CORS checker and tester

Run a real request from this page to any URL and see what the browser does with it: whether the server answers at all, whether your request needs a preflight, and which Access-Control header is missing. Everything happens in your browser. We never see the URL.

How to read the result

• Read OK — the server allows this page's origin. Your own page will work the same way if its origin is allowed too.
• Reachable, but blocked — the request left your browser and the server answered, but without the Access-Control-Allow-Origin header, so the browser refused to hand the response to JavaScript. This is the usual CORS error, and it is fixed on the server.
• Not reachable — no answer at all: wrong address, server down, DNS, or a firewall. Nothing to do with CORS.

Full explanation and every fix, including localhost ports and preflight failures: CORS error: what it means and how to fix it.