Registration Data Access Protocol. The successor to WHOIS—a standardized API for querying domain registration data without the mess of parsing plain-text port 43 responses.
RDAP returns structured JSON instead of human-readable text, which means automated tools can actually read it reliably. ICANN mandated registrars support it alongside WHOIS, though compliance varies wildly. It's technically more secure (uses HTTPS, supports authentication) and jurisdictionally aware—registrars can restrict data visibility per GDPR, CCPA, and local privacy laws without building separate systems.
Why it matters: RDAP is what regulators and law enforcement query now. If you run a bulletproof domain, RDAP is where subpoenas and formal requests land. Some registrars (including us) honor legitimate privacy shields via RDAP while keeping WHOIS locked down entirely. It's also useful if you're automating domain monitoring or building infrastructure tools—proper parsing beats regex nightmares.
Related to EPP (the registry protocol that handles transfers) and WHOIS privacy (the mechanism RDAP helps enforce). Not encrypted end-to-end, so assume queries are logged.