diff --git a/app/Http/Controllers/API/SyncController.php b/app/Http/Controllers/API/SyncController.php
index f362391..74c543c 100644
--- a/app/Http/Controllers/API/SyncController.php
+++ b/app/Http/Controllers/API/SyncController.php
@@ -5,7 +5,6 @@ namespace App\Http\Controllers\API;
 use App\Http\Controllers\Controller;
 use App\Http\Requests\Api\Contacts\DestroyContactsRequest;
 use App\Http\Requests\Api\Contacts\UpsertContactsRequest;
-use App\Http\Requests\Api\SendFlyerRequest;
 use App\Http\Resources\ApiResponseResource;
 use App\Http\Resources\AppUserResource;
 use App\Http\Resources\ContactResource;
@@ -37,10 +36,8 @@ class SyncController extends Controller
      */
     public function getUsers(): \App\Http\Resources\ApiResponseResource
     {
-        /** @var string $tenantKey */
-        $tenantKey = request()->tenant;
-        $users     = AppUserResource::collection(
-            AppUser::query()->where('tenant_id', $tenantKey)->where('status', 1)->get()
+        $users = AppUserResource::collection(
+            AppUser::query()->where('tenant_id', \tenant()->getKey())->where('status', 1)->get()
         )->toArray(request());
         return new ApiResponseResource("OK", $users);
     }
@@ -55,11 +52,9 @@ class SyncController extends Controller
      */
     public function getContacts(AppUser $app_user): \Illuminate\Http\Resources\Json\AnonymousResourceCollection
     {
-        /** @var string $tenantKey */
-        $tenantKey = request()->tenant;
         return ContactResource::collection(
-            Contact::query()->whereHas('appUser', function (Builder $q) use ($tenantKey, $app_user) {
-                $q->where('tenant_id', $tenantKey)->where('id', $app_user->id);
+            Contact::query()->whereHas('appUser', function (Builder $q) use ($app_user) {
+                $q->where('tenant_id', \tenant()->getKey())->where('id', $app_user->id);
             })->get()
         );
     }
@@ -75,13 +70,10 @@ class SyncController extends Controller
         UpsertContactsRequest $request,
         AppUser $app_user
     ): \Illuminate\Http\JsonResponse {
-        /** @var string $tenantKey */
-        $tenantKey = $request->tenant;
-
         /** @var \Illuminate\Support\Collection<string,integer> */
         $formularies  = Formulary::query()->pluck('slug')->flip();
-        $contactQuery = Contact::query()->whereHas('appUser', function (Builder $q) use ($tenantKey, $app_user) {
-            $q->where('tenant_id', $tenantKey)->where('id', $app_user->getKey());
+        $contactQuery = Contact::query()->whereHas('appUser', function (Builder $q) use ($app_user) {
+            $q->where('tenant_id', \tenant()->getKey())->where('id', $app_user->getKey());
         });
 
         \collect($request->contacts)->each(
@@ -129,11 +121,9 @@ class SyncController extends Controller
      */
     public function destroyContacts(DestroyContactsRequest $request, AppUser $app_user): \Illuminate\Http\JsonResponse
     {
-        /** @var string $tenantKey */
-        $tenantKey = $request->tenant;
-        Contact::query()->whereIn('id', $request->contactUuidList)
-            ->whereHas('appUser', function (Builder $q) use ($tenantKey, $app_user) {
-                $q->where('tenant_id', $tenantKey)->where('id', $app_user->id);
+        Contact::query()->whereIn('id', $request->validated()['contactUuidList'])
+            ->whereHas('appUser', function (Builder $q) use ($app_user) {
+                $q->where('tenant_id', \tenant()->getKey())->where('id', $app_user->id);
             })->delete();
 
         // * HTTP 200 is ok.
@@ -147,10 +137,8 @@ class SyncController extends Controller
      */
     public function getDirectories(): \Illuminate\Http\Resources\Json\AnonymousResourceCollection
     {
-        /** @var string $tenantKey */
-        $tenantKey = request()->tenant;
         return DirectoryResource::collection(
-            Directory::query()->where('tenant_id', $tenantKey)->orderBy('order')->get()
+            Directory::query()->where('tenant_id', \tenant()->getKey())->orderBy('order')->get()
         );
     }
 
@@ -159,10 +147,8 @@ class SyncController extends Controller
      */
     public function getDocuments(): \Illuminate\Http\Resources\Json\AnonymousResourceCollection
     {
-        /** @var string $tenantKey */
-        $tenantKey = request()->tenant;
         return DocumentResource::collection(
-            Document::query()->where('tenant_id', $tenantKey)->where('status', 1)->get()
+            Document::query()->where('tenant_id', \tenant()->getKey())->where('status', 1)->get()
         );
     }
 
@@ -172,12 +158,16 @@ class SyncController extends Controller
      */
     public function getVersion(Request $request): array
     {
-        /** @var string $tenantKey */
-        $tenantKey    = $request->tenant;
         $app_uuid     = $request->app_uuid;
         $app_version  = $request->app_version;
-        $version      = Setting::query()->where('tenant_id', $tenantKey)->where('key', 'version')->value('value');
-        $ShowIsActive = Setting::query()->where('tenant_id', $tenantKey)->where('key', 'ShowIsActive')->value('value');
+        $version      = Setting::query()
+            ->where('tenant_id', \tenant()->getKey())
+            ->where('key', 'version')
+            ->value('value');
+        $ShowIsActive = Setting::query()
+            ->where('tenant_id', \tenant()->getKey())
+            ->where('key', 'ShowIsActive')
+            ->value('value');
 
         try {
             $client       = new \GuzzleHttp\Client();
@@ -205,10 +195,8 @@ class SyncController extends Controller
      */
     public function getFormularies(): \Illuminate\Http\Resources\Json\AnonymousResourceCollection
     {
-        /** @var string $tenantKey */
-        $tenantKey = request()->tenant;
         return FormularyResource::collection(
-            Formulary::query()->where('tenant_id', $tenantKey)->orderBy('order')->get()
+            Formulary::query()->where('tenant_id', \tenant()->getKey())->orderBy('order')->get()
         );
     }
 
@@ -216,11 +204,9 @@ class SyncController extends Controller
      * @param \App\Http\Requests\Api\SendFlyerRequest $request
      * @return string
      */
-    public function sendFlyer(SendFlyerRequest $request): string
+    public function sendFlyer(Request $request): string
     {
-        /** @var string $tenantKey */
-        $tenantKey   = $request->tenant;
-        $requestData = $request->validated()['emails'];
+        $requestData = $request['emails'];
         $email       = $requestData['email'];
         $subject     = $requestData['subject'];
         $message     = $requestData['message'];
@@ -234,12 +220,12 @@ class SyncController extends Controller
         $noExists  = [];
         foreach ($docs as $doc) {
             $exists = Storage::disk('public')
-                ->exists(sprintf('docs/%s/%s.%s', $tenantKey, $doc['uuid'], $doc['type']));
+                ->exists(sprintf('docs/%s/%s.%s', \tenant()->getKey(), $doc['uuid'], $doc['type']));
             if ($exists) {
                 array_push($attach, URL::temporarySignedRoute(
                     'bo.docs.download',
                     now()->addDays(30),
-                    ['tenant' => $tenantKey, 'uuid' => $doc['uuid']]
+                    ['tenant' => \tenant()->getKey(), 'uuid' => $doc['uuid']]
                 ));
                 array_push($filesName, $doc['title']);
             } else {
@@ -247,7 +233,7 @@ class SyncController extends Controller
             }
         }
         if (count($noExists) === 0) {
-            $message = new SendFlyer([
+            $mail = new SendFlyer([
                 'body'      => $message,
                 'from'      => $user->email,
                 'fromName'  => $user->firstname . ' ' . $user->lastname,
@@ -258,7 +244,7 @@ class SyncController extends Controller
 
             Mail::to($email)->cc($user->email)->queue($message);
         } else {
-            $message = new SendFlyerFailed([
+            $mail = new SendFlyerFailed([
                 'email'     => $email,
                 'message'   => $message,
                 'subject'   => $subject,
@@ -266,7 +252,7 @@ class SyncController extends Controller
                 'noExists'  => $noExists
             ]);
 
-            Mail::to($user->email)->queue($message);
+            Mail::to($user->email)->queue($mail);
         } //end if
         return 'OK';
     }
diff --git a/app/Http/Requests/Api/Contacts/DestroyContactsRequest.php b/app/Http/Requests/Api/Contacts/DestroyContactsRequest.php
index d5a80bd..4a21b6a 100644
--- a/app/Http/Requests/Api/Contacts/DestroyContactsRequest.php
+++ b/app/Http/Requests/Api/Contacts/DestroyContactsRequest.php
@@ -6,6 +6,18 @@ use Illuminate\Foundation\Http\FormRequest;
 
 class DestroyContactsRequest extends FormRequest
 {
+    /**
+     * Prepare the data for validation.
+     *
+     * @return void
+     */
+    protected function prepareForValidation(): void
+    {
+        $this->merge([
+            'contactUuidList' => \collect($this->contactUuidList)->filter()->all(),
+        ]);
+    }
+
     /**
      * Get the validation rules that apply to the request.
      *
diff --git a/app/Http/Requests/Api/Contacts/UpsertContactsRequest.php b/app/Http/Requests/Api/Contacts/UpsertContactsRequest.php
index b6d21b9..a5ffcfb 100644
--- a/app/Http/Requests/Api/Contacts/UpsertContactsRequest.php
+++ b/app/Http/Requests/Api/Contacts/UpsertContactsRequest.php
@@ -55,11 +55,11 @@ class UpsertContactsRequest extends FormRequest
             'contacts'             => 'present|array',
             'contacts.*'           => 'array',
             'contacts.*.id'        => 'uuid',
-            'contacts.*.lastname'  => 'nullable|string|between:3,255',
-            'contacts.*.firstname' => 'nullable|string|between:3,255',
+            'contacts.*.lastname'  => 'nullable|string|between:1,255',
+            'contacts.*.firstname' => 'nullable|string|between:1,255',
             // * Dot not validate email here (soft validate), if it does not pass, app will be blocked.
-            'contacts.*.email'     => 'required|string|between:3,255',
-            'contacts.*.phone'     => 'nullable|string|between:3,255',
+            'contacts.*.email'     => 'required|string|between:1,255',
+            'contacts.*.phone'     => 'nullable|string|between:1,255',
             'contacts.*.timestamp' => 'required|date',
 
             // * DATA
diff --git a/app/Http/Requests/Api/SendFlyerRequest.php b/app/Http/Requests/Api/SendFlyerRequest.php
index 1e17640..3e21bea 100644
--- a/app/Http/Requests/Api/SendFlyerRequest.php
+++ b/app/Http/Requests/Api/SendFlyerRequest.php
@@ -5,6 +5,7 @@ namespace App\Http\Requests\Api;
 use Illuminate\Foundation\Http\FormRequest;
 use Illuminate\Validation\Rule;
 
+/** FIXME: currently not used but will be in the future. */
 class SendFlyerRequest extends FormRequest
 {
     /**
diff --git a/app/Models/Formulary.php b/app/Models/Formulary.php
index e7b2f0e..244fc04 100644
--- a/app/Models/Formulary.php
+++ b/app/Models/Formulary.php
@@ -53,6 +53,7 @@ class Formulary extends Model
     protected $casts = [
         'required'    => 'bool',
         'is_visible'  => 'bool',
+        // FIXME: update the json cast if api crash.
         'placeholder' => 'json',
         'details'     => 'json',
         'type'        => InputTypeEnum::class,
diff --git a/app/Providers/RouteServiceProvider.php b/app/Providers/RouteServiceProvider.php
index aaba0ea..0eaa94a 100644
--- a/app/Providers/RouteServiceProvider.php
+++ b/app/Providers/RouteServiceProvider.php
@@ -41,8 +41,7 @@ class RouteServiceProvider extends ServiceProvider
                 ->namespace($this->namespace)
                 ->group(base_path('routes/web-bo.php'));
 
-            Route::prefix('api')
-                ->middleware('api')
+            Route::middleware('api')
                 ->namespace($this->namespace)
                 ->group(base_path('routes/api.php'));
         });
diff --git a/routes/api.php b/routes/api.php
index 67fd7df..66cdad6 100644
--- a/routes/api.php
+++ b/routes/api.php
@@ -4,6 +4,7 @@ use App\Http\Controllers\API\AppController;
 use App\Http\Controllers\API\SettingsController;
 use App\Http\Controllers\API\SyncController;
 use Illuminate\Support\Facades\Route;
+use Stancl\Tenancy\Middleware\InitializeTenancyByPath;
 
 /*
     |--------------------------------------------------------------------------
@@ -16,7 +17,10 @@ use Illuminate\Support\Facades\Route;
     |
 */
 
-Route::middleware('api.token')
+Route::middleware([
+    InitializeTenancyByPath::class,
+    'api.token',
+])->prefix('{tenant}/api')
     ->name('api.')
     ->group(function () {
         Route::get('settings', [SettingsController::class, 'get'])->name('settings.index');