Developer Reference

Subdomain Finder

Explore Subdomain Finder API documentation, request parameters, response fields, code examples, and error handling for DomScan integrations.

Subdomain Finder

Return a best-effort set of public hostname evidence. The sources=ct parameter selects the compatibility pipeline, which tries crt.sh first and can fall back to HackerTarget, ThreatMiner, the Wayback Machine, and CertSpotter. DomScan does not brute-force names or crawl the target site, so the result is not a complete inventory. Cache-only misses return HTTP 202 and all-source failures return HTTP 503. Credits are refunded for both responses.

GET /v1/subdomains

Query Parameters

Parameter	Type	Description
domain required	string	Root domain to find subdomains for (e.g., "github.com")
prefer_cache optional	boolean token	Serve cached results only. If no fresh or stale cache exists, the API returns 202, queues a background refresh, and refunds the request credits. Accepted values: true, false, 1, 0, yes, and no. Default: false.
sources optional	string	Compatibility selector. Only `ct` is accepted. It starts the passive discovery pipeline, but each result reports the provider that supplied its evidence: `crtsh`, `hackertarget`, `threatminer`, `wayback`, or `certspotter`. Older cached entries may report `ct`.
verify optional	boolean token	Check DNS only for the names already selected for the response. Verification does not discover more names. Accepted values: `true`, `false`, `1`, `0`, `yes`, and `no`. Default: `false`.
include_wildcards optional	boolean token	Return wildcard certificate evidence in a separate `wildcards` array. Wildcards are not mixed into concrete hostname results. Accepted values: `true`, `false`, `1`, `0`, `yes`, and `no`. Default: `false`.
limit optional	integer	Maximum concrete hostname entries to return. Enter an integer from 1 through 2000. Default: 500.

Use Cases

Attack surface mapping and security audits
Review possible forgotten or shadow IT hostnames
Pre-acquisition technical due diligence
Competitive analysis of infrastructure
Bug bounty reconnaissance

Response Fields

Field	Description
`subdomains[].name`	Returned hostname. The apex can appear when a source includes it.
`subdomains[].source`	Provider that supplied the evidence. Possible values are crtsh, hackertarget, threatminer, wayback, certspotter, and legacy cached ct.
`subdomains[].first_seen`	For crt.sh and CertSpotter evidence, the earliest valid certificate not-before value found for the hostname. Passive fallback entries return null because those sources do not provide comparable certificate timing.
`subdomains[].verified`	True only when verify is enabled and DNS resolution succeeds for the returned hostname. Otherwise false.
`subdomains[].dns_records`	A and CNAME records from optional verification of the returned hostname, or null. This field does not add names to the result.
`summary.total_found`	Total concrete hostname entries found before the response limit, including the apex when a source includes it.
`summary.verified_count`	Number of returned hostnames that resolved during optional DNS verification.

HTTP Status Codes

HTTP Status Codes	Description
`200` OK	Request successful
`202` Accepted	Cache-only subdomain miss accepted for background refresh. No credits are charged; retry after the Retry-After delay.
`400` Bad Request	Invalid parameters
`402` Payment Required	Not enough credits to run this request.
`503` Service Unavailable	Upstream service unavailable or temporarily rate limited.
`504` Gateway Timeout	Upstream lookup timed out.

Example Request

curl -H "X-API-Key: your-api-key" "https://domscan.net/v1/subdomains?domain=example.com&sources=ct&include_wildcards=yes&limit=100"

curl -H "X-API-Key: your-api-key" "https://domscan.net/v1/subdomains?domain=example.com&sources=ct&verify=yes&limit=50"

curl -H "X-API-Key: your-api-key" "https://domscan.net/v1/subdomains?domain=example.com&prefer_cache=1"

import requests

domscan = requests.Session()
domscan.headers.update({"X-API-Key": "your-api-key"})

response = domscan.get(
    "https://domscan.net/v1/subdomains",
    params={
        "domain": "example.com",
        "sources": "ct",
        "verify": "yes",
        "include_wildcards": "yes",
        "limit": 100
    }
)
data = response.json()

print(f"Returned {data['summary']['returned']} hostname entries")
print(f"Verified: {data['summary']['verified_count']}")

live_subs = [s for s in data['subdomains'] if s['verified']]
for sub in live_subs[:10]:
    print(f"  {sub['name']}")

const domscanFetch = (url, options = {}) =>
  fetch(url, {
    ...options,
    headers: { ...options.headers, "X-API-Key": "your-api-key" },
  });

const response = await domscanFetch(
  'https://domscan.net/v1/subdomains?' + new URLSearchParams({
    domain: 'example.com',
    sources: 'ct',
    verify: 'yes',
    include_wildcards: 'yes',
    limit: '100'
  })
);
const data = await response.json();

console.log(`Returned ${data.summary.returned} hostname entries`);
console.log(`Verified: ${data.summary.verified_count}`);

data.subdomains
  .filter(s => s.verified)
  .forEach(s => console.log(`  ${s.name}`));

Example Response

{
  "domain": "example.com",
  "subdomains": [
    {
      "name": "api.example.com",
      "source": "crtsh",
      "first_seen": "2025-01-15T00:00:00Z",
      "verified": true,
      "dns_records": {
        "A": ["192.0.2.10"],
        "CNAME": null
      }
    }
  ],
  "wildcards": [
    {
      "pattern": "*.example.com",
      "source": "crtsh",
      "first_seen": "2024-11-20T00:00:00Z"
    }
  ],
  "summary": {
    "total_found": 1,
    "returned": 1,
    "verified_count": 1,
    "unverified_count": 0,
    "sources_used": ["crtsh"],
    "apex_included": false,
    "wildcard_suppressed_count": 1,
    "wildcard_returned_count": 1
  },
  "intelligence_summary": {
    "data_sources": ["crtsh"],
    "source_count": 1,
    "cache_status": "live",
    "returned_count": 1,
    "total_found": 1,
    "truncated": false,
    "limit": 100,
    "verification_requested": true,
    "include_wildcards": true,
    "verified_count": 1,
    "verified_ratio": 1,
    "live_dns_record_count": 1,
    "apex_included": false,
    "wildcard_suppressed_count": 1,
    "wildcard_returned_count": 1,
    "first_seen_oldest": "2025-01-15T00:00:00Z",
    "first_seen_newest": "2025-01-15T00:00:00Z",
    "warning_count": 0
  },
  "meta": {
    "query_time_ms": 184,
    "cached": false
  }
}

202 Accepted

{
  "status": "pending",
  "code": "CACHE_MISS_REFRESH_QUEUED",
  "message": "Try again in a moment",
  "domain": "example.com",
  "retry_after": 30,
  "credits_charged": 0,
  "billing_status": "not_charged",
  "request_id": "m8abc12-x9y8"
}

POST /v1/subdomains/bulk

Body Parameters

Parameter	Type	required
domains	string[]	required
verify	boolean	optional
include_wildcards	boolean	optional
limit	integer	optional

Response Fields

Field	Type
`results[]`	unknown[]
`meta`	object
`meta.total`	integer
`meta.succeeded`	integer
`meta.failed`	integer
`meta.max_items`	integer
`meta.credits_per_item`	integer
`meta.duration_ms`	integer

Example Request

curl -X POST "https://domscan.net/v1/subdomains/bulk" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: $DOMSCAN_API_KEY" \
  -d '{
  "domains": [
    "example.com",
    "cloudflare.com"
  ],
  "verify": false,
  "limit": 500
}'

Example Response

{
  "results": [
    null
  ],
  "meta": {
    "total": 1,
    "succeeded": 1,
    "failed": 1,
    "max_items": 10,
    "credits_per_item": 1,
    "duration_ms": 1
  }
}