diff --git a/.cloudbase-sites/preview.json b/.cloudbase-sites/preview.json
index 9535b25..0d41aa0 100644
--- a/.cloudbase-sites/preview.json
+++ b/.cloudbase-sites/preview.json
@@ -1,12 +1,12 @@
 {
-  "pid": 98343,
-  "port": 17174,
+  "pid": 24641,
+  "port": 17175,
   "host": "0.0.0.0",
   "base": "/",
   "framework": "vite-react",
-  "command": "/Users/jiaunun/.nvm/versions/node/v24.15.0/bin/node /Users/jiaunun/Desktop/36-character-flower/node_modules/vite/bin/vite.js --host 0.0.0.0 --port 17174 --strictPort --base /",
-  "internalUrl": "http://127.0.0.1:17174/",
-  "logPath": "/Users/jiaunun/Desktop/36-character-flower/.cloudbase-sites/logs/preview-1784093877629.log",
+  "command": "/Users/jiaunun/.nvm/versions/node/v24.15.0/bin/node /Users/jiaunun/Desktop/36-character-flower/node_modules/vite/bin/vite.js --host 0.0.0.0 --port 17175 --strictPort --base /",
+  "internalUrl": "http://127.0.0.1:17175/",
+  "logPath": "/Users/jiaunun/Desktop/36-character-flower/.cloudbase-sites/logs/preview-1784622161040.log",
   "cwd": "/Users/jiaunun/Desktop/36-character-flower",
-  "startedAt": "2026-07-15T05:37:58.655Z"
+  "startedAt": "2026-07-21T08:22:42.070Z"
 }
diff --git a/src/api/auth-api.ts b/src/api/auth-api.ts
index edc0d42..1ec9473 100644
--- a/src/api/auth-api.ts
+++ b/src/api/auth-api.ts
@@ -145,16 +145,18 @@ export async function logoutWithPassword(
 export async function registerWithPassword(
   payload: RegisterPayload,
 ): Promise<AuthSessionInput> {
+  const inviteCode = payload.inviteCode?.trim() ?? ''
+  const registerRequest: RegisterRequestDto = {
+    captcha: payload.captcha,
+    device_id: getAuthDeviceId(),
+    password: payload.password,
+    username: payload.mobile,
+    ...(inviteCode ? { invite_code: inviteCode } : {}),
+  }
   const response = await api.post<AuthSessionDto, RegisterRequestDto>(
     AUTH_ENDPOINTS.register,
     {
-      json: {
-        captcha: payload.captcha,
-        device_id: getAuthDeviceId(),
-        invite_code: payload.inviteCode,
-        password: payload.password,
-        username: payload.mobile,
-      },
+      json: registerRequest,
     },
   )
 
diff --git a/src/schema/auth-schema.ts b/src/schema/auth-schema.ts
index a19fcf0..5f985da 100644
--- a/src/schema/auth-schema.ts
+++ b/src/schema/auth-schema.ts
@@ -35,7 +35,6 @@ export const registerFormSchema = z
     inviteCode: z
       .string()
       .trim()
-      .min(1, 'auth.validation.inviteCode.required')
       .max(INVITE_CODE_MAX_LENGTH, 'auth.validation.inviteCode.max'),
     password: passwordSchema,
     mobile: usernameSchema,
diff --git a/src/type/auth.type.ts b/src/type/auth.type.ts
index 895d0ab..1be2be3 100644
--- a/src/type/auth.type.ts
+++ b/src/type/auth.type.ts
@@ -120,7 +120,7 @@ export interface LogoutRequestDto {
 export interface RegisterRequestDto {
   captcha: string
   device_id?: string
-  invite_code: string
+  invite_code?: string
   password: string
   username: string
 }
@@ -148,7 +148,7 @@ export type LogoutPayload = LoginPayload
 
 export interface RegisterPayload {
   captcha: string
-  inviteCode: string
+  inviteCode?: string
   mobile: string
   password: string
 }