Link building glossary

Toxic backlinks

Toxic backlinks is a label SEO tools give to links they predict could harm a site's rankings, such as links from spammy, irrelevant or link-selling sites. It is not a Google term: toxicity scores come from third-party tools, and Google says its systems usually ignore spammy links without the site owner having to act.

Reviewed by Gareth Hoyle, Managing Director
Last reviewed 31 October 2026

Where does the toxic score come from?

Each tool builds its own score. Semrush's Backlink Audit, for example, rates a domain's Overall Toxicity Score as high, medium or low depending on the share of backlinks its system marks as toxic: more than 10%, 3 to 9% or under 3%. Ahrefs' help centre calls toxic backlinks a term made up by certain SEO tools and notes that Google sets no metric or score threshold for spammy links. Google said in March 2024 that third-party reputation or authority scores do not correspond to any of its own signals.

What has Google said about toxic links?

John Mueller has addressed the idea several times.

January 2022, on Twitter: Google does not have a notion of toxic links, and some tools make assumptions about Google that are not correct
May 2024, on Reddit: the concept of toxic links is made up by SEO tools so that you pay them regularly
December 2024, on Bluesky: disavowing links that tools flag as toxic is a billable waste of time

When do bad links matter?

Since Penguin became part of the core algorithm on 23 September 2016, Google has said it devalues spam rather than demoting a whole site. The December 2022 link spam update used SpamBrain to neutralise unnatural links so the credit they pass is lost.

The exception is links built by you or for you: paid links that pass ranking credit, link networks and keyword-rich guest posts. These can lead to a manual action, shown in Search Console, and that is when Google recommends removal and the disavow tool. We judge a link profile by those patterns, not by a tool's score.

Example

A tool flags 1,200 links as toxic, mostly from scraper sites and auto-generated directories that copied the site's content. The site has no manual action and has never bought links. The right response is usually to do nothing.