Free SEO audit tools compared: 8 services and their real limits (2026)
A free website audit comes in two kinds: a single-page check in seconds and a full crawl of the site. We compared 8 free SEO audit tools using their official pages in October 2026: Ahrefs Webmaster Tools, Screaming Frog, Netpeak Spider, Semrush, Seoptimer, SEO Site Checkup and two PromoPilot tools. How many pages are free, whether you need an account and what stays hidden.
Free SEO audit tools come in two kinds: a single-page check that takes seconds and a full crawl of the site. Every tool has its own free limit, from one page to 5,000 pages a month, and almost all of them have a catch: sign-up, site verification, a desktop install or hidden details. We compared 8 tools that offer a free website audit, using their official pages as of October 2026: what exactly gets checked, how many pages, whether you need an account and what the next step will cost. Two of them are ours: a free website SEO audit for a single page and an express crawl of 100 pages. We are not the leaders on free volume, and we show that openly.
At a glance: 8 free SEO audit tools in one table
| Tool | What's free | Conditions | Where it runs | Paid |
|---|---|---|---|---|
| PromoPilot: page audit | A 0–100 score and about 30 checks of one page | No sign-up: 10 checks a day, with an account: 30 | Online | The tool is free |
| PromoPilot SEO Audit: express | Crawl of up to 100 pages of any site | Free account, up to 30 runs a day; some details hidden, no export | Online, cloud crawler | $5 per site up to 5,000 pages, $25 up to 50,000, one-off |
| Ahrefs Webmaster Tools | Site Audit: 5,000 crawl credits a month per project | Only your own verified sites | Online | Extended access: Starter at $29 a month |
| Screaming Frog SEO Spider | Crawl of up to 500 URLs | Download and install the program; no JS rendering in the free version | Windows, macOS, Linux | £199 ($279) a year per licence |
| Netpeak Spider | Crawl of up to 500 URLs, 5 threads | Install the program | Windows, macOS | Pro at $20 a month, $193 a year |
| Semrush Site Audit | 100 pages a month | Free account | Online | From $139 a month |
| Seoptimer | Single-page analysis by URL | Limits not stated on the site | Online | From $29 a month, site crawl on paid plans |
| SEO Site Checkup | 1 site check a day | — | Online | From $39 a month |
Two other well-known tools have no free plan, only a trial: SE Ranking (14 days) and Sitebulb (14 days). We left them out of the table, but if you need a one-off audit, a trial is an option too.
Two different kinds of free website audit
Half the confusion around "free website audit" comes from the fact that the phrase covers two different tools.
- Single-page check. You paste a URL and a few seconds later get a score and a list of checks: title, description, H1, canonical, server response time, HTTPS, Open Graph, structured data. That's how our page audit, Seoptimer and SEO Site Checkup work. It's handy for a first look, but duplicates, broken internal links and click depth can't be seen from one page.
- Site crawl. A program or a cloud service follows the links and checks every page it finds. That's the only way to catch duplicate titles, orphan pages, redirect chains and broken internal links. This is Screaming Frog, Netpeak Spider, Site Audit in Ahrefs and Semrush, and our SEO Audit.
The usual order: check the homepage and a couple of key pages in a minute, then run a full crawl.
Tool by tool: what each one gives you for free
PromoPilot: free page audit
About 30 checks in seconds and a 0–100 score: server response time, meta tags, social previews, security headers, content, links. Without an account you see the score and the result of every check; a free account unlocks all priority actions and raises the daily limit from 10 to 30 checks. Limitations: one page, JavaScript isn't executed, Core Web Vitals aren't measured.
PromoPilot SEO Audit: express audit
The cloud crawler covers up to 100 pages of any site, with nothing to install and no ownership verification, up to 30 times a day. It shows the Health Score, the main issues by category and the size of the site, so you see the exact price of a full audit before paying. In free mode some details are hidden, and there's no export or AI report. A full audit costs $5 per site up to 5,000 pages and $25 up to 50,000, one-off.
Ahrefs Webmaster Tools
Ahrefs Webmaster Tools has the most generous free volume: 5,000 crawl credits a month for each verified project. But you can only audit a site you've verified, so it won't work for a prospect's site before you sign a contract, or for a competitor. We compared it with our audit in detail in Ahrefs Webmaster Tools vs PromoPilot SEO Audit.
Screaming Frog SEO Spider and Netpeak Spider
Screaming Frog SEO Spider and Netpeak Spider are desktop programs. Both crawl up to 500 URLs for free, five times more than our express audit. You need to download and install the program, and your computer has to stay on for the whole crawl. The free version of Screaming Frog has no JavaScript rendering; Netpeak Spider gives you 5 threads for free. This is the best free option for a technical user with Windows or a Mac. We worked out when a paid licence pays off in our article on the free Screaming Frog alternative.
Semrush Site Audit
Semrush gives you 100 pages a month in the cloud for free. That's enough to assess a small site and get a feel for the interface; a full audit is available on plans from $139 a month.
Seoptimer and SEO Site Checkup
Seoptimer and SEO Site Checkup are online checkers that work from a page URL. SEO Site Checkup gives you one free site check a day, with paid plans from $39 a month. Seoptimer offers a free analysis right on its homepage with no stated limits; a full-site crawl (SEO Crawler) is on paid plans from $29 a month.
What a free SEO audit usually won't show
How to audit a site for free in 15 minutes
Check the key pages
Run a free page audit on the homepage, a service or category page and a popular article. In a couple of minutes you'll know whether there are empty titles, a second H1, canonical errors or HTTPS problems.
Crawl the site
Run a 100-page express audit in SEO Audit, with nothing to install, from a phone or a laptop. If the site is yours and verified in Ahrefs Webmaster Tools, add its Site Audit; if you have a computer and need more pages, use the free Screaming Frog or Netpeak Spider for 500 URLs.
Fix what affects indexing
Start with errors that keep pages out of the index or make them duplicate each other, not with warnings about description length. We covered how to set priorities in what to fix first after an SEO audit.
Which free audit fits which job
| Your task | What to use |
|---|---|
| Quickly check one page before launch | PromoPilot page audit, Seoptimer or SEO Site Checkup |
| Your own site, as many free pages as possible | Ahrefs Webmaster Tools |
| You have a computer, site up to 500 pages | Screaming Frog SEO Spider or Netpeak Spider (free versions) |
| A client's or competitor's site, no install | PromoPilot SEO Audit express audit |
| A client report in English, Polish, Ukrainian or Russian | PromoPilot full audit ($5 or $25) with an AI report |
| Regular audits of dozens of sites | A paid desktop crawler licence: at volume it beats paying per audit |
A detailed comparison of our full audit with Screaming Frog, including a yearly cost calculation, is on the PromoPilot SEO Audit vs Screaming Frog page.
Frequently asked questions
Where can I get a free SEO audit of my website online?
For a single page, use the PromoPilot free page audit (no sign-up, 10 checks a day), Seoptimer or SEO Site Checkup. To crawl a whole site online, there's the PromoPilot SEO Audit express audit of 100 pages with a free account, Site Audit in Ahrefs Webmaster Tools for your own verified site, or Semrush with 100 pages a month.
Which free SEO audit tool checks the most pages?
According to the official pages as of October 2026, it's Ahrefs Webmaster Tools: 5,000 crawl credits a month for each verified project, but only for your own sites. Screaming Frog SEO Spider and Netpeak Spider crawl 500 URLs each for free, PromoPilot SEO Audit crawls 100 pages up to 30 times a day, and Semrush gives 100 pages a month.
Can I audit someone else's site for free?
Yes. Single-page checks work with any URL. To crawl someone else's site without installing a program, use the PromoPilot SEO Audit express audit; no ownership verification is needed. Ahrefs Webmaster Tools only audits sites you have verified.
How is a free website audit different from a paid one?
Usually in volume and detail. Free modes cap the number of pages, hide some of the data and don't include export or a report. At PromoPilot a full audit costs 5 dollars per site up to 5,000 pages and 25 dollars up to 50,000, one-off, and includes all details, CSV export, a PDF version and an AI report in English, Polish, Ukrainian or Russian.
Do I need to install software for an SEO audit?
Not necessarily. Screaming Frog and Netpeak Spider are desktop programs, but they crawl 500 URLs each for free. Cloud services such as PromoPilot SEO Audit, Ahrefs Webmaster Tools and Semrush run in the browser, and the crawl keeps going even if you close the tab.
How accurate is the site score in free tools?
A score from 0 to 100 is each tool's own formula based on its own thresholds, not a Google metric and not a guarantee of rankings. Different tools will give the same site different scores, so the list of specific errors and their impact on indexing matters more.
Sources: official pages of Ahrefs Webmaster Tools, Screaming Frog SEO Spider (pricing), Netpeak Spider (pricing), Semrush (plans and Site Audit help), Seoptimer (pricing), SEO Site Checkup (pricing), SE Ranking and Sitebulb, checked in October 2026. PromoPilot features and prices as of October 2026. Terms change, so check them on the official sites. This review was prepared by the PromoPilot team and is not sponsored by the companies mentioned.
