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UtilitiesCORS Checker

CORS Checker

Online CORS check

Not just ACAO: actual + OPTIONS preflight and why the browser will allow or block the request.

URLOriginMethodAccess-Control-Request-Headers (comma-separated)Do not paste Authorization/Cookie — blocked in the public MVP.Credentials expected (cookies / client cert) — like fetch credentials: 'include'Reflection probes — several synthetic Origins (diagnostic only)Probe Origin: nullFollow redirects and inspect ACAO per hop (SSRF re-check)

Related: HTTP Inspector

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