# Domain Metrics API — Rank, Authority & Referring Domains

> A domain metrics API returning rank, authority score, referring domain count, and outbound links for any domain in one call. REST + MCP, free tier included.

- Canonical page: https://backlinkmcp.com/domain-metrics-api
- MCP endpoint: `POST https://backlinkmcp.com/api/mcp` (JSON-RPC 2.0, streamable HTTP, no install, 13 tools)
- REST: `GET https://backlinkmcp.com/api/v1/authority?domain=example.com`, `/api/v1/backlinks?domain=example.com` ([docs](https://backlinkmcp.com/docs.md))
- Pricing: Free = 10 lookups/day per IP, 25 backlink rows, no signup. Pro = $19/mo, unlimited daily lookups, 100 rows, `ai_visibility_report` (operator-issued; self-serve checkout is not live)
- Data limits: the index is domain-level (referring domains with authority + outbound counts). No per-link URLs, anchor text or rel/dofollow. `domain_rating` is not Moz DA and not a Google factor
- Site index for agents: https://backlinkmcp.com/llms.txt

---

One call returns a domain's full metrics bundle — rank/authority score, referring domain count, and outbound links — instead of separate endpoints for each number.

Updated 2026-10-15

"Domain rank," "domain rating," and "domain authority" all describe the same kind of number across different tools. Here it's one field, `domain_rating`, returned alongside referring-domain and outbound-link counts in a single response.

Different SEO tools name their headline domain metric differently — Moz calls it Domain Authority, Ahrefs calls it Domain Rating, others call it "domain rank." They're all trying to answer the same question with one number: how much should a search engine or a careful reader trust this domain, based on who links to it. BacklinkMCP's version is `domain_rating`, an editorial-authority score weighted toward high-trust wiki, edu, gov, and news referrers, returned together with the referring-domain count and outbound-link count that give that score context.

## Try it

## The endpoint

```
curl "https://backlinkmcp.com/api/v1/authority?domain=stripe.com"
```

Response shape — every domain metric BacklinkMCP tracks, in one call:

```
{
  "ok": true,
  "authority": {
    "domain": "stripe.com",
    "found": true,
    "domain_rating": 80.9,
    "referring_domains": 702082,
    "links_out": 41
  }
}
```

## The metrics, field by field

Rank / authority

domain_rating

Link popularity

referring_domains

Hub signal

links_out

Data present?

found

- `domain_rating` — whichever term you're used to (rank, rating, authority), this is that number for this API.

- `referring_domains` — pair this with the score before drawing conclusions: a high rating on a handful of referring domains reads very differently than the same rating spread across thousands.

- `links_out` — outbound link count for the queried domain, a rough signal of whether it's a curated hub or a destination site.

- `found` — `false` if the domain has no inlinks on record. Not an error, just an uninteresting answer for very new or obscure domains.

For how `domain_rating` is actually computed — the editorial weighting that favors wiki/edu/gov/news referrers and why — see the [domain authority API](https://backlinkmcp.com/domain-authority-api) methodology page. This page is the fast reference for all four fields together; that one is the deep dive on the score itself.

For the ranked list of who's actually linking in — not just the count — see the [bulk backlink analysis API](https://backlinkmcp.com/bulk-backlink-analysis-api). For the full case against dashboard-first tools like Ahrefs, see the [Ahrefs alternative](https://backlinkmcp.com/ahrefs-alternative) comparison.

## Calling it from code

```
const r = await fetch(
  "https://backlinkmcp.com/api/v1/authority?domain=" + encodeURIComponent(domain)
);
const { ok, authority } = await r.json();
if (ok && authority.found) {
  console.log(authority.domain_rating, authority.referring_domains, authority.links_out);
}
```

Also exposed as the `domain_authority_score` MCP tool, so any MCP-aware agent can pull the full metrics bundle mid-conversation with zero integration code. See the [MCP install docs](https://backlinkmcp.com/docs#mcp-install).

## Rate limits and pricing

10 lookups/day per IP on the free tier, no signup. Unlimited on the [$19/mo Pro plan](https://backlinkmcp.com/pricing).

## Frequently asked questions

### What's the difference between "domain rank" and "domain authority" here?

Same underlying field — `domain_rating`. Different SEO tools call the same kind of number "rank," "authority," or "rating." Ours is a single roughly-0-to-100 editorial-authority score, weighted toward links from high-trust wiki, edu, gov, and news domains.

### What metrics does the API return for a domain?

`domain_rating` (rank/authority), `referring_domains`, `links_out`, and `found` — all in one response, described field by field above.

### Is this a live crawl or a stored index?

It reflects the current state of our link index, not a live crawl at request time. `verify_link_live` fetches a linking domain's homepage (not inner pages) to confirm a live href today.

### Do I need an API key?

Not for the free tier — 10 lookups/day per IP, no signup. A [Pro key](https://backlinkmcp.com/pricing) removes the daily limit.

### Can an AI agent pull these metrics without integration code?

Yes, via the `domain_authority_score` MCP tool, callable directly by any MCP-aware agent mid-conversation.

## Related tools & guides

[Domain authority API](https://backlinkmcp.com/domain-authority-api)
[Bulk backlink API](https://backlinkmcp.com/bulk-backlink-analysis-api)
[What is domain authority?](https://backlinkmcp.com/articles/what-is-domain-authority)
[MCP + REST docs](https://backlinkmcp.com/docs)