Referring Domains API

Returns how many distinct domains link to a domain in the Rankfield web graph, and the 20 strongest of them with their Site Strength.

Need every linking domain, not the top 20? Use All Referring Domains.

GEThttps://rankfield.dev/v1/domains/{domain}/referring-domains

Send Authorization: Bearer YOUR_API_KEY. Get a free key; no account needed.

curl "https://rankfield.dev/v1/domains/github.com/referring-domains" \
  -H "Authorization: Bearer $RANKFIELD_API_KEY"

import os
import requests

response = requests.get(
    "https://rankfield.dev/v1/domains/github.com/referring-domains",
    headers={"Authorization": f"Bearer {os.environ['RANKFIELD_API_KEY']}"},
)
print(response.json())

const response = await fetch("https://rankfield.dev/v1/domains/github.com/referring-domains", {
  headers: {
    Authorization: `Bearer ${process.env.RANKFIELD_API_KEY}`,
  },
});
console.log(await response.json());

Response

{
  "domain": "github.com",
  "referringDomains": 748920,
  "topReferrers": [
    { "domain": "googleapis.com", "siteStrength": 100, "observations": 1 },
    { "domain": "google.com", "siteStrength": 100, "observations": 1 },
    { "domain": "youtube.com", "siteStrength": 100, "observations": 1 }
  ]
}

Parameters#

Name	Type	Description
`domain`path, required	string	A domain such as `github.com`. Case and a leading `www.` are ignored; a URL works too, URL-encoded.

Response#

Field	Type	Description
`domain`	string	The domain as we read it.
`inGraph`	boolean	Only when the domain isn't in our link graph yet: `false`, with zeros. Absent otherwise.
`referringDomains`	integer \| null	Distinct domains that link to it. `null` when the count is unavailable.
`topReferrers`	array	Up to 20 linking domains, strongest first: `domain`, `siteStrength` (0 to 100, or `null` when unscored) and `observations`.
`topReferrers[].observations`	integer	Always `1` today: one domain-to-domain connection. It is not a count of pages or backlinks.

Errors#

Errors come as {"error":{"message":"…"}} with the HTTP status.

Status	When
`400`	The domain is not valid: `{"error":{"message":"Invalid domain"}}`.
`401`	The key is missing, unknown or revoked.
`429`	Only while the graph service is down and its fallback is busy. Wait for `Retry-After`.
`503`	The graph is briefly unavailable. Retry after `Retry-After`.

Price and limits#

Free; no per-call charge.
No daily quota or concurrency cap per key.

Notes#

Data: the Rankfield web graph, built from public web crawl data of May–July 2026 (2026-may-jun-jul), 117,963,409 domains. Dataset Status tells you which release answered. A domain that isn't in our link graph yet answers 200 with "inGraph": false and zeros; the field is absent otherwise, and a malformed domain gets 400.