Is the CORS error occurring in Webflow or on the server hosting the custom code?

A CORS (Cross-Origin Resource Sharing) error occurs not in Webflow but on the server hosting the custom code or API you’re trying to call.

1. Webflow Does Not Control CORS Policy

• Webflow sites are front-end frameworks and do not manage server-side headers like Access-Control-Allow-Origin.
• If your Webflow project is making an API request (via JavaScript) to another server (like a custom backend, Firebase, or a third-party API), the destination server must be configured to permit cross-origin requests.

2. Cause of the CORS Error

• A CORS error happens when the target server blocks requests from a different origin (e.g., your Webflow site domain).
• This is typical of APIs or self-hosted services that do not include appropriate headers like Access-Control-Allow-Origin: * or Access-Control-Allow-Origin: https://your-webflow-site.com.

3. How to Fix It

• If you're using your own backend, update its CORS configuration to allow requests from Webflow. Include headers such as:
• Access-Control-Allow-Origin: * (for open access) or
• Access-Control-Allow-Origin: https://your-webflow-site.com (for restricted access)
• If using a third-party API, check their documentation. Many have specific requirements for allowed origins or API key usage.
• If testing locally, note that local server setups (like localhost) might behave differently and still trigger CORS issues not seen in production.

Summary

The CORS error occurs on the server you're trying to access, not within Webflow itself. Ensure that the target server is configured to allow cross-origin requests from your Webflow domain.