The Gravity Forms API provides developers with a future-proof way to access some of the common core functionality in Gravity Forms.
There are two ways to access the API:
API Functions in the GFAPI class
Use the API Functions to access the Gravity Forms install on the same server as your code, for example, if you're developing an add-on for Gravity Forms.
Via HTTP using the Web API
Use the Web API to access a Gravity Forms install on a remote server, for example, if you're developing a mobile app.