diff --git a/CHANGELOG.md b/CHANGELOG.md
index 407c653..1c55506 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## [2.0.0] - 2023-XX-XX
+- Prepare for Craft 4 compatibility
+- ...
+
 ## [1.9.2] - 2022-03-26
 - Fix issues with Supertable / exclude SuperTableBlockElement
 
diff --git a/composer.json b/composer.json
index 913f2a1..4ff3c15 100644
--- a/composer.json
+++ b/composer.json
@@ -24,11 +24,13 @@
     }
   ],
   "require": {
-    "craftcms/cms": "^3.2.0",
+    "craftcms/cms": "^4.1.0",
     "guzzlehttp/guzzle": "^6.5.5|^7.2.0"
   },
   "require-dev": {
-    "vimeo/psalm": "^4.4"
+    "vimeo/psalm": "^4.4",
+    "craftcms/rector": "dev-main",
+    "craftcms/phpstan": "dev-main"
   },
   "autoload": {
     "psr-4": {
@@ -45,5 +47,14 @@
     "hasCpSettings": false,
     "hasCpSection": false,
     "changelogUrl": "https://raw.githubusercontent.com/ostark/upper/master/CHANGELOG.md"
+  },
+  "minimum-stability": "dev",
+  "prefer-stable": true,
+  "config": {
+    "allow-plugins": {
+      "yiisoft/yii2-composer": true,
+      "craftcms/plugin-installer": true,
+      "composer/package-versions-deprecated": true
+    }
   }
 }
diff --git a/phpstan.neon b/phpstan.neon
new file mode 100644
index 0000000..60da242
--- /dev/null
+++ b/phpstan.neon
@@ -0,0 +1,10 @@
+includes:
+    - vendor/craftcms/phpstan/phpstan.neon
+
+parameters:
+    level: 0
+    paths:
+        - src
+    treatPhpDocTypesAsCertain: false
+    ignoreErrors:
+        - "#Unsafe usage of new static#"
diff --git a/src/EventRegistrar.php b/src/EventRegistrar.php
index 156e44c..255dd12 100644
--- a/src/EventRegistrar.php
+++ b/src/EventRegistrar.php
@@ -65,6 +65,7 @@ public static function registerFrontendEvents()
             $request->getIsActionRequest() ||
             !$request->getIsGet()
         ) {
+            /** @var \ostark\upper\behaviors\CacheControlBehavior|\ostark\upper\behaviors\TagHeaderBehavior|Response  $response */
             $response = \Craft::$app->getResponse();
             $response->addCacheControlDirective('private');
             $response->addCacheControlDirective('no-cache');
@@ -93,7 +94,7 @@ public static function registerFrontendEvents()
         // Add the tags to the response header
         Event::on(View::class, View::EVENT_AFTER_RENDER_PAGE_TEMPLATE, function (TemplateEvent $event) {
 
-            /** @var \yii\web\Response $response */
+            /** @var \yii\web\Response|\ostark\upper\behaviors\CacheControlBehavior|\ostark\upper\behaviors\TagHeaderBehavior $response */
             $response      = \Craft::$app->getResponse();
             $plugin        = Plugin::getInstance();
             $tagCollection = $plugin->getTagCollection();
@@ -121,7 +122,7 @@ public static function registerFrontendEvents()
 
             // Flag truncation
             if (count($tags) > count($maxedTags)) {
-                $headers->set(Plugin::TRUNCATED_HEADER_NAME, count($tags) - count($maxedTags));
+                $headers->set(Plugin::TRUNCATED_HEADER_NAME, (string) (count($tags) - count($maxedTags)));
             }
 
             $response->setSharedMaxAge($maxAge);
diff --git a/src/Plugin.php b/src/Plugin.php
index 255e0fa..73e4d5e 100644
--- a/src/Plugin.php
+++ b/src/Plugin.php
@@ -41,7 +41,7 @@ class Plugin extends BasePlugin
     const INFO_HEADER_NAME = 'X-UPPER-CACHE';
     const TRUNCATED_HEADER_NAME = 'X-UPPER-CACHE-TRUNCATED';
 
-    public $schemaVersion = '1.0.1';
+    public string $schemaVersion = '1.0.1';
 
 
     /**
@@ -108,11 +108,9 @@ public function getTagCollection(): TagCollection
     // =========================================================================
 
     /**
-     * Creates and returns the model used to store the plugin’s settings.
-     *
-     * @return \craft\base\Model|null
+     * Creates and returns the model used to store the plugin’s settings
      */
-    protected function createSettingsModel()
+    protected function createSettingsModel(): Settings
     {
         return new Settings();
     }
@@ -122,7 +120,7 @@ protected function createSettingsModel()
      * Is called after the plugin is installed.
      * Copies example config to project's config folder
      */
-    protected function afterInstall()
+    protected function afterInstall(): void
     {
         $configSourceFile = __DIR__ . DIRECTORY_SEPARATOR . 'config.example.php';
         $configTargetFile = \Craft::$app->getConfig()->configDir . DIRECTORY_SEPARATOR . $this->handle . '.php';
diff --git a/src/TwigExtension.php b/src/TwigExtension.php
index d27fb58..9d95413 100644
--- a/src/TwigExtension.php
+++ b/src/TwigExtension.php
@@ -11,7 +11,7 @@ class TwigExtension extends AbstractExtension implements GlobalsInterface
      *
      * @return array An array of global variables
      */
-    public function getGlobals()
+    public function getGlobals(): array
     {
         return [
             'upper' => [
diff --git a/src/drivers/AbstractPurger.php b/src/drivers/AbstractPurger.php
index 826b159..e0d5f7b 100644
--- a/src/drivers/AbstractPurger.php
+++ b/src/drivers/AbstractPurger.php
@@ -46,6 +46,20 @@ public function purgeUrlsByTag(string $tag)
         return false;
     }
 
+
+    /**
+     * @param array $urls
+     *
+     * @return bool
+     */
+    public function purgeUrls(array $urls)
+    {
+        $joinedUrls = implode(',', $urls);
+        \Craft::warning("Method purgeUrls([$joinedUrls]') was called - not implemented by driver ", "upper");
+
+        return true;
+    }
+
     /**
      * Get cached urls by given tag
      *
@@ -113,4 +127,7 @@ public function clearLocalCache()
 
     }
 
+
+
+
 }
diff --git a/src/drivers/Cloudflare.php b/src/drivers/Cloudflare.php
index 6e5ab33..a8d9aee 100644
--- a/src/drivers/Cloudflare.php
+++ b/src/drivers/Cloudflare.php
@@ -101,7 +101,7 @@ public function purgeAll()
      * @return bool
      * @throws \ostark\upper\exceptions\CloudflareApiException
      */
-    protected function sendRequest($method = 'DELETE', string $type, array $params = [])
+    protected function sendRequest($method = 'DELETE', string $type = 'purge_cache', array $params = [])
     {
         $client = $this->getClient();
 
diff --git a/src/drivers/Fastly.php b/src/drivers/Fastly.php
index 90a64d5..5c18316 100644
--- a/src/drivers/Fastly.php
+++ b/src/drivers/Fastly.php
@@ -111,7 +111,7 @@ public function purgeAll()
      * @return bool
      * @throws \ostark\upper\exceptions\FastlyApiException
      */
-    protected function sendRequest(string $method = 'PURGE', string $uri, array $headers = [])
+    protected function sendRequest(string $method = 'PURGE', string $uri = '', array $headers = [])
     {
         $client = new Client([
             'base_uri' => self::API_ENDPOINT,
diff --git a/src/drivers/Keycdn.php b/src/drivers/Keycdn.php
index 1ff8b45..b06ef55 100644
--- a/src/drivers/Keycdn.php
+++ b/src/drivers/Keycdn.php
@@ -72,7 +72,7 @@ public function purgeAll()
      * @return bool
      * @throws \ostark\upper\exceptions\KeycdnApiException
      */
-    protected function sendRequest($method = 'DELETE', string $type, array $params = [])
+    protected function sendRequest($method = 'DELETE', string $type = 'purgetag', array $params = [])
     {
         $token  = base64_encode("{$this->apiKey}:");
         $client = new Client([
diff --git a/src/jobs/PurgeCacheJob.php b/src/jobs/PurgeCacheJob.php
index 7210177..8d0f4d3 100644
--- a/src/jobs/PurgeCacheJob.php
+++ b/src/jobs/PurgeCacheJob.php
@@ -19,10 +19,10 @@ class PurgeCacheJob extends BaseJob
     /**
      * @inheritdoc
      */
-    public function execute($queue)
+    public function execute($queue): void
     {
         if (!$this->tag) {
-            return false;
+            return;
         }
 
         // Get registered purger
diff --git a/src/models/Settings.php b/src/models/Settings.php
index 047ced7..8bf3d17 100644
--- a/src/models/Settings.php
+++ b/src/models/Settings.php
@@ -77,7 +77,7 @@ class Settings extends Model
      *
      * @return array
      */
-    public function rules()
+    public function rules(): array
     {
         return [
             [['driver', 'drivers','keyPrefix'], 'required'],