RDAP (the Registration Data Access Protocol) is the internet registry system's replacement for classic WHOIS. It answers the same underlying question — who registered this domain, and what's on record for it — but does so through a modern, standardized protocol rather than WHOIS's decades-old plain-text format.
Why RDAP exists
Classic WHOIS has no fixed output format. Every registry and registrar can format its response slightly differently, which makes it genuinely hard for software to parse reliably — one registry might label a field "Registrant Name," another "Registrant Contact," another might omit it in a different order entirely. RDAP fixes this by defining a strict, structured JSON format that every RDAP server returns the same way.
Key differences from WHOIS
| WHOIS | RDAP | |
|---|---|---|
| Format | Unstructured plain text | Structured JSON |
| Standardization | Varies by registry | Strictly defined (IETF standard) |
| Redaction handling | Inconsistent | Standardized |
| Machine-readability | Poor | Built for it |
Does RDAP replace WHOIS entirely?
For most gTLDs (like .com and .org), yes — RDAP is now the authoritative source, and many registries have deprecated their old WHOIS ports. Some country-code TLDs (ccTLDs) still rely on WHOIS only, so having access to both remains genuinely useful.
How to check it yourself
Our RDAP Lookup tool queries the actual RDAP protocol directly and shows you the structured result. If you're not sure which one you need, our WHOIS Lookup tool is the more familiar starting point for most people — for the vast majority of domains today, both ultimately draw on the same underlying registry data.