CORS Header Generator

CORS controls whether browser JavaScript can read responses from another origin. Backend APIs often work in curl or Postman but fail in the browser because CORS headers are missing or too restrictive. Correct headers are essential for frontend apps, dashboards, embedded widgets, and local development.

This generator creates common CORS response headers for allowed origins, methods, and request headers. It is meant to help you understand what your server should return, not to bypass browser security. The browser enforces CORS, and only the target server can truly fix a CORS error.

Use it when configuring Express, Next.js route handlers, Cloudflare Workers, Nginx, API gateways, or serverless functions. Avoid using * with credentials; choose explicit origins for private APIs.