Domain Rating, Domain Authority, Authority Score, Trust Flow, and the rest are numbers invented and calculated by SEO software companies. They mostly estimate the size and quality of a site’s backlink profile, meaning the links pointing to it from other websites. Google doesn’t publish any site-wide score like this, and Google’s documentation states that third-party tools have no access to its internal ranking data. These numbers are useful for comparison and useless as a target.
In plain English
Think of a credit score invented by a company your bank has never heard of.
The company is serious. It looks at real financial behavior, applies a consistent formula, and produces a number between 0 and 100. Comparing two applicants on that number tells you something real about how they differ.
But the bank doesn’t see it. The bank has its own information, far more of it, and makes its own decision. If you spend a year optimizing the number instead of your finances, you’ve optimized for the wrong audience.
That’s what these scores are. Real measurements of something, produced by a company that isn’t the one making the decision.
What they actually measure
Each vendor crawls the web with its own software and builds its own index of links. From that, it estimates how much link support a site has and how good that support looks. The exact formulas aren’t published.
Because each company crawls a different portion of the web and weighs what it finds differently, the same site can score noticeably differently across tools. None of them is lying. They’re measuring their own index, not the web, and certainly not Google’s view of the web.
Most of these scores also run on a curve, so moving from 20 to 30 is far easier than moving from 60 to 70. A score that hasn’t moved in six months isn’t necessarily evidence that nothing happened.
What they can’t tell you
Google’s published guidance on third-party tools is direct on this point: Google doesn’t evaluate third-party services, those services have no access to Google’s internal ranking data, and they can’t guarantee performance. Any prediction a tool makes is its own, and as Google puts it, like predictions generally, may not happen.
So these scores can’t tell you whether Google trusts your site, whether you’ll outrank a competitor, or whether a particular link helped. Anything presenting them as a Google measurement is either mistaken or selling something.
Google’s guidance also covers tools that promise better performance in AI answers, sometimes marketed as AEO or GEO tools. The same caution applies, in Google’s own wording as well as ours.
Where they are still useful
They’re genuinely good at one job: sorting. If you’re looking at 200 sites that link to a competitor and deciding which 10 to look at first, a score gets you a rough ordering in seconds. That’s off-page triage, and it’s the job they were built for.
They’re also reasonable for tracking direction over a long period. If the number has climbed steadily across two years while your traffic climbed too, that’s consistent. It isn’t proof of anything on its own.
What people usually get wrong
“Our DA went up, so SEO is working.” The score moved inside one vendor’s index. Check whether clicks and inquiries moved.
“We need DR 50 links.” No such threshold exists at Google. A relevant link from a small, real site in your field is worth more than a high-scoring link from a site with no connection to what you do.
“Our score dropped, we’ve been attacked.” Vendors recrawl and adjust their formulas. Score drops with no matching change in traffic are usually the vendor, not your site.
“This proposal guarantees DR 40 in six months.” That’s a promise about a number the seller can influence directly through link buying, which is against Google’s spam policies. Treat it as a warning rather than a commitment.
What you can do about it
Use the scores to sort and compare. Don’t set them as goals.
If a report leads with these numbers, ask what happened to clicks and inquiries in the same period.
Keep Google Search Console as your reference point for anything about your own site, since it’s the only source reporting what Google actually did. Google recommends the same thing at the end of its guidance, and it’s worth knowing that the recommendation comes from them rather than from us.
When a score and your actual numbers disagree, believe the actual numbers.
Google’s guidance on third-party SEO tools and advice is short and worth reading in full if someone has quoted a score at you.
Words you will hear
Backlink. A link pointing to your site from another website.
Backlink profile. The full set of links pointing to your site, and what they look like taken together.
Index (of a tool). The portion of the web that one company’s crawler has found and stored. Every tool has a different one.
Logarithmic scale. A scale where each step up takes much more than the last, which is how most of these scores behave.
For link profile, nofollow and paid links, see What is off-page SEO? For where these numbers sit among everything else, see How SEO is measured.
