What's the difference between UAPI and WHMAPI1?
WHM offers two different API's, the WHMAPI and UAPI. What API you use will depend on if you're operating as the root user or a cPanel user.
WHMAPI is what you will use when making changes an administrator would usually make, such as creating a new account and enabling services.
You use the UAPI when you want to perform actions as the user. Examples of operations performed by the UAPI are creating an e-mail account and creating an e-mail account.
The port you call the WHMAPI, and the UAPI is also different. WHMAPI uses port 2087, and UAPI uses port 2083.