Free Domain Authority API for Developers

Crawly's free domain authority API lets you query DA scores, referring domain counts, backlink totals, and spam scores for any domain programmatically. No credit card required. 100 requests per day on the free tier.

The API is designed for developers who need SEO data baked into their own tools: rank trackers, agency dashboards, prospecting scripts, or internal reporting pipelines.

What does the domain authority API return?

A single request to /api/v1/domain-authority returns:

• Authority score: a 0–100 score reflecting the strength of the domain's backlink profile
• Referring domains: the number of unique domains linking to the target
• Total backlinks: the total number of inbound links across all referring domains
• Harmonic rank: a ranking based on the harmonic centrality of the domain across the web graph
• PageRank rank: an estimated PageRank-based ranking position

{
  "domain": "example.com",
  "summary": {
    "referring_domains": 1284,
    "total_links": 9430
  },
  "score": {
    "harmonic_rank": 124500,
    "harmonic_score": 0.81,
    "pagerank_rank": 892000,
    "host_count": 460
  }
}

How to get your free API key

1. Go to getcrawly.com/api
2. Enter a project name and email address
3. Your API key is generated instantly, no verification step required

The key format is crawly_live_xxxxxxxxxxxxxxxx. Pass it as a Bearer token in the Authorization header, or as a key query parameter.

Making your first request

curl

curl "https://www.getcrawly.com/api/v1/domain-authority?domain=example.com" \
  -H "Authorization: Bearer crawly_live_your_key"

JavaScript

const res = await fetch(
  "https://www.getcrawly.com/api/v1/domain-authority?domain=example.com",
  { headers: { Authorization: "Bearer crawly_live_your_key" } }
);
const data = await res.json();
console.log(data.summary.referring_domains);

Python

import requests

res = requests.get(
    "https://www.getcrawly.com/api/v1/domain-authority",
    params={"domain": "example.com"},
    headers={"Authorization": "Bearer crawly_live_your_key"},
)
data = res.json()
print(data["summary"]["referring_domains"])

Common use cases

Link prospecting scripts

When building a list of link prospects, you want to filter quickly by authority before spending time on manual review. A short script can loop through a list of domains, query the API for each one, and output only those above your threshold:

import requests, time

domains = ["site-a.com", "site-b.com", "site-c.com"]
key = "crawly_live_your_key"

for domain in domains:
    res = requests.get(
        "https://www.getcrawly.com/api/v1/domain-authority",
        params={"domain": domain},
        headers={"Authorization": f"Bearer {key}"},
    )
    data = res.json()
    rd = data["summary"]["referring_domains"]
    print(f"{domain}: {rd} referring domains")
    time.sleep(0.5)  # respect rate limits

Agency client dashboards

Build a dashboard that monitors your clients' domain authority over time. Query the API monthly, store the results, and chart the trend. The API returns consistent JSON across requests, making it straightforward to pipe into any database or spreadsheet.

CRM enrichment

If your sales team works a list of prospects, enriching each domain with referring domain count and authority score gives them context on whether a company has an established web presence. A simple enrichment script can add this data to any CSV export.

Backlink audit tooling

Combine the domain authority endpoint with the backlinks endpoint and spam score endpoint to build a lightweight backlink auditing tool. Query each referring domain for its authority and spam score, then flag anything above your spam threshold for manual review.

Rate limits

Tier	Requests per day	Reset
Free	100	Every 24 hours

100 requests per day covers most individual use cases: prospecting lists, monthly client reports, and ad hoc research. For higher volumes, contact us at getcrawly.com/contact.

Also available: spam score and backlinks

The same API key gives you access to two additional endpoints:

• /api/v1/spam-score: returns a 0–100 spam risk score for any domain
• /api/v1/backlinks: returns the full backlink profile including individual referring domains and outbound links

All three endpoints share the same authentication model and rate limit pool.

See the full API documentation for endpoint references, response schemas, and error codes.

---

Get your free API key at getcrawly.com/api. No credit card, no verification, 100 requests per day.