While calling the api from JavaScript This HTTP request works fine https://api.pcloud.com/userinfo?username=xxxx@gmail.com&password=xxxx In the below code I want to call via JavaScript output in console XMLHttpRequest cannot load https://api.pcloud.com/userinfo?{}. Request header field Authorization is not allowed by Access-Control-Allow-Headers in preflight response. If someone can provide a solution or enhance the code. Answer Pass the username and password in the data