CORS Checker

Browsers do not let a page spoof the real Origin header. This tool sends a normal browser request and an OPTIONS-style preflight probe where possible, then explains what the browser allows this page to see.

Result

About this tool

Check whether a URL can be read by JavaScript from this site origin. The tool sends a browser fetch request and, where possible, an OPTIONS-style probe, then reports what the browser allowed the page to see. It cannot spoof arbitrary Origin headers because browsers deliberately do not allow that.

Questions

Why does it say blocked without showing the server headers?
When CORS blocks a response, the browser hides the response from JavaScript. That is the rule this tool is testing, so sometimes the only honest answer is that the page could not read the details.