# Associated Domain Finder

Finds domains associated with a domain: same registrant email, organization or phone, same name servers, IP, mail servers or SSL organization.

Source: https://docs.deepinfo.com/reference/discovery/associated-domain-finder/

Last updated: 2026-09-27

---
`GET https://api.deepinfo.com/v1/discovery/associated-domain-finder`

Finds domains associated with a domain: same registrant email, organization or phone, same name servers, IP, mail servers or SSL organization. Choose the `association` type(s); `strict` requires every association to match.

## Authentication

Send your API key in the `apikey` request header.

## Query Parameters

| Parameter | Required | Description | Example |
|---|---|---|---|
| `domain` | Required |  | `deepinfo.com` |
| `page_size` | Optional | Min `25`, max `100`. Default `100`. | `25` |
| `ordering` | Optional |  |  |
| `export` | Optional | Default `false`. |  |
| `export_format` | Optional | One of: `json`, `csv`. |  |
| `export_scope` | Optional | One of: `basic`, `default`, `extended`. |  |
| `association` | Optional |  |  |
| `strict` | Optional | Default `false`. |  |
| `include_subdomains` | Optional | Default `false`. |  |
| `page` | Optional | Min `1`, max `400`. Default `1`. | `1` |

## Response Fields

| Field | Type | Description |
|---|---|---|
| `page` | integer |  |
| `page_size` | integer |  |
| `result_count` | integer |  |
| `results` | array of object |  |
| `domain` | string |  |
| `requested_association_parameters` | array of string |  |
| `applied_association_parameters` | array of string |  |
| `results[].punycode` | string |  |
| `results[].unicode` | string |  |
| `results[].is_idn` | boolean |  |
| `results[].subdomain` | object |  |
| `results[].subdomain_last` | object |  |
| `results[].subdomain_root` | object |  |
| `results[].name` | object |  |
| `results[].domain` | object |  |
| `results[].type` | integer |  |
| `results[].subdomain_level_count` | integer |  |
| `results[].dns` | object |  |
| `results[].dns_last_change_date` | string | date-time |
| `results[].ip_history` | array of string |  |
| `results[].ssl` | object |  |
| `results[].ssl_last_change_date` | string | date-time |
| `results[].webdata` | object |  |

Paginated. See [Getting Started → Pagination](/getting-started/pagination/).

## Response Schema

_Inferred from examples._ Built from the saved 2xx example response: the fields it contains, with the types seen there. It is not a contract.

| Field | Type |
|---|---|
| `page` | number |
| `page_size` | number |
| `result_count` | number |
| `results` | array |
| `domain` | string |
| `requested_association_parameters` | array<string> |
| `applied_association_parameters` | array |

## Examples

### 200 · OK

```bash
curl 'https://api.deepinfo.com/v1/discovery/associated-domain-finder?domain=deepinfo.com&page_size=25' \
  -H 'apikey: YOUR_API_KEY' \
  -H 'Accept: application/json'
```

`Content-Type: application/json` · `deepinfo-request-id: 5f0c6a8e-1b2d-4c3e-9f4a-7b8c9d0e1f2a`

```json
{
  "page": 1,
  "page_size": 25,
  "result_count": 0,
  "results": [],
  "domain": "deepinfo.com",
  "requested_association_parameters": [
    "whois_registrant_email",
    "whois_registrant_email_apex_normalized"
  ],
  "applied_association_parameters": []
}
```

### 400 · Invalid Parameter (invalid export=notabool)

```bash
curl 'https://api.deepinfo.com/v1/discovery/associated-domain-finder?export=notabool&domain=deepinfo.com' \
  -H 'apikey: YOUR_API_KEY' \
  -H 'Accept: application/json'
```

`Content-Type: application/json` · `deepinfo-request-id: 5f0c6a8e-1b2d-4c3e-9f4a-7b8c9d0e1f2a`

```json
{
  "code": 10400,
  "parameters": [
    {
      "param": "export",
      "details": [
        "Must be a valid boolean."
      ]
    }
  ],
  "solution": "https://docs.deepinfo.com/reference/"
}
```

## Worked Examples

Worked examples of this endpoint, each on its own page with the exact request and its response: [Associated Domain Finder Examples](/reference/discovery/associated-domain-finder/examples/).

- [Domains Associated With a Domain](/reference/discovery/associated-domain-finder/examples/default/): Every association type for paypal.com: 3,334 related domains, found through registrant organization, name servers, mail servers and certificate.
- [Every Association Must Match (Strict)](/reference/discovery/associated-domain-finder/examples/strict/): With strict=true, every applied association must match: 29 domains for paypal.com instead of 3,334.
- [Same Registrant Organization](/reference/discovery/associated-domain-finder/examples/whois-registrant-organization/): The domains registered to the same organization as paypal.com (“paypal inc.”): 3,187.