sharepoint

Add iframe to sharepoint Page  2013, Online. Solution : Site settings > Site Collection Administration > HTML Field Security > add your domain that you want to be allowed to be inframed in sharepoint. Direct Url to settings page : https://yourdomain.sharepoint.com/_layouts/15/HtmlFieldSecurity.aspx for online https://yourdomain.com/_layouts/15/HtmlFieldSecurity.aspx  for on premises 

Allow SharePoint 2013 site to load into IFRAME in non-SharePoint application add the code highligted to all of your master pages if you have multiple masterpages. <WebPartPages:AllowFraming runat="server" />