When an ecommerce site starts losing positions or stops growing in organic traffic, the usual reaction is to hire an audit tool. And there the fork appears: a free plan with limits or a subscription costing hundreds of euros a month? The short answer is that neither option works on its own, and the useful answer requires understanding what specific decisions you’re going to make with the data you extract.
In this analysis you’ll see where a free audit really delivers on online stores, where it breaks down, and what a paid tool provides that you can’t replicate any other way. Also the mistakes that repeat even in teams with a budget.
What an audit on an online store has to answer for you
Before comparing tools, it’s worth defining the deliverable. In an ecommerce, an SEO audit is not a list of issues exported to PDF. The points that really move the needle are four:
- Indexing and crawl budget: how many URLs Google receives, how many are junk (facets, sorting parameters, infinite pagination) and how many important ones are left out.
- Duplication from product variants: the classic structural problem of ecommerce. The same product with five sizes and three colors can generate dozens of nearly identical URLs.
- Performance on category and product page templates: Core Web Vitals aren’t measured per individual page, but by template type and by device.
- Product and offer structured data: without correct Product and Offer there are no rich results, and without rich results the CTR in commercial results drops.
If the tool you choose doesn’t cover these four fronts, it doesn’t matter how pretty its dashboard is.
What a free audit really covers
The free versions of well-known suites (now almost all with credit or project limits) are good for three very specific things that are poorly solved by other means:
1. Quick detection of crawl errors on a small domain
If the store has fewer than 500 indexable URLs, a free crawler with a 500-page limit gives you 100% of the site in one pass. There you see chained redirects, duplicate titles and broken links without paying anything.
2. Cross-checking with Google’s own data
Search Console is free and remains the most reliable source of real indexing. A misread coverage report explains more traffic drops than any paid tool. Many teams pay for a subscription without having first reviewed the “Pages” report in Search Console.
3. Manual template checks
With the URL inspector you can verify how Google renders a product page, whether the canonical points to the correct variant and whether the price appears in the initial HTML. It’s free and no tool replaces it.
Where the free approach breaks down
The limit isn’t usually in the number of pages, but in the depth of the analysis. A specific and common case: a store with 12,000 SKUs and attribute filters generates more than 300,000 crawlable URLs. A free crawler capped at 500 pages doesn’t even get into the catalog. The audit becomes a sample of the homepage and three categories, and the conclusions you draw are statistically useless.
There’s a second, less obvious limit: temporal comparison. To know whether a fix worked you need a history of positions, coverage and internal links. Free plans almost never keep more than a few weeks of data, so you can’t demonstrate impact. And without demonstrating impact, the development team stops prioritizing your tickets.
A mistake I see repeated: using the “SEO health” score that some free tools give as a KPI. That number weights issues with arbitrary criteria and has no relationship to traffic. I’ve seen stores with a score of 95 and a 40% drop due to badly set canonicals on variants.
What a paid tool provides beyond just volume
Paying for an audit makes sense when you need three capabilities that free doesn’t provide:
Segmentation by template and by attribute
Paid suites let you group URLs by pattern (product page, category, filter, blog) and analyze performance by group. In ecommerce, 80% of problems are concentrated in two or three templates. Without segmentation, you prioritize by number of incidents rather than by impact.
Cross-referencing crawl data with server logs
Here’s the real difference. Comparing what Googlebot requests (logs) with what it should request (sitemap and audit) reveals crawl budget leaks that no free tool detects. It’s the technique that explains why a new category takes weeks to get indexed.
Continuous monitoring and alerts
A one-off audit expires the day you publish. Paid tools with scheduled tracking warn you when an accidental noindex or a badly generated canonical appears after a deployment. On stores with weekly releases, this saves more than any monthly report.
Practical comparison by scenario
| Scenario | Sensible option | Why |
|---|---|---|
| Store with fewer than 500 URLs and a stable catalog | Free + Search Console | The full crawl fits within the limit and there are no frequent releases |
| Platform migration with URL changes | Temporary paid (1–3 months) | You need to compare before/after with history and a complete redirect map |
| Catalog with facets and thousands of combinations | Paid | Without segmentation by pattern you can’t decide what to block in robots.txt |
| Internal team without a tools budget | Free + own scripts | With the Search Console API and an open source crawler you cover the essentials |
| Ecommerce with weekly releases | Paid with alerts | Early detection prevents weeks of lost traffic |
A specific case: the canonical on color variants
In a footwear store with 3,000 models and up to eight colors per model, the template generated one URL per color with nearly identical content except for the image. The free tool flagged “duplicate titles” on 18,000 pages. The temptation is to rewrite titles one by one. The real solution was different: canonicalize the variants to the main model, leave only the variant with stock as indexable and adjust the structured data so that the Offer reflected availability by size.
That diagnosis doesn’t come from the list of issues. It comes from understanding the business and checking how Google renders the product page. The tool only confirms the volume. It’s the difference between auditing with judgment and auditing with a template.
Limitations worth acknowledging
No tool, free or paid, tells you whether your content matches search intent. It can flag that a title is 70 characters long, but not that it’s focused on the wrong keyword. Nor does it detect business problems: a catalog with discontinued products that remain indexed is a stock management problem, not a technical SEO one, and no suite solves it.
There’s also no guarantee of results. An impeccable audit doesn’t compensate for a catalog without demand or a category structure that doesn’t match how people search. According to official Google documentation, the quality and usefulness of content remain central signals; no technical fix replaces that.
How to decide without overspending
An operational criterion that works: always start with the free option for two weeks. Crawl the site, review Search Console, inspect two templates and note down which questions you can’t answer. If those questions are about volume (how many filter URLs are there?), a one-off paid plan will probably solve them. If they’re about causality (why did this category drop?), the problem isn’t the tool, but the lack of history and monitoring.
And if the budget is limited, prioritize a subscription with logs and alerts over one with a flashy “SEO score.” The first warns you about a failure in production on a Tuesday morning. The second gives you a number that nobody knows how to interpret.