Technical SEO is the foundation that all other SEO work depends on. You can publish excellent content and earn quality backlinks — but if Google cannot properly crawl, render, and index your site, none of that effort reaches its potential. A systematic technical audit identifies and resolves the issues that silently limit your organic performance.
Here are the 25 most impactful technical SEO issues found in audits of business websites, with specific guidance on how to identify and fix each one.
Crawlability and Indexation
1. Pages blocked by robots.txt: Confirm your robots.txt file is not accidentally blocking important pages or directories. Fetch it at yoursite.com/robots.txt and review every Disallow directive. Compare against your XML sitemap to identify any sitemap URLs that are also blocked.
2. Pages excluded from the sitemap: Your XML sitemap should include all indexable, canonical pages. Use Screaming Frog or Semrush Site Audit to find indexable pages missing from your sitemap. Submit the sitemap in Google Search Console and monitor for errors.
3. Noindex on important pages: A noindex meta tag or X-Robots-Tag HTTP header prevents Google from indexing a page. Check all important service and blog pages for accidental noindex tags — these are frequently introduced accidentally during site migrations or CMS updates.
4. Orphaned pages: Pages with no internal links pointing to them are hard for crawlers to discover and lack internal PageRank. Identify orphaned pages with a crawl tool and add appropriate internal links from relevant parent pages.
5. Crawl budget waste: Faceted navigation, URL parameters, and session IDs can create thousands of low-value duplicate URLs that consume crawl budget without contributing to rankings. Use URL parameter handling in Search Console and canonical tags to consolidate.
Core Web Vitals
6. Poor LCP (Largest Contentful Paint): LCP should be under 2.5 seconds. The most common causes are unoptimised hero images (use WebP format, add width/height attributes, preload the LCP image), render-blocking CSS, and slow server response time. Check your LCP element in PageSpeed Insights.
7. High CLS (Cumulative Layout Shift): CLS should be under 0.1. Caused by images without specified dimensions, dynamically injected content above existing content, and web fonts that swap with fallbacks. Reserve space for all images and embeds; use font-display: optional for non-critical fonts.
8. Poor INP (Interaction to Next Paint): INP replaced FID as a Core Web Vital in 2024 and should be under 200ms. Poor INP is almost always caused by excessive JavaScript execution on the main thread. Audit your JavaScript with Chrome DevTools Performance panel and defer or remove non-critical scripts.
Duplicate Content and Canonicalisation
9. Missing or incorrect canonical tags: Every page should either be canonical itself or point to the canonical version. Check for pages where the canonical tag is absent, points to a different page unintentionally, or is self-referencing when it should consolidate to a parent page.
10. HTTP and HTTPS serving the same content: Your site should serve exclusively on HTTPS. Confirm HTTP redirects 301 to HTTPS for all pages. Check HSTS headers are set.
11. Trailing slash inconsistency: /page and /page/ are technically different URLs. Pick one convention and redirect all instances of the other. Canonical tags alone are insufficient — fix the actual redirect.
12. WWW and non-WWW serving the same content: Only one version (www or non-www) should be canonical. Confirm the other redirects 301 to your preferred version. Check this is consistent in Search Console property settings.
On-Page Technical Factors
13. Missing or duplicate title tags: Every page needs a unique, descriptive title tag under 60 characters. Run a crawl and check for missing, duplicate, or overly long title tags across your entire site.
14. Missing meta descriptions: While not a direct ranking factor, missing meta descriptions reduce CTR. Google writes its own snippet in their absence, often less compellingly than a crafted description.
15. Missing H1 tags: Every page should have exactly one H1 that includes the page's primary keyword. Multiple H1s or absent H1s are common technical issues found in CMS-generated sites.
16. Broken internal links: Links to 404 pages waste crawl budget and create poor user experience. Run a full site crawl monthly to identify and fix or redirect broken internal links.
17. Slow server response time (TTFB): Time to First Byte above 600ms signals server performance issues. Investigate hosting performance, enable server-side caching, and use a CDN for static assets.
Structured Data
18. Missing Organization schema: Add Organization schema to your homepage with name, URL, logo, contactPoint, and sameAs (social profiles). This helps Google understand and represent your brand correctly.
19. Missing Service schema on service pages: Service pages without Service schema miss potential rich result eligibility and topical signals.
20. Missing Article schema on blog posts: BlogPosting or Article schema with proper datePublished, author, and headline properties improves blog indexation and potential for article rich results.
21. Schema validation errors: Invalid schema reduces its effectiveness. Validate all schema markup using Google's Rich Results Test and Schema.org validator. Fix any errors flagged.
Mobile and Accessibility
22. Mobile usability errors: Check Google Search Console's Mobile Usability report. Common issues: clickable elements too close together, content wider than screen, text too small to read without zoom. Fix all errors — mobile-first indexing means mobile issues directly affect rankings.
23. Missing image alt text: Alt text serves both accessibility and SEO. Images without alt attributes are missed opportunities for image search and contextual page relevance signals. Audit all images and add descriptive alt text.
Security and Technical
24. Mixed content warnings: Pages served on HTTPS that load resources (images, scripts, CSS) over HTTP generate mixed content warnings in browsers and may have partial ranking impact. Identify with Chrome DevTools Security panel and update all resource URLs to HTTPS.
25. Redirect chains and loops: Redirect chains (A → B → C) dilute link equity and slow page load. Redirect loops cause 500 errors. Audit your site for redirect chains with Screaming Frog and fix each to redirect directly from the original URL to the final destination.
Running Your Audit
A full technical audit should be conducted annually at minimum, and after any major site changes. Tools needed: Google Search Console (free), Screaming Frog (free up to 500 URLs, paid for larger sites), PageSpeed Insights or Chrome DevTools for Core Web Vitals, and Semrush or Ahrefs for comprehensive site audits.
Our SEO team conducts comprehensive technical audits and provides prioritised remediation plans. We also work directly with development teams to implement fixes correctly. Book a technical SEO audit for your website.