diff --git a/src/Core/Constants/IntegrationSources.php b/src/Core/Constants/IntegrationSources.php
new file mode 100644
index 0000000..f593dcd
--- /dev/null
+++ b/src/Core/Constants/IntegrationSources.php
@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Core\Constants;
+
+final class IntegrationSources
+{
+    public const ALLEGRO = 'allegro';
+    public const SHOPPRO = 'shoppro';
+    public const APACZKA = 'apaczka';
+    public const INPOST  = 'inpost';
+}
diff --git a/src/Core/Constants/RedirectPaths.php b/src/Core/Constants/RedirectPaths.php
new file mode 100644
index 0000000..53c4262
--- /dev/null
+++ b/src/Core/Constants/RedirectPaths.php
@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Core\Constants;
+
+final class RedirectPaths
+{
+    public const ALLEGRO_INTEGRATION         = '/settings/integrations/allegro';
+    public const ALLEGRO_SETTINGS_TAB        = '/settings/integrations/allegro?tab=settings';
+    public const ALLEGRO_STATUSES_TAB        = '/settings/integrations/allegro?tab=statuses';
+    public const ALLEGRO_DELIVERY_TAB        = '/settings/integrations/allegro?tab=delivery';
+    public const ALLEGRO_OAUTH_CALLBACK_PATH = '/settings/integrations/allegro/oauth/callback';
+
+    public const SHOPPRO_INTEGRATION = '/settings/integrations/shoppro';
+}
diff --git a/src/Modules/Settings/AllegroIntegrationController.php b/src/Modules/Settings/AllegroIntegrationController.php
index 3029492..44cce5c 100644
--- a/src/Modules/Settings/AllegroIntegrationController.php
+++ b/src/Modules/Settings/AllegroIntegrationController.php
@@ -13,8 +13,10 @@ use App\Modules\Auth\AuthService;
 use App\Modules\Cron\CronRepository;
 use DateInterval;
 use DateTimeImmutable;
+use App\Core\Constants\IntegrationSources;
+use App\Core\Constants\RedirectPaths;
+use App\Core\Exceptions\IntegrationConfigException;
 use RuntimeException;
-use AppCoreExceptionsIntegrationConfigException;
 use Throwable;
 
 final class AllegroIntegrationController
@@ -99,8 +101,8 @@ final class AllegroIntegrationController
             'errorMessage' => (string) Flash::get('settings_error', ''),
             'successMessage' => (string) Flash::get('settings_success', ''),
             'warningMessage' => (string) Flash::get('settings_warning', ''),
-            'deliveryMappings' => $this->deliveryMappings !== null ? $this->deliveryMappings->listMappings('allegro', 0) : [],
-            'orderDeliveryMethods' => $this->deliveryMappings !== null ? $this->deliveryMappings->getDistinctOrderDeliveryMethods('allegro', 0) : [],
+            'deliveryMappings' => $this->deliveryMappings !== null ? $this->deliveryMappings->listMappings(IntegrationSources::ALLEGRO, 0) : [],
+            'orderDeliveryMethods' => $this->deliveryMappings !== null ? $this->deliveryMappings->getDistinctOrderDeliveryMethods(IntegrationSources::ALLEGRO, 0) : [],
             'allegroDeliveryServices' => $deliveryServicesData[0],
             'apaczkaDeliveryServices' => $deliveryServicesData[1],
             'allegroDeliveryServicesError' => $deliveryServicesData[2],
@@ -115,7 +117,7 @@ final class AllegroIntegrationController
 
     public function save(Request $request): Response
     {
-        $redirectTo = $this->resolveRedirectPath((string) $request->input('return_to', '/settings/integrations/allegro'));
+        $redirectTo = $this->resolveRedirectPath((string) $request->input('return_to', RedirectPaths::ALLEGRO_INTEGRATION));
         if (!Csrf::validate((string) $request->input('_token', ''))) {
             Flash::set('settings_error', $this->translator->get('auth.errors.csrf_expired'));
             return Response::redirect($redirectTo);
@@ -178,7 +180,7 @@ final class AllegroIntegrationController
         $intervalMinutes = max(1, min(1440, $intervalMinutesRaw));
         if ($intervalMinutesRaw !== $intervalMinutes) {
             Flash::set('settings_error', $this->translator->get('settings.allegro.validation.orders_import_interval_invalid'));
-            return Response::redirect('/settings/integrations/allegro?tab=settings');
+            return Response::redirect(RedirectPaths::ALLEGRO_SETTINGS_TAB);
         }
 
         $statusSyncDirection = trim((string) $request->input(
@@ -187,7 +189,7 @@ final class AllegroIntegrationController
         ));
         if (!in_array($statusSyncDirection, $this->allowedStatusSyncDirections(), true)) {
             Flash::set('settings_error', $this->translator->get('settings.allegro.validation.status_sync_direction_invalid'));
-            return Response::redirect('/settings/integrations/allegro?tab=settings');
+            return Response::redirect(RedirectPaths::ALLEGRO_SETTINGS_TAB);
         }
 
         $statusSyncIntervalRaw = (int) $request->input(
@@ -197,7 +199,7 @@ final class AllegroIntegrationController
         $statusSyncInterval = max(1, min(1440, $statusSyncIntervalRaw));
         if ($statusSyncIntervalRaw !== $statusSyncInterval) {
             Flash::set('settings_error', $this->translator->get('settings.allegro.validation.status_sync_interval_invalid'));
-            return Response::redirect('/settings/integrations/allegro?tab=settings');
+            return Response::redirect(RedirectPaths::ALLEGRO_SETTINGS_TAB);
         }
 
         $existing = $this->findImportSchedule();
@@ -243,7 +245,7 @@ final class AllegroIntegrationController
             );
         }
 
-        return Response::redirect('/settings/integrations/allegro?tab=settings');
+        return Response::redirect(RedirectPaths::ALLEGRO_SETTINGS_TAB);
     }
 
     public function saveStatusMapping(Request $request): Response
@@ -259,17 +261,17 @@ final class AllegroIntegrationController
 
         if ($allegroStatusCode === '') {
             Flash::set('settings_error', $this->translator->get('settings.allegro.statuses.flash.allegro_status_required'));
-            return Response::redirect('/settings/integrations/allegro?tab=statuses');
+            return Response::redirect(RedirectPaths::ALLEGRO_STATUSES_TAB);
         }
 
         if ($orderproStatusCode === '') {
             Flash::set('settings_error', $this->translator->get('settings.allegro.statuses.flash.orderpro_status_required'));
-            return Response::redirect('/settings/integrations/allegro?tab=statuses');
+            return Response::redirect(RedirectPaths::ALLEGRO_STATUSES_TAB);
         }
 
         if (!$this->orderStatusCodeExists($orderproStatusCode)) {
             Flash::set('settings_error', $this->translator->get('settings.allegro.statuses.flash.orderpro_status_not_found'));
-            return Response::redirect('/settings/integrations/allegro?tab=statuses');
+            return Response::redirect(RedirectPaths::ALLEGRO_STATUSES_TAB);
         }
 
         try {
@@ -279,7 +281,7 @@ final class AllegroIntegrationController
             Flash::set('settings_error', $this->translator->get('settings.allegro.statuses.flash.save_failed') . ' ' . $exception->getMessage());
         }
 
-        return Response::redirect('/settings/integrations/allegro?tab=statuses');
+        return Response::redirect(RedirectPaths::ALLEGRO_STATUSES_TAB);
     }
 
     public function saveStatusMappingsBulk(Request $request): Response
@@ -294,7 +296,7 @@ final class AllegroIntegrationController
         $selectedOrderproCodes = $request->input('orderpro_status_code', []);
         if (!is_array($codes) || !is_array($names) || !is_array($selectedOrderproCodes)) {
             Flash::set('settings_error', $this->translator->get('settings.allegro.statuses.flash.save_failed'));
-            return Response::redirect('/settings/integrations/allegro?tab=statuses');
+            return Response::redirect(RedirectPaths::ALLEGRO_STATUSES_TAB);
         }
 
         try {
@@ -310,7 +312,7 @@ final class AllegroIntegrationController
 
                 if ($orderproStatusCode !== null && !$this->orderStatusCodeExists($orderproStatusCode)) {
                     Flash::set('settings_error', $this->translator->get('settings.allegro.statuses.flash.orderpro_status_not_found'));
-                    return Response::redirect('/settings/integrations/allegro?tab=statuses');
+                    return Response::redirect(RedirectPaths::ALLEGRO_STATUSES_TAB);
                 }
 
                 $this->statusMappings->upsertMapping(
@@ -325,7 +327,7 @@ final class AllegroIntegrationController
             Flash::set('settings_error', $this->translator->get('settings.allegro.statuses.flash.save_failed') . ' ' . $exception->getMessage());
         }
 
-        return Response::redirect('/settings/integrations/allegro?tab=statuses');
+        return Response::redirect(RedirectPaths::ALLEGRO_STATUSES_TAB);
     }
 
     public function deleteStatusMapping(Request $request): Response
@@ -338,7 +340,7 @@ final class AllegroIntegrationController
         $mappingId = max(0, (int) $request->input('mapping_id', 0));
         if ($mappingId <= 0) {
             Flash::set('settings_error', $this->translator->get('settings.allegro.statuses.flash.mapping_not_found'));
-            return Response::redirect('/settings/integrations/allegro?tab=statuses');
+            return Response::redirect(RedirectPaths::ALLEGRO_STATUSES_TAB);
         }
 
         try {
@@ -348,7 +350,7 @@ final class AllegroIntegrationController
             Flash::set('settings_error', $this->translator->get('settings.allegro.statuses.flash.delete_failed') . ' ' . $exception->getMessage());
         }
 
-        return Response::redirect('/settings/integrations/allegro?tab=statuses');
+        return Response::redirect(RedirectPaths::ALLEGRO_STATUSES_TAB);
     }
 
     public function syncStatusesFromAllegro(Request $request): Response
@@ -371,7 +373,7 @@ final class AllegroIntegrationController
             Flash::set('settings_error', $this->translator->get('settings.allegro.statuses.flash.sync_failed') . ' ' . $exception->getMessage());
         }
 
-        return Response::redirect('/settings/integrations/allegro?tab=statuses');
+        return Response::redirect(RedirectPaths::ALLEGRO_STATUSES_TAB);
     }
 
     public function startOAuth(Request $request): Response
@@ -397,7 +399,7 @@ final class AllegroIntegrationController
             return Response::redirect($url);
         } catch (Throwable $exception) {
             Flash::set('settings_error', $exception->getMessage());
-            return Response::redirect('/settings/integrations/allegro');
+            return Response::redirect(RedirectPaths::ALLEGRO_INTEGRATION);
         }
     }
 
@@ -411,7 +413,7 @@ final class AllegroIntegrationController
                 $message .= ' ' . $description;
             }
             Flash::set('settings_error', $message);
-            return Response::redirect('/settings/integrations/allegro');
+            return Response::redirect(RedirectPaths::ALLEGRO_INTEGRATION);
         }
 
         $state = trim((string) $request->input('state', ''));
@@ -419,13 +421,13 @@ final class AllegroIntegrationController
         unset($_SESSION[self::OAUTH_STATE_SESSION_KEY]);
         if ($state === '' || $expectedState === '' || !hash_equals($expectedState, $state)) {
             Flash::set('settings_error', $this->translator->get('settings.allegro.flash.oauth_state_invalid'));
-            return Response::redirect('/settings/integrations/allegro');
+            return Response::redirect(RedirectPaths::ALLEGRO_INTEGRATION);
         }
 
         $authorizationCode = trim((string) $request->input('code', ''));
         if ($authorizationCode === '') {
             Flash::set('settings_error', $this->translator->get('settings.allegro.flash.oauth_code_missing'));
-            return Response::redirect('/settings/integrations/allegro');
+            return Response::redirect(RedirectPaths::ALLEGRO_INTEGRATION);
         }
 
         try {
@@ -458,7 +460,7 @@ final class AllegroIntegrationController
             Flash::set('settings_error', $this->translator->get('settings.allegro.flash.oauth_failed') . ' ' . $exception->getMessage());
         }
 
-        return Response::redirect('/settings/integrations/allegro');
+        return Response::redirect(RedirectPaths::ALLEGRO_INTEGRATION);
     }
 
     public function importSingleOrder(Request $request): Response
@@ -471,7 +473,7 @@ final class AllegroIntegrationController
         $checkoutFormId = trim((string) $request->input('checkout_form_id', ''));
         if ($checkoutFormId === '') {
             Flash::set('settings_error', $this->translator->get('settings.allegro.flash.checkout_form_id_required'));
-            return Response::redirect('/settings/integrations/allegro');
+            return Response::redirect(RedirectPaths::ALLEGRO_INTEGRATION);
         }
 
         try {
@@ -504,7 +506,7 @@ final class AllegroIntegrationController
             );
         }
 
-        return Response::redirect('/settings/integrations/allegro');
+        return Response::redirect(RedirectPaths::ALLEGRO_INTEGRATION);
     }
 
     public function saveDeliveryMappings(Request $request): Response
@@ -516,7 +518,7 @@ final class AllegroIntegrationController
 
         if ($this->deliveryMappings === null) {
             Flash::set('settings_error', 'Delivery mappings not configured.');
-            return Response::redirect('/settings/integrations/allegro?tab=delivery');
+            return Response::redirect(RedirectPaths::ALLEGRO_DELIVERY_TAB);
         }
 
         $orderMethods = (array) $request->input('order_delivery_method', []);
@@ -549,13 +551,13 @@ final class AllegroIntegrationController
         }
 
         try {
-            $this->deliveryMappings->saveMappings('allegro', 0, $mappings);
+            $this->deliveryMappings->saveMappings(IntegrationSources::ALLEGRO, 0, $mappings);
             Flash::set('settings_success', $this->translator->get('settings.allegro.delivery.flash.saved'));
         } catch (Throwable $exception) {
             Flash::set('settings_error', $this->translator->get('settings.allegro.delivery.flash.save_failed') . ' ' . $exception->getMessage());
         }
 
-        return Response::redirect('/settings/integrations/allegro?tab=delivery');
+        return Response::redirect(RedirectPaths::ALLEGRO_DELIVERY_TAB);
     }
 
     /**
@@ -669,7 +671,7 @@ final class AllegroIntegrationController
             $base = 'http://localhost:8000';
         }
 
-        return rtrim($base, '/') . '/settings/integrations/allegro/oauth/callback';
+        return rtrim($base, '/') . RedirectPaths::ALLEGRO_OAUTH_CALLBACK_PATH;
     }
 
     private function validateCsrf(string $token): ?Response
@@ -679,17 +681,17 @@ final class AllegroIntegrationController
         }
 
         Flash::set('settings_error', $this->translator->get('auth.errors.csrf_expired'));
-        return Response::redirect('/settings/integrations/allegro');
+        return Response::redirect(RedirectPaths::ALLEGRO_INTEGRATION);
     }
 
     private function resolveRedirectPath(string $candidate): string
     {
         $value = trim($candidate);
         if ($value === '') {
-            return '/settings/integrations/allegro';
+            return RedirectPaths::ALLEGRO_INTEGRATION;
         }
         if (!str_starts_with($value, '/settings/integrations')) {
-            return '/settings/integrations/allegro';
+            return RedirectPaths::ALLEGRO_INTEGRATION;
         }
 
         return $value;
diff --git a/src/Modules/Settings/AllegroOrderImportService.php b/src/Modules/Settings/AllegroOrderImportService.php
index 3f3faad..09b9394 100644
--- a/src/Modules/Settings/AllegroOrderImportService.php
+++ b/src/Modules/Settings/AllegroOrderImportService.php
@@ -6,8 +6,8 @@ namespace App\Modules\Settings;
 use App\Core\Support\StringHelper;
 use App\Modules\Orders\OrderImportRepository;
 use App\Modules\Orders\OrdersRepository;
-use RuntimeException;
-use AppCoreExceptionsAllegroApiException;
+use App\Core\Constants\IntegrationSources;
+use App\Core\Exceptions\AllegroApiException;
 use Throwable;
 
 final class AllegroOrderImportService
@@ -68,7 +68,7 @@ final class AllegroOrderImportService
                 'import',
                 $summary,
                 [
-                    'source' => 'allegro',
+                    'source' => IntegrationSources::ALLEGRO,
                     'source_order_id' => trim($checkoutFormId),
                     'created' => $wasCreated,
                 ],
@@ -155,7 +155,7 @@ final class AllegroOrderImportService
 
         $order = [
             'integration_id' => $this->integrationRepository->getActiveIntegrationId(),
-            'source' => 'allegro',
+            'source' => IntegrationSources::ALLEGRO,
             'source_order_id' => $checkoutFormId,
             'external_order_id' => $checkoutFormId,
             'external_platform_id' => trim((string) ($payload['marketplace']['id'] ?? 'allegro-pl')),
diff --git a/src/Modules/Settings/AllegroStatusSyncService.php b/src/Modules/Settings/AllegroStatusSyncService.php
index 729e107..d993f38 100644
--- a/src/Modules/Settings/AllegroStatusSyncService.php
+++ b/src/Modules/Settings/AllegroStatusSyncService.php
@@ -3,6 +3,7 @@ declare(strict_types=1);
 
 namespace App\Modules\Settings;
 
+use App\Core\Constants\IntegrationSources;
 use App\Modules\Cron\CronRepository;
 use PDO;
 use Throwable;
@@ -94,7 +95,7 @@ final class AllegroStatusSyncService
                 ORDER BY source_updated_at DESC
                 LIMIT ' . self::MAX_ORDERS_PER_RUN
             );
-            $params = array_merge(['allegro'], self::FINAL_STATUSES);
+            $params = array_merge([IntegrationSources::ALLEGRO], self::FINAL_STATUSES);
             $statement->execute($params);
 
             return $statement->fetchAll(PDO::FETCH_ASSOC) ?: [];
diff --git a/src/Modules/Settings/ShopproIntegrationsController.php b/src/Modules/Settings/ShopproIntegrationsController.php
index ec346b9..6e283ee 100644
--- a/src/Modules/Settings/ShopproIntegrationsController.php
+++ b/src/Modules/Settings/ShopproIntegrationsController.php
@@ -13,6 +13,8 @@ use App\Modules\Auth\AuthService;
 use App\Modules\Cron\CronRepository;
 use DateInterval;
 use DateTimeImmutable;
+use App\Core\Constants\IntegrationSources;
+use App\Core\Constants\RedirectPaths;
 use RuntimeException;
 use Throwable;
 
@@ -72,10 +74,10 @@ final class ShopproIntegrationsController
             ? $this->loadDeliveryServices()
             : [[], [], ''];
         $deliveryMappings = $selectedIntegration !== null
-            ? $this->deliveryMappings->listMappings('shoppro', (int) ($selectedIntegration['id'] ?? 0))
+            ? $this->deliveryMappings->listMappings(IntegrationSources::SHOPPRO, (int) ($selectedIntegration['id'] ?? 0))
             : [];
         $orderDeliveryMethods = $selectedIntegration !== null
-            ? $this->deliveryMappings->getDistinctOrderDeliveryMethods('shoppro', (int) ($selectedIntegration['id'] ?? 0))
+            ? $this->deliveryMappings->getDistinctOrderDeliveryMethods(IntegrationSources::SHOPPRO, (int) ($selectedIntegration['id'] ?? 0))
             : [];
 
         $html = $this->template->render('settings/shoppro', [
@@ -113,7 +115,7 @@ final class ShopproIntegrationsController
     {
         $integrationId = max(0, (int) $request->input('integration_id', 0));
         $tab = $this->resolveTab((string) $request->input('tab', 'integration'));
-        $redirectBase = '/settings/integrations/shoppro';
+        $redirectBase = RedirectPaths::SHOPPRO_INTEGRATION;
         $redirectTo = $this->buildRedirectUrl($integrationId, $tab);
 
         if (!Csrf::validate((string) $request->input('_token', ''))) {
@@ -203,7 +205,7 @@ final class ShopproIntegrationsController
     {
         $integrationId = max(0, (int) $request->input('integration_id', 0));
         $tab = $this->resolveTab((string) $request->input('tab', 'integration'));
-        $redirectBase = '/settings/integrations/shoppro';
+        $redirectBase = RedirectPaths::SHOPPRO_INTEGRATION;
         $redirectTo = $this->buildRedirectUrl($integrationId, $tab);
 
         if (!Csrf::validate((string) $request->input('_token', ''))) {
@@ -382,7 +384,7 @@ final class ShopproIntegrationsController
         }
 
         try {
-            $this->deliveryMappings->saveMappings('shoppro', $integrationId, $mappings);
+            $this->deliveryMappings->saveMappings(IntegrationSources::SHOPPRO, $integrationId, $mappings);
             Flash::set('settings_success', $this->translator->get('settings.integrations.delivery.flash.saved'));
         } catch (Throwable $exception) {
             Flash::set(
@@ -585,7 +587,7 @@ final class ShopproIntegrationsController
 
     private function buildRedirectUrl(int $integrationId, string $tab): string
     {
-        $url = '/settings/integrations/shoppro';
+        $url = RedirectPaths::SHOPPRO_INTEGRATION;
         $query = [];
         if ($integrationId > 0) {
             $query['id'] = (string) $integrationId;
diff --git a/src/Modules/Settings/ShopproOrdersSyncService.php b/src/Modules/Settings/ShopproOrdersSyncService.php
index d36a004..8039624 100644
--- a/src/Modules/Settings/ShopproOrdersSyncService.php
+++ b/src/Modules/Settings/ShopproOrdersSyncService.php
@@ -3,6 +3,7 @@ declare(strict_types=1);
 
 namespace App\Modules\Settings;
 
+use App\Core\Constants\IntegrationSources;
 use App\Core\Support\StringHelper;
 use App\Modules\Orders\OrderImportRepository;
 use App\Modules\Orders\OrdersRepository;
@@ -420,10 +421,10 @@ final class ShopproOrdersSyncService
 
         $order = [
             'integration_id' => $integrationId,
-            'source' => 'shoppro',
+            'source' => IntegrationSources::SHOPPRO,
             'source_order_id' => $sourceOrderId,
             'external_order_id' => $sourceOrderId,
-            'external_platform_id' => 'shoppro',
+            'external_platform_id' => IntegrationSources::SHOPPRO,
             'external_platform_account_id' => null,
             'external_status_id' => $effectiveStatus,
             'external_payment_type_id' => StringHelper::nullableString((string) $this->readPath($payload, ['payment_method', 'payment.method', 'payments.method'])),
diff --git a/src/Modules/Settings/ShopproPaymentStatusSyncService.php b/src/Modules/Settings/ShopproPaymentStatusSyncService.php
index 98510c3..43ef42c 100644
--- a/src/Modules/Settings/ShopproPaymentStatusSyncService.php
+++ b/src/Modules/Settings/ShopproPaymentStatusSyncService.php
@@ -3,6 +3,7 @@ declare(strict_types=1);
 
 namespace App\Modules\Settings;
 
+use App\Core\Constants\IntegrationSources;
 use App\Core\Support\StringHelper;
 use App\Modules\Orders\OrdersRepository;
 use PDO;
@@ -147,7 +148,7 @@ final class ShopproPaymentStatusSyncService
             '(payment_status IS NULL OR payment_status <> :paid_status)',
         ];
         $params = [
-            'source' => 'shoppro',
+            'source' => IntegrationSources::SHOPPRO,
             'integration_id' => $integrationId,
             'paid_status' => self::PAID_STATUS,
         ];