Most Technical SEO Tools Are Free

The authoritative source for Core Web Vitals. Shows both lab data (Lighthouse) and field data (CrUX). Field data is what Google actually uses for rankings. Check the field data first, then use lab data for debugging.

Follow redirect chains. See all hops and status codes in a redirect sequence. Essential for debugging redirect chains and verifying migrations.

Network diagnostic tools. DNS, blacklist, SMTP, and security checks. Useful for email deliverability and DNS troubleshooting.

Quick SEO audit tool. Generates reports covering on-page, performance, and technical basics. Good for fast overviews, not deep analysis.

Built into Chrome DevTools. Run locally for consistent testing without network variability. Audits performance, accessibility, SEO, and best practices. The treemap view shows exactly what's slowing your page.

Google's official documentation on Core Web Vitals. Explains what LCP, INP, and CLS actually measure. Read this before optimizing anything. Understanding the metrics prevents wasted effort.

Real user data from Chrome users. This is what Google uses for rankings. Access via BigQuery for deep analysis or via PageSpeed Insights for quick checks. The source of truth for Core Web Vitals assessment.

Performance testing with waterfall analysis. Good visualization of resource loading. Useful for debugging, but PageSpeed Insights is authoritative for CWV. Use GTmetrix for detailed waterfalls.

Legacy speed test tool. The metrics don't align with Core Web Vitals. Use PageSpeed Insights or GTmetrix instead. Pingdom is useful for uptime monitoring, not SEO.

Essential for technical SEO. Network panel shows resource loading. Coverage tab shows unused CSS/JS. Rendering tab simulates JavaScript disabled. Performance tab shows main thread blocking. Learn this before anything else.

Validates HTML against standards. Useful for finding structural issues that might confuse crawlers. Perfect validation isn't required for ranking, but gross errors can cause problems.

Quick bulk check of HTTP status codes. Essential for verifying redirects work correctly. Paste a list of URLs, see the response codes. Simple but useful.

Aleyda Solis's tool for generating hreflang tags. Gets the syntax right. Hreflang errors are common and often subtle. Use a generator to avoid mistakes.

Visual accessibility checker. Shows issues in context on the page. Easier to understand than validator output. Good starting point for accessibility audits.

Official accessibility guidelines with examples. Reference this when fixing accessibility issues. The full spec is dense, but this quick reference is navigable.

Checks HTTP security headers. CSP, X-Frame-Options, HSTS, etc. Not directly an SEO ranking factor, but HTTPS and security affect trust signals.

Crawls your site and generates a sitemap. Useful for small sites without CMS sitemap generation. For larger sites, generate sitemaps programmatically or use your CMS.

Finds duplicate content within your site. From the makers of Copyscape. Useful for detecting internal duplication issues. Free for small scans.

Collection of technical SEO tools: schema generator, robots.txt tester, hreflang validator. All free, all useful. Bookmark this site.