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My frontend and my API are on two different domains, and every fetch call just dies with a CORS error in the console.
What you'll have at the end
A cross-domain fetch call that succeeds instead of failing in the browser console
You need
A React frontend deployed at its own address, an Express API deployed at a different one, and at least one route on that API that checks a JSON Web Token sent in an Authorization header.
Not covered
Cookie-based sessions and credentialed requests, hardening the rest of the API with security headers or rate limits, and a setup where the frontend and API already share one address.
Leans on
Have you added CORS, Helmet and rate limiting to your Express API?
For hardening the rest of the API, security headers and rate limits, once this recipe's allowlist and mount order already work.
Your Express API still only runs locally
If the API isn't reachable at a real address at all yet, that's the more basic gap to close first.
Checked 25 Aug 2026
Part of the Full-Stack Application Deployment cookbook