Best Domain Authority Checker APIs in 2026: Compare DA, PA & Backlink APIs

If you're building an SEO platform, lead generation software, backlink checker, browser extension, or website audit tool, one of the most valuable metrics you can provide is website authority.

However, "Domain Authority" isn't a single universal metric. Different SEO providers calculate website authority using their own methodologies. Moz introduced Domain Authority (DA), Ahrefs measures Domain Rating (DR), and Semrush uses Authority Score (AS). Each metric evaluates a website differently based on backlinks, referring domains, traffic signals, and other ranking indicators. Google itself does not use Domain Authority as a ranking factor, but these metrics are widely used across the SEO industry to estimate a site's relative strength. :contentReference[oaicite:0]{index=0}

In this guide, we'll compare the best Domain Authority Checker APIs available in 2026, explain their differences, and help you choose the right solution for your application.

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Table of Contents

• What is a Domain Authority API?
• Why Developers Need DA APIs
• Understanding DA vs DR vs Authority Score
• Features to Look For
• Best Domain Authority APIs
• Comparison Table
• Common Use Cases
• Frequently Asked Questions
• Final Thoughts

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What is a Domain Authority Checker API?

A Domain Authority API allows developers to retrieve website authority metrics programmatically.

Instead of checking websites manually, applications can instantly retrieve SEO metrics including:

• Domain Authority (DA)
• Page Authority (PA)
• Domain Rating (DR)
• Authority Score (AS)
• Referring Domains
• Backlinks
• Spam Indicators
• Trust Metrics
• Organic Traffic Estimates

Most APIs return JSON responses through REST endpoints, making them easy to integrate into websites, SaaS platforms, browser extensions, and SEO dashboards.

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Why Developers Use Domain Authority APIs

Domain Authority APIs are widely used in SEO software because they simplify competitive analysis and website evaluation.

Developers use them to build:

• SEO Audit Tools
• Website Authority Checkers
• Lead Generation Platforms
• Link Building Software
• Browser Extensions
• Competitor Analysis Tools
• Domain Marketplaces
• Digital Marketing Dashboards

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DA vs PA vs DR vs Authority Score

Many beginners assume these metrics are identical, but each provider calculates authority differently.

Metric	Provider	Measures
Domain Authority (DA)	Moz	Predicts a domain's ranking potential using backlink-based machine learning.
Page Authority (PA)	Moz	Predicts the ranking strength of an individual page.
Domain Rating (DR)	Ahrefs	Measures backlink strength based primarily on referring domains.
Authority Score (AS)	Semrush	Combines backlinks, organic traffic, and spam signals into a single score.

Because every provider uses a different methodology, it's common to see different scores for the same website. :contentReference[oaicite:1]{index=1}

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Benefits of Domain Authority APIs

Instant Website Evaluation

Analyze any domain in seconds.

Automated SEO Reports

Generate reports without manual lookups.

Better Lead Qualification

Prioritize high-value prospects based on authority metrics.

Competitor Monitoring

Compare domain strength over time.

Scalable Applications

Process thousands of domains automatically.

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Features to Look For

Choose an API that offers:

• Domain Authority
• Page Authority
• Backlink Counts
• Referring Domains
• Spam Detection
• Organic Traffic Metrics
• Bulk Lookup Support
• Fast Response Times
• REST API
• JSON Responses
• Reliable Documentation

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Best Domain Authority Checker APIs in 2026

1. Moz API

Overview

Moz introduced the original Domain Authority metric and remains one of the industry's most recognized authority providers.

Features

• Domain Authority
• Page Authority
• Link Explorer
• Spam Score
• Link Metrics

Best For

Traditional SEO software and authority analysis.

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2. Ahrefs API

Overview

Ahrefs focuses heavily on backlink intelligence and Domain Rating.

Features

• Domain Rating
• Referring Domains
• Live Backlinks
• Anchor Text
• Link Growth

Best For

Backlink analysis tools.

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3. Semrush API

Overview

Semrush provides Authority Score along with one of the most complete SEO datasets available.

Features

• Authority Score
• Organic Traffic
• Backlinks
• Keywords
• Competitor Research

Best For

Enterprise SEO platforms.

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4. DataForSEO API

Overview

DataForSEO offers comprehensive SEO APIs for developers.

Features

• SERP Data
• Backlinks
• Keywords
• Domain Metrics
• Traffic Estimates

Best For

SEO SaaS applications.

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5. Majestic API

Overview

Majestic specializes in backlink intelligence.

Features

• Trust Flow
• Citation Flow
• Referring Domains
• Backlink Analysis

Best For

Professional link-building software.

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6. Open Marketplace Domain Authority APIs

Overview

Open Marketplace allows developers to discover multiple Domain Authority, backlink, and SEO APIs from a single marketplace.

Developers can explore APIs for:

• Domain Authority
• Page Authority
• Website Traffic
• Backlinks
• Domain Metrics
• SEO Analytics

This simplifies API discovery and integration without searching across multiple providers.

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Comparison Table

API	DA	PA	Backlinks	Traffic	REST API	Best For
Moz	✅	✅	✅	❌	✅	Domain Authority
Ahrefs	❌	❌	✅	❌	✅	Domain Rating
Semrush	❌	❌	✅	✅	✅	Authority Score
DataForSEO	✅	Limited	✅	✅	✅	SEO Platforms
Majestic	❌	❌	✅	❌	✅	Link Intelligence
Open Marketplace	Multiple APIs	Multiple APIs	✅	✅	✅	Developers

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Common Use Cases

SEO Software

Display authority metrics inside SEO dashboards.

Lead Generation

Filter prospects by domain authority.

Link Building

Evaluate backlink opportunities before outreach.

Website Audits

Include authority metrics in technical SEO reports.

Browser Extensions

Show authority scores directly on websites.

Competitor Analysis

Compare multiple domains automatically.

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Best Practices

• Cache API responses to reduce request volume.
• Compare multiple authority metrics instead of relying on only one.
• Use backlink data alongside authority scores.
• Respect provider rate limits.
• Refresh metrics regularly for accurate reporting.

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Frequently Asked Questions

What is Domain Authority?

Domain Authority (DA) is a metric developed by Moz to estimate a website's likelihood of ranking in search engines based primarily on its backlink profile. :contentReference[oaicite:2]{index=2}

Does Google use Domain Authority?

No. Google has stated that it does not use Domain Authority as a ranking signal. DA is an industry-created metric for comparing websites. :contentReference[oaicite:3]{index=3}

What's the difference between DA and DR?

DA (Domain Authority) is created by Moz, while DR (Domain Rating) is created by Ahrefs. Both estimate website strength but use different calculation methods. :contentReference[oaicite:4]{index=4}

Which API is best for backlinks?

Ahrefs, Majestic, DataForSEO, and Semrush are widely used for backlink intelligence.

Which API provides Page Authority?

Moz provides both Domain Authority and Page Authority metrics.

Can I check multiple domains at once?

Many providers offer bulk lookup endpoints for enterprise applications.

Are Domain Authority APIs suitable for commercial software?

Yes. Most providers offer commercial licensing and API access through paid plans.

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Final Thoughts

Domain Authority APIs are an essential component of modern SEO software, helping developers evaluate website quality, monitor competitors, and automate SEO analysis.

Rather than relying on a single metric, consider combining Domain Authority, Domain Rating, Authority Score, backlink data, and traffic estimates to build a more complete picture of a website's authority.

If you're looking to compare multiple SEO APIs in one place, Open Marketplace makes it easy to discover Domain Authority, backlink, traffic, and SEO APIs for your next project.