CORS Tester: Does the Stream Server Allow Access from a Browser?

If a stream does not open in a browser-based player but opens on a TV, the reason is almost always CORS. The tool tries the address three ways (a direct CORS request, no-cors access and reading the server's CORS header) and turns the result into a clear verdict: it can be played in a browser, the server is reachable but CORS is closed or it is unreachable.