domain-availability-checker.underscoredone.com

answering

Give this API up to 10 domain names and it tells you whether each has a registration record at the official registry. It uses RDAP, the structured replacement for WHOIS, so there is no free-text parsing. Each domain comes back as 'registered', 'unregistered', or 'indeterminate' when the registry has no RDAP for that ending. 'Unregistered' means no record was found, which usually means available - but reserved and premium names also return no record. Registration status only; no pricing.

Endpoint: https://domain-availability-checker.underscoredone.com/check
Price: $0.01 / call
Settles via: cdp
Category: —
Last seen live: Tue, 08 Sep 2026 05:23:37 UTC
Last probed: Tue, 08 Sep 2026 05:23:37 UTC
First indexed: Tue, 08 Sep 2026 05:22:22 UTC
Sources: cdp-x402

Probe history

Last 1 probes, newest on the right. 100% answered with a payment challenge.

When	Result	Method	Status	Latency
Tue, 08 Sep 2026 05:23:37 UTC	challenge	http-402	402	723 ms

JSON: /api/v1/services/domain-availability-checker.underscoredone.com. Own this service? Update the listing.