Referring domains is the count of unique websites that link to a domain. It's different from backlinks, which counts every individual link. If one blog links to you from 50 different pages, that's 50 backlinks but only 1 referring domain.
Why referring domains matter more than backlinks
Search engines value link diversity. Ten links from ten different websites signal broader trust than a hundred links from a single site. That's why referring domains is considered a stronger ranking signal than raw backlink count.
Think of it like recommendations. If one friend tells ten people you're a great developer, that's nice. But if ten different people independently vouch for you, that carries more weight. Same logic applies to links.
The quality of those referring domains matters too. A hundred referring domains from low-quality directories won't help much. But 30 referring domains from real businesses and respected industry blogs? That's a strong profile. And if some of those are .edu or .gov domains, even better.
Referring domains and expired domains
When looking at an expired domain, referring domains is one of the first things to check. A domain with 500+ referring domains built up over years represents real authority that's hard to replicate from scratch. It would take months or years of outreach and content marketing to earn those links organically.
But watch out for inflated numbers. Some domains have thousands of referring domains from spam networks or automated link building. Cross-reference with Trust Flow and dofollow percentage to verify the links are legitimate.
Referring domains on CatchDoms
CatchDoms shows referring domains in the RD column, pulled from DataForSEO and SEObserver. You can filter for domains with a minimum number of referring domains. And the domain score algorithm weights referring domains heavily when calculating overall quality.