CORS & Headers Checker
Test your API for CORS policies, CSP, HSTS, and Cookie security configurations instantly.
Cross-Origin Resource Sharing (CORS)
Cookies
Security Headers
All Raw Headers
About the CORS & Headers Checker
The CORS & Headers Checker by Grab-Kit is a free online tool designed for web developers, security engineers, and API integrators. Cross-Origin Resource Sharing (CORS) is a browser security mechanism that restricts web pages from making requests to a different domain than the one that served the page. Misconfigured CORS headers are the #1 cause of blocked API requests in frontend applications. Additionally, missing HTTP Security headers (like CSP, HSTS) can expose your website to XSS and clickjacking attacks. Our tool helps you audit all of these configurations in one place.
Using the tool is incredibly straightforward. Paste the URL of the API or web page you want to inspect into the input field above and click "Check Headers". The tool will fetch the HTTP response headers and analyze them. It provides a quick overview dashboard showing if CORS is enabled, if HSTS (Strict-Transport-Security) is active, and if a Content-Security-Policy is defined. Below the dashboard, you will find detailed breakdowns of the exact directives used for CORS, Cookie security flags (HttpOnly, Secure, SameSite), and all other security headers.
Why use Grab-Kit?
All our tools run entirely in your browser. This means your API endpoints are tested directly from your machine's network, giving you an accurate representation of what your application experiences. It is completely free, requires no signup, and works flawlessly on both desktop and mobile devices, making it the perfect utility for debugging your web architecture.