The Atlas API does not yet support CORS. Without CORS, calling the API from within a browser, using a React Client, for example, fails the 'preflight checks'.

"...has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource...."

If the Atlas API could add the 'Access-Control-Allow-Origin: *in the header response, then browsers would permit the API to be called.

Note: for the pre-flight check, the browsers call the OPTION method.