklist::class,
+				'cidr_match',
+				array( '2001:db8:a0b:12f0::1:132:465', '2001:db8:a0b:12f0::1/96 ' )
 			)
 		);
 	}
 
 	/**
-	 * Test sanitization of IP addresses
+	 * Test sanitization of IP addresses.
+	 *
+	 * @return void
 	 */
-	public function testSanitizeIPs() {
+	public function test_sanitize_ips() {
 		// IPv4 tests.
 		$valid   = array( '192.0.2.123', '192.0.2.123/32', '192.0.2.0/24', '192.0.2.128/25' );
 		$invalid = array( '12.34.56.789', '192.0.2.123/33', '192.0.2.123/-1' );
-		$result  = invokeStatic( StatifyBlacklist_Admin::class, 'sanitizeIPs', array( array_merge( $valid, $invalid ) ) );
+		$result  = invoke_static( StatifyBlacklist_Admin::class, 'sanitize_ips', array( array_merge( $valid, $invalid ) ) );
 		$this->assertNotFalse( $result );
-		$this->assertInternalType( 'array', $result );
+
+		/*
+		 * Unfortunately this is necessary as long as we run PHP 5 tests, because "assertInternalType" is deprecated
+		 * as of PHPUnit 8, but "assertIsArray" has been introduces in PHPUnit 7.5 which requires PHP >= 7.1.
+		 */
+		if ( method_exists( $this, 'assertIsArray' ) ) {
+			$this->assertIsArray( $result );
+		} else {
+			$this->assertInternalType( 'array', $result );
+		}
 		$this->assertEquals( $valid, $result );
 
 		// IPv6 tests.
@@ -327,28 +389,34 @@ public function testSanitizeIPs() {
 			'2001:db8:a0b:12f0::/129',
 			'1:2:3:4:5:6:7:8:9',
 		);
-		$result  = invokeStatic( StatifyBlacklist_Admin::class, 'sanitizeIPs', array( array_merge( $valid, $invalid ) ) );
+		$result  = invoke_static( StatifyBlacklist_Admin::class, 'sanitize_ips', array( array_merge( $valid, $invalid ) ) );
 		$this->assertNotFalse( $result );
-		$this->assertInternalType( 'array', $result );
+		if ( method_exists( $this, 'assertIsArray' ) ) {
+			$this->assertIsArray( $result );
+		} else {
+			$this->assertInternalType( 'array', $result );
+		}
 		$this->assertEquals( $valid, $result );
 	}
 
 	/**
 	 * Test IP filter (#7).
+	 *
+	 * @return void
 	 */
-	public function testIPFilter() {
+	public function test_ip_filter() {
 		// Prepare Options: 2 blacklisted IPs, disabled.
-		StatifyBlacklist::$_options = array(
+		StatifyBlacklist::$options = array(
 			'referer' => array(
 				'active'    => 0,
 				'cron'      => 0,
-				'regexp'    => 0,
+				'regexp'    => StatifyBlacklist::MODE_NORMAL,
 				'blacklist' => array(),
 			),
 			'target'  => array(
 				'active'    => 0,
 				'cron'      => 0,
-				'regexp'    => 0,
+				'regexp'    => StatifyBlacklist::MODE_NORMAL,
 				'blacklist' => array(),
 			),
 			'ip'      => array(
@@ -368,7 +436,7 @@ public function testIPFilter() {
 		$_SERVER['REMOTE_ADDR'] = '192.0.2.123';
 		$this->assertNull( StatifyBlacklist::apply_blacklist_filter() );
 		// Activate filter.
-		StatifyBlacklist::$_options['ip']['active'] = 1;
+		StatifyBlacklist::$options['ip']['active'] = 1;
 		$this->assertTrue( StatifyBlacklist::apply_blacklist_filter() );
 		// Try matching v6 address.
 		$_SERVER['REMOTE_ADDR'] = '2001:db8:a0b:12f0::1';
@@ -379,11 +447,11 @@ public function testIPFilter() {
 		$_SERVER['REMOTE_ADDR'] = '2001:db8:a0b:12f0::2';
 		$this->assertNull( StatifyBlacklist::apply_blacklist_filter() );
 		// Subnet matching.
-		StatifyBlacklist::$_options['ip']['blacklist'] = array(
+		StatifyBlacklist::$options['ip']['blacklist'] = array(
 			'192.0.2.0/25',
 			'2001:db8:a0b:12f0::/96',
 		);
-		$_SERVER['REMOTE_ADDR']                        = '192.0.2.123';
+		$_SERVER['REMOTE_ADDR']                       = '192.0.2.123';
 		$this->assertTrue( StatifyBlacklist::apply_blacklist_filter() );
 		$_SERVER['REMOTE_ADDR'] = '192.0.2.234';
 		$this->assertNull( StatifyBlacklist::apply_blacklist_filter() );
@@ -405,20 +473,22 @@ public function testIPFilter() {
 
 	/**
 	 * Test simple target filter.
+	 *
+	 * @return void
 	 */
-	public function testTargetFilter() {
+	public function test_target_filter() {
 		// Prepare Options: 2 blacklisted domains, disabled.
-		StatifyBlacklist::$_options = array(
+		StatifyBlacklist::$options = array(
 			'referer' => array(
 				'active'    => 0,
 				'cron'      => 0,
-				'regexp'    => 0,
+				'regexp'    => StatifyBlacklist::MODE_NORMAL,
 				'blacklist' => array(),
 			),
 			'target'  => array(
 				'active'    => 0,
 				'cron'      => 0,
-				'regexp'    => 0,
+				'regexp'    => StatifyBlacklist::MODE_NORMAL,
 				'blacklist' => array(
 					'/excluded/page/' => 0,
 					'/?page_id=3'     => 1,
@@ -451,7 +521,7 @@ public function testTargetFilter() {
 		$this->assertNull( StatifyBlacklist::apply_blacklist_filter() );
 
 		// Activate filter and run tests again.
-		StatifyBlacklist::$_options['target']['active'] = 1;
+		StatifyBlacklist::$options['target']['active'] = 1;
 
 		unset( $_SERVER['REQUEST_URI'] );
 		$this->assertNull( StatifyBlacklist::apply_blacklist_filter() );
@@ -483,11 +553,11 @@ public function testTargetFilter() {
 	 */
 	public function test_combined_filters() {
 		// Prepare Options: simple referer + simple target + ip.
-		StatifyBlacklist::$_options = array(
+		StatifyBlacklist::$options = array(
 			'referer' => array(
 				'active'    => 1,
 				'cron'      => 0,
-				'regexp'    => 0,
+				'regexp'    => StatifyBlacklist::MODE_NORMAL,
 				'blacklist' => array(
 					'example.com' => 0,
 				),
@@ -495,15 +565,15 @@ public function test_combined_filters() {
 			'target'  => array(
 				'active'    => 1,
 				'cron'      => 0,
-				'regexp'    => 0,
+				'regexp'    => StatifyBlacklist::MODE_NORMAL,
 				'blacklist' => array(
-					'/excluded/page/' => 0
+					'/excluded/page/' => 0,
 				),
 			),
 			'ip'      => array(
 				'active'    => 1,
 				'blacklist' => array(
-					'192.0.2.123'
+					'192.0.2.123',
 				),
 			),
 			'version' => StatifyBlacklist::VERSION_MAIN,
@@ -514,8 +584,8 @@ public function test_combined_filters() {
 
 		// No match.
 		$_SERVER['HTTP_REFERER'] = 'https://example.net';
-		$_SERVER['REQUEST_URI'] = '/normal/page/';
-		$_SERVER['REMOTE_ADDR'] = '192.0.2.234';
+		$_SERVER['REQUEST_URI']  = '/normal/page/';
+		$_SERVER['REMOTE_ADDR']  = '192.0.2.234';
 		unset( $_SERVER['HTTP_X_FORWARDED_FOR'] );
 		unset( $_SERVER['HTTP_X_REAL_IP'] );
 
@@ -525,7 +595,7 @@ public function test_combined_filters() {
 
 		// Matching target.
 		$_SERVER['HTTP_REFERER'] = 'https://example.net';
-		$_SERVER['REQUEST_URI'] = '/excluded/page/';
+		$_SERVER['REQUEST_URI']  = '/excluded/page/';
 		$this->assertTrue( StatifyBlacklist::apply_blacklist_filter() );
 
 		// Matching IP.
@@ -535,16 +605,21 @@ public function test_combined_filters() {
 		$_SERVER['REMOTE_ADDR'] = '192.0.2.234';
 
 		// Same for RegExp filters.
-		StatifyBlacklist::$_options['referer']['regexp'] = 1;
-		StatifyBlacklist::$_options['referer']['blacklist'] = array( 'example\.com' => 0 );
-		StatifyBlacklist::$_options['target']['regexp'] = 1;
-		StatifyBlacklist::$_options['target']['blacklist'] = array( '\/excluded\/.*' => 0 );
+		StatifyBlacklist::$options['referer']['regexp']    = StatifyBlacklist::MODE_REGEX;
+		StatifyBlacklist::$options['referer']['blacklist'] = array( 'example\.com' => 0 );
+		StatifyBlacklist::$options['target']['regexp']     = StatifyBlacklist::MODE_REGEX;
+		StatifyBlacklist::$options['target']['blacklist']  = array( '/excluded/.*' => 0 );
 
 		$this->assertNull( StatifyBlacklist::apply_blacklist_filter() );
 		$_SERVER['HTTP_REFERER'] = 'https://example.com';
 		$this->assertTrue( StatifyBlacklist::apply_blacklist_filter() );
+		// Check case-insensitive match.
+		$_SERVER['HTTP_REFERER'] = 'https://eXaMpLe.com';
+		$this->assertNull( StatifyBlacklist::apply_blacklist_filter() );
+		StatifyBlacklist::$options['referer']['regexp'] = StatifyBlacklist::MODE_REGEX_CI;
+		$this->assertTrue( StatifyBlacklist::apply_blacklist_filter() );
 		$_SERVER['HTTP_REFERER'] = 'https://example.net';
-		$_SERVER['REQUEST_URI'] = '/excluded/page/';
+		$_SERVER['REQUEST_URI']  = '/excluded/page/';
 		$this->assertTrue( StatifyBlacklist::apply_blacklist_filter() );
 		$_SERVER['REQUEST_URI'] = '/normal/page/';
 		$_SERVER['REMOTE_ADDR'] = '192.0.2.123';
@@ -556,9 +631,9 @@ public function test_combined_filters() {
 
 
 /** @ignore */
-function invokeStatic( $class, $methodName, $parameters = array() ) {
+function invoke_static( $class, $method_name, $parameters = array() ) {
 	$reflection = new \ReflectionClass( $class );
-	$method     = $reflection->getMethod( $methodName );
+	$method     = $reflection->getMethod( $method_name );
 	$method->setAccessible( true );
 
 	return $method->invokeArgs( null, $parameters );
diff --git a/views/settings-page.php b/views/settings-page.php
index 2213995..4b188e4 100755
--- a/views/settings-page.php
+++ b/views/settings-page.php
@@ -9,6 +9,8 @@
  * @since      1.0.0
  */
 
+// phpcs:disable WordPress.WhiteSpace.PrecisionAlignment.Found
+
 // Quit.
 defined( 'ABSPATH' ) || exit;
 
@@ -19,7 +21,7 @@
 
 	// Check user capabilities.
 	if ( ! current_user_can( 'manage_options' ) ) {
-		die( __( 'Are you sure you want to do this?' ) );
+		die( esc_html__( 'Are you sure you want to do this?' ) );
 	}
 
 	if ( ! empty( $_POST['cleanUp'] ) ) {
@@ -27,24 +29,63 @@
 		StatifyBlacklist_Admin::cleanup_database();
 	} else {
 		// Extract referer array.
-		if ( empty( trim( $_POST['statifyblacklist']['referer']['blacklist'] ) ) ) {
+		if ( isset( $_POST['statifyblacklist']['referer']['blacklist'] ) ) {
+			$referer_str = sanitize_textarea_field( wp_unslash( $_POST['statifyblacklist']['referer']['blacklist'] ) );
+		}
+		if ( empty( trim( $referer_str ) ) ) {
 			$referer = array();
 		} else {
-			$referer = explode( "\r\n", $_POST['statifyblacklist']['referer']['blacklist'] );
+			$referer = array_filter(
+				array_map(
+					function ( $a ) {
+						return trim( $a );
+					},
+					explode( "\r\n", $referer_str )
+				),
+				function ( $a ) {
+					return ! empty( $a );
+				}
+			);
 		}
 
 		// Extract target array.
-		if ( empty( trim( $_POST['statifyblacklist']['target']['blacklist'] ) ) ) {
+		if ( isset( $_POST['statifyblacklist']['target']['blacklist'] ) ) {
+			$target_str = sanitize_textarea_field( wp_unslash( $_POST['statifyblacklist']['target']['blacklist'] ) );
+		}
+		if ( empty( trim( $target_str ) ) ) {
 			$target = array();
 		} else {
-			$target = explode( "\r\n", str_replace( '\\\\', '\\', $_POST['statifyblacklist']['target']['blacklist'] ) );
+			$target = array_filter(
+				array_map(
+					function ( $a ) {
+						return trim( $a );
+					},
+					explode( "\r\n", str_replace( '\\\\', '\\', $target_str ) )
+				),
+				function ( $a ) {
+					return ! empty( $a );
+				}
+			);
 		}
 
 		// Extract IP array.
-		if ( empty( trim( $_POST['statifyblacklist']['ip']['blacklist'] ) ) ) {
+		if ( isset( $_POST['statifyblacklist']['ip']['blacklist'] ) ) {
+			$ip_str = sanitize_textarea_field( wp_unslash( $_POST['statifyblacklist']['ip']['blacklist'] ) );
+		}
+		if ( empty( trim( $ip_str ) ) ) {
 			$ip = array();
 		} else {
-			$ip = explode( "\r\n", $_POST['statifyblacklist']['ip']['blacklist'] );
+			$ip = array_filter(
+				array_map(
+					function ( $a ) {
+						return trim( $a );
+					},
+					explode( "\r\n", $ip_str )
+				),
+				function ( $a ) {
+					return ! empty( $a );
+				}
+			);
 		}
 
 		// Update options (data will be sanitized).
@@ -79,21 +120,33 @@
 
 		// Generate messages.
 		if ( false !== $statifyblacklist_update_result ) {
-			if ( array_key_exists( 'referer', $statifyblacklist_update_result ) ) {
-				$statifyblacklist_post_warning = __( 'Some URLs are invalid and have been sanitized.', 'statify-blacklist' );
-			} elseif ( array_key_exists( 'ip', $statifyblacklist_update_result ) ) {
+			$statifyblacklist_post_warning = array();
+			if ( ! empty( $statifyblacklist_update_result['referer']['diff'] ) ) {
+				$statifyblacklist_post_warning[] = __( 'Some URLs are invalid and have been sanitized.', 'statify-blacklist' );
+			}
+			if ( ! empty( $statifyblacklist_update_result['referer']['invalid'] ) ) {
+				$statifyblacklist_post_warning[] = __( 'Some regular expressions are invalid:', 'statify-blacklist' ) . '<br>' . implode( '<br>', $statifyblacklist_update_result['referer']['invalid'] );
+			}
+			if ( ! empty( $statifyblacklist_update_result['ip']['diff'] ) ) {
 				// translators: List of invalid IP addresses (comma separated).
-				$statifyblacklist_post_warning = sprintf( __( 'Some IPs are invalid : %s', 'statify-blacklist' ), implode( ', ', $statifyblacklist_update_result['ip'] ) );
+				$statifyblacklist_post_warning[] = sprintf( __( 'Some IPs are invalid: %s', 'statify-blacklist' ), implode( ', ', $statifyblacklist_update_result['ip']['diff'] ) );
 			}
 		} else {
 			$statifyblacklist_post_success = __( 'Settings updated successfully.', 'statify-blacklist' );
 		}
-	} // End if().
-} // End if().
+	}
+}
+
+/*
+ * Disable some code style rules that are impractical for textarea content:
+ *
+ * phpcs:disable Squiz.PHP.EmbeddedPhp.ContentBeforeOpen
+ * phpcs:disable Squiz.PHP.EmbeddedPhp.ContentAfterEnd
+ */
 ?>
 
 <div class="wrap">
-	<h1><?php esc_html_e( 'Statify Blacklist', 'statify-blacklist' ) ?></h1>
+	<h1><?php esc_html_e( 'Statify Blacklist', 'statify-blacklist' ); ?></h1>
 	<?php
 	if ( is_plugin_inactive( 'statify/statify.php' ) ) {
 		print '<div class="notice notice-warning"><p>';
@@ -101,11 +154,12 @@
 		print '</p></div>';
 	}
 	if ( isset( $statifyblacklist_post_warning ) ) {
-		print '<div class="notice notice-warning"><p>' .
-			esc_html( $statifyblacklist_post_warning );
-		print '<br/>';
-		esc_html_e( 'Settings have not been saved yet.', 'statify-blacklist' );
-		print '</p></div>';
+		foreach ( $statifyblacklist_post_warning as $w ) {
+			print '<div class="notice notice-warning"><p>' .
+				wp_kses( $w, array( 'br' => array() ) ) .
+				'</p></div>';
+		}
+		print '<div class="notice notice-warning"><p>' . esc_html__( 'Settings have not been saved yet.', 'statify-blacklist' ) . '</p></div>';
 	}
 	if ( isset( $statifyblacklist_post_success ) ) {
 		print '<div class="notice notice-success"><p>' .
@@ -114,179 +168,223 @@
 	}
 	?>
 	<form action="" method="post" id="statify-blacklist-settings">
-		<fieldset>
-			<h2><?php esc_html_e( 'Referer blacklist', 'statify-blacklist' ); ?></h2>
-			<ul style="list-style: none;">
-				<li>
+		<?php wp_nonce_field( 'statify-blacklist-settings' ); ?>
+
+		<h2><?php esc_html_e( 'Referer blacklist', 'statify-blacklist' ); ?></h2>
+
+		<table class="form-table">
+			<tbody>
+			<tr>
+				<th scope="row">
 					<label for="statify-blacklist_active_referer">
-						<input type="checkbox" name="statifyblacklist[referer][active]"
-							   id="statifyblacklist_active_referer"
-							   value="1" <?php checked( StatifyBlacklist::$_options['referer']['active'], 1 ); ?> />
-						<?php esc_html_e( 'Activate live fiter', 'statify-blacklist' ); ?>
+						<?php esc_html_e( 'Activate live filter', 'statify-blacklist' ); ?>
 					</label>
-				</li>
-				<li>
+				</th>
+				<td>
+					<input type="checkbox" name="statifyblacklist[referer][active]"
+						   id="statify-blacklist_active_referer"
+						   value="1" <?php checked( StatifyBlacklist::$options['referer']['active'], 1 ); ?>>
+					<p class="description">
+						<?php esc_html_e( 'Filter at time of tracking, before anything is stored', 'statify-blacklist' ); ?>
+					</p>
+				</td>
+			</tr>
+			<tr>
+				<th scope="row">
 					<label for="statify-blacklist_cron_referer">
-						<input type="checkbox" name="statifyblacklist[referer][cron]" id="statifyblacklist_cron_referer"
-							   value="1" <?php checked( StatifyBlacklist::$_options['referer']['cron'], 1 ); ?> />
 						<?php esc_html_e( 'CronJob execution', 'statify-blacklist' ); ?>
-						<small>(<?php esc_html_e( 'Clean database periodically in background', 'statify-blacklist' ); ?>
-							)
-						</small>
 					</label>
-				</li>
-				<li>
-					<label for="statify-blacklist_referer_regexp">
-						<?php esc_html_e( 'Use regular expressions', 'statify-blacklist' ); ?>:
-						<br />
-						<select name="statifyblacklist[referer][regexp]" id="statifyblacklist_referer_regexp">
-							<option value="0" <?php selected( StatifyBlacklist::$_options['referer']['regexp'], 0 ); ?>>
-								<?php esc_html_e( 'Disabled', 'statify-blacklist' ); ?>
-							</option>
-							<option value="1" <?php selected( StatifyBlacklist::$_options['referer']['regexp'], 1 ); ?>>
-								<?php esc_html_e( 'Case-sensitive', 'statify-blacklist' ); ?>
-							</option>
-							<option value="2" <?php selected( StatifyBlacklist::$_options['referer']['regexp'], 2 ); ?>>
-								<?php esc_html_e( 'Case-insensitive', 'statify-blacklist' ); ?>
-							</option>
-						</select>
-						<small>
-							(<?php esc_html_e( 'Performance slower than standard filter. Recommended for cron or manual execition only.', 'statify-blacklist' ); ?>
-							)
-						</small>
-					</label>
-				</li>
-				<li>
-					<label for="statify-blacklist_referer">
-						<?php esc_html_e( 'Referer blacklist', 'statify-blacklist' ); ?>:<br />
-						<textarea cols="40" rows="5" name="statifyblacklist[referer][blacklist]" id="statify-blacklist_referer"><?php
-						if ( isset( $statifyblacklist_update_result['referer'] ) ) {
-							print esc_html( implode( "\r\n", array_keys( $statifyblacklist_update_result['referer'] ) ) );
-						} else {
-							print esc_html( implode( "\r\n", array_keys( StatifyBlacklist::$_options['referer']['blacklist'] ) ) );
-						}
-							?></textarea>
-						<br />
-						<small>
-							(<?php esc_html_e( 'Add one domain (without subdomains) each line, e.g. example.com', 'statify-blacklist' ); ?>
-							)
-						</small>
-					</label>
-				</li>
-			</ul>
-		</fieldset>
+				</th>
+				<td>
+					<input type="checkbox" name="statifyblacklist[referer][cron]" id="statify-blacklist_cron_referer"
+						   value="1" <?php checked( StatifyBlacklist::$options['referer']['cron'], 1 ); ?>>
+					<p class="description"><?php esc_html_e( 'Periodically clean up database in background', 'statify-blacklist' ); ?></p>
+				</td>
+			</tr>
+			<tr>
+				<th scope="row">
+					<label for="statify-blacklist_referer_regexp"><?php esc_html_e( 'Matching method', 'statify-blacklist' ); ?></label>
+				</th>
+				<td>
+					<select name="statifyblacklist[referer][regexp]" id="statify-blacklist_referer_regexp">
+						<option value="<?php print esc_attr( StatifyBlacklist::MODE_NORMAL ); ?>" <?php selected( StatifyBlacklist::$options['referer']['regexp'], StatifyBlacklist::MODE_NORMAL ); ?>>
+							<?php esc_html_e( 'Domain', 'statify-blacklist' ); ?>
+						</option>
+						<option value="<?php print esc_attr( StatifyBlacklist::MODE_KEYWORD ); ?>" <?php selected( StatifyBlacklist::$options['referer']['regexp'], StatifyBlacklist::MODE_KEYWORD ); ?>>
+							<?php esc_html_e( 'Keyword', 'statify-blacklist' ); ?>
+						</option>
+						<option value="<?php print esc_attr( StatifyBlacklist::MODE_REGEX ); ?>" <?php selected( StatifyBlacklist::$options['referer']['regexp'], StatifyBlacklist::MODE_REGEX ); ?>>
+							<?php esc_html_e( 'RegEx case-sensitive', 'statify-blacklist' ); ?>
+						</option>
+						<option value="<?php print esc_attr( StatifyBlacklist::MODE_REGEX_CI ); ?>" <?php selected( StatifyBlacklist::$options['referer']['regexp'], StatifyBlacklist::MODE_REGEX_CI ); ?>>
+							<?php esc_html_e( 'RegEx case-insensitive', 'statify-blacklist' ); ?>
+						</option>
+					</select>
+
+					<p class="description">
+						<?php esc_html_e( 'Domain', 'statify-blacklist' ); ?> - <?php esc_html_e( 'Match given domain including subdomains', 'statify-blacklist' ); ?>
+						<br>
+						<?php esc_html_e( 'Keyword', 'statify-blacklist' ); ?> - <?php esc_html_e( 'Match every referer that contains one of the keywords', 'statify-blacklist' ); ?>
+						<br>
+						<?php esc_html_e( 'RegEx', 'statify-blacklist' ); ?> - <?php esc_html_e( 'Match referer by regular expression', 'statify-blacklist' ); ?>
+					</p>
+				</td>
+			</tr>
+			<tr>
+				<th scope="row">
+					<label for="statify-blacklist_referer"><?php esc_html_e( 'Referer blacklist', 'statify-blacklist' ); ?></label>
+				</th>
+				<td>
+					<textarea cols="40" rows="5" name="statifyblacklist[referer][blacklist]" id="statify-blacklist_referer"><?php
+					if ( empty( $statifyblacklist_update_result['referer'] ) ) {
+						print esc_html( implode( "\r\n", array_keys( StatifyBlacklist::$options['referer']['blacklist'] ) ) );
+					} else {
+						print esc_html( implode( "\r\n", array_keys( $statifyblacklist_update_result['referer']['sanitized'] ) ) );
+					}
+					?></textarea>
+					<p class="description">
+						<?php esc_html_e( 'Add one domain (without subdomains) each line, e.g. example.com', 'statify-blacklist' ); ?>
+					</p>
+				</td>
+			</tr>
+			</tbody>
+		</table>
 
-		<fieldset>
-			<h2><?php esc_html_e( 'Target blacklist', 'statify-blacklist' ); ?></h2>
-			<ul style="list-style: none;">
-				<li>
+		<h2><?php esc_html_e( 'Target blacklist', 'statify-blacklist' ); ?></h2>
+
+		<table class="form-table">
+			<tbody>
+			<tr>
+				<th scope="row">
 					<label for="statify-blacklist_active_target">
-						<input type="checkbox" name="statifyblacklist[target][active]"
-							   id="statifyblacklist_active_target"
-							   value="1" <?php checked( StatifyBlacklist::$_options['target']['active'], 1 ); ?> />
-						<?php esc_html_e( 'Activate live fiter', 'statify-blacklist' ); ?>
+						<?php esc_html_e( 'Activate live filter', 'statify-blacklist' ); ?>
 					</label>
-				</li>
-				<li>
+				</th>
+				<td>
+					<input type="checkbox" name="statifyblacklist[target][active]"
+						   id="statify-blacklist_active_target"
+						   value="1" <?php checked( StatifyBlacklist::$options['target']['active'], 1 ); ?>>
+					<p class="description">
+						<?php esc_html_e( 'Filter at time of tracking, before anything is stored', 'statify-blacklist' ); ?>
+					</p>
+				</td>
+			</tr>
+			<tr>
+				<th scope="row">
 					<label for="statify-blacklist_cron_target">
-						<input type="checkbox" name="statifyblacklist[target][cron]" id="statifyblacklist_cron_target"
-							   value="1" <?php checked( StatifyBlacklist::$_options['target']['cron'], 1 ); ?> />
 						<?php esc_html_e( 'CronJob execution', 'statify-blacklist' ); ?>
-						<small>(<?php esc_html_e( 'Clean database periodically in background', 'statify-blacklist' ); ?>
-							)
-						</small>
 					</label>
-				</li>
-				<li>
+				</th>
+				<td>
+					<input type="checkbox" name="statifyblacklist[target][cron]" id="statify-blacklist_cron_target"
+						   value="1" <?php checked( StatifyBlacklist::$options['target']['cron'], 1 ); ?>>
+					<p class="description">
+						<?php esc_html_e( 'Clean database periodically in background', 'statify-blacklist' ); ?>
+					</p>
+				</td>
+			</tr>
+			<tr>
+				<th scope="row">
 					<label for="statify-blacklist_target_regexp">
-						<?php esc_html_e( 'Use regular expressions', 'statify-blacklist' ); ?>:
-						<br />
-						<select name="statifyblacklist[target][regexp]" id="statifyblacklist_target_regexp">
-							<option value="0" <?php selected( StatifyBlacklist::$_options['target']['regexp'], 0 ); ?>>
-								<?php esc_html_e( 'Disabled', 'statify-blacklist' ); ?>
-							</option>
-							<option value="1" <?php selected( StatifyBlacklist::$_options['target']['regexp'], 1 ); ?>>
-								<?php esc_html_e( 'Case-sensitive', 'statify-blacklist' ); ?>
-							</option>
-							<option value="2" <?php selected( StatifyBlacklist::$_options['target']['regexp'], 2 ); ?>>
-								<?php esc_html_e( 'Case-insensitive', 'statify-blacklist' ); ?>
-							</option>
-						</select>
-						<small>
-							(<?php esc_html_e( 'Performance slower than standard filter. Recommended for cron or manual execition only.', 'statify-blacklist' ); ?>
-							)
-						</small>
+						<?php esc_html_e( 'Matching method', 'statify-blacklist' ); ?>
 					</label>
-				</li>
-				<li>
+				</th>
+				<td>
+					<select name="statifyblacklist[target][regexp]" id="statify-blacklist_referer_regexp">
+						<option value="<?php print esc_attr( StatifyBlacklist::MODE_NORMAL ); ?>" <?php selected( StatifyBlacklist::$options['target']['regexp'], StatifyBlacklist::MODE_NORMAL ); ?>>
+							<?php esc_html_e( 'Exact', 'statify-blacklist' ); ?>
+						</option>
+						<option value="<?php print esc_attr( StatifyBlacklist::MODE_REGEX ); ?>" <?php selected( StatifyBlacklist::$options['target']['regexp'], StatifyBlacklist::MODE_REGEX ); ?>>
+							<?php esc_html_e( 'RegEx case-sensitive', 'statify-blacklist' ); ?>
+						</option>
+						<option value="<?php print esc_attr( StatifyBlacklist::MODE_REGEX_CI ); ?>" <?php selected( StatifyBlacklist::$options['target']['regexp'], StatifyBlacklist::MODE_REGEX_CI ); ?>>
+							<?php esc_html_e( 'RegEx case-insensitive', 'statify-blacklist' ); ?>
+						</option>
+					</select>
+
+					<p class="description">
+						<?php esc_html_e( 'Exact', 'statify-blacklist' ); ?> - <?php esc_html_e( 'Match only given targets', 'statify-blacklist' ); ?>
+						<br>
+						<?php esc_html_e( 'RegEx', 'statify-blacklist' ); ?> - <?php esc_html_e( 'Match target by regular expression', 'statify-blacklist' ); ?>
+					</p>
+				</td>
+			</tr>
+			<tr>
+				<th scope="row">
 					<label for="statify-blacklist_target">
-						<?php esc_html_e( 'Target blacklist', 'statify-blacklist' ); ?>:<br />
-						<textarea cols="40" rows="5" name="statifyblacklist[target][blacklist]" id="statify-blacklist_target"><?php
-						if ( isset( $statifyblacklist_update_result['target'] ) ) {
-							print esc_html( implode( "\r\n", array_keys( $statifyblacklist_update_result['target'] ) ) );
-						} else {
-							print esc_html( implode( "\r\n", array_keys( StatifyBlacklist::$_options['target']['blacklist'] ) ) );
-						}
-							?></textarea>
-						<br />
-						<small>
-							(<?php esc_html_e( 'Add one target URL each line, e.g.', 'statify-blacklist' );
-							print ' /, /test/page/, /?page_id=123' ?>
-							)
-						</small>
+						<?php esc_html_e( 'Target blacklist', 'statify-blacklist' ); ?>
 					</label>
-				</li>
-			</ul>
-		</fieldset>
+				</th>
+				<td>
+					<textarea cols="40" rows="5" name="statifyblacklist[target][blacklist]" id="statify-blacklist_target"><?php
+					if ( empty( $statifyblacklist_update_result['target'] ) ) {
+						print esc_html( implode( "\r\n", array_keys( StatifyBlacklist::$options['target']['blacklist'] ) ) );
+					} else {
+						print esc_html( implode( "\r\n", array_keys( $statifyblacklist_update_result['target']['sanitized'] ) ) );
+					}
+					?></textarea>
+
+					<p class="description">
+						(<?php esc_html_e( 'Add one target URL each line, e.g.', 'statify-blacklist' ); ?> /, /test/page/, /?page_id=123)
+					</p>
+				</td>
+			</tr>
+			</tbody>
+		</table>
 
-		<fieldset>
-			<h2><?php esc_html_e( 'IP blacklist', 'statify-blacklist' ); ?></h2>
-			<ul style="list-style: none;">
-				<li>
+		<h2><?php esc_html_e( 'IP blacklist', 'statify-blacklist' ); ?></h2>
+
+		<table class="form-table">
+			<tbody>
+			<tr>
+				<th scope="row">
 					<label for="statify-blacklist_active_ip">
-						<input type="checkbox" name="statifyblacklist[ip][active]" id="statifyblacklist_active_ip"
-							   value="1" <?php checked( StatifyBlacklist::$_options['ip']['active'], 1 ); ?> />
-						<?php esc_html_e( 'Activate live fiter', 'statify-blacklist' ); ?>
-					</label>
-				</li>
-				<li>
-					<small>
-						(<?php esc_html_e( 'Cron execution is not possible for IP filter, because IP addresses are not stored.', 'statify-blacklist' ); ?>
-						)
-					</small>
-				</li>
-				<li>
-					<label for="statify-blacklist_ip">
-						<?php esc_html_e( 'IP blacklist', 'statify-blacklist' ); ?>:<br />
-						<textarea cols="40" rows="5" name="statifyblacklist[ip][blacklist]" id="statify-blacklist_ip"><?php
-						if ( isset( $statifyblacklist_update_result['ip'] ) ) {
-							print esc_html( $_POST['statifyblacklist']['ip']['blacklist'] );
-						} else {
-							print esc_html( implode( "\r\n", StatifyBlacklist::$_options['ip']['blacklist'] ) );
-						}
-							?></textarea>
-						<br />
-						<small>
-							(<?php esc_html_e( 'Add one IP address or range per line, e.g.', 'statify-blacklist' ) ?>
-							127.0.0.1, 192.168.123.0/24, 2001:db8:a0b:12f0::1/64
-							)
-						</small>
+						<?php esc_html_e( 'Activate live filter', 'statify-blacklist' ); ?>
 					</label>
-				</li>
-			</ul>
-		</fieldset>
+				</th>
+				<td>
+					<input type="checkbox" name="statifyblacklist[ip][active]" id="statify-blacklist_active_ip"
+						   value="1" <?php checked( StatifyBlacklist::$options['ip']['active'], 1 ); ?>>
+					<p class="description">
+						<?php esc_html_e( 'Filter at time of tracking, before anything is stored', 'statify-blacklist' ); ?>
+						<br>
+						<?php esc_html_e( 'Cron execution is not possible for IP filter, because IP addresses are not stored.', 'statify-blacklist' ); ?>
+					</p>
+				</td>
+			</tr>
+			<tr>
+				<th scope="row">
+					<label for="statify-blacklist_ip"><?php esc_html_e( 'IP blacklist', 'statify-blacklist' ); ?></label>:
+				</th>
+				<td>
+					<textarea cols="40" rows="5" name="statifyblacklist[ip][blacklist]" id="statify-blacklist_ip"><?php
+					if ( empty( $statifyblacklist_update_result['ip'] ) ) {
+						print esc_html( implode( "\r\n", StatifyBlacklist::$options['ip']['blacklist'] ) );
+					} else {
+						print esc_html( implode( "\r\n", $statifyblacklist_update_result['ip']['sanitized'] ) );
+					}
+					?></textarea>
 
-		<?php wp_nonce_field( 'statify-blacklist-settings' ); ?>
+					<p class="description">
+						<?php esc_html_e( 'Add one IP address or range per line, e.g.', 'statify-blacklist' ); ?>
+						127.0.0.1, 192.168.123.0/24, 2001:db8:a0b:12f0::1/64
+					</p>
+				</td>
+			</tr>
+			</tbody>
+		</table>
 
 		<p class="submit">
-			<input class="button-primary" type="submit" name="submit" value="<?php esc_html_e( 'Save Changes' ) ?>">
-		<hr />
-		<input class="button-secondary" type="submit" name="cleanUp"
-			   value="<?php esc_html_e( 'CleanUp Database', 'statify-blacklist' ) ?>"
-			   onclick="return confirm('Do you really want to apply filters to database? This cannot be undone.');">
-		<br />
-		<small><?php esc_html_e( 'Applies referer and target filter (even if disabled) to data stored in database.', 'statify-blacklist' ); ?>
-			<em><?php esc_html_e( 'This cannot be undone!', 'statify-blacklist' ); ?></em></small>
+			<input class="button-primary" type="submit" name="submit" value="<?php esc_html_e( 'Save Changes' ); ?>">
+			<hr>
+			<input class="button-secondary" type="submit" name="cleanUp"
+				   value="<?php esc_html_e( 'CleanUp Database', 'statify-blacklist' ); ?>"
+				   onclick="return confirm('Do you really want to apply filters to database? This cannot be undone.');">
+			<br>
+			<p class="description">
+				<?php esc_html_e( 'Applies referer and target filter (even if disabled) to data stored in database.', 'statify-blacklist' ); ?>
+				<em><?php esc_html_e( 'This cannot be undone!', 'statify-blacklist' ); ?></em>
+			</p>
 		</p>
 	</form>
 </div>