How to Fix CORS Blocked Errors in Express.js APIs Under Production Domains
Deploying a decoupled full-stack application frequently introduces one of the most frustrating security roadblocks in modern web development: Access to XMLHttpRequest at ‘API_URL’ from origin ‘FRONTEND_URL’ has been blocked by CORS policy. This runtime exception completely halts communication between your frontend user interface and your backend microservices. Cross-Origin Resource Sharing (CORS) is a strict browser-level…