How to Fix CORS Errors in a React App (Step by Step)

How to Fix CORS Errors in a React App (Step by Step)

CORS errors have a clear fix once you understand them. Here is a step-by-step guide for both development and production.

Step 1: Confirm It Is CORS

Look at the browser console. A CORS error specifically mentions cross-origin or the Access-Control headers. Other errors are not CORS even if they happen during a fetch.

Step 2: In Development, Use a Proxy

The cleanest local fix is a proxy. Configure your bundler to proxy API requests to the target server, or run a small backend proxy. The proxy makes the request from a server-side origin, bypassing browser CORS.

Step 3: For Quick Testing, Use a Browser Extension

A CORS-disabling extension works for quick local checks. It is not a real fix and must never be used in production or asked of users.

Step 4: In Production, Route Through Your Backend

Call the third-party API from your own backend, which can add the correct headers or proxy the response. Never expose users to raw third-party CORS issues.

Step 5: If You Control the API, Set CORS Headers

If the API is yours, configure it to return the Access-Control-Allow-Origin header with your allowed origins. This is the real server-side fix.

Step 6: Never Disable CORS for Users

CORS protects users. Telling users to disable it is never the answer. The fix is always server-side, either on the API or through your backend.

The Takeaway

Confirm it is CORS, use a proxy in development, route through your backend in production, and if you control the API, set the right headers. Never disable CORS for users.