Domain Authority is a score from 1 to 100, published by the search engine optimisation (SEO) software company Moz, that estimates how likely a website is to rank in search results compared with other websites. It is built almost entirely from links: how many separate sites point to a domain, how strong those sites are and whether the pattern looks natural. The score exists because Google has never published a site-level measure of strength, while marketers wanted a common yardstick for comparing competitors, choosing where to seek links and pricing placements.

Domain Authority, shortened to DA, is Moz's forecast rather than Google's, and the company states that it has no effect on search results. Google applies the same caveat to every such score. "Third-party tools don't have access to our internal ranking data," its Search Central documentation reads.

How the score is built

Moz crawls the web to build its own link map, the index behind its Link Explorer tool, which held more than 35 trillion links when the current model launched in 2019. From that graph it extracts domain-level features. The most important is linking root domains, the count of distinct sites linking in: many links from one site count for less than single links from many sites. Total link volume, the strength of the linking sites and manipulation signals from Moz's separate Spam Score metric are also fed in.

Those features go into a machine-learning model, a neural network since March 2019. Trained against real Google results, it learns which link profiles belong to domains that tend to outrank rivals across thousands of search engine results pages (SERPs), then scores every domain in the index on that pattern. The output is squeezed onto a scale that is not linear. According to Moz, climbing from 20 to 30 is considerably easier than climbing from 70 to 80, and every new site starts at 1.

Because the score is relative, it can fall without a domain losing a single link. Moz's own illustration is that if Facebook acquired a billion new links, other sites' scores would drop against it.

DA reaches users through Moz Pro, the free MozBar extension and the Moz application programming interface (API). Screaming Frog's SEO Spider moved to version 3 of that API in June 2025, adding Brand Authority and Spam Score alongside DA and Page Authority.

Both sides of a market rely on it. Buyers of visibility - SEO agencies, in-house teams and public relations (PR) staff - use DA to shortlist outreach targets, report link-building progress and screen domains before purchase. Sellers price by it. Rhino Rank, a UK link-building firm, tiers guest posts by the minimum DA of the host site, from $75 per placement at DA10+ to $400 at DA60+, according to the company. Expired-domain brokers quote it as a guide to what a lapsed site's old links might still carry.

Origin and evolution

Links were a ranking signal long before any third-party score. Lycos was counting inbound links in 1996, and Google launched in 1998 with PageRank, which captures a page's quality and authoritativeness from the frequency and importance of the links pointing to it. Google long displayed a coarse 10-point version in its browser toolbar, a public grade for SEO practitioners until its retirement in 2016.

Moz, founded in Seattle in 2004 as SEOmoz by Rand Fishkin and Gillian Muessig, built a commercial substitute on its own index. The launch date is disputed. Search Engine Land found in 2023 that some accounts date the first release to 2006, which Moz could not confirm. When Moz announced a rebuilt model on February 5, 2019, Sarah Bird, then chief executive, said the old version had "served the industry well for more than eight years", which dates it to early 2011 at the latest.

In 2018 Link Explorer replaced Open Site Explorer, Moz's link tool since 2008, with an index the company said was 35 times larger and 30 times fresher. Domain Authority 2.0 went live on March 5, 2019. It swapped a linear model for a neural network and folded in Spam Score and patterns of link quality and traffic; Russ Jones, then Moz's principal search scientist, said it was designed to weed out manipulation. Page Authority, the page-level counterpart, was rebuilt the same way on September 30, 2020.

Ownership changed on June 4, 2021, when iContact, a unit of J2 Global, acquired Moz; J2 renamed itself Ziff Davis later that year. Rivals had their own scores by then, among them Ahrefs' Domain Rating (DR). Semrush rebuilt its Authority Score on January 31, 2023 to weigh estimated organic traffic and spam signals alongside links. Moz added Brand Authority on August 7, 2023, a 1-100 measure based mainly on branded search demand.

Why marketers track it

The appeal is compression: a competitive gap reduced to one number. When a teenager trying to rescue a family holiday-rental business sought help on Reddit's r/bigseo forum in March 2026, the site's score of about 13 framed the contest with Booking.com and Airbnb more starkly than any audit could.

Moz has used the metric to read Google's own updates. A September 2024 study by Tom Capper, Moz's head of search science, found that sites hurt by the helpful content update (HCU) had DA-to-Brand Authority ratios of about 2:1, against 1.4:1 for other sites. Link strength unmatched by brand demand offered little protection.

The idea also runs through media economics. On March 5, 2024, Google introduced spam policies against expired domain abuse and site reputation abuse, the latter aimed at third-party pages that borrow a host site's standing. A November 2024 revision made first-party oversight no defence. Research published in April 2025 found that 16 media companies dominate Google results partly by launching new properties on the strength of established domains. Much of that content is sponsored or affiliate material, tying a link-graph metric to how publishers sell space.

Limits, criticisms and disputes

Google's position is the first difficulty. "We don't have anything like a website authority score," Mueller said in 2016. In a late 2020 interview he allowed that some of Google's site-level metrics "might kind of map into similar things", and on January 28, 2022 he wrote: "We don't count links on a domain level." The May 2024 leak of Google's Content Warehouse API documentation muddied that record. The material included a field named siteAuthority among some 14,000 attributes, and Google confirmed the documents were authentic on May 29, 2024. What the field measures is unknown; analysis on the Ahrefs blog judged a link-based reading plausible but unproven.

Granularity is the second. Gary Illyes of Google said on October 2, 2026 that core updates target content at page level rather than domain level, according to a recap of his Barcelona talk. ClickUp shows how far a domain score can drift from outcomes: its blog lost 97.6% of its organic traffic between January 2025 and April 2026, while the domain's Domain Rating rose from 87 to 90. On one contested keyword, a DR 46 site outranked it.

Manipulation is the third. Inputs a tool can see are inputs that can be bought. Ahrefs has acknowledged on its blog that black-hat operators inflated DR with link spam and profited from it, and listings on the freelance marketplace Fiverr offer to lift a site to DR 70 from $50. Google, by contrast, discounts links without announcing it. SpamBrain has targeted both buyers and sellers of links since December 14, 2022, and Pedro Dias, a former Google spam engineer, has described silent actions that stop a site from passing PageRank. No third-party index sees those decisions, so a seller's DA can stay high after Google has stopped counting its links.

Validity remains open. A peer-reviewed study published in 2023 found that DA, Semrush's Authority Score and Ahrefs' DR agree closely, with a rank correlation of about 0.9. Agreement between tools is not agreement with Google. A study of more than 40,000 sites in the catalogue of Collaborator, a placement marketplace, put the correlation between DA and traffic at 0.238 in August 2026, as summarised by Rhino Rank.

Not the same as

Domain authority, in lower case, is the generic idea of a site's overall strength, also called website authority. Ahrefs uses the phrase that way; the capitalised name refers only to Moz's metric.

Page Authority (PA) is Moz's prediction for a single page on the same 1-100 scale. A strong domain can still host weak pages.

Domain Rating and Authority Score (AS) are competing scores. Ahrefs' DR is purely link-based, and each linking domain splits its strength equally among the sites it links to, so a DR 10 site linking to three domains can outweigh a DR 80 site linking to a million. Semrush's AS adds traffic and spam checks and is refreshed every two weeks.

PageRank and the leaked siteAuthority field are Google's internal signals. Moz can observe neither.

Recent developments

Google hardened its line on June 5, 2026 with a new Search Central page warning that some users mistake third-party tool data for Google's own.

Evidence from artificial intelligence (AI) search is also unflattering. Cyrus Shepard's review of 54 studies placed domain authority in the bottom tier of 23 factors associated with AI citations. In July 2025, Reboot Online steered answers in ChatGPT and Perplexity using ten expired domains with a DR below 5. And a Semrush study published in September 2026 found that engineerfix.com, the domain AI systems cited most often in manufacturing, carries an Authority Score of 17, against 77 for made-in-china.com.

As of October 2026, no successor to Domain Authority 2.0 had been announced. Moz now applies DA to the domains cited in AI answers it tracks, according to a review by Style Factory.

Timeline

  • 1996: Lycos measures how many links point to a page as a relevance signal
  • 1998: Google launches with PageRank as its central link-based signal
  • 2004: SEOmoz is founded in Seattle by Rand Fishkin and Gillian Muessig
  • 2006 to early 2011: Domain Authority is first released, with accounts differing on the year
  • 2008: Moz launches Open Site Explorer
  • 2013: SEOmoz rebrands as Moz
  • 2016: Google retires public toolbar PageRank; John Mueller says Google has nothing like a website authority score
  • September 2017: Moz begins tracking DA, PA and linking domain counts over time
  • 2018: Link Explorer replaces Open Site Explorer with an index 35 times larger and 30 times fresher
  • February 5, 2019: Moz announces Domain Authority 2.0
  • March 5, 2019: Domain Authority 2.0 goes live on a neural network with Spam Score as an input
  • September 30, 2020: Page Authority 2.0 launches
  • Late 2020: Mueller says some Google site-level metrics might map into similar things
  • June 4, 2021: iContact, a unit of J2 Global, acquires Moz; J2 later renames itself Ziff Davis
  • January 28, 2022: Mueller states that Google does not count links on a domain level
  • December 14, 2022: Google's link spam update deploys SpamBrain against link buyers and sellers
  • January 31, 2023: Semrush rebuilds Authority Score around link power, organic traffic and spam factors
  • August 7, 2023: Moz launches Brand Authority at MozCon
  • March 5, 2024: Google introduces expired domain abuse and site reputation abuse policies
  • May 27, 2024: Rand Fishkin publishes leaked Content Warehouse API documentation including siteAuthority
  • May 29, 2024: Google confirms the leaked documents are authentic
  • September 2024: Moz publishes Tom Capper's analysis of DA-to-Brand Authority ratios among HCU losers
  • November 2024: Google rules that first-party oversight does not exempt content from site reputation abuse
  • June 2025: Screaming Frog moves its integration to version 3 of the Moz API
  • July 15, 2025: Reboot Online publishes its experiment using expired domains below DR 5
  • April 2026: Analysis of ClickUp shows a 97.6% blog traffic loss alongside a Domain Rating rise from 87 to 90
  • June 5, 2026: Google publishes guidance stating third-party tools lack access to its ranking data
  • August 27, 2026: Collaborator study reports a 0.238 correlation between DA and traffic
  • September 2026: Semrush finds the most-cited manufacturing domain in AI answers has an Authority Score of 17
  • October 2, 2026: Gary Illyes says core updates target content at page level rather than domain level

Summary

Who: Moz, owned by Ziff Davis since 2021, calculates and sells Domain Authority. SEO agencies, in-house teams and PR staff use it to compare sites and vet links; publishers, link vendors and expired-domain brokers price by it. Ahrefs and Semrush publish rival scores, and Google says it uses none of them.

What: A 1-100 non-linear score predicting how likely a domain is to rank, produced by a neural network trained on Google results and fed mainly by Moz's link index: linking root domains, total links, link quality and Spam Score.

When: First released at some point between 2006 and early 2011, with accounts differing; rebuilt as Domain Authority 2.0 on March 5, 2019; joined by Brand Authority on August 7, 2023. As of October 2026, no successor model had been announced.

Where: In Moz Pro, the MozBar extension, Moz's free domain analysis page and the Moz API, from which it flows into crawlers, checkers and the price lists of link sellers.

Why: Google publishes no site-level authority score, and marketers wanted a common yardstick for competition and link value. The score fills that gap with a model of Google, not a measurement of it, which is why its use for pricing and forecasting remains contested.