# Site Strength API

> Returns Rankfield's 0–100 score for a domain's link strength, computed from PageRank and harmonic centrality on the Rankfield web graph. Use it to compare and sort domains. It is our own score, not Moz DA or Ahrefs DR.

Need who links, not how strong? Use [Referring Domains](https://rankfield.dev/endpoints/referring-domains).

- Page: https://rankfield.dev/endpoints/site-strength
- Full reference: https://rankfield.dev/docs/site-strength/get-site-strength

## Request

`GET https://rankfield.dev/v1/domains/{domain}/site-strength`

Send `Authorization: Bearer YOUR_API_KEY`. Get a free key at https://rankfield.dev/?tab=key#playground (no account).

```bash
curl "https://rankfield.dev/v1/domains/github.com/site-strength" \
  -H "Authorization: Bearer $RANKFIELD_API_KEY"
```

Response:

```json
{
  "domain": "github.com",
  "siteStrength": 100
}
```

## Parameters

| Name | In | Type | Required | Default | Description |
|---|---|---|---|---|---|
| `domain` | path | string | yes |  | 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: lowercase, without `www.`. |
| `inGraph` | boolean | Only when the domain isn't in our link graph yet: `false`, with zeros. Absent otherwise. |
| `siteStrength` | integer | 0 to 100. Higher means the domain is better linked across the web. |

## 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.
- Usually answers in under half a second.

## 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](https://rankfield.dev/endpoints/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`.

## MCP

Tools on https://rankfield.dev/mcp: `get_site_strength`.