🔄 CORS Checker
Test Cross-Origin Resource Sharing configuration and debug CORS issues
💡 About CORS
CORS (Cross-Origin Resource Sharing) is a security mechanism that allows web pages to make requests to a different domain than the one that served the page. It's implemented via HTTP headers that indicate which origins are permitted to read the response.
Key CORS Headers:
Access-Control-Allow-Origin: Specifies which origins can access the resource
Access-Control-Allow-Methods: Allowed HTTP methods (GET, POST, etc.)
Access-Control-Allow-Headers: Allowed request headers
Access-Control-Allow-Credentials: Whether credentials can be included
Common CORS Errors: "No 'Access-Control-Allow-Origin' header present" - This means the server hasn't enabled CORS for your origin.
To identify the server's origin and network details, try our IP Address Lookup tool.
❓ Frequently Asked Questions
What is CORS?
CORS (Cross-Origin Resource Sharing) is a security mechanism that allows web pages to make requests to a different domain than the one that served the page. It uses HTTP headers to control access.
Why am I getting a CORS error?
CORS errors occur when the server doesn't include the Access-Control-Allow-Origin header or doesn't allow your origin. Configure the server to include proper CORS headers.
What is a preflight request?
A preflight request is an OPTIONS request sent before the actual request to check if the server allows the cross-origin request. It's required for requests with custom headers or non-simple methods like PUT/DELETE.
How do I fix CORS in my API?
Add Access-Control-Allow-Origin header to your server responses. Set it to '*' for public APIs or to specific origins for restricted access. Most frameworks have CORS middleware available.
Is using '*' for Access-Control-Allow-Origin safe?
Using '*' allows any origin, which is fine for public APIs without authentication. For APIs with credentials (cookies, authorization headers), you must specify exact origins instead of '*'.