🏷️Domain Availability Check
Check whether a domain name is registered or available, via the official RDAP registry protocol (404 = available). For registered domains it also returns the registrar and creation/expiration dates — useful when an agent needs to name a product or verify how long a business has existed.
Worked examples
Registered domain
GET /api/v1/dev/domain-availability?domain=example.com
Result: ✗ example.com is REGISTERED
Available-sounding domain
GET /api/v1/dev/domain-availability?domain=qx7v2-availability-check.com
Result: ✓ qx7v2-availability-check.com appears AVAILABLE
io domain
GET /api/v1/dev/domain-availability?domain=vercel.com
Result: ✗ vercel.com is REGISTERED
Machine API (x402)
$0.001 / callThis tool is also a JSON API for AI agents. Requests without payment receive 402 Payment Required plus instructions; agents pay USDC on Base via the x402 protocol — no accounts, no API keys.
GET /api/v1/dev/domain-availability?domain=example.com HTTP/1.1
Host: agenttools-hub.vercel.app
→ 402 (payment required, instructions in headers)
→ 200 (after X-PAYMENT header; JSON body below)
{
"tool": "dev/domain-availability",
"input": {"domain":"example.com"},
"result": { "value": 0, "answer": "✗ example.com is REGISTERED" }
}Agent docs: /llms.txt · OpenAPI spec · integration guide
About this tool
Authoritative domain availability via the RDAP protocol — the modern replacement for WHOIS. 404 means the registry has no record (available); a record returns the registrar and key dates. The reliable way for an agent to name things or check a company's age.
Frequently asked questions
Why does 'available' have a caveat?
RDAP covers most gTLDs (.com, .io, .ai…) but not every ccTLD has a public RDAP service. A 404 from an uncovered TLD means 'no RDAP data', not necessarily 'available'.
Is this WHOIS?
It's RDAP — the structured, rate-limit-friendly JSON successor to port-43 WHOIS, run by the same registries.