CORS Tester
Run OPTIONS and GET requests with an Origin and custom headers to evaluate CORS responses.
How to Test CORS?
- Enter the API endpoint URL you want to test.
- Specify the Origin header (your website's URL).
- Select HTTP method (OPTIONS for preflight, GET for actual request).
- Optionally add custom request headers (one per line: Name: Value).
- Click Run Test to see CORS headers and allowed origins.
Free CORS Headers Tester
Test Cross-Origin Resource Sharing (CORS) configuration for any API endpoint. CORS is a browser security mechanism that controls which origins can make requests to your API. Misconfigured CORS causes cryptic errors in web apps — this tool helps you diagnose them without writing code.
What This Tool Checks
- Preflight Requests — Sends an OPTIONS request to check if the browser's preflight will succeed
- Allowed Origins — Verifies that Access-Control-Allow-Origin includes your domain
- Allowed Methods & Headers — Confirms the HTTP methods and headers your app needs are permitted
- Credentials Support — Checks Access-Control-Allow-Credentials for cookie-based auth
Ideal for debugging CORS errors during API integration, validating third-party API configurations, and testing before deployment.
