API to an Online platform

Hello, i was wondering what are the requirements are to do an API, from frappe to an online website that i am working on, my main features are similiar to airbnb, so when a client wants to reserve a room from my platform, i want a proforma invoice to be created on ERPNext, when approved to send an api to my platform so the user knows that it is approved,

any one can assist?

If you want to do this without custom app development you can utilize Server Scripts through the API script type.

This will work for GET requests with no authorization required. This is more than sufficient for your use case.

For POST you would need to develop a custom app.

You can also utilize Webhooks.

Any LLM will help you set these up, just strip them from any imports and doc hooks