Free SEO audit tools and their limits

By Matt Kerr·Published 10 August 2026·Updated 9 November 2026

For a free SEO audit, use a page checker for faults on one URL, a crawler for faults across a site, and Search Console for what Google has seen. The tools below do different jobs. Start with the question you need answered and check the free limit before you run an audit. We make Check Engine, including the free checker listed here.

Which free SEO audit tool fits the job?

New to audits? What an SEO audit includes gives you a checklist. For a single access question, the robots.txt tester shows which rule allows or blocks a page.

Google Lighthouse: free, open source, already installed

Lighthouse is "an open-source, automated tool" you can run from Chrome DevTools, the command line, a Node module or a web UI. If you use Chrome, you already have it: open DevTools, pick Lighthouse, run it.

What it is genuinely good at: performance on a single page, measured properly. It is also what powers PageSpeed Insights, which "uses Lighthouse to analyze the given URL in a simulated environment" for its lab data.

What it does not do, in its own words: its SEO category declares ten scored audits and describes itself as "basic search engine optimization advice", noting that there are more checks it does not perform. It is also per page. It has no concept of your site as a whole, so orphan pages, canonical conflicts across templates and hreflang reciprocity are all invisible to it by design.

Google Search Console: free, and Google's own data about your site

Search Console tells you what Google did with your site: which queries brought impressions, which pages were indexed and which were not. It is free, and for anything about your standing in Google specifically it is the primary source.

The limits are published and worth knowing before you rely on it. Reports show "a maximum of 1,000 rows, so some rows might be omitted". Data is not live: "normally, however, collected data should be available in 2-3 days". Google "might not track some queries that are made a very small number of times", so the long tail is partly absent. The URL Inspection API is capped at "2000 QPD" and "600 QPM" per site. These limits cap how fast a large site can be inspected page by page, even by script.

Its Core Web Vitals report is field data: "the data for the Core Web Vitals report comes from the CrUX report", gathered from real visitors. That is more truthful than any simulation, and it needs enough traffic to exist. How much is not published: "An exact number is not disclosed."

And it only works on sites you own. You verify the property first, which makes it useless for looking at a competitor, or at a site you are about to take on as a client.

Screaming Frog, free tier: a real crawler, capped

The free tier is limited to 500 URLs. For a small brochure site that is the whole site, and you get an actual crawl rather than a page-at-a-time check: redirect chains, broken links, duplicate titles across pages. If you need more than the free tier, the Screaming Frog alternatives for Mac and Windows sets the paid and free ones side by side.

It is the right free answer for anyone comfortable reading crawl data and deciding what matters. If a spreadsheet of every URL and its status codes is a useful artefact to you rather than a wall of numbers, take this one.

Check Engine's free SEO checker: one page, no sign-up

We make this one, so read it with that in mind. Paste the address of any page into the free SEO checker and it returns a score out of 100, the problems on that page by area, and the worst one in full with the change that fixes it. It runs in your browser with nothing to install, and it works on any site, yours or a competitor's, so there is nothing to verify first.

What it checks: whether Googlebot, Bingbot and the AI search crawlers may read the page, noindex and canonical tags, redirects and HTTPS, the width of the title and description, headings, structured data and sharing tags. What it does not: speed, which is Lighthouse's job, and anything between pages, because it reads one page at a time.

Is there a free SEO audit plugin?

For Chrome, our free Check Engine SEO add-on checks the page in the tab you are on, in your browser, with nothing uploaded and no account. It is a page check, not a whole-site crawl.

What does a free SEO audit report show?

The online checker shows a page score, problems by area and the top problem with its fix. It does not audit the whole website. For a site audit, Check Engine's download runs on your computer. Free: your score, how many problems in each category, and the top problem in full with its fix. Pro: the rest of the problems, the ranked fix plan and the markup to paste. The free result is a starting point, not the full paid report.

So when is anything paid worth it?

When the free version you use has stopped answering your question:

• More than 500 URLs, where the free crawl tier stops.
• Whole-site relationships: a canonical pointing at a noindex page, an hreflang set that is not reciprocated, a page nothing links to. These need a site crawl, not just a per-page check.
• Being told what to do first. Every tool above hands you findings. Ordering them by what they cost you is a separate job from finding them.

If the paid tool you already have is Ahrefs, its crawler is Ahrefs Site Audit; our comparison sets out what it checks and how a crawl is paid for.

Check Engine's paid version is $59 once and adds the full ranked plan. If the free tools already tell you what to fix, keep using them. For a paid crawler or platform, SE Ranking vs Screaming Frog sets out the different ways their audits are paid for.

Download Check Engine · see how it compares, tool by tool

Checked 19 October 2026. The factual claims about this product were read from its own pages on that date: the SEO category declares ten scored audits (is-crawlable, document-title, meta-description, http-status-code, link-text, crawlable-anchors, robots-txt, image-alt, hreflang and canonical) plus one manual entry, structured-data, carrying a weight of zero; is-crawlable is weighted so that failing it alone fails the category (source); the category describes itself as "basic search engine optimization advice", adding that "there are many additional factors Lighthouse does not score here that may affect your search ranking" (source); it is "an open-source, automated tool" run from Chrome DevTools, the command line, a Node module or PageSpeed Insights; you give it a URL to audit, and its documentation lists five sets of audits: performance, accessibility, best practices, SEO and agentic browsing (source); the same config declares an agentic browsing category, shown as a fraction rather than a score out of 100, whose audits are agent-accessibility-tree, three WebMCP audits (form coverage, registered tools, schema validity), cumulative-layout-shift, llms-txt and ard-schema (an Agentic Resource Discovery manifest); none of them is named for a per-crawler robots.txt check (source); PageSpeed Insights "uses Lighthouse to analyze the given URL in a simulated environment" for its lab data, while its field data is "powered by the Chrome User Experience Report (CrUX) dataset" (source); the data behind Search Console's Core Web Vitals report "comes from the CrUX report", which gathers metrics "from actual users visiting your URL (called field data)" (source). Products change and pricing changes; if something here has gone out of date, tell us and it will be corrected. Everything else on this page is a comparison of approach, not a claim about their roadmap.

Checked 19 October 2026. The factual claims about this product were read from its own pages on that date: the URL Inspection API quota is "2000 QPD" and "600 QPM" per site (source); "Our tables can show a maximum of 1,000 rows, so some rows might be omitted" (source); "Normally, however, collected data should be available in 2-3 days" (source); Google "might not track some queries that are made a very small number of times", and most reports "only cover a representative sample" of a site's URLs (source); "The data for the Core Web Vitals report comes from the CrUX report": field data from real visitors, reported at the 75th percentile, and "A URL group without threshold data for both LCP and CLS will not be on the report" (source); how much traffic a page needs before CrUX will report on it is not published: "An exact number is not disclosed" (source). Products change and pricing changes; if something here has gone out of date, tell us and it will be corrected. Everything else on this page is a comparison of approach, not a claim about their roadmap.

Checked 4 November 2026. The factual claims about this product were read from its own pages on that date: renders with the "integrated Chromium WRS" (source); its feature list describes the User-Agent setting as crawling "as a search bot such as Googlebot or Bingbot, AI crawlers, or your own custom UA" (source); free tier limited to 500 URLs; paid crawl limit "Unlimited", with the maximum "dependent on allocated memory and storage" (source). Products change and pricing changes; if something here has gone out of date, tell us and it will be corrected. Everything else on this page is a comparison of approach, not a claim about their roadmap.

Common questions

Is there a free SEO audit plugin?

Yes. Our free Check Engine SEO add-on for Chrome checks the page in the tab you are on, in your browser, with nothing uploaded and no account. It checks one page, not the whole site.

What does a free SEO audit report include?

Check Engine's free online checker shows a page score, problems by area and the top problem with its fix. The free desktop download gives a site score, counts by category and the top problem in full. The rest of the problems and ranked plan are paid.

What is the best free SEO audit tool?

For a single page, Lighthouse. It is open source, built into Chrome DevTools, and powers PageSpeed Insights. For how Google actually treats your site, Search Console. For crawling a small site, Screaming Frog's free tier, capped at 500 URLs.

Can I audit my website free without signing up?

Our free Check Engine SEO checker checks one page in the browser with no sign-up. Lighthouse runs inside Chrome, and Screaming Frog's free tier crawls up to 500 URLs.

Is Google Lighthouse enough for SEO?

For one page at a time, often. Its SEO category describes itself as “basic search engine optimization advice” and notes there are checks it does not perform, and it has no view of your site as a whole, so canonical conflicts, hreflang reciprocity and orphan pages are invisible to it.

Why can't Search Console tell me everything?

Its limits are published: reports show at most 1,000 rows, data lags by about two to three days, very rare queries may not be tracked, and it only works on properties you have verified, so it cannot look at a competitor's site.

When is a paid SEO audit tool worth it?

When a site is bigger than the free crawl tier, when the problems are relationships between pages rather than faults on one page, or when you need the findings ordered rather than listed. Below that, the free tools are enough.