RDAP

RDAP (Registration Data Access Protocol) is the IETF-standardised successor to WHOIS. It delivers the same kind of registration data — for domain names, IP allocations and ASNs — but over HTTPS with structured JSON responses, a consistent schema across registries, native internationalisation, and proper support for differentiated access (anonymous vs authenticated queries can return different levels of detail).

RDAP exists because WHOIS has well-known structural problems: responses are free-form text that varies per server, there is no standard way to express dates, contacts or status values, no transport security, and no mechanism to authenticate clients or rate-limit by identity. RDAP fixes all of these. Clients discover the authoritative server for a given object through the IANA bootstrap registries (one each for domains, IPv4, IPv6 and ASNs), then issue a normal HTTPS GET such as /domain/example.com, /ip/192.0.2.0, or /autnum/15169. The JSON response uses a fixed vocabulary (events, entities, status, nameservers), so the same parser works against every RIR and registry.

Because the protocol is HTTPS, responses can be cached and rate-limited per identity using ordinary API infrastructure. Objects carry standardised fields such as events (registration, last changed, expiry), entities with roles (registrant, administrative, technical, abuse), status (e.g. client transfer prohibited) and nameservers. International characters are returned as real Unicode rather than being truncated or romanised, and GDPR redaction is signalled explicitly through remarks objects instead of silently disappearing from the text. RDAP also defines differentiated access: anonymous clients receive a minimum set of fields, while authorised clients (law enforcement, registrars, trademark holders) can obtain expanded data by authenticating to the server — a mechanism WHOIS never had.