# check_subdomain_available

Source: https://modulify.ai/docs/mcp/sites/check-subdomain-available

Checks whether a free modulify.website subdomain is still available before change_subdomain takes it.

- Title: Check a free subdomain is available
- Scope: `sites:read`
- Access: Read only

The subdomain is the free public web address of a site, which it holds whether or not it is published, and it is how a site is identified everywhere else. The check answers `ok` when the subdomain is free and `not-ok` when it is taken.

The answer is platform-wide, since a subdomain is unique across all of Modulify, and the `projectId` only says which workspace the call belongs to. Testing the address the site already holds reports it as taken, because the check cannot tell that the holder is you, and a deleted site keeps holding its subdomain.

A subdomain that breaks the rules `change_subdomain` applies, on length, characters or reserved words, comes back as an error rather than as taken. See [Your free web address](https://modulify.ai/docs/publish/your-web-address#availability).

## Inputs

| Input | Type | Required | Description |
| --- | --- | --- | --- |
| `projectId` | string | Yes | The site id. It only decides which workspace the call belongs to. |
| `subdomain` | string | Yes | The subdomain to test, without the `.modulify.website` suffix. |