Where is the RPC API documentation?

[visualbasic6]

Hi,

Where are the docs for HTTP RPC API?

All requests, e.g.

POST /tx HTTP/1.1
Host: node-ip:9933
Accept: text/plain
Content-Type: application/json
Content-Length: 76

{"tx": "0x40eb21f2e4c29522b094223180e3822164ba7c2e0dea3dc92bc58827e54cbf85"}

produce this result:

HTTP/1.1 200 OK
content-type: application/json; charset=utf-8
content-length: 80
date: Fri, 11 Nov 2022 07:58:43 GMT

{"jsonrpc":"2.0","error":{"code":-32600,"message":"Invalid request"},"id":null}

Why is there an open RPC API port (9933) but no documentation for it?

Can you share some API endpoints as examples? How do we pull metrics and blocks, etc.?