What is CORS Tester?
CORS Tester checks Cross-Origin Resource Sharing policies for any API endpoint. It helps diagnose CORS issues by showing which origins, methods, and headers are allowed by the server.
Common Use Cases
API Development
Verify CORS is configured correctly on your APIs.
Debugging
Diagnose "CORS blocked" errors in browser console.
Integration
Check if third-party APIs allow your origin.
Security Review
Audit CORS policies for overly permissive settings.
How to Use This Tool
- Enter the API endpoint URL
- Select the HTTP method to test
- Enter your origin (or use default)
- View CORS headers in the response
Frequently Asked Questions
What is CORS?
CORS is a security feature that restricts web pages from making requests to different origins unless explicitly allowed.
Why do I get CORS errors?
The server hasn't included your origin in Access-Control-Allow-Origin, or doesn't support the method/headers you're using.
What is a preflight request?
Browsers send OPTIONS requests before "complex" requests to check if the actual request is allowed.