Domain authority checkers
that give reliable scores.

The 7 Best Domain Authority Checkers: Free and Paid Options Compared

Domain authority is one of the most widely referenced metrics in SEO, yet it is also one of the most misunderstood. The score your site receives from a domain authority checker does not come from Google — it is a third-party estimate, calculated differently by every tool that produces one, and it is not a direct input into how Google ranks your pages. And yet the metric has genuine practical value when used correctly: as a benchmarking tool, a progress indicator, and a filter for evaluating the quality of potential link building targets.

This guide covers what domain authority is, how the major tools calculate it, which checkers are worth using (and when the free options are sufficient), and how to interpret scores in a way that actually informs your SEO decisions.

What Domain Authority Is — and What It Is Not

Domain authority — sometimes referred to as website authority — is a score that attempts to quantify the overall strength and trustworthiness of a domain's backlink profile. It is expressed as a number between 0 and 100. New domains start at 0 and accumulate score over time as they attract quality backlinks from other established sites.

The concept was coined by Moz, and the specific term "Domain Authority" (DA) is Moz's proprietary metric. Other tools have developed their own equivalents: Ahrefs uses Domain Rating (DR), SEMrush uses Authority Score (AS), and Majestic uses Trust Flow (TF) and Citation Flow (CF). These metrics are all attempting to approximate the same underlying concept, but they use different data sources and calculation methods, which is why the same domain can produce meaningfully different scores across tools.

The most important thing to understand about all of these metrics:

Google has confirmed it does not use any third-party domain authority score in its ranking algorithm. A Google representative explicitly stated the company has no "website authority score." What Google does use is its own internal version of PageRank, which assesses the quality and quantity of a site's backlinks — but this is a private system, not accessible to SEOs. Third-party DA metrics are approximations of that underlying quality signal, useful as directional indicators but not as ground truth.

The practical consequence: domain authority scores should be treated as relative benchmarks, not absolute targets. A site with DA 45 is not necessarily better positioned than one with DA 43. What matters is where your score sits relative to the sites you are competing against for specific keywords.

What Domain Authority Checkers Actually Measure

While every tool's algorithm is proprietary, they broadly assess the same underlying factors. The most consistently weighted inputs across tools include:

• The number of unique domains linking to the site (referring domains)
• The authority of those linking domains — links from high-authority sites carry more weight
• The naturalness and diversity of the overall link profile
• The number of outbound links on each referring page (a link from a page linking to hundreds of sites is worth less than one from a page linking to only a few)
• Organic traffic volume and keyword rankings
• Content quality signals and on-page optimisation indicators
• Site age and crawl history
• Technical factors including page speed and site structure

Most tools also incorporate spam signals — low-quality or manipulative links pointing to a domain are weighted negatively, not just excluded. This is why a site that has used link farms or PBN-based link building may have a lower DA than its raw link count suggests.

The 7 Best Domain Authority Checkers

At a Glance

1. Moz

Moz created the Domain Authority metric and remains the definitive source for it. The free Domain Analysis tool at moz.com/domain-analysis accepts any URL and returns a detailed profile that goes well beyond a single number.

What the free Moz tool shows:

• Domain Authority score (0–100)
• Page Authority for the specific URL entered
• Linking root domains — the number of unique domains sending inbound links
• Total ranking keywords
• Spam Score — the percentage likelihood that the site's link profile resembles known spam patterns
• Top pages by Page Authority
• Top linking domains by DA
• Top ranking keywords
• Top organic competitors
• Common questions the domain ranks for

The spam score is particularly useful when evaluating potential link building targets — it gives an immediate signal about whether a site's link profile looks manipulative before you invest time in manual assessment.

Full Moz Pro subscription: $99/month, unlocking full link explorer access, keyword research, rank tracking, and site auditing.

Best for: Practitioners who want the richest free DA reporting available, particularly those who need spam scoring as part of link prospect vetting.

2. Ahrefs

Ahrefs calls its metric Domain Rating (DR) rather than Domain Authority, which is a deliberate distinction — the company uses a specific calculation focused heavily on the quality and quantity of unique referring domains weighted by their own DR scores. The result is a metric that many practitioners consider more resistant to manipulation than some alternatives, since artificially inflating DR through low-quality links is harder when the weighting system discounts links from low-DR sources.

How DR is calculated — key inputs:

• Number of unique domains linking to the site
• The DR of each linking domain
• How many unique external domains each linking domain itself links to
• Organic traffic estimates and keyword rankings
• Overall content and site quality signals

What the free Ahrefs Website Authority Checker shows:

• Domain Rating (DR)
• Total backlinks
• Number of unique referring websites

The free tool is intentionally limited. The real value of Ahrefs as a domain authority checker comes with a paid subscription, which unlocks the full backlink explorer, anchor text analysis, broken link detection, referring domain growth history, and the ability to export data for bulk analysis.

Full Ahrefs subscription: Starts at $99/month.

Best for: Practitioners running active link building campaigns who need deep backlink analysis beyond a headline score. The DR metric is widely trusted in the industry and used by most professional link building teams as a primary quality filter.

3. SEMrush

SEMrush's Authority Score (AS) is distinguished from Moz DA and Ahrefs DR by its broader data inputs. While Moz and Ahrefs focus primarily on backlink signals, SEMrush combines backlink data with organic search performance data and website traffic data in its calculation. The theory is that a site genuinely trusted by Google — one that earns organic traffic across many queries — should score higher than a site that has accumulated backlinks through manipulation without corresponding search visibility.

Inputs in the SEMrush AS calculation:

• Referring domains and their authority
• Monthly organic visitors
• Number of outbound links
• Number of ranking keywords
• Spam signals in the link profile

Free access: SEMrush provides 10 free Authority Score lookups before requiring a subscription.

Full SEMrush subscription: $119.95/month, providing access to the full suite including keyword research, competitor analysis, site audit, and backlink analytics.

Best for: Practitioners who want a domain authority metric that factors in organic search performance alongside backlink quality, particularly useful for evaluating whether a prospective link target's authority is backed by genuine search visibility.

4. Majestic

Majestic takes a different approach to the single-number DA model, instead producing two primary metrics — Trust Flow and Citation Flow — which are designed to be used in combination.

Trust Flow (TF) measures the quality of a site's backlinks based on their proximity to a set of manually curated "seed sites" that Majestic considers inherently trustworthy. A site that receives links from trusted sources — major news publications, government sites, academic institutions — scores higher. The metric is specifically designed to be resistant to manipulation through low-quality link volume.

Citation Flow (CF) measures the sheer volume of links pointing to a site, without quality weighting. A site can have a high CF through bulk link building even if those links come from low-quality sources.

Majestic's recommended interpretation: The ideal TF:CF ratio is approximately 1:2. A site with TF 30 and CF 60 is in a healthy balance — its link volume is proportional to its trust level. A site with TF 10 and CF 60 has accumulated far more links than its quality justifies, which is a strong signal of manipulative link building.

Majestic also offers Topical Trust Flow — a breakdown of which topic categories the site's backlinks come from. This is particularly useful for assessing topical relevance when evaluating link prospects.

Free access: Basic Flow scores are available with a free account. Full visualisations and detailed data require a subscription.

Full Majestic subscription: Lite plan at $49.99/month — the most affordable paid option among the major DA tools.

Best for: Practitioners who want to assess the quality composition of a backlink profile rather than just the headline score, and anyone evaluating the trust-to-volume balance of a potential link target.

5. Website SEO Checker

Website SEO Checker's Domain Authority Checker is a free tool that pulls Moz data and presents a useful range of Moz metrics together, making it a good option for practitioners who want more than just a DA number without paying for Moz Pro.

What it shows for free:

• Domain Authority (Moz)
• Page Authority (Moz)
• MozTrust
• Spam Score
• Number of external links

The inclusion of MozTrust and Spam Score alongside the standard DA gives a more nuanced picture of a domain's quality than most free tools provide. It is best treated as a free supplement to the Moz free tool for anyone who wants Moz data without committing to a paid subscription.

Cost: Completely free.

6. SEO Review Tools

SEO Review Tools' Website Authority Checker is a straightforward free Moz-powered tool for quick DA lookups. It returns three metrics per domain: DA, Page Authority, and external link count.

It lacks the depth of the Moz free tool but requires no account creation and produces results instantly, making it well suited to quick spot-checks when evaluating a potential link placement or comparing a small set of competitors.

What it shows:

• Domain Authority (Moz)
• Page Authority
• External links count

Cost: Completely free.

7. SmallSEOTools

SmallSEOTools is known for offering one of the largest collections of free SEO utilities available anywhere, and its Domain Authority Checker carries one feature that distinguishes it from the other free tools on this list: the ability to check up to 10 domains simultaneously.

What it shows per domain:

• Domain Authority (Moz)
• Page Authority
• Moz Rank

The bulk comparison capability makes it directly useful for competitive analysis — paste in your site and up to nine competitors to get an immediate side-by-side DA comparison without any paid subscriptions or account setup.

Cost: Completely free.

How to Interpret Domain Authority Scores

The number itself means relatively little in isolation. The useful question is always: what does this score mean relative to the sites you are competing with?

General score orientation across major tools:

Several important caveats apply to these ranges:

Scores are logarithmic. Moving from DA 10 to DA 20 requires far less link building than moving from DA 60 to DA 70. The difficulty of increasing a score accelerates significantly at higher levels, which is why chasing a specific number is less productive than focusing on the quality of links being built.

Scores are relational. If every site in your niche increases their backlink profiles simultaneously, your score can drop even if your absolute link profile has improved. DA is calculated relative to the full index of sites the tool is measuring, not against a fixed benchmark.

Scores can be inflated. A high DA does not guarantee quality. Sites that have used PBNs, expired domain networks, or link farm schemes can produce inflated scores that bear no relationship to their actual ranking ability or trustworthiness. This is particularly relevant when vetting link building targets — always supplement DA with a manual check of the site's organic traffic and content quality.

The right benchmark is your specific competitive set. If you want to rank for a set of keywords, the DA scores that matter are those of the pages currently occupying the top positions for those queries. A DA 40 site competing against DA 35 competitors is in a strong position; the same DA 40 site competing against DA 70 incumbents faces a significant gap that needs to be closed through sustained link building.

Three Practical Uses for Domain Authority Checkers

1. Competitive Benchmarking

The most immediately actionable use of DA tools is understanding where your site sits relative to direct competitors. Export DA scores for the top five to ten competitors in your niche, compare them against your own, and identify the gap. A meaningful gap — particularly when competitors have higher DA scores and consistently outrank you despite comparable content quality — is a reliable indicator that link building investment is the primary lever available to close the difference.

2. Measuring Link Building Progress

DA scores change slowly and are influenced by many factors, which makes them an imperfect campaign performance metric. But an upward trend over a six-to-twelve-month link building campaign is a meaningful signal that the campaign is building genuine authority rather than just link volume. The important habit is to record baseline scores at the start of any campaign and check them at consistent intervals — monthly or quarterly — rather than checking after every link placement.

3. Vetting Link Building Targets and Prospects

When evaluating whether a site is a worthwhile target for a guest post, niche edit, or link exchange, DA or DR is a useful first filter. Most professional link building practitioners set minimum thresholds — commonly DR 30 or DA 25 as a floor, with higher thresholds for competitive niches. However, the score should always be combined with a check of the site's organic traffic (a high-DA site with no organic traffic is almost certainly a PBN or link farm), content quality, and topical relevance to your niche.

Which Tool Should You Use?

The answer depends on your budget and the depth of data you need:

• Free, quick checks: SmallSEOTools for bulk comparison; SEO Review Tools for single domain lookups
• Free with more depth: Moz's free Domain Analysis tool for spam scores and richer profiling
• Professional link building campaigns: Ahrefs DR is the industry standard metric for active campaign management; its paid plan provides the backlink explorer depth that makes it the most useful tool for ongoing link prospecting
• Authority quality assessment: Majestic Trust Flow for evaluating the quality-to-volume balance of any domain's backlink profile
• Organic authority signals: SEMrush Authority Score when you want to cross-reference backlink quality with organic search visibility

Ready to Improve Your Domain Authority?

A domain authority score is only as useful as the action it informs. If your DA audit reveals a significant gap between your site and the competitors you want to outrank, the path forward is systematic, high-quality link building focused on earning genuine editorial backlinks from relevant, authoritative domains. If you want to discuss what that looks like in practice for your specific niche and competitive landscape, get in touch at [email protected] — we are happy to take a look at where you stand and map out what is needed.