Trying to embed the standard Genesys Cloud messenger widget into a Next.js app. Using server-side rendering. Getting a CORS error every time the client tries to connect to the Genesys endpoints.
Access to fetch at 'https://api.us.genesyscloud.com/v2/conversations/messaging' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.
The widget script loads fine. The UI renders. But the underlying REST calls fail. We’ve added the origin to the allowed list in the Genesys admin console. Still failing.
Is there a specific header or config I’m missing in the Next.js setup? Or is this a known limitation with SSR? The docs mention adding a meta tag, but that didn’t fix the fetch error.
Code snippet for the script injection:
useEffect(() => {
const script = document.createElement('script');
script.src = 'https://files.megacool.me/genesyscloud-messenger-1.0.0.min.js';
document.body.appendChild(script);
}, []);
Any ideas?
Next.js SSR is the culprit here. The browser sends the request from localhost, but the Genesys API doesn’t whitelist that for direct fetch calls from client-side code unless it’s the official widget script handling it internally. If you’re manually calling /v2/conversations/messaging, you’re bypassing the widget’s CORS handling.
Don’t call Genesys APIs directly from the browser in a Next.js app. Use a Next.js API route as a proxy. It runs on the server, so CORS isn’t an issue.
// pages/api/messaging.ts
export default async function handler(req, res) {
const response = await fetch('https://api.us.genesyscloud.com/v2/conversations/messaging', {
method: 'POST',
headers: {
'Authorization': `Bearer ${process.env.GENESYS_TOKEN}`,
'Content-Type': 'application/json'
},
body: JSON.stringify(req.body)
});
const data = await response.json();
res.status(200).json(data);
}
Call /api/messaging from your frontend instead. Keeps the token safe and sidesteps the CORS block entirely.
Spot on with the proxy suggestion. I’ve seen this exact CORS headache pop up in Next.js deployments before, especially when teams try to be clever and call the Genesys APIs directly from client components. The browser security model just doesn’t play nice with localhost:3000 hitting genesyscloud.com directly unless you’re using the official widget snippet which handles its own iframe sandboxing.
If you’re building a custom UI, you absolutely need that server-side middleware layer. It’s not just about bypassing CORS, it’s also about keeping your OAuth secrets out of the browser bundle. Here’s how I’ve structured a simple Next.js API route to proxy those messaging requests securely. This keeps the client clean and lets the server handle the token exchange.
// pages/api/genproxy/messaging.js
import { PlatformClient } from '@genesyscloud/genesyscloud';
export default async function handler(req, res) {
// Only allow POST requests for creating conversations
if (req.method !== 'POST') {
res.status(405).json({ error: 'Method Not Allowed' });
return;
}
try {
// Initialize the client with your service account credentials
// These should be in your .env.local file
const client = new PlatformClient();
await client.auth.loginServiceAccount(
process.env.GC_ORGANIZATION_ID,
process.env.GC_CLIENT_ID,
process.env.GC_CLIENT_SECRET
);
// Forward the payload to Genesys Cloud
const response = await client.conversationsApi.postConversationsMessaging({
body: req.body
});
res.status(200).json(response.body);
} catch (error) {
console.error('Genesys Proxy Error:', error);
res.status(500).json({ error: 'Failed to connect to Genesys' });
}
}
Make sure your next.config.js allows the necessary headers if you’re doing any streaming, but for standard REST calls, this proxy pattern works reliably. Just remember to rotate those service account credentials regularly.