An SEO audit finds the problems killing your organic traffic. Broken links, missing meta tags, slow pages, crawl errors, thin content — all invisible until you look for them. The good news: every audit tool you need is available for free.
Here are the 10 best, organized by what they catch.
Essential (Use These First)
1Google Search Console
The most important SEO tool, period. It shows you exactly what Google sees: which pages are indexed, which have errors, which keywords drive traffic, and how your Core Web Vitals perform. Every other tool is supplementary; this one is foundational.
Every website owner. Non-negotiable. Set up before doing anything else. Check weekly.
2Screaming Frog SEO Spider (Free)
The gold standard for technical SEO audits. Crawls your site like a search engine and reports every issue: broken links, duplicate titles, missing alt text, redirect chains, and 200+ other checks. The free version crawls up to 500 URLs.
Technical SEO audits on sites under 500 pages. Developers and SEO professionals. Finding the specific issues blocking your rankings.
3Ahrefs Webmaster Tools
Ahrefs' free tier for verified site owners. Provides backlink data, keyword rankings, and a site audit — features that usually cost $99+/month. The most generous free backlink tool available.
Backlink monitoring and site health audits. Freelancers offering SEO services who need professional-grade data on client sites.
Speed & Performance
4Google PageSpeed Insights
Tests your page speed and Core Web Vitals on both mobile and desktop. Uses real-world Chrome user data (CrUX) alongside lab data (Lighthouse). Google uses these metrics for ranking, making this tool directly tied to SEO outcomes.
Testing individual pages for speed issues. Diagnosing Core Web Vitals failures. Optimizing key landing pages.
5GTmetrix
A more detailed speed testing tool than PageSpeed Insights. Shows a waterfall chart of every resource loaded, timing breakdowns, and historical performance tracking (free account).
Diagnosing why a specific page is slow. The waterfall chart shows exactly which resource is the bottleneck. Use ToolKit.dev's Image Compressor to fix image-related speed issues it identifies.
On-Page & Content
6Ubersuggest (Free Tier)
Neil Patel's SEO tool with a limited but useful free tier. Provides keyword suggestions, content ideas, backlink data, and a basic site audit. Good for keyword research alongside auditing.
Quick keyword research alongside your audit. Finding content opportunities. Beginners who want one tool that does a bit of everything.
7Yoast SEO / Rank Math (WordPress)
If your site runs on WordPress, these plugins audit on-page SEO in real time as you write. Traffic light system (red/yellow/green) for readability, keyword usage, meta tags, and internal linking.
WordPress users who want ongoing on-page optimization. Content writers checking SEO basics before publishing.
Specialized Audits
8Google Rich Results Test
Tests your structured data (Schema.org markup) and shows whether your pages are eligible for rich results in Google search — star ratings, FAQ dropdowns, product cards, recipes, and more.
Validating FAQ, Product, Article, and HowTo schema markup. Essential if you've added JSON-LD to your pages. Use ToolKit.dev's Meta Tag Generator to create optimized meta tags alongside your schema.
9Lighthouse (Chrome DevTools)
Built into every Chrome browser. Right-click, Inspect, Lighthouse tab, run audit. Tests performance, accessibility, best practices, and SEO — all in one report with specific fix recommendations.
Developers running quick audits during development. Checking accessibility alongside SEO. No internet connection needed (runs locally).
10Seobility (Free)
An online SEO checker that crawls up to 1,000 pages on the free plan and generates a comprehensive report with a score, issues list, and fix recommendations. One of the most generous free crawlers.
Small to medium sites (under 1,000 pages) that want a Screaming Frog alternative without installing software. Non-technical users who want a clear report with priorities.
Quick Comparison
| Tool | Type | Free Limit | Technical | Content | Backlinks |
|---|---|---|---|---|---|
| Search Console | Dashboard | Your sites | Yes | Partial | Yes |
| Screaming Frog | Crawler | 500 URLs | Excellent | Good | No |
| Ahrefs WT | Dashboard | Your sites | Good | Partial | Excellent |
| PageSpeed | Speed test | Unlimited | Speed only | No | No |
| GTmetrix | Speed test | Unlimited | Speed only | No | No |
| Ubersuggest | All-in-one | 3/day | Basic | Good | Basic |
| Yoast/Rank Math | WP plugin | Unlimited | On-page | Good | No |
| Rich Results | Schema test | Unlimited | Schema only | No | No |
| Lighthouse | Browser | Unlimited | Good | Basic | No |
| Seobility | Crawler | 1,000 URLs | Good | Good | Basic |
The Free SEO Audit Stack
You don't need all 10. Use this stack for a comprehensive free audit:
- Google Search Console — Check indexing, Core Web Vitals, and search performance. (5 min)
- Screaming Frog — Crawl the site for technical issues: broken links, duplicates, missing tags. (15 min)
- PageSpeed Insights — Test your top 5 pages for speed and Core Web Vitals. (10 min)
- Ahrefs Webmaster Tools — Check backlink health and site audit score. (10 min)
- ToolKit.dev Meta Tag Generator — Optimize title tags and descriptions for pages flagged by Screaming Frog. (10 min)
Total time: about 50 minutes. Do this quarterly and you'll catch 95% of SEO issues before they hurt your traffic. Also ensure your robots.txt is properly configured and your privacy policy is linked sitewide.
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Get the Playbook — $10Frequently Asked Questions
Google Search Console (essential for every site), Screaming Frog (best technical crawler, 500 URL free limit), Ahrefs Webmaster Tools (best free backlink data). Use all three together.
Full technical audit quarterly. Quick Search Console checks weekly. After major site changes, immediately. 30 minutes quarterly prevents problems from compounding.
5 categories: technical (crawl errors, broken links, speed), on-page (titles, descriptions, headings), content (thin/duplicate pages), backlinks (toxic links, anchor text), performance (Core Web Vitals). Start with technical.
Yes. Search Console + Screaming Frog free + PageSpeed Insights + Ahrefs WT + ToolKit.dev tools cover 90% of what paid tools do. Free tools are sufficient for sites under 500 pages.
Optimize Your Entire Online Presence
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