Which tool is best for an SEO audit?

Short answer

Google Search Console, before anything you pay for. Then a desktop crawler for the site structure, and a backlink index if links might be the problem. Every audit tool flags far more than matters, so the best tool is the one whose output you know how to ignore.

This question usually arrives with a specific tool in mind and a subscription about to renew. So let me answer it the way I actually work, which is with a small set of tools used for different jobs rather than one platform that claims to do everything.

Start with the free one Google gives you

Search Console is the only tool that shows you Google’s own data about your site. What it has indexed and what it has dropped. Which queries each page appears for, at what average position, with how many clicks. Which pages it found but chose not to index. No third-party tool can see any of that directly. They estimate it.

It has limits worth knowing. The performance tables show a maximum of 1,000 rows, rare queries are not reported, and “position” is the topmost position occupied by a link to your property, averaged across all queries, which is not the same as where a page usually sits. But it is still the first thing I open on every audit, and the place most of the useful findings come from.

Then a crawler

A desktop crawler, such as Screaming Frog or Sitebulb, walks your site the way a search engine would and records every URL, status code, redirect, canonical, title and internal link. It is how you find orphan pages, redirect chains, broken links and the parameter URLs nobody meant to create.

The cloud audit tools inside the big SEO suites do a version of the same thing with a friendlier report. They are fine for monitoring. For diagnosis I prefer a desktop crawler, because it lets me look at the raw data rather than a score.

Then links, if links are the question

If the site might be held back by its link profile, or you are trying to understand why a competitor is stronger, you need a backlink index: Ahrefs, Semrush or Majestic. None of them sees the whole web, and they disagree with each other, so use one consistently rather than switching between them.

Why the tool matters less than you think

Every audit tool produces far more warnings than matter. I once audited a site where the tool reported 1,562 missing H1 tags on one template and seven H1s on another page, and treated both as the same severity. One was cosmetic. The other was a symptom of a theme problem that was genuinely in the way. I wrote that case up as two opposite heading problems, because it is the clearest example I have of a tool being technically right and practically misleading.

The scale of it is easy to underestimate. The HTTP Archive found that only 67.2% of mobile pages have a meta description. Every tool will flag the missing third as an issue. On most sites, writing them would not move a single ranking.

The test I use on any warning: if I fixed this across the whole site tomorrow, would anything a customer does change? If the honest answer is no, it goes to the bottom of the list, however red the tool makes it.

A minimal kit that covers most sites

Search Console. Free. Indexing, queries, positions, manual actions.
Analytics. Free. What the traffic does once it arrives, and which pages actually convert.
A desktop crawler. A free tier covers small sites. Structure, status codes, internal links.
The search results themselves. Free, and the most neglected. Look at who ranks for your queries and what their pages do that yours do not.

Add a backlink index if links are in question, and log file access if the site is large enough for crawl behaviour to matter. Beyond that, extra tools mostly add more warnings.

What to avoid

Do not let a score drive the roadmap. A site can score 62 and rank well, or 98 and be invisible because of one canonical rule.

Do not buy a tool because it promises to do the audit for you. It will produce the inventory. Deciding what matters is still a person’s job.

What changes with site size

On a small service business with fifty pages, Search Console and a free crawl are genuinely enough. The problems on sites that size are usually visible in an afternoon: a wrong primary category, thin service pages, nothing linking to the pages that sell.

On a store or a publisher with tens of thousands of URLs, the tooling earns its cost. You need a crawler that can handle the volume, ideally server logs to see what Googlebot actually requested, and some way of grouping URLs by template so that one decision can be applied to thousands of pages at once. That is where paid tools stop being optional. Even then, the output is still an inventory. Someone has to decide which ten rows out of fifty thousand are the reason the site is stuck.

If you would rather skip the tools and get the diagnosis, my SEO audit uses all of the above and hands you a ranked list of what is actually costing you, including what I would ignore.