CORS Tester
Test Cross-Origin Resource Sharing (CORS) headers for any URL and troubleshoot CORS issues.
Understanding CORS
CORS (Cross-Origin Resource Sharing) is a security feature implemented by browsers that restricts web pages from making requests to a different domain than the one serving the web page.
Simple Requests
GET, HEAD, or POST requests with simple headers do not trigger a preflight check.
Preflight Requests
Complex requests send an OPTIONS request first to check if the actual request is safe.