Marketplace · API · x402

domain-availability-checker.underscoredone.com/check

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`
Trust	✓ Verified callable · 100% uptime over 1 checks · ~74 ms
Pricing	Pay per call with x402, no account. Call it to get an exact quote before paying.
network	eip155:8453
scheme	exact
pay to	0xE9740820225B3918b4ddd1292C7cA4Ca0e2C2F08
method	POST
last updated	2026-11-08T11:35:28.77Z

Use it

Call it (an x402 client pays automatically)

curl -i https://domain-availability-checker.underscoredone.com/check
# 402 reply -> sign PAYMENT-REQUIRED with an x402 client (e.g. @x402/fetch) -> retry with PAYMENT-SIGNATURE

This listing as JSON

curl https://aipaygen.com/v1/catalog/api/x402-ec6a7dc9ed867354

Search the whole marketplace from your agent (MCP)

{
  "mcpServers": {
    "aipaygen": {
      "url": "https://aipaygen.com/mcp"
    }
  }
}

Domain name availability (AIPayGen)
API$0.002/call

domain-availability-checker.underscoredone.com/check

Use it

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