A free AI SEO audit tool should tell you whether search engines and AI systems can read your pages, and whether chat engines already mention you. Most "free AI audits" only grade HTML. They never ask ChatGPT anything.
That split matters. A missing llms.txt is not the same problem as "Perplexity cites three competitors and not you." One is a file. The other is a market.
This list separates page checkers (free, useful, limited) from engine scans (they query models). I include AI SEO Tracker's$49 one-time audit because it actually runs ChatGPT, Perplexity, Gemini, Copilot, and AI Overviews. It is not free. I say so in the section.
Live answers from ChatGPT, Perplexity, Gemini, Copilot, Overviews
Full technical crawl of 10,000 URLs
Use both. A free page audit finds crawl and structure bugs. An engine scan finds mention gaps. GEO work needs the second number.
How I picked these audit tools
I fetched competitor free tools and the pages that rank for free AI SEO audit tools, including SEOmator, Ahrefs' visibility roundup, Frase's checker, and several 2026 listicles. A tool made the list if:
There is a real free run (no fake 7-day trial sold as free), or I label the paid exception.
The output is a report you can read, not a lead form that emails a teaser.
It covers classic SEO, AI-readiness, or live model answers. I say which.
I did not count AI writers. I did not count "contact sales for your free audit."
Best for: A real engine scan, not a meta-tag score Price: $49 once (50 prompts, 7-day scan week, permanent read) Free layer: Type a domain on aiseotracker.com, preview three sample prompts, then pay. No free full scan. The public leaderboard is free to open.
This is the honest exception on a free-tools list. Free checkers grade your HTML. They do not log into ChatGPT and ask "best [your category]."
The $49 report does:
Up to 50 prompts written from your URL
Daily scans for 7 days on ChatGPT, Perplexity, Gemini, Copilot, and AI Overviews
Competitor gaps and cited sources
A prioritized action plan
Login that still opens the report after day 7
Weekly tracking is separate: Basic $79/mo, Pro $199/mo. MCP (OAuth, no API keys) is for agents that need to read the same project. Page Inspector is on the higher plan.
Use it when: you need to know if models mention you, which listicles they cite, and which prompts you lose. That is the audit LLM SEO actually needs.
Skip it when: you only wanted a free Lighthouse clone.
Pros:
Queries the engines buyers use
You keep the report
$49 is one-time, not a disguised subscription
Cons:
Not free
7 days of new scans, then you subscribe or stop
Not a 172-rule technical crawler
If you want the preview first, use the scan box. If the three prompts look right, pay. If you only want to see how a category ranks today, open a public rankings table.
2. SEOmator free SEO audit
Best for: A no-signup page audit that includes AI-visibility rules Price: Free for one URL. A free account opens full-site crawls. Signup: No for the public report
SEOmator's free SEO audit renders the page in a headless browser, runs 172 checks across 16 categories, and pulls Lighthouse. PDF export is included. No email wall on the first report.
AI visibility is five rules in the same run: semantic HTML, parseable structure, AI-crawler robots.txt, llms.txt, schema matching visible text. That is readiness, not "does ChatGPT recommend you."
Limits they state themselves: one page per free run. Orphans, duplicates, and internal-link graphs need the full crawl.
Use it when: you want a 30-second technical diagnosis you can hand to a developer.
Skip it when: you already know the HTML is fine and you need mention data.
3. Mangools AI Search Grader
Best for: A free 0–100 AI visibility score Price: Free. Full model set wants a free Mangools account. Signup: Optional for extra models
Ahrefs lists Mangools AI Search Grader as the free monitoring-style grader: visibility, average position, competitor snapshot. Third-party 2026 lists still call it the easiest no-cost pulse.
Treat the score as directional. It is not a 50-prompt, five-engine evidence pack. It is a way to see if you are roughly on the board.
Use it when: you need a number for a slide this afternoon.
Skip it when: you need cited URLs and a 7-day history.
4. Ahrefs Webmaster Tools
Best for: A real site audit on a domain you own, for $0 Price: Free for verified sites Signup: Yes, and you must verify
Ahrefs Webmaster Tools is the free slice of Ahrefs: site audit, backlinks to your domain, ranking keywords. Right Blogger and other free-tool roundups still list it because the audit is a crawler, not a one-page linter.
It does not replace Brand Radar. Brand Radar's AI indexes start at $199/mo each. Do not expect ChatGPT mention tracking in AWT.
Use it when: you need crawl errors, redirects, and index bloat on your own site.
Skip it when: the question is "does Gemini name us?"
5. Google Search Console and PageSpeed Insights
Best for: First-party Google data and lab/field speed Price: Free Signup: GSC needs Search Console access. PageSpeed can run any URL.
No AI audit is complete without Search Console. It is the only free tool that tells you which queries Google already shows you for. PageSpeed Insights (or Lighthouse in Chrome) covers Core Web Vitals.
Google is not ChatGPT. GSC will not list Perplexity citations. Use it as the SEO half of the audit, then add an engine scan.
Use it when: you own the site.
Skip it when: you are auditing a competitor you cannot verify.
6. Frase AI Visibility Checker
Best for: A free peek at who AI cites for a domain Price: Free checker. Paid platform for tracking. Signup: No for the checker (per Frase, 2026)
Frase's 2026 visibility roundup leads with its own checker and GEO Score. The checker is the free part: paste a domain, see citation-style results. Continuous tracking and the content loop sit on paid plans (Frase lists plans from $39/mo billed yearly).
Useful as a second opinion next to Mangools. Not a 7-day monitor.
Use it when: you want a zero-dollar citation sniff test.
Skip it when: you need Copilot and AI Overviews in the same export.
7. WordLift AI Audit
Best for: "Can an LLM parse this page?" Price: Free public check (as listed in 2026 audit roundups) Signup: Not required for the basic run
WordLift's AI audit is the cleanest example of a machine-readability check: structured data, JavaScript rendering, whether agents can reach the content. Distribb and similar lists still send people here for the LLM-readability job.
It will not tell you your share of ChatGPT answers. It will tell you if the page is a blob of client-rendered nothing.
Use it when: the site is a JS app and you suspect GPTBot sees an empty shell.
Skip it when: you need competitor mention tables.
8. HubSpot AEO Grader
Best for: A free-ish visibility baseline if you will consider HubSpot Price: Grader is the free entry. Paid AEO tracking is $50/mo for 25 prompts (Semrush, 2026). Signup: Account for the grader
HubSpot's AEO grader is the "easiest free baseline" in several monitoring roundups. Paid AEO then tracks ChatGPT, Gemini, and Perplexity only. No Copilot, no Overviews on that three-engine set.
Fine as a teaser. Weak as your only audit if Copilot or Google's AI features matter.
Use it when: marketing already runs on HubSpot.
Skip it when: you refuse another HubSpot module.
What a free audit still misses
Free HTML audits cannot:
Run your 50 category prompts on five models
Show the listicle that keeps winning the citation
Keep a week of answer text you can export
Free graders cannot:
Crawl 10,000 URLs
Find orphan pages
Replace Search Console
Do the cheap page audit first. Fix robots, titles, schema, and crawler blocks. Then run an engine scan. That order matches how you rank in ChatGPT: the model has to fetch you, then it has to choose you.
A practical free-plus-paid sequence
PageSpeed + GSC (free, if you own the site).
SEOmator on the homepage and one template page (free).
Mangools or Frase checker for a visibility sniff (free).
AI SEO Tracker $49 audit if you need mentions, sources, and a week of scans you keep.
Subscribe only if you will re-run every week.
That is the stack. Not twelve overlapping "AI auditors."
For HTML and AI-readiness, SEOmator is the strongest no-signup page audit I found. For a visibility score, Mangools AI Search Grader. For live ChatGPT/Perplexity mentions, there is no serious free five-engine scan. AI SEO Tracker is $49 once.
Is there a free scan on aiseotracker.com?
No full scan. You can type a domain, preview three sample prompts, and browse public rankings. The audit is $49. About and pricing pages both say there is no free trial.
Do free tools check ChatGPT visibility?
Most do not. They check llms.txt, robots, and schema. Graders and checkers (Mangools, Frase, HubSpot) get closer. Only paid engine scans rerun your prompt list across ChatGPT, Gemini, Copilot, and Overviews.
Is a $49 audit worth it vs a free checker?
If you need cited URLs and competitor names in the answers, yes. If you needed alt text and LCP, no. Use SEOmator or PageSpeed for that.
How often should I re-audit?
Technical: after deploys, and monthly. Visibility: weekly if the category moves. The $49 product is a one-week snapshot you keep. Ongoing tracking starts at $79/mo.
ChatGPT
Perplexity
Claude
Grok
