CORS Headers Generator

Generate CORS headers

Cross-Origin Resource Sharing, or CORS, is the mechanism that lets a web page on one origin make requests to a server on another, controlled by a set of response headers. This generator builds those headers from your settings: the allowed origin, the permitted HTTP methods, the allowed request headers, whether credentials like cookies may be sent, and how long browsers may cache the preflight result. The output is ready to add to your server responses.

Specifying an exact origin rather than a wildcard is more secure, and it is required when credentials are allowed.

Getting CORS right and safe

CORS is frequently misconfigured in ways that either break legitimate requests or open security holes. Allowing any origin with a wildcard while also allowing credentials is forbidden by browsers and dangerous, which is why this tool encourages naming a specific origin. Granting only the methods and headers your API actually needs follows the principle of least privilege and reduces attack surface.

The Max-Age header reduces repeated preflight requests by letting the browser cache the permission. Review the generated headers against what your application truly requires. All generation happens locally in your browser.

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