diff --git a/README.md b/README.md
index 5ed8bd4..3f5bd50 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 a minimal, smooth file transfer service with 10-minute auto-deletion.
 
-> **Note**: This repository uses a placeholder backend URL (`https://YOUR_BACKEND_URL.trycloudflare.com`) so no private endpoints are exposed publicly.
+> **Backend API**: The official backend is powered by a permanent Cloudflare Tunnel at `https://katdrop-api.oiupoyt.space`.
 
 ## features
 
diff --git a/public/js/app.js b/public/js/app.js
index 790e1ed..c105c2b 100644
--- a/public/js/app.js
+++ b/public/js/app.js
@@ -21,7 +21,7 @@
   let selectedFiles = [];
 
   // API Configuration (configurable via URL param ?api=... or localStorage)
-  const DEFAULT_REMOTE_API = 'https://lucia-hang-jackson-suggests.trycloudflare.com';
+  const DEFAULT_REMOTE_API = 'https://katdrop-api.oiupoyt.space';
   const urlParams = new URLSearchParams(window.location.search);
   if (urlParams.has('api')) {
     const customApi = urlParams.get('api').replace(/\/+$/, '');