TLD Lookup

Check whether a domain extension supports RDAP or WHOIS lookups, and find its registry information.

Enter a bare extension (e.g. io) or a full domain — either works.

About this tool

Not every domain extension supports every lookup protocol. This tool checks the current IANA RDAP bootstrap registry (the authoritative list of which registries offer RDAP, and where) and IANA's WHOIS referral service, so you can see upfront whether a given extension will return full registration data through our WHOIS Lookup and RDAP Lookup tools, or whether it's an extension we don't yet have a supported path for.

Why this varies by extension

RDAP adoption has grown steadily since ICANN began requiring it for gTLDs, but many country-code domains (ccTLDs) run their own registry infrastructure independently and adopt RDAP on their own timeline, if at all. This tool reflects the current, real state of that support rather than assuming every extension works the same way.

Related tools:

WHOIS Lookup RDAP Lookup Domain Information