Spam Score is a metric from the SEO software company Moz that estimates, as a percentage, how closely a website resembles sites Moz has found to be penalised or banned by Google. It is a prediction based on shared features, not a measurement of anything Google itself holds.
How Spam Score works
Moz studied large numbers of sites that had been penalised or dropped from Google’s index and looked for features they had in common, then built a model from them. When it scores a site, it checks how many of those features the site shares and expresses the result as the percentage of sites with a similar profile that Moz found penalised. A score of 60% does not mean the site is 60% spam; it means that in Moz’s data, six in ten sites with similar characteristics had been penalised or banned.
The signals involve things such as a thin or unusual link profile, very little content, a lack of contact information and patterns typical of link networks. Moz groups the results as low (1 to 30%), medium (31 to 60%) and high (61 to 100%). You will see it in Moz Link Explorer and the MozBar extension, often alongside Domain Authority.
Why it matters
For anyone building or reviewing links, Spam Score is a quick way to sort a long list. If you have 800 referring domains to look at after a previous agency’s work, scoring them first tells you which ones deserve a closer manual check. When prospecting for new links, a high score is a reason to look twice before spending time on outreach to that site.
Its limits matter just as much. It is a third-party estimate built on correlation. A genuine local site, such as a parish council page or a small club in Yorkshire with a dated design and few links, can score high while being exactly the kind of relevant, real link a local business should want.
It is also a sensible check before agreeing to any paid sponsorship or partnership that involves a link. If a site asking for payment for a “feature” has a high Spam Score, thin content and outbound links to unrelated casinos and loan companies, that tells you what kind of neighbourhood your link would sit in.
Common mistakes
- Disavowing on the score alone. Bulk-uploading every high-scoring domain to a disavow file can throw away genuine links.
- Treating it as Google’s view. Google does not see, use or publish Spam Score.
- Worrying about your own score in isolation. A new site with few links can show a medium score simply because it looks thin to the model.
- Using it as the only quality filter. Relevance, real traffic and whether the page has an editorial reason to link matter more.
How to act on it
Use Spam Score to prioritise, then judge each site by eye. Open the linking page and ask simple questions: is it a real business or publication, is it relevant to your field or area, does it show signs of selling links, and is it part of an obvious network such as a private blog network? Those answers decide what you do, not the number.
For your own site, a high score is a prompt to check your backlink profile and the basics of the site itself: clear contact details, real content, and no history of bought links. If you want a second opinion on a link profile or a plan for earning links that will hold up, that is part of my link building work.