Free SEO Audit Tools: What Each One Actually Checks

An SEO audit tool reads your website the way a crawler would and reports what is broken: pages it cannot reach, missing titles, markup that fails validation, pages that load badly. The free ones all do some version of that job, and what separates them is not the feature list. It is how much of your site each one reads before it stops, and what it does when it gets there. This comparison is for someone running a SaaS or B2B site who cannot justify a paid seat yet, and it ranks ten tools on exactly that: pages read free, account friction, and the limit each vendor states in its own documentation.

The short version

• The page cap is the comparison. Across the ten free plans below, published crawl allowances run from 100 pages to 5,000 crawl credits a month, while the lists of what each one checks sit much closer together.
• Only one tool here crawls a site end to end on a permanently free basis without asking for an account, and it stops at 500 URLs.
• Google's three tools cost nothing and cap no page count, though Search Console's URL Inspection carries a daily request limit whose size Google keeps to itself.
• One of the ten has no free plan at all. It has a 14-day trial, which is a different thing.
• What a tool does when it hits its own cap tells you more than the score it prints afterwards.

What does an SEO audit tool actually check?

Five things, in roughly this order of importance. The category names differ between vendors; the underlying checks do not.

• Crawlability: whether a bot can reach a page at all. Server errors, redirect chains, robots.txt rules, broken internal links.
• Indexability: whether a reachable page is allowed into the index. noindex directives, canonicals pointing somewhere unexpected, duplicate URLs competing with each other.
• On-page elements: titles, meta descriptions, heading structure, image alt text, thin or duplicated body copy.
• Structured data: whether schema markup parses, and whether it qualifies for the rich result it is aiming at.
• Performance: Core Web Vitals and the loading behavior behind them.

A tool that reads every page covers all five across the whole site. A tool that reads one URL per run covers all five on that URL. That distinction decides the ordering below. For the checks themselves rather than the software, our SEO audit checklist sets out what to look at and in what order.

How are these ten free SEO audit tools ranked?

By how much of your site each tool reads in one free pass, then by the account friction it costs to get there. Not brand, not feature count, and not whether we make one of them. The criterion produces three bands:

• Entries 1 to 3: tools with no vendor plan metering what they read.
• Entries 4 to 7: free plans that crawl a whole website, ordered by the allowance they publish, with lower friction breaking ties.
• Entries 8 to 10: free plans that read about 100 pages, plus one tool whose free access expires.

Tool	Pages read on the free plan	Account needed	What it will not tell you
1. Google Search Console	Whatever Google has crawled of a property you own, with no page cap on the reports	Google account plus property verification	Anything about a site you do not own, or pages Google never fetched
2. Google PageSpeed Insights	One URL per run, no published limit on runs	No	Real-user field data for a page with too few samples in the Chrome User Experience Report
3. Google Lighthouse	One page per run, no published limit on runs	No	Anything about pages other than the one you just ran it on
4. Ahrefs Webmaster Tools	5,000 crawl credits a month, per verified project	Account plus verified ownership of the domain	Anything about a competitor's site, which the vendor reserves for paid plans
5. Screaming Frog SEO Spider, free version	500 URLs per crawl, unlimited crawls	No sign-up and no email capture, per the vendor	Structured data validation, JavaScript-rendered content and Search Console data, all paid-only
6. Bing Webmaster Tools Site Scan	A monthly per-site quota Bing calculates and publishes no figure for	Microsoft account plus site verification	Your quota before you open the tool, and it cannot be raised on request
7. GrowthHasten	One website of up to 900 pages, and three re-analyses	Account	Rankings over time, search volume, keyword difficulty and CPC, none of which it produces
8. Seobility, free Basic plan	100 pages per crawl, one project	Account, no credit card	More than 10 tracked keywords or 5 tool credits a day
9. Semrush, free account	100 pages per month, and 100 pages in any single audit	Account, no credit card	Anything past 10 reports a day, and leftover crawl budget does not roll over
10. Sitebulb	Not produced. There is no free plan, only a 14-day Pro trial	Trial activation, which the vendor says needs no credit card	Anything at all once the 14 days are up, unless you subscribe

Every limit in this table was read from the vendor's own pricing page or documentation on 5 October 2026. These caps drift, so treat the date as part of the data.

Which free SEO audit tools come from Google?

Three, and they are the only ones here that no vendor plan meters. They are also the least substitutable, because two of them report data no third party holds.

1. Google Search Console

The index-side view of your site, straight from the source.

• Pages read free: every URL Google has crawled on a property you verified. No page cap on the reports, which hold 16 months of history.
• Account needed: a Google account and verified ownership of the property.
• What it checks: index coverage and why a URL was excluded, Core Web Vitals from field data, structured data eligibility, and the queries, clicks, impressions and positions Google recorded.
• Stated limit: it is not a crawler you aim at your site. It reports what Google already fetched, so a page Google has never seen is invisible to it. Google's documentation adds that URL Inspection has a daily request limit per property, without publishing the number, and that the URL you inspect must sit inside a property you own.

That first limit is the one people trip on. A page sitting at crawled but currently not indexed shows up here. A page nothing links to, which Google has never requested, mostly does not.

2. Google PageSpeed Insights

A single-URL performance report combining lab measurement with real-user data.

• Pages read free: one URL per run. Google publishes no limit on how often you run it.
• Account needed: none.
• What it checks: Core Web Vitals and supporting metrics, measured both in a lab environment and from real Chrome users over the previous 28 days, plus loading opportunities and diagnostics.
• Stated limit: the real-user half can be missing entirely. Google's documentation says a recently published page, or one with too few samples, falls back to origin-level data, and where the origin also has too little data it shows no real-user data at all.

3. Google Lighthouse

The open-source audit engine inside PageSpeed Insights, run locally.

• Pages read free: one page per run. No published limit on runs.
• Account needed: none. It ships inside Chrome DevTools.
• What it checks: performance, accessibility, SEO and best practices, each a scored category with its individual audits listed underneath.
• Stated limit: one page at a time, and nothing about the rest of the site. Chrome's Lighthouse documentation notes that the browser extension cannot test local or authenticated pages, while the DevTools and command-line versions can.

That last point is why Lighthouse earns a slot beside PageSpeed Insights: it runs against pages that are not on the public internet yet, so a staging build can be audited before anyone outside the team can load it.

Which free tiers crawl a whole website?

Four, and this is where the caps bite. Each points a crawler at your domain and follows links, so the published allowance is a real ceiling on how much gets looked at.

4. Ahrefs Webmaster Tools

A free account for verified site owners, now branded Ahrefs Free, bundling three of the paid tools.

• Pages read free: a verified project gets 5,000 crawl credits a month. Ahrefs states a credit is spent only on an HTML page returning status 200, so redirects, dead URLs and non-HTML resources cost nothing against it.
• Account needed: an account plus verified ownership of each domain. Verified sites are unlimited.
• What it checks: Site Audit covers what Ahrefs describes as 170+ technical and on-page issues, with a health score over time, plus Site Explorer for keywords and backlinks.
• Stated limit: Site Explorer shows 1,000 backlinks and 1,000 keywords at a time, and the free tier covers only sites you have verified. Ahrefs says analyzing competing websites belongs to its paid subscriptions.

5. Screaming Frog SEO Spider, free version

A desktop crawler, and the only tool here that reads a whole site end to end, up to its 500-URL cap, while asking for nothing.

• Pages read free: 500 URLs per crawl, with no limit on how many crawls you run.
• Account needed: none. Screaming Frog states that the lite version is free to download and use without any sign up or email capture.
• What it checks: the free column covers the crawl layer and the markup layer and stops there. Server errors and dead internal links, redirect behavior, titles and descriptions, robots directives, hreflang, byte-identical duplicate pages, plus sitemap export and the crawl visualization views.
• Stated limit: the free column on Screaming Frog's pricing page excludes JavaScript rendering, structured data validation, saved crawls, crawl configuration, scheduling, near-duplicate detection, custom extraction, accessibility auditing, the Google integrations and technical support.

It reads fewer pages than two tools below it and still ranks fifth, because the second half of the criterion is friction and this one has none. The exclusion list is the real cost: a crawl that cannot render JavaScript under-reports a site whose content arrives client-side. Past 500 URLs, we compare what each free desktop crawler actually crawls separately.

6. Bing Webmaster Tools Site Scan

An on-demand crawl inside Bing's free webmaster suite, scoped to a site you have verified.

• Pages read free: a monthly quota per site. Bing's help documentation says the quota is calculated automatically from the signals available to Bing, publishes no figure for it, and states that requests to raise it are not currently supported.
• Account needed: a Microsoft account plus site verification.
• What it checks: common technical SEO issues across a crawl scoped to a website, a sitemap or a URL list, sorted into errors, warnings and notices.
• Stated limit: you cannot plan around a number you cannot see until you open the tool. Bing's own guidance is to be mindful of the monthly quota, because a large site can consume all of it in one scan.

It sits above GrowthHasten on the benefit of the doubt. Bing publishes no figure, so there is no honest way to rank it below a tool that publishes 900.

7. GrowthHasten

Our own SEO software, included on the same evidence as everything else on this page.

• Pages read free: one website of up to 900 pages, plus three re-analyses for the life of the account. Re-running the checks over pages already stored is not rationed.
• Account needed: yes, with no card and no trial clock.
• What it checks: Site Audit runs 130+ deterministic checks across 12 scored categories and ranks every page by what to fix first, and it can read 16 months of your Search Console data alongside the crawl.
• Stated limit: it does not track rankings or follow positions over time. It reports no search volume, no keyword difficulty and no CPC, because it does not hold that data. Weekly automatic re-analysis and a second website sit outside the free plan, and paid plans are coming.

Position seven is where the stated criterion puts it. Google's three cap nothing, Ahrefs publishes a larger monthly allowance, Screaming Frog asks for no account at all, and Bing publishes no number we could rank below 900. Those four reasons are the same ones we would apply to anyone else's tool.

Which free audit tools stop at 100 pages, or stop being free?

Three, and they are worth knowing precisely rather than dismissing. Two read about a hundred pages, which covers a small site or a deliberate sample. The third is not free at all.

8. Seobility, free Basic plan

A free account with no expiry, scoped tightly.

• Pages read free: 100 pages per crawl, on one website project.
• Account needed: yes. Seobility's pricing page says no credit card is required and the Basic account runs for unlimited time.
• What it checks: what Seobility labels a Limited Website Audit, alongside keyword tracking for 10 terms, 5 tool credits a day and 3 tracked AI prompts.
• Stated limit: the audit is labeled limited by the vendor itself, and the keyword, credit and project caps are low enough that most sites outgrow them fast.

9. Semrush, free account

The free entry point to a large paid platform, and the page allowance reflects that.

• Pages read free: 100 pages per month, and 100 pages in any single audit. Semrush states that leftover crawl budget does not roll over and that limits reset on the first of each month.
• Account needed: yes. Semrush's pricing page lists the free plan at zero cost with no credit card required.
• What it checks: Site Audit runs what Semrush's documentation describes as over 140 on-page and technical checks, including a category aimed at AI search.
• Stated limit: one demo project with 10 reports a day across the platform's main tools. The ceiling is monthly, not per crawl, so a second audit in the same month has nothing left to spend.

10. Sitebulb

A desktop auditor with a generous trial and no free plan behind it.

• Pages read free: up to 500,000 URLs per audit during a 14-day trial, after which nothing is free.
• Account needed: a trial activation. Sitebulb says the trial is equivalent to Sitebulb Pro on desktop and needs no credit card or up-front commitment.
• What it checks: Sitebulb's pricing page lists 300+ prioritized hints on Pro, with JavaScript crawling, duplicate content, crawl maps and the Google integrations across all plans.
• Stated limit: there is no free tier. The pricing page lists only paid plans, starting at a Lite tier capped at 10,000 URLs per audit, so the trial is the whole of the free access.

It ranks tenth on this list's criterion and would rank first on raw crawl size. Both statements are true, which is exactly why a ranking criterion has to be stated out loud rather than implied by the order.

What happens when a free audit tool hits its page cap?

The crawl stops, and the report that follows describes a sample rather than your site. That is the quietest source of wrong conclusions in a free audit, because a truncated crawl still produces a report that looks complete.

Two concrete failures. A crawler that stops at 500 of your 2,000 URLs reports an orphan-page count, and that count is wrong, because the pages linking to those orphans sit among the 1,500 it never read. It also reports a percentage of pages missing meta descriptions, and that percentage describes the sample rather than the site, in the same font as everything else.

GrowthHasten handles its own 900-page ceiling by refusing rather than truncating. A website above the cap is refused before anything is read or stored, with a message saying so, instead of being crawled to 900 pages and scored as though the result described the site. The stated reasoning on our product page is that a partial crawl presented as a whole one produces a score that looks like a verdict on your site and is not. The same principle runs through the scoring: a dimension that could not be measured is named as unmeasured rather than scored zero. We have written separately about why a score should say what it could not measure.

Refusing has an obvious cost. A 3,000-page site gets nothing from us on the free plan, where a tool that truncates at least hands it a partial report. Whether an accurately labeled partial report beats a refusal is a fair argument, and one we may lose. Across the vendor pages read for this comparison, Bing is the only other one that raises the risk at all, and it does so as a warning to the user rather than as a behavior of the product.

Which free SEO audit tool should you start with?

Search Console first, always, then pick the crawler by the size of your site. Past that, it is almost entirely a page-count decision.

Site size	Start here	Why
Under 100 URLs	Search Console, then Seobility or the Semrush free audit	A hundred pages covers the whole site, so the tightest free plans are no constraint yet.
100 to 500 URLs	Search Console, then Screaming Frog free	It reads the whole site, costs nothing and needs no account. Run Lighthouse on one page per template beside it.
500 to 900 URLs	Search Console, then a free plan that covers the whole site in one pass	Past 500 URLs the desktop free tier truncates, so the question is which free plan reads all of it.
900 to 5,000 URLs	Search Console, then Ahrefs Webmaster Tools	It publishes the largest free monthly crawl allowance in this list.
Above 5,000 URLs	Search Console, plus a paid crawler	No free plan here reads a site that size in one pass. Sampling is the honest free option, and it has to be labeled as sampling.

What will these free audit tools not tell you?

Four things, and all ten share the gap, which is worth listing once rather than discovering one tool at a time.

• Historical rank tracking: Search Console reports your real average position for queries you already appear on, which beats a rank tracker for your own site. None of these free plans follows a chosen keyword list over time, GrowthHasten included.
• Search volume, keyword difficulty and CPC: these are licensed datasets. Free plans either omit them or show narrow ranges. GrowthHasten reports none of the three rather than estimating them.
• Competitor data: Ahrefs restricts its free tier to domains you have verified, and the pattern holds across the band. Free audit tools are built to look at your own site.
• Whether a fix will work: every tool here reports findings. None predicts a ranking or a traffic number, and anything that offers to is selling something other than an audit.

Read against that list, the free stack is not a cut-down paid stack. It answers a narrower question completely: the current state of the site you control. For the rest of that stack mapped out by job, we cover the wider free SEO toolset elsewhere.

Every figure a free audit hands you is a figure about a sample, and the size of that sample is the one number the report never prints beside it. So write it in yourself: at the top of whatever you export, record the cap the tool stopped at and the date you ran it. A share of pages missing descriptions means one thing across 500 of your 500 URLs and something else entirely across 500 of your 2,000, and nothing in the report will tell you which one you are looking at.