diff --git a/app/Backend/config/passport-config.js b/app/Backend/config/passport-config.js
index 26d2f29..8861f21 100644
--- a/app/Backend/config/passport-config.js
+++ b/app/Backend/config/passport-config.js
@@ -14,14 +14,20 @@ const getCleanEnvVar = (varName) => {
 // Get and validate Google OAuth credentials
 const clientID = getCleanEnvVar('GOOGLE_CLIENT_ID');
 const clientSecret = getCleanEnvVar('GOOGLE_CLIENT_SECRET');
-const callbackURL = getCleanEnvVar('GOOGLE_CALLBACK_URL') || 'http://localhost:5000/auth/google/callback';
+
+// Determine callback URL
+let defaultCallback = 'http://localhost:3000/auth/google/callback';
+if (process.env.PORT) {
+  defaultCallback = `http://localhost:${process.env.PORT}/auth/google/callback`;
+}
+const callbackURL = getCleanEnvVar('GOOGLE_CALLBACK_URL') || defaultCallback;
 
 if (!clientID || !clientSecret) {
     console.error('\n❌ Missing required Google OAuth environment variables!\n');
     console.error('Add these to your .env file (WITHOUT quotes):');
     console.error('  GOOGLE_CLIENT_ID=your_client_id_here');
     console.error('  GOOGLE_CLIENT_SECRET=your_client_secret_here');
-    console.error('  GOOGLE_CALLBACK_URL=http://localhost:5000/auth/google/callback');
+    console.error(`  GOOGLE_CALLBACK_URL=${defaultCallback}`);
     console.error('  SESSION_SECRET=your_random_secret\n');
     throw new Error('Missing Google OAuth credentials');
 }
diff --git a/app/Backend/routes/auth.js b/app/Backend/routes/auth.js
index 65498a7..72e2cd8 100644
--- a/app/Backend/routes/auth.js
+++ b/app/Backend/routes/auth.js
@@ -79,8 +79,11 @@ router.get('/check-name/:name', async (req, res) => {
  */
 const checkUsernameHandler = async (req, res) => {
   try {
+    // Force JSON content type
+    res.setHeader('Content-Type', 'application/json');
+
     // accepting from query (GET) or body (POST)
-    const username = req.query.username || req.body.username || req.params.username;
+    const username = req.query.username || req.body.username || req.params.username || req.query.name || req.body.name;
 
     if (!username || username.trim().length < 2) {
       return res.status(400).json({
diff --git a/app/Backend/server.js b/app/Backend/server.js
index 49f1b62..230cbb7 100644
--- a/app/Backend/server.js
+++ b/app/Backend/server.js
@@ -73,9 +73,34 @@ app.get("/debug/cookies", (req, res) => {
 });
 
 // ✅ Configure CORS *before* Helmet or routes
+const allowedOrigins = [
+  "http://localhost:5173",
+  "http://localhost:3000",
+  "http://localhost:5000",
+];
+
+if (process.env.FRONTEND_URL) {
+  allowedOrigins.push(process.env.FRONTEND_URL);
+}
+
 app.use(
   cors({
-    origin: process.env.FRONTEND_URL || "http://localhost:5173",
+    origin: function (origin, callback) {
+      // Allow requests with no origin (like mobile apps or curl requests)
+      if (!origin) return callback(null, true);
+
+      if (allowedOrigins.includes(origin) || origin.endsWith('.vercel.app')) {
+        return callback(null, true);
+      }
+
+      // In development, allow all
+      if (process.env.NODE_ENV !== 'production') {
+        return callback(null, true);
+      }
+
+      const msg = 'The CORS policy for this site does not allow access from the specified Origin.';
+      return callback(new Error(msg), false);
+    },
     credentials: true,
     methods: ["GET", "POST", "PUT", "DELETE", "OPTIONS"],
     allowedHeaders: ["Content-Type", "Authorization", "Cache-Control", "Pragma"],
diff --git a/vercel.json b/vercel.json
index 58a9143..7f48227 100644
--- a/vercel.json
+++ b/vercel.json
@@ -18,9 +18,20 @@
             "src": "/api/(.*)",
             "dest": "/app/Backend/server.js"
         },
+        {
+            "src": "/auth/(.*)",
+            "dest": "/app/Backend/server.js"
+        },
         {
             "src": "/(.*)",
             "dest": "/app/frontend/$1"
+        },
+        {
+            "handle": "filesystem"
+        },
+        {
+            "src": "/(.*)",
+            "dest": "/app/frontend/index.html"
         }
     ]
-}
\ No newline at end of file
+}