Technical SEO is the foundation that all other SEO activity builds on. Without it, the best content and link-building strategy in the world won't deliver consistent rankings — and it's often the reason most websites don't rank despite appearing to do everything else right. This checklist covers the 20 most commonly missed technical SEO items on UK websites — work through it systematically and you'll have a stronger foundation than most of your competitors.
Crawlability & Indexing (Items 1–5)
1. Verify your site is indexed.
Search site:yourdomain.com in Google. You should see all your important pages. If you see nothing, or far fewer pages than you expected, you have a crawling or indexing issue.
2. Submit your sitemap to Google Search Console.
Log into Search Console → Sitemaps → Enter your sitemap URL (usually /sitemap.xml). Check for any errors Google reports.
3. Audit your robots.txt file.
Navigate to yourdomain.com/robots.txt. Ensure no important pages or directories are blocked. The most common mistake: Disallow: / in robots.txt, which blocks Google from crawling your entire site.
4. Check for accidental noindex tags.
Search Console's "Coverage" report shows pages that are marked noindex. Pages intended for Google should not have <meta name="robots" content="noindex"> in their <head>.
5. Ensure all important pages are reachable in three clicks from the homepage. Google's crawler prioritises pages that are easily accessible from the homepage. If an important page requires six clicks to reach, it will receive less crawl priority and rank lower.
Core Web Vitals & Performance (Items 6–10)
For a deep-dive into fixing each of these metrics on a Next.js site, see our step-by-step Core Web Vitals guide.
6. Check LCP on your homepage and key landing pages. Use PageSpeed Insights. LCP should be under 2.5 seconds on mobile. If it's over 4 seconds, you have a significant problem affecting both ranking and conversion.
7. Fix INP across all interactive pages.
INP should be under 200ms. High INP is usually caused by heavy JavaScript. On Next.js, audit which components are unnecessarily marked "use client".
8. Resolve CLS issues. CLS should be under 0.1. Run a Lighthouse report and examine the CLS opportunities section. The most common causes: images without explicit width/height, late-loading web fonts, injected banners.
9. Verify all images use WebP or AVIF format.
Legacy JPEG and PNG images should be converted. On Next.js, use next/image and it handles this automatically. Otherwise, use Squoosh or ImageOptim to compress and convert.
10. Check TTFB (Time to First Byte). TTFB should be under 800ms. Use WebPageTest.org and check the "Time to First Byte" metric. If it's over 1 second, your hosting infrastructure needs upgrading.
On-Page SEO Fundamentals (Items 11–15)
11. Ensure every page has a unique, keyword-rich title tag. No duplicate titles. Each title should be 50–60 characters, contain the primary keyword, and include your brand name at the end. Check duplicates in Search Console under "Page titles" in the Performance report.
12. Write unique meta descriptions for all key pages. Meta descriptions don't directly affect rankings but significantly affect click-through rate. 150–155 characters, include the keyword, and give the user a compelling reason to click.
13. Verify your H1 contains the primary keyword. Every page should have exactly one H1 that includes the page's target keyword. Use a browser extension like "Detailed SEO Extension" to audit H1 tags across your site.
14. Check all images have descriptive alt text. Alt text serves both accessibility and SEO. It should describe the image content accurately and include relevant keywords where they fit naturally. Never keyword-stuff alt text.
15. Audit your internal linking structure. Important pages (service pages, money pages) should receive internal links from multiple other pages on your site. Use Search Console → Links → Internal links to see which pages have the most internal links.
Structured Data & Schema (Items 16–18)
16. Implement Organisation schema on your homepage.
At minimum, every UK business website should have Organization schema with your name, URL, address, phone number, and contact details. Use Google's Rich Results Test to verify it's valid.
17. Add BreadcrumbList schema to all inner pages. Breadcrumb schema helps Google understand your site structure and displays breadcrumb paths in search results, improving click-through rate for inner pages.
18. Test all structured data with Google's Rich Results Test. Navigate to the Rich Results Test, enter any URL on your site, and confirm there are no errors or warnings in your JSON-LD. Errors prevent rich results from appearing even if the schema is present.
Security & Mobile (Items 19–20)
19. Verify HTTPS is active and correctly configured. Your site should serve all pages over HTTPS with a valid SSL certificate. Mixed content (HTTP images or scripts on an HTTPS page) will trigger browser warnings and affect ranking. Use Why No Padlock to check for mixed content issues.
20. Test your site on a real mobile device — not just Chrome DevTools. DevTools mobile simulation is useful but imperfect. Test your site on an actual mid-range Android device (Samsung A series) and an iPhone with a normal connection. Check navigation usability, form inputs, and button tap targets.
How to Prioritise This List
Don't try to fix everything at once. Work through in this order:
- Indexing issues (items 1–5) — nothing else matters if Google can't reach your pages
- Core Web Vitals (6–10) — directly affects ranking and conversion
- On-page fundamentals (11–15) — highest direct impact on ranking
- Structured data (16–18) — rich results and click-through improvements
- Security and mobile (19–20) — table stakes in 2026
If working through this list reveals significant issues you're not sure how to fix, a free audit from Dricomm will tell you exactly what's wrong and how to prioritise it. Our technical SEO and web design services cover all of the above as standard for every site we build.
Ready to grow your business online? Get your free audit →