diff --git a/app/ErrorHandler/CustomHtmlErrorRenderer.php b/app/ErrorHandler/CustomHtmlErrorRenderer.php
index c2238aa..16af79b 100644
--- a/app/ErrorHandler/CustomHtmlErrorRenderer.php
+++ b/app/ErrorHandler/CustomHtmlErrorRenderer.php
@@ -85,21 +85,23 @@ class CustomHtmlErrorRenderer extends AbstractErrorRenderer
   public function renderHtmlBody(string $title = '', string $html = ''): string
   {
     return sprintf(
-      '<html>' .
-        '   <head>' .
-        "       <meta http-equiv='Content-Type' content='text/html; charset=utf-8'>" .
-        '       <title>%s</title>' .
-        '       <style>' .
-        '           body{margin:0;padding:30px;font:12px/1.5 Helvetica,Arial,Verdana,sans-serif}' .
-        '           h1{margin:0;font-size:48px;font-weight:normal;line-height:48px}' .
-        '           strong{display:inline-block;width:65px}' .
-        '       </style>' .
-        '   </head>' .
-        '   <body>' .
-        '       <h1>%s</h1>' .
-      '       <div>%s</div>' .
-        '   </body>' .
-        '</html>',
+      <<<HTML
+      <html>
+        <head>
+        <meta http-equiv='Content-Type' content='text/html; charset=utf-8'>
+        <title>%s</title>
+        <style>
+          body{margin:0;padding:30px;font:12px/1.5 Helvetica,Arial,Verdana,sans-serif}
+          h1{margin:0;font-size:48px;font-weight:normal;line-height:48px}
+          strong{display:inline-block;width:65px}
+        </style>
+        </head>
+        <body>
+        <h1>%s</h1>
+        <div>%s</div>
+        </body>
+      </html>
+      HTML,
       $title,
       $title,
       $html
diff --git a/app/Kernel.php b/app/Kernel.php
index afda506..f6a52f1 100644
--- a/app/Kernel.php
+++ b/app/Kernel.php
@@ -8,14 +8,12 @@ use Dotenv\Dotenv;
 use Dotenv\Exception\InvalidPathException;
 use Slim\Factory\AppFactory;
 
-require_once __DIR__ . '/helpers.php';
-
 class Kernel
 {
   private static $app;
   private static $env;
 
-  private static function _build()
+  private static function build()
   {
     self::$app = AppFactory::create();
 
@@ -34,7 +32,7 @@ class Kernel
     // Add Routing Middleware
     self::$app->addRoutingMiddleware();
 
-    self::$app->add(new ThrottleMiddleware);
+    self::$app->add(new ThrottleMiddleware());
 
     /**
      * Add Error Handling Middleware
@@ -79,21 +77,24 @@ class Kernel
     }
 
     switch (strtolower($value)) {
-      case 'true':
       case '(true)':
-        return true;
+        $value = true;
+        break;
 
       case 'false':
       case '(false)':
-        return false;
+        $value = false;
+        break;
 
       case 'empty':
       case '(empty)':
-        return '';
+        $value = '';
+        break;
 
       case 'null':
       case '(null)':
-        return;
+        $value = null;
+        break;
     }
 
     return $value;
@@ -101,7 +102,7 @@ class Kernel
 
   public static function run()
   {
-    self::_build();
+    self::build();
     self::$app->run();
   }
 }
diff --git a/app/Middlewares/ThrottleMiddleware.php b/app/Middlewares/ThrottleMiddleware.php
index 5dc8384..6216e2a 100644
--- a/app/Middlewares/ThrottleMiddleware.php
+++ b/app/Middlewares/ThrottleMiddleware.php
@@ -20,7 +20,7 @@ class ThrottleMiddleware
    */
   public function __invoke(Request $request, RequestHandler $handler): Response
   {
-    $throttle = new LeakyBucket;
+    $throttle = new LeakyBucket();
     //! Enable APC in Laragon https://forum.laragon.org/topic/1245/regarding-caching-plugin-availability/4
     $storage = new \Stiphle\Storage\Apcu();
     $throttle->setStorage($storage);
diff --git a/app/Routes/web.php b/app/Routes/web.php
index 82a4e7c..8ebe278 100644
--- a/app/Routes/web.php
+++ b/app/Routes/web.php
@@ -6,7 +6,8 @@ use jucksearm\barcode\Datamatrix;
 Kernel::app()->get('/{code}', function ($request, $response, $args) {
   $s = intval($request->getQueryParams()['s'] ?? 300);
   $s = is_int($s) ? $s : 300;
-  $s = $s <= env('MinPixSize', 60) ? env('MinPixSize', 60) : ($s >= env('MaxPixSize', 2000) ? env('MaxPixSize', 2000) : $s);
+  $s = $s <= env('MinPixSize', 60) ?
+    env('MinPixSize', 60) : ($s >= env('MaxPixSize', 2000) ? env('MaxPixSize', 2000) : $s);
   $m = round(20 * 2 / 300);
   $m = $m <= 5 ? 5 : ($m >= 300 ? 300 : $m);
   $image = @Datamatrix::factory()
diff --git a/phpcs.xml b/phpcs.xml
new file mode 100644
index 0000000..a852cef
--- /dev/null
+++ b/phpcs.xml
@@ -0,0 +1,33 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ruleset name="RealWorld" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="vendor/squizlabs/php_codesniffer/phpcs.xsd">
+    <!-- <arg name="basepath" value="./"/> -->
+    <arg name="colors"/>
+    <arg name="extensions" value="php"/>
+    <arg name="tab-width" value="2"/>
+    <file>app/</file>
+    <file>public/</file>
+    <rule ref="PSR1"/>
+    <rule ref="PSR2"/>
+    <rule ref="PSR12"/>
+    <rule ref="PSR2">
+      <!-- Disable PSR-2 indentation rules that are buggy with 2 spaces -->
+      <exclude name="PSR2.ControlStructures.SwitchDeclaration.BreakIndent"/>
+    </rule>
+    <rule ref="Generic.WhiteSpace.ScopeIndent">
+        <properties>
+            <property name="indent" value="2"/>
+            <property name="tabIndent" value="false"/>
+        </properties>
+    </rule>
+    <rule ref="Squiz.Functions.MultiLineFunctionDeclaration">
+        <properties>
+            <property name="indent" value="2" />
+        </properties>
+    </rule>
+    <rule ref="PSR2.Methods.FunctionCallSignature">
+        <properties>
+            <property name="indent" value="2" />
+        </properties>
+    </rule>
+    <arg name="tab-width" value="4"/>
+</ruleset>
diff --git a/public/index.php b/public/index.php
index 70d02cf..d58c17c 100644
--- a/public/index.php
+++ b/public/index.php
@@ -1,6 +1,7 @@
 <?php
 
 require __DIR__ . '/../vendor/autoload.php';
+require_once __DIR__ . '/../app/helpers.php';
 
 use App\Kernel;