RDAP

RDAP is the protocol that replaced WHOIS for looking up who registered a domain, when it expires and what status codes it carries. It returns the same kind of data WHOIS did, but as structured JSON instead of a wall of text that every registrar formatted differently.

ICANN stopped requiring gTLD registrars and registries to run WHOIS in January 2025. RDAP is now the official source for .com, .net and every new gTLD. Some country-code extensions still run their own WHOIS, and a few publish nothing useful at all.

If you buy expiring domains, this matters more than it sounds. The expiration date and the EPP status codes you see on a listing almost always came from an RDAP lookup. When a tool says a domain is in redemptionPeriod or autoRenewPeriod, RDAP is where it learned that.