Cors Error while using api proxy in checkout ui extensions node template

Shopify Plus

Topic summary

A developer is experiencing a CORS (Cross-Origin Resource Sharing) error when attempting to make API calls from a Shopify Checkout UI extension to their Express backend server.

Technical Setup:

  • Using the API proxy approach with a Checkout UI extension
  • Making a POST request to https://dev-ravindra.myshopify.com/apps/survey
  • Sending JSON payload with survey response data
  • Including Access-Control-Allow-Origin: * header in the request

Current Issue:
Despite implementing the API proxy pattern and adding CORS headers to the client-side request, the CORS error persists.

Status: The issue remains unresolved with no responses or solutions provided yet. The developer likely needs guidance on proper CORS configuration for their Express server or correct implementation of Shopify’s API proxy for Checkout UI extensions.

Summarized with AI on October 31. AI used: claude-sonnet-4-5-20250929.
1

I’m trying to make an API call to my Express app from a Checkout UI extension using an API proxy, but I’m still encountering a CORS error.
checkout.jsx -

const response = fetch("https://dev-ravindra.myshopify.com/apps/survey", { 
          method: "POST",
          headers: {
            "Content-Type": "application/json",
            "Access-Control-Allow-Origin": "*", 
          },
          body: JSON.stringify({ surveyResponse: "example" }), 
        });