Site audit tools crawl a website the way a search engine does and report technical and on-page problems: broken links, redirect chains, missing tags, duplicate content, slow pages, indexing blocks. The right one depends less on feature lists than on three questions: how big the site is, whether you need backlink and keyword data in the same tool, and who will read the output.
This comparison covers the tools most teams actually choose between, with prices checked in September–October 2026.
Three kinds of site audit tool
Desktop crawlers (Screaming Frog, Sitebulb desktop) run on your computer. They're cheap, highly configurable and handle JavaScript rendering well. Crawl size is limited by your machine's memory and disk, not a monthly allowance.
Cloud crawlers inside SEO suites (Semrush Site Audit, Ahrefs Site Audit) run on the vendor's servers, schedule recurring crawls and sit next to keyword, ranking and backlink data. You pay for the whole suite, and crawls draw on a page or credit allowance.
Google's own tools (Search Console, PageSpeed Insights, Rich Results Test) don't crawl your whole site on demand, but they're the only source of what Google actually indexed, which canonical it chose and real-user speed data. No third-party tool replaces them.
Most professional audits combine one crawler with Google's tools.
The tools compared
Screaming Frog SEO Spider
The default desktop crawler for technical SEOs. The free version crawls up to 500 URLs; a licence costs £199 per year per user (1–4 licences) and removes the limit.
- Strengths: deep configuration, JavaScript rendering, custom extraction (pull any element from every page), raw vs. rendered HTML comparison, Search Console and PageSpeed integrations, crawl comparison.
- Limits: desktop-only, so large crawls need a capable machine or a server; the interface assumes you know what you're looking for; prioritisation is up to you.
- Best for: technical audits, migrations, anyone who wants raw data.
Sitebulb
A desktop (and cloud) crawler built around explaining issues. Lite is $18/month and Pro $42/month for a single user; Sitebulb Cloud starts at $245/month.
- Strengths: "Hints" that explain each issue and why it matters, prioritisation, visual crawl maps, client-ready PDF reports.
- Limits: less raw flexibility than Screaming Frog; Cloud pricing is a step up.
- Best for: consultants and in-house teams who need to present findings to non-SEOs.
Semrush Site Audit
Part of the Semrush suite. A free account audits 100 pages per month; Pro costs $139.95/month, or $117.33/month billed annually.
- Strengths: scheduled cloud crawls, a "Site Health" score, issue explanations, and keyword, ranking and competitor data in the same login.
- Limits: page limits per plan; the health score is Semrush's own weighting; you pay for a whole suite to get the audit.
- Best for: teams that already use Semrush for keywords and rank tracking.
Ahrefs Site Audit
Part of the Ahrefs suite. The free plan includes Site Audit and Site Explorer for sites you verify; Lite costs $129/month, with crawling paid in credits.
- Strengths: good issue grouping, scheduled crawls, and the backlink index Ahrefs is known for alongside it.
- Limits: on paid plans, credits are consumed per page crawled, so frequent audits of large sites get expensive. Toolradar notes a 50,000-page site can use about half of Lite's monthly allowance in one cycle.
- Best for: site owners auditing their own verified sites free; teams that rely on Ahrefs for links.
Google Search Console
Free, and not optional. Search Console doesn't crawl on demand, but it tells you which URLs Google indexed, why others were excluded, which canonical Google selected, and how real users experience page speed. Every finding from a third-party crawler should be checked against it.
Other tools
Moz Pro, SE Ranking, Ubersuggest, WooRank and Seoptimer all include site audit features. They're reasonable choices if you already pay for them, but none changes the core comparison: a crawler for the data, Google's tools for the truth. For genuinely free options, see our guide to free SEO audit tools.
Cost and limits side by side
| Tool | Type | Free option | Entry paid price | Crawl limit model |
|---|---|---|---|---|
| Screaming Frog | Desktop | 500 URLs | £199/year per licence | Your machine's memory/storage |
| Sitebulb | Desktop / cloud | Free trial | $18/month (Lite), $42/month (Pro) | Desktop: your machine; Cloud from $245/month |
| Semrush Site Audit | Cloud suite | 100 pages/month | $139.95/month ($117.33 annual) | Pages per plan |
| Ahrefs Site Audit | Cloud suite | Free for verified sites | $129/month (Lite) | Credits per page on paid plans |
| Google Search Console | Google data | Free | — | Your verified properties |
*Prices from vendor pages via Toolradar and Capterra, September–October 2026. Check the vendor's pricing page before buying.*
The order-of-magnitude point matters more than the exact numbers: a desktop crawler costs a few hundred a year; a suite costs well over a thousand. You're paying the difference for keyword, ranking and backlink data, not for a better crawl.
Which tool for which situation
| Situation | Best fit | Why |
|---|---|---|
| Site under 500 pages, tight budget | Screaming Frog free + Search Console | Full crawl at no cost |
| Your own site, any size, no budget | Ahrefs free plan + Search Console | Free cloud audits for verified sites |
| Technical audit or migration | Screaming Frog (paid) | Rendering, extraction, crawl comparison |
| Reporting to clients or executives | Sitebulb | Explanations and presentable reports |
| Ongoing monitoring plus keyword work | Semrush or Ahrefs | Scheduled crawls next to ranking data |
| Large sites (100k+ URLs) | Screaming Frog on a server, or an enterprise cloud crawler | Suite credit and page limits get costly |
| Auditing a site you don't control | Desktop crawler with a browser-like user agent | Some sites block named audit bots (AhrefsBot appears in 9.3% of robots.txt files, SemrushBot in 3.0%) |
What none of them do
Run four tools on the same site and you'll get four different top-priority lists. That isn't a flaw in any one tool. Crawlers measure technical correctness against their own rules. They can't know:
- Which pages make money, so they can't rank fixes by business impact.
- What Google actually did with your pages. A crawler sees a canonical tag; only Search Console shows whether Google honoured it.
- Whether two pages compete for the same query. Cannibalisation needs query data and judgement.
- Why competitors outrank you, or whether AI answers cite them instead of you.
<!-- TODO-SCREENSHOT: Same site audited in four tools, top three issues highlighted in each | Caption: Same site, four tools, four different top priorities. | Alt: Comparison of top issues reported by four site audit tools on one website. -->
That's the gap between a tool report and an audit. Our SEO site audit guide shows how to turn crawl data into a prioritised plan; if you'd rather buy the finished plan, the TapasSEO Site SEO Audit combines crawl data, Search Console, backlinks and AI citation checks into a ranked fix list.
Frequently asked questions
What is the best site audit tool? For pure crawling, Screaming Frog is the professional standard and the cheapest paid option. If you also need keyword and backlink data, choose Semrush or Ahrefs based on which data set you trust more. Always pair any of them with Google Search Console.
Is Semrush Site Audit free? Partly. A free Semrush account audits up to 100 pages per month. Larger audits need a paid plan, starting at $139.95/month or $117.33/month billed annually.
Is Ahrefs Site Audit free? Yes for sites you own and verify, through Ahrefs' free plan. Paid plans start at $129/month (Lite) and use credits for crawling.
Screaming Frog or Sitebulb? Screaming Frog gives more raw control and costs less per year. Sitebulb explains and prioritises issues better and produces cleaner reports. Many consultants own both.
Do site audit tools check Core Web Vitals? Most pull data from Google's PageSpeed Insights API. For the field data Google actually uses, check Search Console's Core Web Vitals report.
None of these tools tell you what to fix first
Every tool above is good at the same job: finding technical issues. None of them knows which of those issues costs you money, which pages are quietly cannibalising each other, or whether AI engines are citing a competitor instead of you. That reading takes a person, not a crawl.
TapasSEO's Site SEO Audit runs the crawl, cross-checks it against Search Console and your backlink profile, and hands you back a fix list ranked by business impact — not by whichever bug the tool happened to flag first.