diff --git a/backend/src/index.js b/backend/src/index.js
index 616366f..5ce5845 100644
--- a/backend/src/index.js
+++ b/backend/src/index.js
@@ -28,6 +28,16 @@ fs.readdirSync(toolsDir, { withFileTypes: true })
 
 // ── React-Frontend ausliefern ─────────────────────────────────────────────────
 const PUBLIC = path.join(__dirname, '../public');
+
+// Service Worker braucht diesen Header damit er auf '/' zugreifen darf
+app.use((req, res, next) => {
+  if (req.path === '/sw.js') {
+    res.setHeader('Service-Worker-Allowed', '/');
+    res.setHeader('Cache-Control', 'no-cache');
+  }
+  next();
+});
+
 app.use(express.static(PUBLIC));
 app.get('*', (_req, res) => res.sendFile(path.join(PUBLIC, 'index.html')));