Build with web signals.

Get your API key

Open the API key panel and click Copy. No sign-up needed.

Make your first request with curl

In the API workspace, enter a domain and click Copy beside the request. Paste the command into your terminal and run it. Your key is included.

A successful response contains the normalized domain and its 0–100 Site Strength score. Values below are illustrative:

{
  "domain": "example.com",
  "siteStrength": 42
}

Call the API from JavaScript or Node.js

Use the built-in fetch API. Keep the key in an environment variable when running a server-side script.

const apiKey = process.env.API_KEY;
const response = await fetch(
  "https://api.example.com/v1/domains/example.com/site-strength",
  { headers: { Authorization: `Bearer ${apiKey}` } }
);

if (!response.ok) {
  throw new Error(`API request failed: ${response.status}`);
}

const data = await response.json();
console.log(data.siteStrength);

In a browser app hosted on another origin, call your own backend and have it add the bearer header. The API does not enable cross-origin requests.

Call the API from Python

This example uses the standard library, so no package installation is needed.

import json
import os
from urllib.error import HTTPError
from urllib.request import Request, urlopen

url = "https://api.example.com/v1/domains/example.com/referring-domains"
request = Request(
    url,
    headers={"Authorization": f"Bearer {os.environ['API_KEY']}"},
)

try:
    with urlopen(request) as response:
        data = json.load(response)
except HTTPError as error:
    print(error.code, error.read().decode())
    raise

print(data["referringDomains"])

Use both metrics in one workflow

Request Site Strength and referring domains for the same domain.

curl -s \
  -H "Authorization: Bearer $API_KEY" \
  "https://api.example.com/v1/domains/example.com/site-strength"

curl -s \
  -H "Authorization: Bearer $API_KEY" \
  "https://api.example.com/v1/domains/example.com/referring-domains"

Use siteStrength as a score on the 0–100 scale. Use referringDomains as the observed count when it is available.

Connect an AI agent

Give your agent the Rankfield onboarding skill. It explains how to issue an accountless key, call both GET endpoints, and use the MCP tools.

curl -sS https://api.example.com/agent-onboarding/SKILL.md

For MCP clients that support remote Streamable HTTP, use https://api.example.com/mcp with Authorization: Bearer <key>. Available tools are get_site_strength and get_referring_domains; each accepts a root domain. Replace api.example.com with the host serving this API.

Opening /mcp in a browser sends GET and shows connection instructions. To call a tool, your MCP client sends an authenticated JSON-RPC POST request.

Handle authentication errors and missing data

401 — invalid or missing key

Check that the key is active and that the header is exactly Authorization: Bearer <key>. The response shape is {"error":{"message":"A valid API key is required"}}.

404 — domain not in the current graph

The current Common Crawl graph has no result for that domain. Check the domain spelling and try a domain present in the crawl. The response shape is {"error":{"message":"Domain was not found in the current Common Crawl graph"}}.

A successful response with a null referring domain value

A graph result may exist even when the referring-domain count pack is unavailable. In that case referringDomains is null. Preserve it as unavailable; do not convert it to zero.

Site Strength responses contain a domain and score. Referring domain responses also include topReferrers, with each source domain's Site Strength and observations. An unavailable count or source score is null.

Keep your key safe

• Do not commit the key or paste it into public issues, logs, screenshots, or shared code.
• For scripts, load it from an environment variable or a secret store. Do not embed it in browser JavaScript or a public mobile app.
• Send it only in the HTTPS Authorization header. Avoid putting keys in URLs, where they can appear in history and logs.