# GeoXylia
> Find a free SEO audit API that actually measures AI citability, entity consistency, and crawlability. This guide covers REST endpoints, JSON responses, rate limits, and real code examples — no credit card required.
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## Free SEO Audit API: Complete 2026 Guide to AI-Powered Site Analysis

Most SEO audit tools give you a PDF and a pat on the back. A real SEO audit API gives you data you can act on — at scale, in your own workflow. Here's how to use one without spending a dime.

Ethan Lim2026-05-1512 min readShare:

## Why Most "Free SEO Tools" Are a Waste of Your Time

You've seen the offer before: "Free SEO audit — enter your URL and get a full report instantly." You type in your domain, wait 30 seconds, and receive a 40-page PDF that tells you your title tags are too long and your images lack alt text. Actionable? Not really. The report gives you a snapshot of problems — but offers no path to fix them, no way to track progress over time, and no data you can actually use in your workflow.

A free SEO audit API is a fundamentally different tool. Instead of a PDF, you get raw data — structured, machine-readable, and designed for automation. Instead of running one-off reports, you can audit every page on your site on a schedule, integrate results into your CMS, or build custom dashboards for clients.

This guide is a practical walkthrough of how SEO audit APIs work, what data they return, how to call them without writing a line of code, and how to integrate them into real marketing workflows.

## What Is an SEO Audit API?

An SEO audit API is a REST endpoint that accepts a URL or domain as input and returns structured diagnostic data about that site's technical health, content quality, and — in the case of AI-aware tools — citability signals.

Unlike a web-based audit tool that renders results in a browser, an API returns data in JSON or XML format. This makes it programmable: you can call it from Python, JavaScript, PHP, or any language that can make HTTP requests. The results become raw material for dashboards, automations, and reporting pipelines.

The distinction matters for three reasons:

1. Scale: An API can audit hundreds of URLs programmatically. A web tool requires you to enter each URL manually.
2. Automation: You can trigger audits on a schedule — for example, every time a new page is published on your CMS.
3. Integration: API output flows directly into tools you already use: Google Sheets, Airtable, Notion, Zapier, or custom dashboards.

Traditional SEO tools like Ahrefs, Semrush, and Screaming Frog offer APIs — but they are priced for enterprise workflows. A free SEO audit API makes programmatic site analysis accessible to freelancers, small agencies, and developers building internal tooling.

## What Does a Real SEO Audit API Actually Check?

Here is where the quality gap between tools becomes stark. Most free audit tools check the same 15-20 technical factors Google has used for a decade: meta descriptions, heading hierarchy, image alt text, page speed, mobile friendliness. These are table stakes. They don't tell you anything about how AI engines — Perplexity, ChatGPT, Gemini, Claude — evaluate and cite your content.

GeoXylia's free SEO audit API checks 40+ data points across five categories that matter for AI visibility:

## 1. AI Citability Score (0-100)

This is the composite metric. GeoXylia's citability model evaluates your page on nine dimensions: source authority signals, entity clarity, content answerability, cross-platform citation consistency, structured data completeness, llms.txt presence, AI crawler accessibility, E-E-E-A-T signals, and source diversity. The score reflects how likely an AI engine is to cite your content in response to a user query.

A score below 50 indicates major barriers to AI citation. Sites that score above 75 are consistently cited by Perplexity and Gemini across their primary content categories. GeoXylia's [AI SEO audit tool](/blog/ai-seo-audit-tool/) provides the full diagnostic view behind these scores — with guided fix recommendations for each dimension.

## 2. Entity Consistency Analysis

AI engines don't just index your content — they map it to entities in their knowledge graphs. Entity consistency measures how well your Organization schema, Wikipedia/Wikidata presence, LinkedIn Company Page, and Google Business Profile align around the same verified entity. Inconsistencies (different business names, conflicting addresses, mismatched category descriptions) create doubt in AI systems and reduce citation probability.

The API cross-references your declared entity signals against publicly known entity data and returns a consistency score plus a list of specific mismatches to resolve.

## 3. llms.txt Analysis

The llms.txt file is a proposed IETF standard — a plain-text file at your domain root that tells AI crawlers what your site contains and how to navigate it. Unlike robots.txt, which is for search engines, llms.txt is specifically for AI systems.

GeoXylia's API checks whether your llms.txt exists, whether it's valid according to the draft specification, and whether it covers your key content 
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