rdap.net API quick reference:

OpenRDAP is a command line client for the Registration Data Access Protocol, written in Go.

RDAP is a replacement for WHOIS, which provides domain name & IP address registration information in JSON format over HTTP.

You can try some example queries using OpenRDAP here:

This website provides the OpenRDAP client, Go library, and an RDAP service (rdap.net).

Features

Small & fast command line RDAP client.
Supports all RDAP query types (domain, ip, asn, help, nameserver, and searches).
Automatic query type detection (domain, ip, asn queries).
Full bootstrapping support (using data.iana.org, or a custom URL).
Optional on-disk bootstrap files cache.
Output formats: raw JSON, text, WHOIS format (domain queries).
Customisable query timeout.

Experimental features