Website SEO audit tools: SemChat's full audit on a real site

One sentence typed, a full audit returned: scorecard, diagnosis, action plan. Illustration by Zéro Corvée.

You run a small online store or a business website, and you want to know what’s holding it back in Google. Website SEO audit tools promise a full check-up in minutes, without hiring anyone.

I tested one the way you would: SemChat, an AI assistant you talk to, on plugkit-avis.com, my other affiliate site, on October 29, 2026. Below you’ll find the sentence I typed, what it ran, what it returned, what it got right, what it overstated and what it cost. To compare SemChat’s other audits (technical, on-page, trust, accessibility), start with our page on automated SEO audit tools. The SemChat buttons on this page are affiliate links.

What website SEO audit tools check across a whole site

An SEO audit looks at your whole site, not one page. Most tools check the same families of things: can Google reach and read your pages, are your titles and headings clear and unique, do other sites link to you, and where do you stand against competitors.

Technical errors, found page by page

The tool visits your pages like a search engine would. It flags broken pages (the “404” errors), pages Google can’t index, duplicate titles, missing headings and slow pages. On our test site, SemChat’s audit reported 189 indexable pages and “0” 4xx or 5xx errors.

Issues ranked by priority, with plain explanations

A long list of issues helps no one. Good website SEO audit tools sort them: what to fix this week, what can wait. Semrush, for example, says its Site Audit gives “a prioritized fix list” (Semrush page for solopreneurs, read October 29, 2026). SemChat goes one step further: it writes the plan in plain language, inside a conversation.

Step 1: type one sentence and let SemChat pick the full audit skill

SemChat sorts its know-how into 17 skills (list in the app, October 29, 2026). You can pick one from a menu, or just type your request. I typed mine in a new chat, and SemChat picked the “Audit SEO Complet” (full SEO audit) skill by itself.

The sentence we typed, in French (English test still to come)

The test ran in French, on a French site, with the app in French. Here is the exact sentence:

“Fais un audit SEO de mon site plugkit-avis.com et donne-moi un plan d’action clair, par priorité.” (Run an SEO audit of my site plugkit-avis.com and give me a clear action plan, by priority.)

The same request typed in English hasn’t been tested yet: missing data (planned source: an English test, T36). The account was on the Free plan, with no credit card.

There’s a second way in. Under “Sites,” you add your site and click the button to analyze it: that analysis took 1 min 38 s the same day, and SemChat then opened a conversation under the same skill on its own (lesson L04 of the SemChat course).

Step 2: watch the tools it runs, in about 3 minutes

About 3 minutes passed between sending the sentence and getting the action plan (read on screen, from about 5:20 to 5:23 p.m.). You don’t wait in the dark: SemChat lists each tool as it runs.

Pages, rankings, backlinks, competitors: the data it pulls

Here is what it ran on plugkit-avis.com:

• page reading, then a crawl of the whole site;
• a domain overview;
• the site’s rankings in Google (89 results) and its best-performing pages (30);
• the backlink profile, meaning the links from other sites;
• competitors (10), then a keyword gap against 5 of them.

For a French site, this data comes from Haloscan, a French keyword tool (email from Haloscan’s Adrian Delmarre, October 29, 2026).

Step 3: read the scorecard, the diagnosis and the action plan

The audit opens with 8 key figures for plugkit-avis.com, as of October 29, 2026:

• organic traffic, estimated: 28 visits a month;
• 61 ranking keywords, about 10 of them in positions 1 to 3;
• technical score: 99 out of 100, with no 4xx or 5xx errors;
• 189 indexable pages;
• duplicate titles on 100 pages (53%);
• duplicate main headings (H1) on 102 pages (54%);
• 1 referring domain;
• accessibility: 70 out of 100.

The technical score is what a dedicated technical SEO tool digs into, from robots.txt to AI crawlers. The accessibility score belongs with accessibility testing software.

Then comes a five-point diagnosis, written in plain French and in a friendly tone. It names a top technical problem, a top opportunity and a top gap against competitors.

One figure to handle with care: the top opportunity, the keyword “manychat,” comes with a search volume given by SemChat. In tests of 7 of its skills, the SemChat course found its volumes off from DataForSEO’s Google Ads figures, in both directions (October 29, 2026). Cross-check a volume before you write a page for it.

A website audit report you can copy or download

The full audit also opens in a side panel: a dated, 10-section document called “Audit SEO complet” (Full SEO audit), with one button to copy it and one to download it. Handy to keep, or to send to whoever runs your site.

The action plan saved on your site’s page

The conversation ends with 3 actions for the week: create the missing contact page, make the titles of each language version different, and expand a 495-word comparison page.

The full plan is saved on your site’s page, under “Sites”: 18 tasks in 4 stages, from setting the basics to getting recommended. Each task has a button that reopens a conversation to work on it.

A small detail: the conversation said the contact page returned a 404 error, while the plan said no contact page was found. Same finding, two wordings.

The raw data behind each step, with CSV export

Each step has a “Voir détails” (See details) button. It opens the raw data table, which you can filter and export as a CSV file.

Step 4: check what it found on a real site

I checked its findings the same day with curl, a small program that requests a page the way a browser does.

The missing contact page: an accurate finding

On October 29, 2026, the French contact page, /fr/contact/, returned a 404 error: the site had no contact page, and the contact details sat in the legal notice. Accurate.

The site has changed since: on October 30, 2026, the same address returns a working page. An audit describes your site on the day it runs, not today.

Duplicate titles: real, but caused by the US and UK English versions

Also accurate: the US English review page and its UK English version had the same title tag. But those two pages are declared to Google as language variants, with hreflang tags. Google asks for exactly that: “Use hreflang to tell Google about the variations of your content” (Google Search Central, read October 30, 2026). So SemChat’s line, “Google voit des pages miroir au lieu de pages distinctes” (Google sees mirror pages instead of distinct pages), went too far.

The flag was still useful. On October 30, 2026, only one title is still shared across the site’s 194 addresses; the UK review page now has “UK” in its title. The H1 headings are still identical on 104 pages. Titles and headings are checked page by page with an on-page audit tool.

The third action, expanding the comparison page, wasn’t checked.

The trap: this one audit used 100% of the Free quota

This is the limit to know before you start. That single audit used 100% of the Free plan’s monthly quota. The Usage screen said “Usage épuisé” (usage used up), with a reset on November 28.

The split: Documents 39.2%, Site analysis 32%, SEO tools 28.9%. The written report weighs more than the data.

What it means for you: on the Free plan, save your full audit for the site that matters. The Starter plan costs “€20 /mo” (SemChat pricing page, read October 30, 2026). How much of it one full audit takes hasn’t been measured: missing data (planned source: a full audit rerun on the Starter plan; not tested on October 30, 2026).

Website SEO audit tools for free: what you really get

You can start without paying anything:

• Google Search Console: “Search Console tools and reports help you measure your site’s Search traffic and performance, fix issues, and make your site shine in Google Search results” (about page, read October 30, 2026).
• Screaming Frog SEO Spider: “Download & crawl 500 URLs for free” (product page, read October 30, 2026). We haven’t tested it.
• Ahrefs Free: €0, no credit card, no time limit, with Site Audit for sites you prove you own (Ahrefs fiche dated October 29, 2026). Not tested here.
• Semrush Free: “$0” a month, one demo project and 10 reports a day (Semrush fiche dated October 29, 2026). Not tested here.
• SemChat Free: €0, every feature, but one full audit in our test. Our free SEO audit page shows what that audit returns, limits included.

SemChat next to the Semrush, Ahrefs and SE Ranking site audits

Semrush, Ahrefs and SE Ranking weren’t tested on this site. What follows comes only from their dated fiches and their public pages.

Sources: our test of October 29, 2026; Semrush Site Audit page, read October 30, 2026; fiches for Semrush, Ahrefs and SE Ranking dated October 29, 2026 (Ahrefs Site Audit page, SE Ranking FAQ).

A dashboard of issues or a conversation: which one suits you

Semrush, Ahrefs and SE Ranking show you dashboards: scores, issue lists, charts. They suit you if you like to dig, filter and track things over time. SE Ranking describes its public as agencies and marketing teams (fiche dated October 29, 2026).

SemChat hands you a written diagnosis and a short to-do list, in plain words. It suits you if you want to know what to do this week, without learning the tool first. The price: you check its claims yourself, and you watch your quota.

What an automatic score can’t see, and how to audit by hand

An automatic audit reads what is written in your pages and in databases. It doesn’t see your photos or know your trade. SemChat said so itself during its trust audit, our EEAT checker tool test: “mon outil lit le texte, pas les images” (my tool reads the text, not the images), lesson L14 of the SemChat course, October 29, 2026.

Google adds a warning about every tool of this kind: “Google doesn’t evaluate or endorse third-party SEO tools, and these tools don’t have access to Google’s internal ranking data” (Google Search Central, read October 30, 2026). A score of 99 out of 100 doesn’t come from Google.

A website audit checklist to run yourself

You can redo the essentials yourself, for free, with Search Console. Its URL Inspection tool “provides information about Google’s indexed version of a specific page, and also allows you to test whether a URL might be indexable” (Search Console Help, read October 30, 2026). Then:

1. Inspect your most important pages: are they indexed?
2. Read your titles: is each one unique and clear?
3. Check each page has one main heading that matches its title.
4. Make sure your pages link to each other.
5. Look at which sites link to you, in the Links report.

The full method, step by step, is on our SEO audit checklist page. The tool saves you time; your own eyes decide what’s worth fixing.

Website SEO audit tools do the collecting for you. SemChat’s full audit took about 3 minutes in our test and got the essentials right on a real site, in plain words and by priority. It also overstated one finding and burned the whole Free quota in one go. Read every finding, check it on your site, fix one thing at a time. Our full test of the tool is in our SemChat review, and its plans are on our SemChat pricing page.