I tried to implement https://writer.zoho.com/writer/officeapi/v1/document/preview (https://api.office-integrator.in/writer/officeapi/v1/document/preview works for IN) as provided in the below documentation. 

When I use above preview API from AJAX or CURL, I am getting CORS (cross origin request sharing) error; also I am getting method not found error or {"code":"1876","message":"More than the maximum allowed count."} on various trials using AJAX or CURL process. Based on the response I need that response to be shown in the iframe and that opened file to be saved at local.