Domain Availability Checker
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 'registere
Go to this service →Our latest check (2026-10-11)
- Answering
- Yes — valid x402 payment terms
- Time to answer
- 223 ms
- Price
- $0.010 per call
- Paying buyers, last 30 days
- 4 (directory's own records)
- Paid calls, last 30 days
- 6
- Category
- DNS and domains
- Address
- https://domain-availability-checker.underscoredone.com/check
Accuracy
Accuracy scores are published once a seller has enough paid checks against an independent record (at least 7 scored answers over at least 7 days). Until then no score is shown, and a missing score is never a pass.
For agents
This page as JSON: /sellers/03b5c5409eaa.json. Paid lookup by address: GET /api/seller?resource=… ($0.001, x402).