diff --git a/package.json b/package.json
index f29737989..4674e963f 100644
--- a/package.json
+++ b/package.json
@@ -10,7 +10,7 @@
     "dev": "pnpm -r prepack && pnpm start:dev",
     "dev:cloud": "pnpm -r prepack && pnpm start:dev:cloud",
     "start:dev": "pnpm -r --parallel --filter=!@logto/integration-tests --filter=!@logto/cloud dev",
-    "start:dev:cloud": "CONSOLE_PUBLIC_URL=/ pnpm -r --parallel --filter=!@logto/integration-tests dev",
+    "start:dev:cloud": "CONSOLE_PUBLIC_URL=/ IS_CLOUD=1 pnpm -r --parallel --filter=!@logto/integration-tests dev",
     "start": "cd packages/core && NODE_ENV=production node .",
     "start:cloud": "cd packages/cloud && NODE_ENV=production node .",
     "cli": "logto",
diff --git a/packages/cloud/src/middleware/with-spa.ts b/packages/cloud/src/middleware/with-spa.ts
index e54b003b1..69d6c6231 100644
--- a/packages/cloud/src/middleware/with-spa.ts
+++ b/packages/cloud/src/middleware/with-spa.ts
@@ -73,6 +73,7 @@ export default function withSpa<InputContext extends RequestContext>({
         'Content-Type': mime.lookup(pathLike),
         'Last-Modified': stat.mtime.toUTCString(),
         'Cache-Control': `max-age=${maxAge}`,
+        ETag: `"${stat.size.toString(16)}-${stat.mtimeMs.toString(16)}"`,
       },
       stream: createReadStream(pathLike),
       status: 200,
@@ -80,12 +81,6 @@ export default function withSpa<InputContext extends RequestContext>({
   };
 }
 
-const normalize = (pathLike: string) => {
-  const value = path.normalize(pathLike);
-
-  return value.length > 1 && value.endsWith('/') ? value.slice(0, -1) : value;
-};
-
 const tryStat = async (pathLike: string) => {
   try {
     const stat = await fs.stat(pathLike);