Request
Request headers (one per line: Key: Value)
Request body
Analysis
Origin:
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→
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Will browser send preflight (OPTIONS)?：
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Example config / headers
Fix suggestions
Actual request result
Duration：
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Status：
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Response
Diagnostics
Paste response or preflight response headers from DevTools -> Network, one per line: Key: Value.
Paste response headers (optional, for deeper diagnosis)
How to Use
How to Use
- Enter the API URL you want to check (must start with http:// or https://).
- Select the HTTP method (e.g., GET, POST, PUT, DELETE, OPTIONS).
- Set request headers (Key: Value format) and request body (supports JSON, Form, Text) as needed.
- Click "Run check" button. The tool will attempt to send the request and analyze CORS response headers.
Tips & FAQ
- This tool only simulates browser behavior; actual request success depends on the target server's CORS configuration.
- If the request fails with "Failed to fetch", it's usually because the browser blocked the cross-origin response. Check DevTools -> Network for details.
- The "Diagnostics" feature helps analyze response headers you paste to find missing CORS configurations (like Allow-Origin, Allow-Methods).
- All requests are made directly from your browser and are not forwarded through any third-party server.
