CORS Inspector
Run a real CORS preflight from your browser — a cross-origin request that shows whether an endpoint allows it, with the exact server headers to confirm.
How to Use the CORS Inspector
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Frequently Asked Questions
What triggers preflight?
Non-simple methods, custom headers, or non-whitelisted content types.
Which headers matter?
Access-Control-Allow-Origin, Methods, Headers, and Credentials.
Where does the preflight run?
In your browser — the page itself issues the request, so verdicts reflect this origin. Results only, no account needed.
Are CORS inspections stored anywhere?
No account needed — inspections run without sign-in or saved history.
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Last updated October 2026