It's a standard REST API.
Here's the server side of the API.
Here's how you call it from browser-based JavaScript. You can include that code in your apps.
Here's an example app that implements a simple blog builder for my recent posts on RSS.chat. We were thinking about doing this as a project for Claude and myself but decided it would be more fun to let devs see what they can do here. :-)
And finally here are the docs for the API itself.