diff --git a/src/app/Http/Controllers/API/SignupController.php b/src/app/Http/Controllers/API/SignupController.php
--- a/src/app/Http/Controllers/API/SignupController.php
+++ b/src/app/Http/Controllers/API/SignupController.php
@@ -230,16 +230,20 @@
      */
     public function signupValidate(Request $request)
     {
+        $rules = [
+            'login' => 'required|min:2',
+            'password' => ['required', 'confirmed', new Password()],
+            'domain' => 'required',
+            'voucher' => 'max:32',
+        ];
+
+        // Direct signup by token
+        if ($request->token) {
+            $rules['token'] = ['required', 'string', new SignupToken()];
+        }
+
         // Validate input
-        $v = Validator::make(
-            $request->all(),
-            [
-                'login' => 'required|min:2',
-                'password' => ['required', 'confirmed', new Password()],
-                'domain' => 'required',
-                'voucher' => 'max:32',
-            ]
-        );
+        $v = Validator::make($request->all(), $rules);
 
         if ($v->fails()) {
             return response()->json(['status' => 'error', 'errors' => $v->errors()], 422);
@@ -247,8 +251,16 @@
 
         $settings = [];
 
-        // Plan parameter is required/allowed in mandate mode
-        if (!empty($request->plan) && empty($request->code) && empty($request->invitation)) {
+        if (!empty($request->token)) {
+            // Token mode, check the plan
+            $plan = $request->plan ? Plan::withEnvTenantContext()->where('title', $request->plan)->first() : null;
+
+            if (!$plan || $plan->mode != Plan::MODE_TOKEN) {
+                $msg = self::trans('validation.exists', ['attribute' => 'plan']);
+                return response()->json(['status' => 'error', 'errors' => ['plan' => $msg]], 422);
+            }
+        } elseif (!empty($request->plan) && empty($request->code) && empty($request->invitation)) {
+            // Plan parameter is required/allowed in mandate mode
             $plan = Plan::withEnvTenantContext()->where('title', $request->plan)->first();
 
             if (!$plan || $plan->mode != Plan::MODE_MANDATE) {
diff --git a/src/tests/Feature/Controller/SignupTest.php b/src/tests/Feature/Controller/SignupTest.php
--- a/src/tests/Feature/Controller/SignupTest.php
+++ b/src/tests/Feature/Controller/SignupTest.php
@@ -64,6 +64,8 @@
         IP4Net::where('net_number', inet_pton('127.0.0.0'))->delete();
         VatRate::query()->delete();
 
+        @unlink(storage_path('signup-tokens.txt'));
+
         parent::tearDown();
     }
 
@@ -910,6 +912,68 @@
         // TODO: Test POST params validation
     }
 
+    /**
+     * Test signup via token
+     */
+    public function testSignupToken(): void
+    {
+        Queue::fake();
+
+        $plan = Plan::create([
+                'title' => 'test',
+                'name' => 'Test Account',
+                'description' => 'Test',
+                'free_months' => 1,
+                'discount_qty' => 0,
+                'discount_rate' => 0,
+                'mode' => Plan::MODE_TOKEN,
+        ]);
+
+        $post = [
+            'plan' => $plan->title,
+            'token' => 'abc',
+            'login' => 'test-inv',
+            'domain' => 'kolabnow.com',
+            'password' => 'testtest',
+            'password_confirmation' => 'testtest',
+        ];
+
+        // Test invalid token
+        $response = $this->post('/api/auth/signup', $post);
+        $response->assertStatus(422);
+        $json = $response->json();
+
+        $this->assertSame('error', $json['status']);
+        $this->assertSame(['token' => ["The signup token is invalid."]], $json['errors']);
+
+        file_put_contents(storage_path('signup-tokens.txt'), "abc\n");
+
+        // Test invalid plan (existing plan with another mode)
+        $post['plan'] = 'individual';
+        $response = $this->post('/api/auth/signup', $post);
+        $response->assertStatus(422);
+        $json = $response->json();
+
+        $this->assertSame('error', $json['status']);
+        $this->assertSame(['plan' => "The selected plan is invalid."], $json['errors']);
+
+        // Test valid input
+        $post['plan'] = $plan->title;
+        $response = $this->post('/api/auth/signup', $post);
+        $response->assertStatus(200);
+
+        $json = $response->json();
+
+        $this->assertSame('success', $json['status']);
+        $this->assertSame('test-inv@kolabnow.com', $json['email']);
+
+        // Check if the user has been created
+        $user = User::where('email', 'test-inv@kolabnow.com')->first();
+
+        $this->assertNotEmpty($user);
+        $this->assertSame($plan->id, $user->getSetting('plan_id'));
+    }
+
     /**
      * Test signup validation (POST /signup/validate)
      */