What’s the best free SEO audit tool you actually rely on?

General
1

I’m trying to improve my site’s rankings and need a reliable free SEO audit tool that goes beyond basic checks. I’ve tried a few, but they either limit key features or miss important technical issues like crawl errors and duplicate content. What free tools are you using that give solid, actionable SEO audit insights without hitting a paywall right away?

2

For a free audit that goes beyond toy stuff, my go to stack is:

  1. Google Search Console
    You already know it, but use it harder.
  • Coverage report for crawl errors, soft 404s, server errors.
  • Page indexing to see “Crawled, not indexed”, “Discovered, not indexed”.
  • URL Inspection for live tests and rendered HTML.
  • Core Web Vitals for field data, not only lab tests.
    This is where you see what Google is struggling with on your site.
  1. Ahrefs Webmaster Tools (free)
    This is the closest to a “real” paid style audit without paying.
  • Site Audit crawler up to a decent limit for most small or mid sites.
  • Flags broken links, redirect chains, canonical issues, hreflang errors, mixed content, slow pages, etc.
  • Finds orphan pages if you connect GSC.
  • Site Explorer for your own site, basic backlink and anchor data.
    If you only pick one, go with this plus GSC.
  1. Screaming Frog free version
    Desktop app, free up to 500 URLs per crawl.
  • Great for technical checks on small sites or sections.
  • Look at status codes, meta tags, canonicals, response times, internal linking depth.
  • Spot duplicate titles, missing H1s, noindex and nofollow problems.
    500 URLs is enough if you crawl by folder, like /blog/ first, then /category/ etc.
  1. PageSpeed Insights + Lighthouse
    Use PSI for lab + field data from CrUX.
    Use Lighthouse (in Chrome DevTools) for:
  • CLS, LCP, TBT, image issues, unused JS and CSS.
  • See which scripts slow your site.
    Take the suggestions, then retest core templates, not every single URL.
  1. Site: search + manual checks
  • site:yourdomain.com on Google to spot junk indexed pages, tag archives, test URLs.
  • Manually check key templates, like home, category, product, article.
  • Look at title tags, H1, internal links to and from those pages.

Practical workflow you can follow:

Step 1: Start in GSC

  • Fix server errors, 404s, and “blocked by robots.txt” if they should be indexable.
  • Address “Alternate page with proper canonical tag” and “Duplicate without user selected canonical” issues.

Step 2: Run Ahrefs WMT Site Audit

  • Prioritize 404s, redirect chains, 5xx, and long response times.
  • Clean internal links to non-200 URLs.
  • Check for missing titles, meta descriptions, H1 duplicates.

Step 3: Crawl main sections with Screaming Frog

  • Export crawls and filter by status code, indexability, and canonical.
  • Identify pages deeper than 3 clicks and add better internal links.
  • Check that canonical, hreflang (if used), meta robots, and sitemap align.

Step 4: Fix performance

  • Test a couple of templates in PageSpeed Insights.
  • Compress and resize images.
  • Remove or defer non critical scripts.
  • Use a CDN if you do not already.

Step 5: Re submit in GSC

  • Use URL Inspection “Request indexing” on key fixed pages.
  • Monitor Coverage and Core Web Vitals over a few weeks.

Stuff I tried and stopped using as a “main” free audit tool:

  • Ubersuggest free tier, way too limited and noisy.
  • SEMrush free, cap is tight and reports feel more like ads for the paid plan.
  • Random “100 point SEO audit” sites, they spit out generic tips and miss real technical issues.

So if you want one name: Ahrefs Webmaster Tools plus GSC.
If you want deeper tech checks: add Screaming Frog on top and you are set.

3

I’m with @voyageurdubois on a lot of that stack, but if you want something that feels closer to a single “audit tool” and not just a pile of utilities, my sleeper pick is:

Seobility + your browser + GSC.

Not as famous as Ahrefs WMT, but:

  • Seobility free account
    • Crawls up to 1,000 pages, daily. For most small / mid sites that’s plenty.
    • Actually gives you a structured “SEO audit” view:
      • Technical: status codes, redirects, canonical, indexability, robots, sitemap, broken links.
      • Content: title & description length, duplicate titles, thin content flags, word count, headings.
      • Internal linking: click depth, internal link counts, anchor text.
    • Decent prioritization: “Errors / Warnings / Notices” with a score, so you don’t drown in noise like some tools.
    • Nice for spotting dumb stuff paid tools also find: pages with no title, accidental noindex, trailing slash inconsistencies, etc.

Where I disagree slightly with @voyageurdubois:
Relying too heavily on Screaming Frog free can be a pain once you’re past 500 URLs. Constantly slicing by folders and stitching exports gets old fast. Seobility’s hosted crawl is easier to re-run, store history, and compare before/after without fiddling with CSVs every time. SF is still amazing, but if you want “one free audit tool” experience, Seobility feels closer.

How I’d use it without redoing their workflow:

  1. Hook up Seobility & run a full crawl

    • Let it finish and go to the “technical” section first:
      • Fix 4xx / 5xx, incorrect redirects, non-200 in sitemaps.
      • Check indexability vs what should be indexed.
    • Then check click depth: anything important deeper than 3 clicks gets more internal links.

  2. Cross check with GSC

    • Coverage & Page indexing to see if issues Seobility finds actually align with what Google is struggling to index.
    • If Seobility says a page is fine but GSC keeps “Crawled, not indexed”, that’s usually a content / quality / internal linking issue, not pure tech.

  3. Manual spot checks in browser / DevTools

    • Open a few templates (home, category, product/article) and do:
      • view-source: to confirm canonical, meta robots, hreflang if any.
      • Mobile rendering, scroll & test Core Web Vitals in Chrome Lighthouse for just those templates, not every URL.

Tools I’d personally skip as “main free audit”:

  • Ubersuggest, same gripe as @voyageurdubois, it turns into a pitch real quick.
  • Random “SEO score 87/100!” audit sites. They miss real crawl/indexation issues and obsess over keyword density like it’s 2009.

So if you want one primary free tool that feels like a proper audit platform: Seobility.
Then use GSC to ground it in what Google actually sees, and Chrome DevTools/Lighthouse to double check performance and rendering where it really matters.