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API Reference
Registrar

Check domain availability

client.Registrar.Check(ctx, params) (*RegistrarCheckResponse, error)
POST/accounts/{account_id}/registrar/domain-check

Performs real-time, authoritative availability checks directly against domain registries. Use this endpoint to verify a domain is available before attempting registration via POST /registrations.

Important: Unlike the Search endpoint, these results are authoritative and reflect current registry status. Always check availability immediately before registration as domain status can change rapidly.

Note: This endpoint uses POST to accept a list of domains in the request body. It is a read-only operation — it does not create, modify, or reserve any domains.

Extension support

Only domains on extensions supported for programmatic registration by this API can be registered. If you check a domain on an unsupported extension, the response will include registrable: false with a reason field explaining why:

  • extension_not_supported_via_api — Cloudflare Registrar supports this extension in the dashboard, but it is not yet available for programmatic registration via this API. Register via https://dash.cloudflare.com/{account_id}/domains/registrations instead.
  • extension_not_supported — This extension is not supported by Cloudflare Registrar.
  • extension_disallows_registration — The extension’s registry has temporarily or permanently frozen new registrations. No registrar can register domains on this extension at this time.
  • domain_premium — The domain is premium priced. Premium registration is not currently supported by this API.
  • domain_unavailable — The domain is already registered, reserved, or otherwise not available for registration on a supported extension.

The reason field is only present when registrable is false.

Behavior

  • Maximum 20 domains per request
  • Pricing is only returned for domains where registrable: true
  • Results are not cached; each request queries the registry

Workflow

  1. Call this endpoint with domains the user wants to register.
  2. For each domain where registrable: true, present pricing to the user.
  3. If tier: premium, note that premium registration is not currently supported by this API and do not proceed to POST /registrations.
  4. Proceed to POST /registrations only for supported non-premium domains.
Security
API Token

The preferred authorization scheme for interacting with the Cloudflare API. Create a token.

Example:Authorization: Bearer Sn3lZJTBX6kkg7OdcBUAxOO963GEIyGQqnFTOFYY
API Email + API Key

The previous authorization scheme for interacting with the Cloudflare API, used in conjunction with a Global API key.

Example:X-Auth-Email: user@example.com

The previous authorization scheme for interacting with the Cloudflare API. When possible, use API tokens instead of Global API keys.

Example:X-Auth-Key: 144c9defac04969c7bfad8efaa8ea194
ParametersExpand Collapse
params RegistrarCheckParams
AccountID param.Field[string]

Path param: Identifier

maxLength32
Domains param.Field[[]string]

Body param: List of fully qualified domain names (FQDNs) to check for availability. Each domain must include the extension.

  • Minimum: 1 domain
  • Maximum: 20 domains per request
  • Domains on unsupported extensions are returned with registrable: false and a reason field
  • Malformed domain names (e.g., missing extension) may be omitted from the response
ReturnsExpand Collapse
type RegistrarCheckResponse struct{…}

Contains the availability check results.

Domains []RegistrarCheckResponseDomain

Array of domain availability results. Domains on unsupported extensions are included with registrable: false and a reason field. Malformed domain names may be omitted.

Name string

The fully qualified domain name (FQDN) in punycode format for internationalized domain names (IDNs).

Registrable bool

Indicates whether this domain can be registered programmatically through this API based on a real-time registry check.

  • true: Domain is available for registration. The pricing object will be included.
  • false: Domain is not available. See the reason field for why. tier may still be present on some non-registrable results, such as premium domains.
Pricing RegistrarCheckResponseDomainsPricingOptional

Annual pricing information for a registrable domain. This object is only present when registrable is true. All prices are per year and returned as strings to preserve decimal precision.

registration_cost and renewal_cost are frequently the same value, but may differ — especially for premium domains where registries set different rates for initial registration vs. renewal. For a multi-year registration (e.g., 4 years), the first year is charged at registration_cost and each subsequent year at renewal_cost. Registry pricing may change over time; the values returned here reflect the current registry rate. Premium pricing may be surfaced by Search and Check, but premium registration is not currently supported by this API.

Currency string

ISO-4217 currency code for the prices (e.g., “USD”, “EUR”, “GBP”).

RegistrationCost string

The first-year cost to register this domain. For premium domains (tier: premium), this price is set by the registry and may be significantly higher than standard pricing. For multi-year registrations, this cost applies to the first year only; subsequent years are charged at renewal_cost.

RenewalCost string

Per-year renewal cost for this domain. Applied to each year beyond the first year of a multi-year registration, and to each annual auto-renewal thereafter. May differ from registration_cost, especially for premium domains where initial registration often costs more than renewals.

Reason RegistrarCheckResponseDomainsReasonOptional

Present only when registrable is false. Explains why the domain cannot be registered via this API.

  • extension_not_supported_via_api: Cloudflare Registrar supports this extension in the dashboard but it is not yet available for programmatic registration via this API. The user can register via https://dash.cloudflare.com/{account_id}/domains/registrations.
  • extension_not_supported: This extension is not supported by Cloudflare Registrar at all.
  • extension_disallows_registration: The extension’s registry has temporarily or permanently frozen new registrations. No registrar can register domains on this extension at this time.
  • domain_premium: The domain is premium priced. Premium registration is not currently supported by this API.
  • domain_unavailable: The domain is already registered, reserved, or otherwise not available on a supported extension.
One of the following:
const RegistrarCheckResponseDomainsReasonExtensionNotSupportedViaAPI RegistrarCheckResponseDomainsReason = "extension_not_supported_via_api"
const RegistrarCheckResponseDomainsReasonExtensionNotSupported RegistrarCheckResponseDomainsReason = "extension_not_supported"
const RegistrarCheckResponseDomainsReasonExtensionDisallowsRegistration RegistrarCheckResponseDomainsReason = "extension_disallows_registration"
const RegistrarCheckResponseDomainsReasonDomainPremium RegistrarCheckResponseDomainsReason = "domain_premium"
const RegistrarCheckResponseDomainsReasonDomainUnavailable RegistrarCheckResponseDomainsReason = "domain_unavailable"
Tier RegistrarCheckResponseDomainsTierOptional

The pricing tier for this domain. Always present when registrable is true; defaults to standard for most domains. May be absent when registrable is false.

  • standard: Standard registry pricing
  • premium: Premium domain with higher pricing set by the registry
One of the following:
const RegistrarCheckResponseDomainsTierStandard RegistrarCheckResponseDomainsTier = "standard"
const RegistrarCheckResponseDomainsTierPremium RegistrarCheckResponseDomainsTier = "premium"

Check domain availability

package main

import (
  "context"
  "fmt"

  "github.com/cloudflare/cloudflare-go"
  "github.com/cloudflare/cloudflare-go/option"
  "github.com/cloudflare/cloudflare-go/registrar"
)

func main() {
  client := cloudflare.NewClient(
    option.WithAPIToken("Sn3lZJTBX6kkg7OdcBUAxOO963GEIyGQqnFTOFYY"),
  )
  response, err := client.Registrar.Check(context.TODO(), registrar.RegistrarCheckParams{
    AccountID: cloudflare.F("023e105f4ecef8ad9ca31a8372d0c353"),
    Domains: cloudflare.F([]string{"myawesomebrand.com", "myawesomebrand.net", "myawesomebrand.org", "myawesomebrand.app", "myawesomebrand.dev"}),
  })
  if err != nil {
    panic(err.Error())
  }
  fmt.Printf("%+v\n", response.Domains)
}

{
  "errors": [],
  "messages": [],
  "result": {
    "domains": [
      {
        "name": "xq7mz9brand.com",
        "pricing": {
          "currency": "USD",
          "registration_cost": "8.57",
          "renewal_cost": "8.57"
        },
        "registrable": true,
        "tier": "standard"
      },
      {
        "name": "xq7mz9brand.net",
        "pricing": {
          "currency": "USD",
          "registration_cost": "9.95",
          "renewal_cost": "9.95"
        },
        "registrable": true,
        "tier": "standard"
      }
    ]
  },
  "success": true
}
{
  "errors": [],
  "messages": [],
  "result": {
    "domains": [
      {
        "name": "example.com",
        "reason": "domain_unavailable",
        "registrable": false
      },
      {
        "name": "example.net",
        "reason": "domain_unavailable",
        "registrable": false
      },
      {
        "name": "example.org",
        "reason": "domain_unavailable",
        "registrable": false
      }
    ]
  },
  "success": true
}
{
  "errors": [],
  "messages": [],
  "result": {
    "domains": [
      {
        "name": "cloudflare.com",
        "reason": "domain_unavailable",
        "registrable": false
      },
      {
        "name": "my-unique-startup-name-2024.com",
        "pricing": {
          "currency": "USD",
          "registration_cost": "8.57",
          "renewal_cost": "8.57"
        },
        "registrable": true,
        "tier": "standard"
      },
      {
        "name": "my-unique-startup-name-2024.dev",
        "pricing": {
          "currency": "USD",
          "registration_cost": "10.11",
          "renewal_cost": "10.11"
        },
        "registrable": true,
        "tier": "standard"
      }
    ]
  },
  "success": true
}
{
  "errors": [],
  "messages": [],
  "result": {
    "domains": [
      {
        "name": "coffee.xyz",
        "reason": "domain_premium",
        "registrable": false,
        "tier": "premium"
      }
    ]
  },
  "success": true
}
{
  "errors": [],
  "messages": [],
  "result": {
    "domains": [
      {
        "name": "example.py",
        "reason": "extension_disallows_registration",
        "registrable": false
      }
    ]
  },
  "success": true
}
{
  "errors": [],
  "messages": [],
  "result": {
    "domains": [
      {
        "name": "example.horse",
        "reason": "extension_not_supported",
        "registrable": false
      }
    ]
  },
  "success": true
}
{
  "errors": [],
  "messages": [],
  "result": {
    "domains": [
      {
        "name": "mybrand.uk",
        "reason": "extension_not_supported_via_api",
        "registrable": false
      },
      {
        "name": "mybrand.com",
        "pricing": {
          "currency": "USD",
          "registration_cost": "8.57",
          "renewal_cost": "8.57"
        },
        "registrable": true,
        "tier": "standard"
      }
    ]
  },
  "success": true
}
{
  "errors": [
    {
      "code": 1006,
      "message": "domains array must contain at least one domain"
    }
  ],
  "messages": [],
  "result": null,
  "success": false
}
{
  "errors": [
    {
      "code": 1008,
      "message": "None of the provided domains are valid or have supported extensions"
    }
  ],
  "messages": [],
  "result": null,
  "success": false
}
{
  "errors": [
    {
      "code": 1007,
      "message": "domains array exceeds maximum of 20 domains"
    }
  ],
  "messages": [],
  "result": null,
  "success": false
}
Returns Examples
{
  "errors": [],
  "messages": [],
  "result": {
    "domains": [
      {
        "name": "xq7mz9brand.com",
        "pricing": {
          "currency": "USD",
          "registration_cost": "8.57",
          "renewal_cost": "8.57"
        },
        "registrable": true,
        "tier": "standard"
      },
      {
        "name": "xq7mz9brand.net",
        "pricing": {
          "currency": "USD",
          "registration_cost": "9.95",
          "renewal_cost": "9.95"
        },
        "registrable": true,
        "tier": "standard"
      }
    ]
  },
  "success": true
}
{
  "errors": [],
  "messages": [],
  "result": {
    "domains": [
      {
        "name": "example.com",
        "reason": "domain_unavailable",
        "registrable": false
      },
      {
        "name": "example.net",
        "reason": "domain_unavailable",
        "registrable": false
      },
      {
        "name": "example.org",
        "reason": "domain_unavailable",
        "registrable": false
      }
    ]
  },
  "success": true
}
{
  "errors": [],
  "messages": [],
  "result": {
    "domains": [
      {
        "name": "cloudflare.com",
        "reason": "domain_unavailable",
        "registrable": false
      },
      {
        "name": "my-unique-startup-name-2024.com",
        "pricing": {
          "currency": "USD",
          "registration_cost": "8.57",
          "renewal_cost": "8.57"
        },
        "registrable": true,
        "tier": "standard"
      },
      {
        "name": "my-unique-startup-name-2024.dev",
        "pricing": {
          "currency": "USD",
          "registration_cost": "10.11",
          "renewal_cost": "10.11"
        },
        "registrable": true,
        "tier": "standard"
      }
    ]
  },
  "success": true
}
{
  "errors": [],
  "messages": [],
  "result": {
    "domains": [
      {
        "name": "coffee.xyz",
        "reason": "domain_premium",
        "registrable": false,
        "tier": "premium"
      }
    ]
  },
  "success": true
}
{
  "errors": [],
  "messages": [],
  "result": {
    "domains": [
      {
        "name": "example.py",
        "reason": "extension_disallows_registration",
        "registrable": false
      }
    ]
  },
  "success": true
}
{
  "errors": [],
  "messages": [],
  "result": {
    "domains": [
      {
        "name": "example.horse",
        "reason": "extension_not_supported",
        "registrable": false
      }
    ]
  },
  "success": true
}
{
  "errors": [],
  "messages": [],
  "result": {
    "domains": [
      {
        "name": "mybrand.uk",
        "reason": "extension_not_supported_via_api",
        "registrable": false
      },
      {
        "name": "mybrand.com",
        "pricing": {
          "currency": "USD",
          "registration_cost": "8.57",
          "renewal_cost": "8.57"
        },
        "registrable": true,
        "tier": "standard"
      }
    ]
  },
  "success": true
}
{
  "errors": [
    {
      "code": 1006,
      "message": "domains array must contain at least one domain"
    }
  ],
  "messages": [],
  "result": null,
  "success": false
}
{
  "errors": [
    {
      "code": 1008,
      "message": "None of the provided domains are valid or have supported extensions"
    }
  ],
  "messages": [],
  "result": null,
  "success": false
}
{
  "errors": [
    {
      "code": 1007,
      "message": "domains array exceeds maximum of 20 domains"
    }
  ],
  "messages": [],
  "result": null,
  "success": false
}