A website audit is a structured health inspection — and skipping regular ones means discovering broken indexation, duplicate metadata and dead links only after traffic has already bled. Capable free website SEO audit tools now grade all of it without charging, provided you accept page ceilings and daily limits.
Quick Answer: Run Semrush's Site Audit or Seobility for prioritised issue lists, Ubersuggest for simple daily checks, GTmetrix plus PageSpeed Insights for speed diagnostics, and Google Search Console as the baseline view of what Google actually sees.
This roundup favours auditor platforms that output ranked fix-lists over single-number graders that hand you a score and shrug. Google's own diagnostics appear too — not because they audit everything, but because first-party truth should anchor every third-party report you read.
What a Credible Audit Must Examine
- Crawlability and indexation — can search engines reach every important URL without hitting loops, dead ends or accidental directives?
- On-page integrity — missing or duplicated titles, thin descriptions, heading chaos, orphaned pages.
- Speed and stability — Core Web Vitals on the templates that carry your traffic.
- Link hygiene — broken internal links, wasteful redirect chains, broken images.
- Mobile behaviour — layouts that work where most visitors actually are.
The Audit Toolkit Compared
| Tool | Best For | Free Option |
|---|---|---|
| Semrush Site Audit | Prioritised issue reports on free account tier | About 100 URLs per crawl |
| Seobility | Scored single-project audits with clear categories | One project, page-capped |
| Ubersuggest | Beginner-friendly recurring site checks | Daily-limited audits |
| GTmetrix | Waterfall-level speed investigation | Yes — limited tests per day |
| PageSpeed Insights | Field plus lab vitals for any URL | Yes — unlimited tests |
| Google Search Console | Index coverage and vitals from Google itself | Yes — fully |
Semrush Site Audit — The Professional Fix-List
Wins: crawl a site on the free account tier (roughly one hundred URLs) and receive issues sorted by severity across crawlability, HTTPS, core web vitals, internal linking and markup — with thematic reports that turn findings into a work order. Repeat crawls show whether fixes landed. Friction: the URL ceiling suits small business sites and blogs; larger properties exhaust it immediately.
Seobility — The Clean Scorecard
Wins: one project audited in full under its free plan, with results graded per category so non-specialists see exactly which area drags. The dashboard reads like a report card, which clients appreciate. Friction: a single project slot and a page cap confine it to focused use, and deeper recommendations sit behind paid tiers.
Ubersuggest — The Low-Effort Routine
Wins: a straightforward site-audit module bundled alongside keyword ideas, runnable daily within its free limits — ideal for building an audit habit without learning a new interface each quarter. Friction: recommendations stay generic, daily caps restrict scheduling freedom, and heavy analysis quickly meets upgrade prompts.
GTmetrix — Speed Under the Microscope
Wins: Lighthouse-powered reports with full waterfalls, showing precisely which scripts, images or server responses delay rendering — the difference between "site is slow" and "this hero video costs two seconds". Alerts flag regressions. Friction: purely a speed lens; content, metadata and indexation fall entirely outside its remit.
PageSpeed Insights and Search Console — The First-Party Anchor
PageSpeed Insights pairs lab simulations with real-user field data and names specific remedies per URL. Search Console contributes the aggregate view: which templates fail vitals at scale, which pages dropped from the index, which directives block crawling. Neither produces a classic audit document — together they fact-check every other tool on this list.
Running Your First Audit This Afternoon
- Define scope: which subdomains count, and what "important" means for this site.
- Run the Semrush or Seobility crawl and export its issue list to a spreadsheet.
- Cross-check indexation claims against Search Console's Pages report before believing either side.
- Spot-check your five highest-traffic URLs in PageSpeed Insights for field-data reality.
- Reorder findings by traffic exposure: errors on earning pages outrank cosmetic warnings anywhere.
- Fix in batches, then schedule the next crawl to confirm nothing regressed.
Reading Scores Without Panicking
Every automated grade is a heuristic. Tools routinely flag intentional noindex pages, "missing" alt text on decorative images and slow scores caused by third-party embeds you consciously chose. Human review is the final step — the audit narrows your attention, it doesn't replace judgement about which imperfections actually cost traffic.
Key Takeaways
- Semrush's free crawl delivers agency-style prioritisation for sites under roughly 100 URLs.
- Seobility's scorecard format suits owners who need clarity more than depth.
- Speed tools diagnose; they never audit structure or content — pair them with a crawler-backed auditor.
- Treat every tool verdict as a hypothesis until Search Console confirms it.