diff --git a/config/prod/config.php b/config/prod/config.php
index f572e70..6f4490b 100644
--- a/config/prod/config.php
+++ b/config/prod/config.php
@@ -3,7 +3,21 @@ if (!defined('ASSET_VERSION')) {
     define('ASSET_VERSION', '2024-11-22'); // oder deine aktuelle Version
 }
 
+// Domain-Konfiguration (kann pro Umgebung angepasst werden)
+if (!defined('APP_DOMAIN_PRIMARY')) {
+    define('APP_DOMAIN_PRIMARY', 'usbcheck.it');
+}
+if (!defined('APP_URL_PRIMARY')) {
+    define('APP_URL_PRIMARY', 'https://' . APP_DOMAIN_PRIMARY);
+}
+if (!defined('APP_DOMAIN_FAKECHECK')) {
+    define('APP_DOMAIN_FAKECHECK', 'ismyusbfake.com');
+}
+if (!defined('APP_URL_FAKECHECK')) {
+    define('APP_URL_FAKECHECK', 'https://' . APP_DOMAIN_FAKECHECK);
+}
+
 // Matomo Einstellungen
 define('MATOMO_URL', 'https://matomo.my-statistics.info/');
 define('MATOMO_ENABLED', true);
-define('MATOMO_SITE_ID', 7);
\ No newline at end of file
+define('MATOMO_SITE_ID', 7);
diff --git a/config/staging/config.php b/config/staging/config.php
index 8405b66..72c3106 100644
--- a/config/staging/config.php
+++ b/config/staging/config.php
@@ -3,7 +3,21 @@ if (!defined('ASSET_VERSION')) {
     define('ASSET_VERSION', time()); // oder deine aktuelle Version
 }
 
+// Domain-Konfiguration (kann pro Umgebung angepasst werden)
+if (!defined('APP_DOMAIN_PRIMARY')) {
+    define('APP_DOMAIN_PRIMARY', 'staging.usbcheck.it');
+}
+if (!defined('APP_URL_PRIMARY')) {
+    define('APP_URL_PRIMARY', 'https://' . APP_DOMAIN_PRIMARY);
+}
+if (!defined('APP_DOMAIN_FAKECHECK')) {
+    define('APP_DOMAIN_FAKECHECK', 'staging.ismyusbfake.com');
+}
+if (!defined('APP_URL_FAKECHECK')) {
+    define('APP_URL_FAKECHECK', 'https://' . APP_DOMAIN_FAKECHECK);
+}
+
 // Matomo Einstellungen
 define('MATOMO_URL', 'https://matomo.my-statistics.info/');
 define('MATOMO_ENABLED', false);
-define('MATOMO_SITE_ID', 8);
\ No newline at end of file
+define('MATOMO_SITE_ID', 8);
diff --git a/partials/landing/fakecheck/webcheck.php b/partials/landing/fakecheck/webcheck.php
index 59a9c64..d4ec3a9 100644
--- a/partials/landing/fakecheck/webcheck.php
+++ b/partials/landing/fakecheck/webcheck.php
@@ -173,6 +173,6 @@
             </p>
         </aside>
     </div>
-        </div>
+    </div>
     </div>
 </section>
diff --git a/partials/landing/main/features.php b/partials/landing/main/features.php
index c89fdcd..8c7d7e5 100644
--- a/partials/landing/main/features.php
+++ b/partials/landing/main/features.php
@@ -32,7 +32,7 @@
                     <li data-i18n="features_free_li4">• Auswahl verschiedener Teststufen (z. B. 200&nbsp;MB, 2&nbsp;GB)</li>
                     <li data-i18n="features_free_li5">• Keine Registrierung erforderlich</li>
                 </ul>
-                <a href="https://usbcheck.it/fakecheck/"
+                <a href="<?= htmlspecialchars(app_primary_url() . '/fakecheck/') ?>"
                    class="inline-flex mt-3 items-center text-sm font-semibold text-brand-primary hover:text-blue-300"
                    data-i18n="features_free_cta">
                     Start free quick check
diff --git a/partials/landing/main/hero.php b/partials/landing/main/hero.php
index 47767a4..549331a 100644
--- a/partials/landing/main/hero.php
+++ b/partials/landing/main/hero.php
@@ -1,3 +1,4 @@
+<?php $primaryFakecheckUrl = app_primary_url() . '/fakecheck/'; ?>
 <section id="hero" class="hero-section relative overflow-hidden">
     <div class="relative px-4 sm:px-6 lg:px-8">
         <div class="section-shell hero-shell items-center">
@@ -15,7 +16,7 @@
 
             <!-- CTAs -->
             <div class="flex flex-col sm:flex-row gap-3 sm:gap-4">
-                <a href="https://usbcheck.it/fakecheck/"
+                <a href="<?= htmlspecialchars($primaryFakecheckUrl) ?>"
                    class="inline-flex items-center justify-center rounded-full bg-brand-primary px-6 py-3 text-sm font-semibold text-brand-bg shadow-soft hover:bg-blue-400 transition-colors"
                    data-i18n="cta_quick">
                     Start free quick check
@@ -109,7 +110,7 @@
                     </div>
                 </div>
 
-                <a href="https://usbcheck.it/fakecheck/"
+                <a href="<?= htmlspecialchars($primaryFakecheckUrl) ?>"
                    class="block text-center rounded-full bg-brand-primary px-4 py-2.5 text-sm font-semibold text-brand-bg hover:bg-blue-400 transition-colors"
                    data-i18n="quick_cta">
                     Go to free quick check
diff --git a/partials/landing/main/how.php b/partials/landing/main/how.php
index 5e3e66b..bfdf1b3 100644
--- a/partials/landing/main/how.php
+++ b/partials/landing/main/how.php
@@ -18,7 +18,7 @@
                     <div>
                         <h3 class="font-semibold text-brand-text" data-i18n="how_step1_title">Browser-Test starten</h3>
                         <p data-i18n="how_step1_text">
-                            Du öffnest den Schnelltest unter <strong>usbcheck.it/fakecheck/</strong>, wählst deinen USB-Stick bzw. einen Ordner darauf aus und definierst, wie viel Daten getestet werden sollen.
+                            Du öffnest den Schnelltest unter <strong><?= htmlspecialchars(app_primary_url()) ?>/fakecheck/</strong>, wählst deinen USB-Stick bzw. einen Ordner darauf aus und definierst, wie viel Daten getestet werden sollen.
                         </p>
                     </div>
                 </li>
diff --git a/partials/structure/footer.php b/partials/structure/footer.php
index c4dd8d3..fa37088 100644
--- a/partials/structure/footer.php
+++ b/partials/structure/footer.php
@@ -3,7 +3,7 @@
 ?>
 <footer class="border-t border-brand-border/70">
     <div class="mx-auto max-w-6xl px-4 sm:px-6 lg:px-8 py-6 flex flex-col sm:flex-row items-center justify-between gap-4 text-xs text-brand-muted">
-        <p>© <?= date('Y') ?> usbcheck.it</p>
+        <p>© <?= date('Y') ?> <?= htmlspecialchars(app_primary_domain()) ?></p>
 
         <div class="flex items-center gap-4">
             <a href="/impressum.php" class="hover:text-brand-primary transition-colors" data-i18n="footer_imprint"></a>
diff --git a/partials/structure/header.php b/partials/structure/header.php
index 37c7614..2099f65 100644
--- a/partials/structure/header.php
+++ b/partials/structure/header.php
@@ -3,7 +3,7 @@
 
 // Aktuelle Domain + Protokoll
 $scheme  = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off') ? 'https' : 'http';
-$host    = $_SERVER['HTTP_HOST'] ?? 'usbcheck.it';
+$host    = $_SERVER['HTTP_HOST'] ?? app_primary_domain();
 $baseUrl = $scheme . '://' . $host;
 
 // Wenn $navAnchors NICHT gesetzt ist → leeres Array
@@ -52,12 +52,12 @@ if ($isLoggedIn) {
         <div class="flex items-center gap-3">
             <a href="/?lang=<?= htmlspecialchars($lang ?? 'de') ?>" class="flex items-center gap-3">
                 <img src="<?= $baseUrl ?>/assets/img/logo_slogan.png"
-                     alt="usbcheck.it Logo"
+                     alt="<?= htmlspecialchars(app_primary_domain()) ?> Logo"
                      class="h-9 w-auto">
 
                 <div class="hidden sm:flex flex-col leading-tight">
                     <span class="font-heading font-bold text-sm uppercase tracking-[0.18em] text-brand-muted">
-                        usbcheck.it
+                        <?= htmlspecialchars(app_primary_domain()) ?>
                     </span>
                     <span class="text-xs text-brand-muted" data-i18n="header_slogan">
                         Test USB drives
diff --git a/partials/structure/layout_start.php b/partials/structure/layout_start.php
index 24e032e..dc629cd 100644
--- a/partials/structure/layout_start.php
+++ b/partials/structure/layout_start.php
@@ -13,7 +13,7 @@ if (!isset($lang) || !in_array($lang, ['de', 'en', 'it', 'fr'], true)) {
 }
 
 if (!isset($pageTitle) || !is_string($pageTitle) || $pageTitle === '') {
-    $pageTitle = 'usbcheck.it';
+    $pageTitle = app_primary_domain();
 }
 
 if (!isset($pageDescription) || !is_string($pageDescription)) {
@@ -110,6 +110,12 @@ foreach ($GLOBALS['page_header_scripts'] as $script) {
     <script>
         window.currentLang  = "<?= htmlspecialchars($lang) ?>";
         window.assetsBase   = "/assets"; // falls du das noch nicht hast
+        window.appDomains   = <?= json_encode([
+            'primaryDomain'        => app_primary_domain(),
+            'primaryUrl'           => app_primary_url(),
+            'fakecheckDomain'      => app_fakecheck_domain(),
+            'fakecheckUrl'         => app_fakecheck_url(),
+        ], JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE) ?>;
     </script>
     <!-- Eigenes CSS -->
     <link rel="stylesheet" href="/assets/css/main.css">
diff --git a/partials/structure/matomo.php b/partials/structure/matomo.php
index 9108449..b8fdb20 100644
--- a/partials/structure/matomo.php
+++ b/partials/structure/matomo.php
@@ -1,10 +1,19 @@
 <?php if (!defined('MATOMO_SITE_ID')) return; ?>
 <?php if (!defined('MATOMO_ENABLED') || !MATOMO_ENABLED) return; ?>
+<?php
+$matomoDomains = [];
+$primaryDomain   = app_primary_domain();
+$fakecheckDomain = app_fakecheck_domain();
+
+$matomoDomains[] = '*.' . $primaryDomain;
+$matomoDomains[] = '*.' . $fakecheckDomain;
+$matomoDomains[] = '*.' . $primaryDomain . '/fakecheck';
+?>
 
 <!-- Matomo -->
 <script>
     var _paq = window._paq = window._paq || [];
-    _paq.push(["setDomains", ["*.usbcheck.it","*.ismyusbfake.com","*.usbcheck.it/fakecheck"]]);
+    _paq.push(["setDomains", <?= json_encode($matomoDomains, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE) ?>]);
     _paq.push(['trackPageView']);
     _paq.push(['enableLinkTracking']);
 
diff --git a/public/_errors/404.php b/public/_errors/404.php
index 99ecf60..05f39a5 100644
--- a/public/_errors/404.php
+++ b/public/_errors/404.php
@@ -8,7 +8,7 @@ $lang = $_GET['lang'] ?? 'de';
 $lang = in_array($lang, ['de','en','it','fr']) ? $lang : 'de';
 
 // Titel & Description
-$pageTitle       = 'Seite nicht gefunden – usbcheck.it';
+$pageTitle       = 'Seite nicht gefunden – ' . app_primary_domain();
 $pageDescription = 'Die angeforderte Seite wurde nicht gefunden.';
 $navAnchors      = []; // Navigation auf der 404 deaktiviert
 
diff --git a/public/assets/i18n/de.json b/public/assets/i18n/de.json
index f3aa0ef..322cfe4 100644
--- a/public/assets/i18n/de.json
+++ b/public/assets/i18n/de.json
@@ -11,7 +11,7 @@
   },
 
   "brand": {
-    "brand_wordmark": "usbcheck.it",
+    "brand_wordmark": "{{primary_domain}}",
     "brand_subtitle": "USB-Sticks auf Fakes testen"
   },
 
@@ -56,7 +56,7 @@
     "how_title": "Schnelltest im Browser, Pro-Modus mit Tiefenanalyse.",
     "how_intro": "USBCheck wurde entwickelt, um zwei Welten zu verbinden: einen einfachen Schnelltest für alle und einen tiefgehenden Pro-Modus für Power-User, Techniker und Admins. Der Schnelltest läuft direkt im Browser, ohne Installation. Für den Pro-Modus wird ein kleines Helfer-Tool verwendet, das auf Wunsch F3- / badblocks-ähnliche Tests ausführt und damit Kapazitäts-Fakes sicher enttarnt.",
     "how_step1_title": "Browser-Test starten",
-    "how_step1_text": "Du öffnest den Schnelltest unter <strong>usbcheck.it/fakecheck/</strong>, wählst deinen USB-Stick bzw. einen Ordner darauf aus und definierst, wie viel Daten getestet werden sollen.",
+    "how_step1_text": "Du öffnest den Schnelltest unter <strong>{{primary_url}}/fakecheck/</strong>, wählst deinen USB-Stick bzw. einen Ordner darauf aus und definierst, wie viel Daten getestet werden sollen.",
     "how_step2_title": "Schreib-, Lese- und Integritätsprüfung",
     "how_step2_text": "Der Browser erstellt Testdateien, misst Schreib- und Leserate und vergleicht Hash-Werte, um Datenfehler zu erkennen – alles lokal und ohne Übertragung deiner Inhalte.",
     "how_step3_title": "Optional: Pro-Modus für Vollscan",
@@ -135,7 +135,7 @@
   "footer": {
     "footer_imprint": "Impressum",
     "footer_privacy": "Datenschutz",
-    "footer_copy": "© {year} usbcheck.it. Alle Rechte vorbehalten."
+    "footer_copy": "© {year} {{primary_domain}}. Alle Rechte vorbehalten."
   },
   "fake": {
   "fake_hero_kicker": "FakeCheck – Browser-Modus",
diff --git a/public/assets/i18n/en.json b/public/assets/i18n/en.json
index 16daede..7a5d17e 100644
--- a/public/assets/i18n/en.json
+++ b/public/assets/i18n/en.json
@@ -11,7 +11,7 @@
   },
 
   "brand": {
-    "brand_wordmark": "usbcheck.it",
+    "brand_wordmark": "{{primary_domain}}",
     "brand_subtitle": "Test USB drives for fakes"
   },
 
@@ -56,7 +56,7 @@
     "how_title": "Browser quick test, Pro mode for deep analysis.",
     "how_intro": "USBCheck was built to combine two worlds: a simple quick test for everyone and a deep Pro mode for power users, technicians and admins. The quick test runs directly in your browser, no install required. The Pro mode uses a small helper tool that can run F3 / badblocks-like checks and reliably detect capacity fakes.",
     "how_step1_title": "Start browser test",
-    "how_step1_text": "Open the quick check at <strong>usbcheck.itcom/fakecheck/</strong>, select your USB drive or a folder on it and define how much data should be tested.",
+    "how_step1_text": "Open the quick check at <strong>{{primary_url}}/fakecheck/</strong>, select your USB drive or a folder on it and define how much data should be tested.",
     "how_step2_title": "Write, read &amp; integrity check",
     "how_step2_text": "The browser creates test files, measures write and read speed and compares hash values to detect data errors – all locally, without uploading your content.",
     "how_step3_title": "Optional: Pro mode full scan",
@@ -135,7 +135,7 @@
   "footer": {
     "footer_imprint": "Imprint",
     "footer_privacy": "Privacy policy",
-    "footer_copy": "© {year} usbcheck.it. All rights reserved."
+    "footer_copy": "© {year} {{primary_domain}}. All rights reserved."
   },
 "fake": {
   "fake_hero_kicker": "FakeCheck – Browser mode",
diff --git a/public/assets/i18n/fr.json b/public/assets/i18n/fr.json
index d094f26..4f6b726 100644
--- a/public/assets/i18n/fr.json
+++ b/public/assets/i18n/fr.json
@@ -11,7 +11,7 @@
   },
 
   "brand": {
-    "brand_wordmark": "usbcheck.it",
+    "brand_wordmark": "{{primary_domain}}",
     "brand_subtitle": "Tester les clés USB contrefaites"
   },
 
@@ -56,7 +56,7 @@
     "how_title": "Test rapide dans le navigateur, mode Pro pour une analyse approfondie.",
     "how_intro": "USBCheck a été conçu pour réunir deux mondes : un test rapide simple pour tous et un mode Pro avancé pour les utilisateurs experts, techniciens et administrateurs. Le test rapide s’exécute dans le navigateur sans installation. Le mode Pro utilise un petit outil pouvant effectuer des tests similaires à F3/badblocks pour détecter les capacités truquées.",
     "how_step1_title": "Démarrer le test dans le navigateur",
-    "how_step1_text": "Ouvrez le test rapide sur <strong>usbcheck.it/fakecheck/</strong>, sélectionnez votre clé ou un dossier puis définissez la quantité de données à tester.",
+    "how_step1_text": "Ouvrez le test rapide sur <strong>{{primary_url}}/fakecheck/</strong>, sélectionnez votre clé ou un dossier puis définissez la quantité de données à tester.",
     "how_step2_title": "Écriture, lecture et contrôle d’intégrité",
     "how_step2_text": "Le navigateur crée des fichiers de test, mesure les vitesses d’écriture/lecture et compare les hash pour détecter les erreurs – le tout localement, sans envoyer vos contenus.",
     "how_step3_title": "Optionnel : mode Pro avec analyse complète",
@@ -135,7 +135,7 @@
   "footer": {
     "footer_imprint": "Mentions légales",
     "footer_privacy": "Confidentialité",
-    "footer_copy": "© {year} usbcheck.it. Tous droits réservés."
+    "footer_copy": "© {year} {{primary_domain}}. Tous droits réservés."
   },
   "fake": {
   "fake_hero_kicker": "FakeCheck – Mode navigateur",
diff --git a/public/assets/i18n/it.json b/public/assets/i18n/it.json
index 9cce283..e28f9d5 100644
--- a/public/assets/i18n/it.json
+++ b/public/assets/i18n/it.json
@@ -11,7 +11,7 @@
   },
 
   "brand": {
-    "brand_wordmark": "usbcheck.it",
+    "brand_wordmark": "{{primary_domain}}",
     "brand_subtitle": "Controlla le chiavette USB contraffatte"
   },
 
@@ -56,7 +56,7 @@
     "how_title": "Test rapido nel browser, modalità Pro per analisi profonde.",
     "how_intro": "USBCheck è pensato per unire due mondi: un test rapido semplice per tutti e una modalità Pro avanzata per utenti esperti, tecnici e amministratori. Il test rapido gira nel browser senza installazione. La modalità Pro usa un piccolo tool che può eseguire test simili a F3/badblocks e individuare capacità contraffatte.",
     "how_step1_title": "Avvia il test nel browser",
-    "how_step1_text": "Apri il test rapido su <strong>usbcheck.it/fakecheck/</strong>, seleziona la chiavetta o una cartella e definisci quanta quantità di dati deve essere testata.",
+    "how_step1_text": "Apri il test rapido su <strong>{{primary_url}}/fakecheck/</strong>, seleziona la chiavetta o una cartella e definisci quanta quantità di dati deve essere testata.",
     "how_step2_title": "Scrittura, lettura e controllo integrità",
     "how_step2_text": "Il browser crea file di test, misura la velocità di scrittura/lettura e confronta gli hash per individuare errori – tutto in locale, senza caricare i tuoi contenuti.",
     "how_step3_title": "Opzionale: modalità Pro con scansione completa",
@@ -135,7 +135,7 @@
   "footer": {
     "footer_imprint": "Note legali",
     "footer_privacy": "Privacy",
-    "footer_copy": "© {year} usbcheck.it. Tutti i diritti riservati."
+    "footer_copy": "© {year} {{primary_domain}}. Tutti i diritti riservati."
   },
   "fake": {
   "fake_hero_kicker": "FakeCheck – Modalità browser",
diff --git a/public/assets/js/lang.js b/public/assets/js/lang.js
index d40db0d..66b8e7e 100644
--- a/public/assets/js/lang.js
+++ b/public/assets/js/lang.js
@@ -29,6 +29,23 @@
     return target;
   }
 
+  function applyDomainPlaceholders(text) {
+    if (typeof text !== "string") return text;
+
+    const domains = window.appDomains || {};
+    const replacements = {
+      "{{primary_domain}}": domains.primaryDomain || "usbcheck.it",
+      "{{primary_url}}": domains.primaryUrl || ("https://" + (domains.primaryDomain || "usbcheck.it")),
+      "{{fakecheck_domain}}": domains.fakecheckDomain || "ismyusbfake.com",
+      "{{fakecheck_url}}": domains.fakecheckUrl || ("https://" + (domains.fakecheckDomain || "ismyusbfake.com")),
+    };
+
+    return Object.keys(replacements).reduce((acc, token) => {
+      const value = replacements[token];
+      return acc.split(token).join(value);
+    }, text);
+  }
+
   function getInitialLang() {
     const urlParams = new URLSearchParams(window.location.search);
     const paramLang = urlParams.get("lang");
@@ -72,6 +89,8 @@
         value = value.replace("{year}", year);
       }
 
+      value = applyDomainPlaceholders(value);
+
       node.innerHTML = value;
     });
   }
diff --git a/public/index.php b/public/index.php
index 6cff852..ba034e2 100644
--- a/public/index.php
+++ b/public/index.php
@@ -10,7 +10,7 @@ $lang = in_array($lang, ['de','en','it','fr']) ? $lang : 'en';
 $userInitials = null;
 
 // Seitentitel & Description für das Layout
-$pageTitle = 'usbcheck.it – Test USB-Sticks';
+$pageTitle = app_primary_domain() . ' – Test USB-Sticks';
 $pageDescription = 'Prüfe deine USB-Sticks auf Geschwindigkeit, Integrität und mögliche Fakes – direkt im Browser.';
 $navAnchors = [
     [ 'href' => '#how',      'key' => 'nav_how' ],
@@ -29,4 +29,4 @@ tpl('features', 'landing', 'main');
 tpl('security', 'landing', 'main'); 
 tpl('faq',      'landing', 'main'); 
 
-tpl('layout_end');                  // structure/footer.phpW
\ No newline at end of file
+tpl('layout_end');                  // structure/footer.phpW
diff --git a/public/landingpage/dashboard/index.php b/public/landingpage/dashboard/index.php
index fc7b59a..d015903 100644
--- a/public/landingpage/dashboard/index.php
+++ b/public/landingpage/dashboard/index.php
@@ -26,7 +26,7 @@ if (!$isLoggedIn) {
 }
 
 // Seitentitel & Description
-$pageTitle       = 'Dashboard – usbcheck.it';
+$pageTitle       = 'Dashboard – ' . app_primary_domain();
 $pageDescription = 'Verwalte deine USB-Tests, Geräte und Pro-Einstellungen in deinem USBCheck-Dashboard.';
 
 // Navigation kannst du für das Dashboard leer lassen oder anpassen
diff --git a/public/landingpage/fakecheck/index.php b/public/landingpage/fakecheck/index.php
index 43720ec..0cbc31f 100644
--- a/public/landingpage/fakecheck/index.php
+++ b/public/landingpage/fakecheck/index.php
@@ -11,21 +11,20 @@ $lang = in_array($lang, ['de','en','it','fr']) ? $lang : 'en';
 $userInitials = null;
 
 // Seitentitel & Description (SEO)
-$pageTitle = 'usbcheck.it – Fake USB Check';
+$pageTitle = app_primary_domain() . ' – Fake USB Check';
 $pageDescription = 'Fake USB-Sticks erkennen: Browser-basierter Schnelltest für Kapazität, Schreib-/Lesegeschwindigkeit und Datenintegrität – ohne Installation.';
 
 // Header-Navigation: auf dieser Seite KEINE Onepager-Anchors anzeigen
 $navAnchors = [];
 
-// Basis-URL für Reports etc. (staging/prod/dev/ismyusbfake-kompatibel)
 $scheme  = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off') ? 'https' : 'http';
-$host    = $_SERVER['HTTP_HOST'] ?? 'usbcheck.it';
+$host    = $_SERVER['HTTP_HOST'] ?? app_primary_domain();
 $baseUrl = $scheme . '://' . $host;
 $lang = $_GET['lang'] ?? 'en';
 $lang = in_array($lang, ['de','en','it','fr']) ? $lang : 'en';
 
 // Basis-URL für Reports
-$baseUrl = "https://usbcheck.it";
+$baseUrl = app_primary_url();
 
 if (function_exists('tpl_add_script')) {
     tpl_add_script('/assets/js/fakecheck.js', 'footer', true, false, '', null);
diff --git a/public/landingpage/login/index.php b/public/landingpage/login/index.php
index 26146f7..9fce82d 100644
--- a/public/landingpage/login/index.php
+++ b/public/landingpage/login/index.php
@@ -9,7 +9,7 @@ $lang = in_array($lang, ['de','en','it','fr']) ? $lang : 'en';
 // später: echte Session
 $userInitials = null;
 
-$pageTitle = 'Login – usbcheck.it';
+$pageTitle = 'Login – ' . app_primary_domain();
 $pageDescription = 'Melde dich bei USBCheck an, um Tests zu speichern, Pro-Modus zu nutzen und mehrere Geräte zu verwalten.';
 
 // Navigation ausblenden:
diff --git a/src/functions.php b/src/functions.php
index d122d26..daa965e 100644
--- a/src/functions.php
+++ b/src/functions.php
@@ -4,6 +4,28 @@ $GLOBALS['page_header_scripts'] = $GLOBALS['page_header_scripts'] ?? [];
 $GLOBALS['page_footer_scripts'] = $GLOBALS['page_footer_scripts'] ?? [];
 $GLOBALS['page_styles']         = $GLOBALS['page_styles'] ?? [];
 
+function app_primary_domain(): string
+{
+    return defined('APP_DOMAIN_PRIMARY') ? APP_DOMAIN_PRIMARY : 'usbcheck.it';
+}
+
+function app_primary_url(): string
+{
+    $url = defined('APP_URL_PRIMARY') ? APP_URL_PRIMARY : 'https://usbcheck.it';
+    return rtrim($url, '/');
+}
+
+function app_fakecheck_domain(): string
+{
+    return defined('APP_DOMAIN_FAKECHECK') ? APP_DOMAIN_FAKECHECK : 'ismyusbfake.com';
+}
+
+function app_fakecheck_url(): string
+{
+    $url = defined('APP_URL_FAKECHECK') ? APP_URL_FAKECHECK : 'https://ismyusbfake.com';
+    return rtrim($url, '/');
+}
+
 /**
  * Script registrieren
  *