She wanted to know which report was right.
They were all right, and all incomplete. Free SEO audit tools are genuinely useful, but each one only sees a slice of the picture, and none of them tell you which of the issues they find actually matters to your business. Here’s what the good ones catch, what they miss, and how to read the results without panicking over a 47-item list.
Google Search Console
This is the one tool on this list you should have running no matter what. It’s the only source that shows you Google’s actual perspective on your site, not a third-party crawler’s guess at it.
What it catches well:
- Indexing status: which pages Google has indexed and why others were skipped
- Real search queries your site already ranks for, including ones you didn’t target on purpose
- Manual actions and security issues, straight from Google
- Core Web Vitals field data from real visitors, not a lab simulation
What it misses: Google Search Console doesn’t crawl your whole site the way a dedicated crawler does, and its data exports cap out fast on larger sites. It also only shows you what Google has already noticed, not issues on pages Google hasn’t crawled yet. It’s a mirror, not a full inspection.
PageSpeed Insights
The standard tool for page speed and Core Web Vitals, built on the same Lighthouse engine that powers the Performance panel in Chrome DevTools.
What it catches well:
- Largest Contentful Paint, Interaction to Next Paint, and Cumulative Layout Shift
- Specific render-blocking resources and oversized images
- A prioritized list of fixes ranked by estimated time savings
What it misses: PageSpeed Insights only tests one URL at a time. It won’t tell you that your product pages are slow while your homepage is fine, unless you test each one individually. I walked through exactly this gap in how I fixed Core Web Vitals on a real client site, where the homepage scored fine and the pages that actually mattered for revenue didn’t.
Screaming Frog (Free Tier)
A desktop crawler that maps your entire site structure the way a search engine bot does. The free version caps at 500 URLs, which covers most small business sites.
What it catches well:
- Broken links, redirect chains, and duplicate title tags across the whole site
- Missing meta descriptions and alt text, site-wide
- Crawl depth, so you can see which pages are buried too many clicks from the homepage
What it misses: it doesn’t judge content quality or search intent. It’ll tell you a page has a title tag; it won’t tell you the title tag is generic and losing clicks to a better-written competitor. It also can’t tell you which of the hundreds of issues it finds are worth your time this week.
Google’s Rich Results Test
Purpose-built for checking whether your structured data (schema markup) is valid and eligible for rich results in search.
What it catches well:
- Syntax errors in JSON-LD schema blocks
- Which rich result types your markup qualifies for
- Warnings for missing recommended fields
What it misses: Google’s Rich Results Test only checks the page you paste in. It won’t scan your site to find pages that are missing schema entirely, and passing this test doesn’t mean Google will actually choose to display the rich result. Eligibility isn’t a guarantee.
Ahrefs Webmaster Tools
The free tier of a paid platform, limited to your own verified site, but genuinely useful for backlink and technical health visibility that Search Console doesn’t show.
What it catches well:
- Your backlink profile, including toxic or spammy links pointing at your site
- Broader technical health checks across more pages than Search Console’s exports allow
- Organic keyword visibility trends over time
What it misses: Ahrefs Webmaster Tools is scoped to sites you own and verify, so it’s not useful for competitor research the way the paid product is. The free tier also nudges you toward the paid upgrade at every turn, which is fair, since it’s a business, but worth knowing going in.
What Every Free Audit Tool Misses
Here’s the actual gap, and it’s the same one my prospective client ran into. None of these tools know your business. A missing H2 on your privacy policy page gets flagged with the same urgency as a noindex tag accidentally left on your highest-converting landing page. The tools don’t prioritize by revenue impact because they have no idea what drives your revenue.
I’ve watched clients spend a weekend fixing every item on a free audit report in the order the tool listed them, top to bottom, and see zero ranking movement two months later. Then I’ve watched a client fix three specific things in an afternoon and see measurable movement within a month. The difference wasn’t effort. It was picking the right three things.
That’s the part that takes judgment, not another tool:
- Which of the 47 flagged issues would actually move a ranking or a conversion if fixed this week
- Whether a “critical” flag is actually critical for a site your size, or boilerplate the tool flags for everyone
- What the tools agree on (fix that first) versus what only one tool caught (investigate before acting)
- The stuff no automated tool catches at all: whether your content actually answers the question a searcher had, whether your service pages read like they were written by someone who’s done the work
Running two or three of the tools above and cross-referencing what they agree on is a solid DIY approach. It’ll catch most of what’s wrong. It won’t tell you what order to fix things in, and that’s usually the difference between an audit that sits in a folder and one that actually changes your rankings.
I see this pattern constantly with new clients. They’ve already run a free audit, sometimes two or three, and they show up with a spreadsheet of forty-plus items and no idea where to start. The technical fix isn’t usually the hard part. Knowing that the noindex tag on your top landing page matters more than the seventeen missing alt tags on your blog archive, that’s the part that takes someone who’s done this enough times to spot the pattern fast.
What This Means for Your Site
If you’re auditing your own site, don’t run one tool and panic at the results. Run Search Console and PageSpeed Insights at minimum, since they’re free, official, and take under an hour combined. Add Screaming Frog if your site is more than a handful of pages.
Then look for the issues every tool agrees on. Start there.
If you’ve already run the free stack and you’re staring at a list you don’t know how to prioritize, that’s the part I actually help with. Tell me about your project and I’ll give you a straight read on what’s worth fixing first, not a 60-page report you’ll never open again.