Link Safety Check

Checks the domain of a URL against the CERT Polska Warning List of malicious domains, whose licence allows commercial use, and reports whether the domain or a parent domain is listed and the date of the list. A URL on no list is not proof it is safe: the list only holds domains that have already been reported, and it checks the domain, not the page.

POST https://YOUR_API_HOST/v1/link-safety

Credits and caching

• Per-call billing. 1 credit per URL checked (a check that cannot run is free). Every completed lookup is charged, found or not.
• Results are cached per account for 0 days. Repeating the same lookup in that window is free and returns cache_hit: true.
• Invalid input, rate limits and errors are never charged.
• Read the billing rules for the full picture.

Request

Send a JSON body with Authorization: Bearer <key>. The body can be up to 64 KB.

Example request

curl -X POST https://YOUR_API_HOST/v1/link-safety \
  -H "Authorization: Bearer $LOOKVALID_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"url":"https://example.com"}'

1const response = await fetch("https://YOUR_API_HOST/v1/link-safety", {
2  method: "POST",
3  headers: {
4    Authorization: `Bearer ${process.env.LOOKVALID_API_KEY}`,
5    "Content-Type": "application/json",
6  },
7  body: JSON.stringify({
8    "url": "https://example.com"
9  }),
10});
11​
12const result = await response.json();
13if (!response.ok) throw new Error(`${result.error.code}: ${result.error.fix}`);
14console.log(result.found, result.data, result.credits_charged);

1import os
2import requests
3​
4response = requests.post(
5    "https://YOUR_API_HOST/v1/link-safety",
6    headers={"Authorization": f"Bearer {os.environ['LOOKVALID_API_KEY']}"},
7    json={
8        "url": "https://example.com",
9    },
10    timeout=30,
11)
12result = response.json()
13if not response.ok:
14    raise RuntimeError(f"{result['error']['code']}: {result['error']['fix']}")
15print(result["found"], result["data"], result["credits_charged"])

Response

The status is 200 whether or not anything was found. Check found. Every response also carries the X-Request-Id, X-Credits-Charged, X-Credits-Remaining and X-RateLimit-* headers.

Envelope

The data object

Present when found is true, otherwise null.

Captured example (2026-10-18)

A real run of this lookup on 2026-10-18, using the request above, which is a public input. The envelope fields are left out.

1{
2  "product": "link-safety",
3  "found": true,
4  "data": {
5    "url": "https://example.com/",
6    "host": "example.com",
7    "verdict": "not_listed",
8    "matches": [],
9    "feeds_checked": [
10      {
11        "id": "cert-pl-warning-list",
12        "name": "CERT Polska Warning List of malicious domains",
13        "data_date": "2026-10-18T03:00:12.000Z",
14        "matched": false,
15        "licence": "Free for any purpose including commercial use (CERT Polska), no attribution required"
16      }
17    ],
18    "feeds_unavailable": [],
19    "disclaimer": "A URL on no list is not proof it is safe: the list only holds domains that have already been reported, and it checks the domain, not the page. A listed domain can be a compromised site that is now clean. Feeds that could not be checked are named under feeds_unavailable."
20  },
21  "sources": [
22    "CERT Polska Warning List of malicious domains (Free for any purpose including commercial use (CERT Polska), no attribution required), data of 2026-10-18"
23  ]
24}

Errors

• 400 invalid_input: The request input is invalid.
• 401 unauthorized: The API key is missing, malformed, revoked or unknown.
• 402 insufficient_credits: The account does not have enough credits for this lookup. Error code: insufficient_credits. During a trial whose allowance is used up the code is trial_allowance_exhausted: nothing is charged and the customer starts the plan from the billing page.
• 405 method_not_allowed: This endpoint does not accept that HTTP method.
• 413 payload_too_large: The request body is too large.
• 429 rate_limited: Too many requests for this API key.
• 500 internal_error: An unexpected error occurred.
• 503 provider_unavailable: The data source for this product is unavailable right now.