Where our data comes from
Updated
The short answer
Every report shows the official Moz Domain Authority, Page Authority and Spam Score, and the official Majestic Trust Flow and Citation Flow, unchanged from what Moz and Majestic report. When link data isn't available for a domain, we show a clearly labelled minimum estimate instead: 65% link popularity, 20% website age and 15% technical health. Every report says which one you're looking at.
The metrics
- Domain Authority (DA) predicts how well a whole domain can rank, from 0 to 100.
- Page Authority (PA) is the same prediction for the homepage.
- Trust Flow (TF) measures link quality: how closely a site is linked to trusted seed sites.
- Citation Flow (CF) measures link volume, regardless of quality. A TF/CF ratio well below 0.5 often points to low-quality backlinks.
- Referring domains and backlinks count the unique sites and total links pointing at a domain.
The fallback minimum estimate
| Input | Weight | How it becomes 0 to 100 |
|---|---|---|
| Link popularity | 65% | Link strength from our backlink index, scaled to 0 to 100. |
| Website age | 20% | Years since the domain was registered, from its live WHOIS record. When a registry hides the date, we use the date the site was first seen online. Logarithmic curve reaching 100 at 25 years. |
| Technical health | 15% | Share of eight checks passed: DNS, HTTPS, HTTP-to-HTTPS redirect, HSTS, a 200 homepage, a response within 1500 ms, robots.txt and an XML sitemap. |
When data is missing
Links are what authority means, so if link data can't be measured it counts as zero and the result is shown as a minimum (“35+”), never as a rating. If website age is missing, it's left out and the other weights are scaled up to add to 100%. We never fill gaps with guesses.
WHOIS and website age
Every check reads the domain's live registration record straight from the registry: registrar, registration, update and expiry dates, name servers, status codes and DNSSEC. Personal registrant details are usually redacted for privacy, and we show them only when the registry publishes them.
Limitations
No backlink index sees the whole web, and no public score is used by Google. Different tools crawl different links, so compare sites within one tool rather than across tools. Treat Domain Authority and Trust Flow as measures of competitive strength, not a verdict on quality.
Our crawler
Live checks request at most four URLs per domain (the homepage over HTTPS and HTTP, robots.txt and the sitemap) and identify as FDACBot. Results are cached for six hours to keep load on checked sites low.
Ready to try it? Check a domain.