CORS Header Validator

Validate Cross-Origin Resource Sharing (CORS) headers for security and compliance

Request Configuration

The URL making the cross-origin request

The API/resource URL being requested

Enter response headers from the server (one per line, in "Name: Value" format)

CORS Headers Reference

Response Headers:

  • Access-Control-Allow-Origin - Allowed origins
  • Access-Control-Allow-Methods - Allowed HTTP methods
  • Access-Control-Allow-Headers - Allowed request headers
  • Access-Control-Allow-Credentials - Allow cookies/auth
  • Access-Control-Max-Age - Preflight cache duration
  • Access-Control-Expose-Headers - Exposed response headers

Best Practices:

  • • Avoid wildcard (*) in production
  • • Use specific origins when possible
  • • Be cautious with credentials
  • • Limit allowed methods and headers
  • • Use HTTPS for secure applications
  • • Set appropriate cache duration
Learn More:

For detailed CORS documentation, visit theMDN CORS Guide