9 Best Free Technical SEO Tools to Audit Your Site

Technical SEO is what separates sites that rank from sites that should rank

You can have the best content on the internet and still rank on page 5. If Googlebot can't crawl your pages, your images have no alt text, your Core Web Vitals are failing, or your heading structure is broken technical issues will cap how high your content can go.

Technical SEO audits used to require expensive tools like Screaming Frog (desktop software, complex setup) or Ahrefs Site Audit ($99+/month). That's no longer true. The 9 tools in this guide cover the most important technical SEO checks for free, with no software installation and no paid account.

Each tool works by analysing a public URL you enter. No plugin, no admin access, no crawl configuration. Paste a URL, get results, fix what's broken.

1. Page Speed Checker — Core Web Vitals in 30 Seconds

Page speed became an official Google ranking factor in 2021 through the Core Web Vitals update. Google now measures LCP (Largest Contentful Paint), CLS (Cumulative Layout Shift), and INP (Interaction to Next Paint) as part of its page experience signals. Sites that fail these thresholds are at a ranking disadvantage vs. equivalent content on faster pages.

The Page Speed Checker runs Google's PageSpeed Insights API on any URL and returns your performance score and all five CWV metrics for both mobile and desktop. The "Opportunities" section identifies the specific issues dragging your score down large images, render-blocking scripts, unused CSS so you know exactly what to fix.

What to act on first

Look at your mobile score first Google uses mobile for ranking, not desktop. If it's below 50, the opportunities section will almost certainly show either large unoptimised images or render-blocking JavaScript as the top culprits. Fix those two before touching anything else.

2. Meta Tag Extractor — See Exactly What Google Reads

Meta tags are invisible to regular website visitors but critical for search engines and social platforms. Title tags tell Google your page's topic. Canonical tags prevent duplicate content. The robots meta tag controls indexing. Open Graph tags control how pages look when shared on LinkedIn or Slack. Getting these wrong causes ranking problems that are difficult to diagnose without directly inspecting what's in the HTML.

The Meta Tag Extractor fetches any URL and lists every meta tag across three groups: Basic SEO tags (title, description, canonical, robots, viewport, charset), Open Graph tags (og:title, og:description, og:image, og:type), and Twitter Card tags. Present tags show with a green check. Missing tags show with a red flag — with the critical ones (title, og:image) flagged more prominently.

The most common issue found

Missing og:image. If you share your pages on social media and the preview looks broken or shows no image, this is almost always why. Add a 1200×630px image with og:image meta tag on every important page.

3. Broken Link Checker — Find 404 Errors Before Google Does

Broken links (404 errors) harm your site in multiple ways. They waste Googlebot's crawl budget, signal poor site maintenance, and break the user experience. If an external site links to one of your pages and you delete that page without a redirect, you lose that link's authority entirely.

The Broken Link Checker extracts all internal and external links from any URL and checks each one in parallel up to 50 links per check. Results are split into three tabs: Broken (404s and timeouts), Redirected (301/302 chains), and Healthy. Each result shows the URL, its HTTP status code, and whether it's internal or external.

Prioritise broken internal links

Internal 404s are more damaging than external ones because they directly affect how Googlebot crawls your site. Fix or redirect broken internal links first. For external links pointing to dead pages, either update the link to a working URL or remove it.

4. Heading Structure Checker — Visualise Your H1–H6 Hierarchy

Headings are how search engines understand the structure and hierarchy of your content. Your H1 is the primary topic signal the most important on-page SEO element after your title tag. H2s define your main sections. Skipped levels (going from H1 to H3), missing H1s, or multiple H1s all send confusing topical signals to Google.

The Heading Structure Checker fetches any URL and displays a colour-coded, indented tree of every heading tag — H1 through H6 — in the order they appear. It automatically flags three critical issues: no H1 present, more than one H1, and skipped heading levels. These three issues appear on a significant number of sites, especially those built with page-builder tools.

What correct heading structure looks like

One H1 at the top containing your primary keyword followed by H2s for major sections, and H3s for subsections within those sections. The structure should read like an outline. If you removed all paragraph text and read just the headings in order, the page topic should still be completely clear.

5. Image Alt Text Checker — Fix Invisible SEO Issues

Every image without alt text is a missed SEO opportunity. Google Image Search drives billions of searches per month. Pages with properly alt-tagged images can appear in image results for relevant queries unlocking a traffic channel many sites ignore entirely. Beyond SEO, missing alt text fails WCAG accessibility standards, which Google increasingly uses as a page quality signal.

The Image Alt Text Checker scans any page and reports every image showing the image URL, its current alt text (or noting it's missing), and whether it's properly tagged. The summary shows counts for images with alt text, empty alt attributes, and missing alt attributes. Use the "Missing only" filter to see just the problem images.

The difference between empty and missing alt

An empty alt="" is intentional it tells screen readers to skip a decorative image. A missing alt attribute entirely is an error. Use empty alt for icons and decorative images. Use descriptive alt text for any image that adds meaning to the content.

6. Robots.txt Tester — Check If Google Can Crawl Any URL

Your robots.txt file controls which URLs crawlers are allowed to access. One wrong `Disallow` rule can accidentally block your entire site from Google. The classic mistake: a developer adds `Disallow: /` to a staging environment's robots.txt to block crawlers then that file gets copied to production during deployment. The site disappears from Google within days.

The Robots.txt Tester fetches your live robots.txt file and tests whether a specific URL path is allowed or blocked for Googlebot. Enter your domain and any page path the tool shows the exact rule that matched, and displays your full robots.txt file so you can spot other issues.

Run this test on your most important pages

Test your homepage (/), your blog (/blog/), your product pages, and any high-value URLs. If any return "blocked," check the matching rule carefully. Remember: Allow rules take priority over Disallow rules when both match the most specific rule wins.

7. Robots.txt Generator — Build a Safe Robots.txt File

If you don't have a robots.txt file yet, or your existing one is outdated, the Robots.txt Generator creates one without requiring you to memorise the syntax. Block specific crawlers, disallow specific paths (like /admin/, /checkout/, or /search/), and set your sitemap URL all through a form interface.

The generated output is valid robots.txt syntax ready to upload to your site's root directory. Upload it to yoursite.com/robots.txt and verify it loaded correctly by visiting that URL directly in your browser.

8. XML Sitemap Generator — Submit All Your Pages to Google

Google discovers pages through two primary methods: following links from other pages, and reading sitemap files you submit in Search Console. For new sites without many inbound links, a sitemap is often the only way Googlebot finds your inner pages quickly. Even for established sites, a sitemap ensures newly published pages get indexed within days rather than weeks.

The XML Sitemap Generator crawls your site and produces a properly structured XML sitemap file. Download it, upload it to your root directory, and submit the URL in Google Search Console under Sitemaps. After submission, Search Console shows how many URLs were found and how many are indexed useful for catching orphaned pages.

9. Redirect Checker — Audit Your Redirect Chains

Redirects pass link equity from old URLs to new ones but each hop in a redirect chain reduces the equity passed. A→B→C→D passes significantly less authority than A→D directly. Redirect chains also slow down page load time (each hop adds latency) and waste crawl budget. Sites that have been through redesigns or migrations often accumulate chains of 3–5 redirects without anyone noticing.

The Redirect Checker follows any URL through its full redirect chain and shows every hop the URL, HTTP status code, and destination until it reaches the final destination. If you see chains longer than one hop, update the original redirect to point directly to the final destination.

When to run this

Run it after any site migration, CMS change, or URL structure update. Also run it on your highest-authority pages the ones that receive the most inbound links to ensure those links are flowing cleanly to their destinations.

Frequently asked questions

Technical SEO is maintenance, not a one-time fix

Technical SEO isn't something you do once and forget. Sites change, content gets added, URLs get restructured, plugins update and new technical issues appear with each change. The 9 tools in this guide give you a way to catch those issues quickly, without a complex toolchain or a monthly subscription.

Make it a habit: run the Page Speed Checker and Broken Link Checker on key pages once a month. Run the Heading Checker and Meta Tag Extractor on every new page before you publish. And run the Robots.txt Tester after any server or CMS change.