CORS Tester

Check if a URL supports Cross-Origin Resource Sharing (CORS) and analyze response headers.

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Check if a URL supports Cross-Origin Resource Sharing (CORS) and analyze response headers.

This page loads the full interactive CORS Tester experience inside Tool Labz. Use it instantly in your browser with no signup and no download.

Repeated identical requests are throttled to reduce accidental API abuse.

Preflight

Browser sends OPTIONS request before actual request if certain conditions are met.

Origin

Headers like Access-Control-Allow-Origin control which domains can access resources.

Credentials

By default, browser doesnt send cookies on cross-origin requests unless allowed.