HTTP API
Most things you can do in the Simple DNS Plus GUI can also be done through the HTTP API, including updating DNS zones and records "on the fly", updating program options, etc. - either directly from a browser, or any other program that can communicate through HTTP.
See How to use HTTP API.
Extending Simple DNS Plus through plug-ins
Simple DNS Plus has an open plug-in architecture. For details see https://simpledns.plus/plugins.