Does Render have built-in CORS config?

No. Render is an infrastructure platform — CORS headers are set by your application, not by Render.

Why does my Render deployment get a CORS error when local works fine?

Local development often runs on the same origin (localhost:3000 calling localhost:3000/api). In production on Render, your frontend and backend are on different domains — a real cross-origin situation that requires CORS headers.

Can I use Render's redirect rules for CORS?

Render's redirect rules handle URL redirects, not HTTP headers. They cannot add CORS headers.

CORS

Fix CORS Error on Render.com

Updated April 2026

 Reading this article? Verify your fix in real-time. Test your Render.com CORS config → CORSFixer

Render.com is a hosting platform — CORS headers are your application's responsibility, not Render's. The fix is in your server code, not Render's dashboard.

The approach

Render runs your Docker container or build output. CORS headers must be set by your application. Apply the standard fix for your framework:

Framework	Fix
Express / Node.js	Express CORS guide →
FastAPI / Python	FastAPI CORS guide →
Django	Django CORS guide →
Flask	Flask CORS guide →
Go	Go CORS guide →
Ruby on Rails	Rails CORS guide →
Static site with Nginx	See Nginx config below

Render with Nginx (static sites or Docker)

# nginx.conf
server { listen 10000;  # Render uses port 10000 by default location / { root /usr/share/nginx/html; index index.html; # CORS for API calls if ($request_method = OPTIONS) { add_header Access-Control-Allow-Origin "https://yourapp.com"; add_header Access-Control-Allow-Methods "GET, POST, PUT, DELETE, OPTIONS"; add_header Access-Control-Allow-Headers "Authorization, Content-Type"; add_header Content-Length 0; return 204; } add_header Access-Control-Allow-Origin "https://yourapp.com" always; }
}

Render environment variables for origin config

# In Render dashboard — Environment tab
CORS_ORIGIN=https://yourapp.com

# In your Express app
const corsOrigin = process.env.CORS_ORIGIN || "http://localhost:3000";
app.use(cors({ origin: corsOrigin }));

Common Render-specific issue — wrong port

# Render requires your app to listen on the PORT env variable
const PORT = process.env.PORT || 3000;
app.listen(PORT);

If your app is not listening on the correct port, Render cannot route requests to it — which appears as a network error, not a CORS error. Check Render logs first.

Render Web Service + separate frontend

If your frontend is on Vercel or Netlify and your backend is on Render, it is a cross-origin setup. Set the backend CORS_ORIGIN env variable to your Vercel/Netlify frontend URL in the Render dashboard.

Test your Render.com CORS config → CORSFixer