diff --git a/apps/web/app/layout.tsx b/apps/web/app/layout.tsx
index 5abef0e..278dcbb 100644
--- a/apps/web/app/layout.tsx
+++ b/apps/web/app/layout.tsx
@@ -1,6 +1,7 @@
 import type { Metadata } from 'next';
 import { GeistSans } from 'geist/font/sans';
 import { GeistMono } from 'geist/font/mono';
+import { SiteBanner } from '@/components/site-banner';
 import './globals.css';
 
 export const metadata: Metadata = {
@@ -13,7 +14,10 @@ export const metadata: Metadata = {
 export default function RootLayout({ children }: { children: React.ReactNode }) {
   return (
     <html lang="en" className={`${GeistSans.variable} ${GeistMono.variable}`} suppressHydrationWarning>
-      <body>{children}</body>
+      <body>
+        <SiteBanner />
+        {children}
+      </body>
     </html>
   );
 }
diff --git a/apps/web/components/site-banner.tsx b/apps/web/components/site-banner.tsx
new file mode 100644
index 0000000..1cdc62c
--- /dev/null
+++ b/apps/web/components/site-banner.tsx
@@ -0,0 +1,15 @@
+// Temporary pre-launch notice. Remove this component and its import in
+// app/layout.tsx once the service is open for production use.
+export function SiteBanner() {
+  return (
+    <div
+      role="status"
+      className="border-b border-[#4f46e5] bg-[--color-accent] px-4 py-2 text-center text-[12.5px] font-medium leading-snug text-white"
+    >
+      <span className="font-semibold uppercase tracking-wide">Preview</span>
+      <span className="px-1.5 opacity-60">·</span>
+      BuildMyMCPServer is not yet open for production use — sign-ups, server
+      generation and billing are still being finalised, and data may be reset.
+    </div>
+  );
+}
