Domain spam score is an estimate of how closely a site resembles spam resources: whether it sells links to anyone who pays, has a toxic link profile, or has been hit by search engine penalties. There is no single “official” metric: Moz calculates Spam Score as a percentage, Semrush flags toxic markers, and Majestic shows the imbalance between Trust Flow and Citation Flow. A high spam score is a signal to drop the donor, because a link from it will at best do nothing and at worst do harm.
Key points in 30 seconds
- Spam score isn’t one number but a set of signals: tool metrics, content, outbound links, domain history.
- A Moz Spam Score up to 30% is considered low; above 60% is high risk.
- The most visible sign: hundreds of outbound links to off-topic commercial sites.
- Google simply ignores most spammy links, but mass placement on such donors is money down the drain.
- The check takes 10 minutes: the site: operator, referring domain charts, anchors, traffic, Wayback.
What domain spam score is and why it matters
A link passes your site not only link equity but also the donor’s “reputation”. If the donor is a site that lives off selling links, with an overoptimized anchor profile and low-quality content, Google’s algorithms (including the SpamBrain system) learn to recognize such sites and devalue all links from them.
Consequences of buying links on spammy donors:
- the links aren’t counted: budget spent, no effect;
- the link profile looks unnatural, which makes further promotion harder;
- with mass placements, there’s a risk of a manual action for buying links;
- spammy donors often drop out of the index, and the links disappear along with them.
How different tools measure spam score
| Tool | Metric | How it works | What counts as a red flag |
| Moz | Spam Score, 1–100% | The percentage of sites with the same signals (out of 27) that were penalized by Google | Above 60% |
| Semrush | Toxic markers / Authority Score | Flags links and domains with signs of manipulation | Many toxic markers in the donor’s profile |
| Majestic | TF/CF | Imbalance between link quality and quantity | TF/CF below 0.3–0.5 |
| Ahrefs | No dedicated metric | Assessed by the referring domains chart, anchors and traffic | Spikes in referring domains, spammy anchors, traffic drops |
None of these metrics is a verdict: a niche forum can have a Spam Score of 35% due to its specific structure, while a site with 5% can be an outright link farm. Metrics are a reason to take a closer look, not a ready answer. More on authority metrics in the article DR, DA and Trust Flow.
12 signs of a spammy donor
- Pages carry dozens of outbound links to off-topic commercial sites.
- A separate section or category of “partner content” with no moderation at all.
- The site is “about everything”: home repair, crypto, medicine and casinos on one page.
- High DR or DA with almost zero organic traffic.
- A sharp jump in the number of referring domains over a short period.
- The donor’s anchor list includes casino, pharma, adult, loans, “buy backlinks”.
- Low-quality content: rewrites, machine translation, texts with no structure.
- Pages are poorly indexed or the site has partially dropped out of the index.
- A sharp traffic drop after a Google update.
- The domain has changed topic or owner (visible in the Wayback Machine).
- No contact details, “About us” page or article authors.
- Marketplace footprints: identical article and link templates across hundreds of sites.
How to check a donor’s spam score in 10 minutes
- The site: operator: enter
site:domain.comin Google. Compare the number of indexed pages with the actual size of the site; look at the latest posts. - Referring domains chart in Ahrefs or Semrush: look for sharp spikes rather than steady growth.
- Donor anchors: if casino, pharma or “buy” dominate the top anchors, the donor sells links to everyone.
- Organic traffic: it should be real and stable; a collapse after an update is a warning sign.
- Outbound links: open 3–5 recent articles and count the external links and their topics.
- Domain history: check in the Wayback Machine what the site was 2–5 years ago.
- Automated check: our free donor checker pulls domain age, archive history, Tranco rank, noindex, number of outbound links and traces of link selling into a single report.
What spam score is acceptable
| Moz Spam Score | Risk | Decision |
| 1–30% | Low | OK to use if other metrics look fine |
| 31–60% | Medium | Check manually: outbound links, traffic, content |
| 61–100% | High | Drop the donor |
For forum crowd links, moderation matters more than the number: a live forum with active moderation is almost always safe, even if its Spam Score is medium. That’s exactly why we place crowd links only on live platforms with real discussions.
What to do if spammy links already point to your site
Don’t panic: every site picks up spammy links over time, and Google simply ignores most of them. Take action if:
- you received a manual action for unnatural links in Google Search Console;
- you see a mass attack: hundreds of new spammy domains within a few days (see negative SEO);
- you yourself once bought links on spammy marketplaces and your rankings dropped.
In these cases, compile a list of toxic domains and disavow them with the Disavow tool. How to tell harmful links from merely weak ones is explained in the article which links hurt your site.
Bottom line
Domain spam score isn’t a number in a tool but a picture made up of a dozen signals. Check the donor before you pay, not after: that way you save budget and don’t pollute your link profile. Start with a donor check, compare the metrics and the domain’s history, and only then place links.
