diff --git a/app/Http/Controllers/UserController.php b/app/Http/Controllers/UserController.php
index beb373e..8827472 100644
--- a/app/Http/Controllers/UserController.php
+++ b/app/Http/Controllers/UserController.php
@@ -210,14 +210,22 @@ public function register(Request $request)
             'method' => 'string|in:code,link|nullable',
             'birthday' => 'date|nullable',
             'gender' => ['integer', 'nullable', Rule::in(User::GENDERS)],
+            'referrer_code' => ['string', 'nullable', 'exists:users,referral_code'],
         ]);
-    
+
           $method = $data['method'] ?? 'link';
             unset($data['method']);
 
             // Extract and remove package_name
             $packageNameValue = $data['package_name'];
             unset($data['package_name']);
+
+            // Resolve referrer code (کد معرف) to the referring user
+            $referrerCode = $data['referrer_code'] ?? null;
+            unset($data['referrer_code']);
+            if ($referrerCode && $referrer = User::where('referral_code', $referrerCode)->first()) {
+                $data['referred_by'] = $referrer->id;
+            }
     
         if (isset($data['mobile'])) {
             $data['mobile'] = MobileNumberHelper::formatMobile($data['mobile']);
diff --git a/app/Models/User.php b/app/Models/User.php
index ed3c9cb..60aa670 100644
--- a/app/Models/User.php
+++ b/app/Models/User.php
@@ -3,6 +3,7 @@
 namespace App\Models;
 
 use App\Traits\HasUuid;
+use App\Traits\HasReferralCode;
 use DateTimeInterface;
 use EloquentFilter\Filterable;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
@@ -13,7 +14,7 @@
 use Illuminate\Support\Str;
 class User extends Authenticatable
 {
-    use HasApiTokens, HasFactory, Notifiable, HasUuid, Filterable;
+    use HasApiTokens, HasFactory, Notifiable, HasUuid, HasReferralCode, Filterable;
 
     const GENDERS = [
         'male' => 1,
@@ -61,6 +62,16 @@ public function otpTokens()
         return $this->hasMany(OtpTokens::class);
     }
 
+    public function referrer()
+    {
+        return $this->belongsTo(User::class, 'referred_by');
+    }
+
+    public function referrals()
+    {
+        return $this->hasMany(User::class, 'referred_by');
+    }
+
     public function transactions()
     {
         return $this->hasMany(Transaction::class);
diff --git a/app/Traits/HasReferralCode.php b/app/Traits/HasReferralCode.php
new file mode 100644
index 0000000..24b42fa
--- /dev/null
+++ b/app/Traits/HasReferralCode.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace App\Traits;
+
+use Illuminate\Support\Str;
+
+trait HasReferralCode
+{
+    public static function bootHasReferralCode(): void
+    {
+        static::creating(function ($model) {
+            if (!$model->referral_code) {
+                $model->referral_code = static::generateReferralCode();
+            }
+        });
+    }
+
+    public static function generateReferralCode(): string
+    {
+        do {
+            $code = strtoupper(Str::random(8));
+        } while (static::where('referral_code', $code)->exists());
+
+        return $code;
+    }
+}
diff --git a/database/migrations/2026_06_06_000000_add_referral_code_and_referred_by_to_users_table.php b/database/migrations/2026_06_06_000000_add_referral_code_and_referred_by_to_users_table.php
new file mode 100644
index 0000000..44fe0af
--- /dev/null
+++ b/database/migrations/2026_06_06_000000_add_referral_code_and_referred_by_to_users_table.php
@@ -0,0 +1,49 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Schema;
+use Illuminate\Support\Str;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::table('users', function (Blueprint $table) {
+            if (!Schema::hasColumn('users', 'referral_code')) {
+                $table->string('referral_code', 12)->nullable()->unique()->after('uuid');
+            }
+            if (!Schema::hasColumn('users', 'referred_by')) {
+                $table->foreignId('referred_by')->nullable()->after('referral_code')
+                    ->constrained('users')->nullOnDelete();
+            }
+        });
+
+        // Backfill a unique referral code for existing users
+        $existing = DB::table('users')->whereNull('referral_code')->pluck('id');
+        $used = DB::table('users')->whereNotNull('referral_code')->pluck('referral_code')->all();
+        $used = array_flip($used);
+
+        foreach ($existing as $id) {
+            do {
+                $code = strtoupper(Str::random(8));
+            } while (isset($used[$code]));
+            $used[$code] = true;
+            DB::table('users')->where('id', $id)->update(['referral_code' => $code]);
+        }
+    }
+
+    public function down(): void
+    {
+        Schema::table('users', function (Blueprint $table) {
+            if (Schema::hasColumn('users', 'referred_by')) {
+                $table->dropForeign(['referred_by']);
+                $table->dropColumn('referred_by');
+            }
+            if (Schema::hasColumn('users', 'referral_code')) {
+                $table->dropColumn('referral_code');
+            }
+        });
+    }
+};