GET /check

ENS: Check Availability

Learn more: ENS API — marketing overview, live demo, pricing tiers, and use cases.

Check if an ENS (Ethereum Name Service) name is available for registration and get pricing information.

Base URL: https://ens.robotdomainsearch.com — The ENS API is a separate service from the main RobotDomainSearch API.

Endpoint

GET https://ens.robotdomainsearch.com/check

Parameters

Parameter	Type	Required	Description
name	string	Yes	ENS name to check (without .eth suffix)

Request

curl "https://ens.robotdomainsearch.com/check?name=vitalik"

Response (Name Taken)

{
  "name": "vitalik.eth",
  "available": false,
  "owner": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
  "resolver": "0x231b0Ee14048e9dCcD1d247744d114a4EB5E8E63",
  "responseMs": 450,
  "source": "rpc",
  "checkedAt": "2025-02-10T12:00:00Z"
}

Response (Name Available)

{
  "name": "myuniqueensname.eth",
  "available": true,
  "registrationPrice": {
    "wei": "158548959918",
    "eth": "0.000000158548959918",
    "usdEstimate": 5.00
  },
  "responseMs": 320,
  "source": "rpc",
  "checkedAt": "2025-02-10T12:00:00Z"
}

Response Fields

Field	Type	Description
name	string	Full ENS name with .eth suffix
available	boolean	Whether the name is available for registration
owner	string	Ethereum address of current owner (only if taken)
resolver	string	Resolver contract address (only if taken)
registrationPrice	object	Registration cost info (only if available)
registrationPrice.wei	string	Annual cost in wei
registrationPrice.eth	string	Annual cost in ETH
registrationPrice.usdEstimate	number	Estimated annual cost in USD
responseMs	number	Response time in milliseconds
source	string	Data source (rpc or rpc+cache)
checkedAt	string	ISO 8601 timestamp

Registration Pricing

ENS uses tiered pricing based on name length:

Name Length	Annual Cost (USD)
3 characters	$640/year
4 characters	$160/year
5+ characters	$5/year

Note: The wei and eth fields reflect the on-chain rent cost when available. The usdEstimate is based on ENS’s standard pricing tiers.

Errors

Code	Error	Description
400	missing_parameter	The name parameter is required
400	invalid_name	Name must be 3-63 chars, lowercase alphanumeric with hyphens
500	check_failed	Ethereum RPC error

Code Examples

curl

curl "https://ens.robotdomainsearch.com/check?name=vitalik"

Python

import requests

response = requests.get(
    "https://ens.robotdomainsearch.com/check",
    params={"name": "vitalik"}
)
data = response.json()

if data["available"]:
    price = data["registrationPrice"]["usdEstimate"]
    print(f"{data['name']} is available! (~${price}/year)")
else:
    print(f"{data['name']} is taken by {data['owner']}")

JavaScript

const response = await fetch(
  "https://ens.robotdomainsearch.com/check?name=vitalik"
);
const data = await response.json();

if (data.available) {
  console.log(`${data.name} is available! (~$${data.registrationPrice.usdEstimate}/year)`);
} else {
  console.log(`${data.name} is taken by ${data.owner}`);
}

Notes

• Names are normalized to lowercase with the .eth suffix added automatically
• The .eth suffix is stripped if provided (you can pass vitalik or vitalik.eth)
• ENS names must be at least 3 characters
• Results are cached for improved performance
• The ETH price fields reflect on-chain data when available

📄 Raw markdown: /docs/api/ens-availability.md