API 2.0 docs API 1.0 docs

Domain Availability API helps you check whether a domain name is available for registration quickly and accurately.

WhoisXmlApi.com provides RESTful APIs. It is designed for server-to-server communication between your system and the WhoisXmlApi.com network using standard HTTP or HTTPS protocols. Query responses are delivered in either XML or JSON format based on your requests which are made via GET/POST methods.

To get started you need a developer's account with WhoisXmlApi.com. Authentication is required each time in order to use the API. The first 500 domain name availability lookups are complimentary when you register for a free developer account.

Making requests


It takes up to 2 minutes to activate your account after Sign Up.

Input parameters: required

Get your personal API KEY on My products page.
The target domain name.

Input parameters: optional

The default mode is the fastest, the DNS_AND_WHOIS mode is slower but more accurate.

Acceptable values: DNS_AND_WHOIS | DNS_ONLY

Default: DNS_ONLY
Response output format.

Acceptable values: JSON | XML

Default: JSON

Free access

After Sign Up you automatically get a free subscription plan limited to 500 queries per month.

Sample output

   "DomainInfo": {
      "domainAvailability": "UNAVAILABLE",
      "domainName": "google.com"
AVAILABLE / UNAVAILABLE registration state of the domain name.
The target domain name.

XML Schema/ Domain Availability Query Result Documentation

You can download the following for your reference:

Account balance information

Required. Get your personal API KEY on My products page.
Optional. A list of the products' IDs can be found in the response.

- You can always check your account balance on the My products page. - Note that the following products use the same WHOIS credits: WHOIS API, Bulk WHOIS API, Domain Availability API. - Note that the following products use the same Domain Research Suite credits: Brand Alert API, Registrant Alert API, Reverse WHOIS API, WHOIS History API, Reverse IP/DNS API, Reverse MX API, Reverse NS API.

List of possible errors

403 Forbidden
Access restricted. Check credits balance or enter the correct API key.
422 Unprocessable Entity
Input correct search term.
429 Too Many Requests
Too Many Requests. Try your call again later.
Internal server error. Try your call again or contact us.

Account balance low or zero notification

When your account balance falls below certain level you will receive an email alert. Another email will be sent when your account balance reaches 0.

You can always change your notifications settings on the Settings - Notifications page.

Usage limits and requests throttling

The maximum number of requests per second is 30. In case that the limit is breached, your subsequent requests will be rejected until the next second.

TLDs supported

We support thousands of TLDs, both gTLDs and ccTLDS. You can see the entire list here.

Printable guide

You can also download the PDF version of this guide.

API status

You can check the API's current performance and availability status on the API Status Page.

Terms of Service or SLA for using Domain Availability API

Please click on the link below to review the Terms of Service

Try our Domain Availability API for free
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