An SEO audit tells you why a page is not getting the traffic it deserves, and exactly what to change. You do not need an agency or a paid subscription to run a useful one. This guide walks through what a real audit checks, how to do it yourself in about half an hour, and where free tools genuinely stop being enough.
What is an SEO audit?
An SEO audit is a structured check of the signals search engines and AI answer engines use to understand, rank and quote your page. A good audit covers four layers: technical (can it be crawled and indexed), on-page (is it clearly about something), content and trust (is it worth ranking), and increasingly AI-search readiness (can a model quote it confidently). Skipping any one of them gives you a misleading picture.
How do I run a free SEO audit?
Work through it in this order, because each step depends on the one before it. There is no point polishing a title tag on a page search engines cannot index.
- Check it can be indexed. Look for a
noindexmeta tag and make sure the page is not blocked in robots.txt. This single issue silently removes more pages from Google than any other. - Confirm one clear H1 and a sensible heading hierarchy. Multiple H1s or none at all muddies what the page is about.
- Check the title and meta description. Aim for roughly 10 to 65 characters for the title and 50 to 165 for the description, written for a human deciding whether to click.
- Add a canonical tag so duplicate URLs do not split your ranking signals.
- Verify mobile rendering with a viewport meta tag, and that the page is served over HTTPS.
- Add structured data (JSON-LD). At minimum an Organization or Person block, plus Article or FAQPage where relevant.
- Check image alt text on every meaningful image.
- Confirm robots.txt and an XML sitemap exist and that the sitemap is referenced from robots.txt.
- Measure the real content length. Count the words in your main content, not the navigation and footer, which is what most naive counters include.
Should I audit one page or my whole website?
Start with one page, then widen. A single-page audit is the fastest way to learn what is wrong, because most problems are template-level: if your blog post is missing schema and a canonical tag, every other post almost certainly is too. Auditing your whole site then tells you which issues repeat across pages, and those are the ones worth fixing first, because one template change lifts every page at once.
That is the practical difference between the two. A single page shows you depth; a site scan shows you scale. Fixing the five issues that appear on forty pages beats fixing forty individual issues.
What can free SEO tools not tell you?
This is where honesty matters, because a lot of tools blur it. Free on-page auditors read your page. They cannot tell you your backlink count, referring domains, domain authority, organic traffic estimates or keyword rankings. Those numbers come from platforms that have crawled a large share of the web and bought clickstream data, and there is no way to derive them from your HTML.
So use a free audit for everything you control directly, which is most of what actually blocks a page from ranking, and treat backlinks and traffic estimates as a separate question requiring a different kind of tool.
One more limitation worth knowing: most auditors read your raw HTML before JavaScript runs, which is roughly how a crawler first sees your page. If your site builds its content with JavaScript, an audit can score it lower than it deserves. That is a real signal, not a bug, because the same gap can affect how easily you get crawled and quoted.
How do I audit for AI search, not just Google?
A growing share of searches now end inside ChatGPT, Perplexity, Gemini or Google AI Overviews without a click. Being quoted there depends on slightly different things than ranking: clean structured data, headings phrased as the questions people actually ask, answers stated directly and early, lists a model can lift cleanly, and trust signals like a named author and a visible date on editorial pages.
A homepage is judged differently here. Nobody expects a byline or a publication date on a homepage, so do not treat their absence as a fault there. On an article, both matter a great deal.
How often should I audit my site?
Run a full audit when you launch or redesign, then re-check your most important pages monthly. Scores drift for reasons that have nothing to do with you: a plugin update strips a meta tag, a migration drops canonical tags, a theme change removes schema. Monitoring a handful of pages catches that within a day instead of a quarter.
Check your page in about thirty seconds
Iris, our free AI SEO optimizer, runs the checklist above automatically and gives you two scores: a classic SEO health score and a separate AI-search readiness score. It also hands you copy-paste-ready fixes, including the exact schema you are missing, so you are not left with a list of problems and no solutions. Paste any public URL, no sign-up needed. On a paid plan you can scan many pages at once and see which issues repeat across your whole site.
Frequently asked questions
How long does an SEO audit take? An automated on-page audit takes seconds. Working through the fixes yourself typically takes an afternoon for one page, and longer if the issues are template-level.
Do I need to pay for an SEO audit? No. Everything on the checklist above is visible in your page's HTML and can be checked free. Paid tools mainly add backlink data, keyword tracking and crawling at scale.
Will fixing these issues guarantee I rank first? No, and be sceptical of anything that promises that. On-page fixes remove the barriers holding a page back; competition, authority and content quality decide the rest.