Site Preview in control panel before switch Nameservers. The other method with /~username is not at all secure and we have disabled it on all servers.
Better preview for sites
As a server administrator I would like cPanel to provide a better and easier way for my users to preview their live website in a way that does not require deep technical knowledge, or present security and usability flaws.
For example, one option (and my preference) would be to use a subdomain based on the customer domain name itself; i.e. customerdomain.hostnamel.com.