Index onlineMerchant portal
Api Endpoint

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 '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.

Open interactive test console

Offering

Provider
domain-availability-checker.underscoredone.com
Method
POST
Offering type
Api Endpoint
Transport type
http
Category
Infrastructure
Delivery
Not provided
Pricing model
Not provided
x402 version
2

Endpoint context

URL
https://domain-availability-checker.underscoredone.com/check
MIME type
application/json
First seen
2026-10-16T01:50:06.715Z
Last seen
Tags
domain availability, is domain available, is domain registered, check domain availability, domain name search

Website

Payment pricing

x402 payment terms are the authoritative price for calling this endpoint.

Payment option 1
0.01 USDC
Atomic price: 10000 · Network: eip155:8453 · Asset: USDC · Scheme: exact
Payment option 2
0.01 USDC
Atomic price: 10000 · Network: solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp · Asset: USDC · Scheme: exact
Raw x402 terms
[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "10000",
    "payTo": "0xE9740820225B3918b4ddd1292C7cA4Ca0e2C2F08"
  },
  {
    "scheme": "exact",
    "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "amount": "10000",
    "payTo": "8ugAWAXDB8V18kiUrGZTq1oMvU3C6Fxs8hfC6rvzQT3b"
  }
]

Observed health

Status
Reachable
Latest latency
76 ms
Average latency
27 ms
HTTP status
405
Last checked
Reachability
66.7% over 3 checks

Latency is measured to the first response headers. A reachable result does not verify response accuracy or merchant identity.

Input schema

{
  "type": "object",
  "properties": {
    "type": {
      "type": "string",
      "const": "http"
    },
    "method": {
      "type": "string",
      "enum": [
        "POST",
        "PUT",
        "PATCH"
      ]
    },
    "bodyType": {
      "type": "string",
      "enum": [
        "json",
        "form-data",
        "text"
      ]
    },
    "body": {
      "type": "object",
      "properties": {
        "domains": {
          "type": "array",
          "description": "Between 1 and 10 domain names to check, like 'example.com' or 'mybrand.ai'. Use the plain registrable domain only — no 'https://', no 'www.', no subdomains."
        }
      },
      "required": [
        "domains"
      ],
      "additionalProperties": false
    }
  },
  "required": [
    "type",
    "method",
    "bodyType",
    "body"
  ],
  "additionalProperties": false
}

Output schema

{
  "type": "object",
  "properties": {
    "type": {
      "type": "string"
    },
    "example": {
      "type": "object",
      "properties": {
        "count": {
          "type": "integer"
        },
        "results": {
          "type": "array",
          "items": {
            "type": "object"
          }
        },
        "queried_at": {
          "type": "string"
        },
        "disclaimer": {
          "type": "string"
        },
        "api_version": {
          "type": "string"
        }
      },
      "required": [
        "count",
        "results",
        "queried_at",
        "disclaimer",
        "api_version"
      ]
    }
  },
  "required": [
    "type"
  ]
}